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  • Articles  (269)
  • Articles: DFG German National Licenses  (269)
  • phosphorus  (92)
  • Oryza sativa  (77)
  • Animals
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  • Electronic structure and strongly correlated systems
  • Solanum tuberosum
  • temperature
  • Springer  (269)
  • 1995-1999  (269)
  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (261)
  • Electrical Engineering, Measurement and Control Technology  (8)
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  • Articles  (269)
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  • Articles: DFG German National Licenses  (269)
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  • Springer  (269)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 29 (1999), S. 1171-1176 
    ISSN: 1572-8838
    Keywords: alloys ; cyclic voltammetry ; electrodeposition ; electroless deposition ; nickel ; phosphorus ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electroless Ni–Zn–P alloy deposition from a sulphate bath, containing sodium hypophosphite as reducer, was investigated. To increase the plating rate, the deposition parameters were optimized. The effect of process parameters (T, pH and [Zn2+]) on the plating rate and deposit composition was examined and it was found that the presence of zinc in the bath has an inhibitory effect on the alloy deposition. As a consequence, the percentage of zinc in the electroless Ni–Zn–P alloys never reaches high values. Using cyclic voltammetry the electrodeposition mechanism of Ni–Zn–P alloys was investigated. It was observed that the zinc deposition inhibits the nickel discharge and, as a consequence, its catalytic activity on hypophosphite oxidation. It was also found that increase in temperature or pH leads to the deposition of nickel rich alloys.
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  • 2
    ISSN: 1572-8838
    Keywords: alloys ; electroless ; microstructure ; morphology ; nickel ; phosphorus ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electroless Ni–Zn–P alloy coatings were obtained on an iron substrate from a sulfate bath at various pH values. The effects of changes in bath pH on alloy composition, morphology, microstructure and corrosion resistance were studied. Scanning electron microscopy was performed to observe the morphological change of the deposits with bath pH. Coating crystallinity was investigated by grazing incidence asymmetric Bragg X-ray diffraction and transmission electron microscopy. A transition from an amorphous to polycrystalline structure was observed on increasing the bath alkalinity, and thus decreasing the phosphorus content of the alloys. A single crystalline phase corresponding to face-centred-cubic nickel was identified in the alloys obtained from a strong alkaline solution. An increase in zinc percentage up to 23% in the deposits does not change the f.c.c. nickel crystalline structure. Corrosion potential and polarization resistance measurements indicated that the corrosion resistance of electroless Ni–Zn–P alloys depends strongly on the microstructure and chemical composition. The deposits obtained at pH 9.0–9.5 and with 11.4–12.5% zinc and 11.8–11.2% phosphorous exhibited the best corrosion resistance.
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  • 3
    Electronic Resource
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    Journal of applied electrochemistry 29 (1999), S. 81-85 
    ISSN: 1572-8838
    Keywords: cupric oxide ; powder ; current density ; temperature ; sodium sulfate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrosynthesis of cupric oxide powder was carried out on a laboratory scale in an electrochemical cell under various experimental conditions. The electrolysis was appraised in terms of the particle size of the cupric oxide product and the anodic dissolution of the copper electrode. Using a previously determined pH value of 7.50, the other optimum electrolysis operating conditions established were a current density of 4000Am−2, temperature of 353K, and Na2SO4 concentration of 0.5m. The optimum values of current efficiency, cell voltage and specific energy consumption for the electrochemical synthesis of cupric oxide powder were determined.
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  • 4
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    Journal of applied electrochemistry 29 (1999), S. 525-528 
    ISSN: 1572-8838
    Keywords: brine ; chlor-alkali cells ; solubility ; sulfate ions ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
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  • 5
    ISSN: 1432-0789
    Keywords: Key words Phosphorus dynamics ; Olsen ; phosphorus ; Soil phosphorus fractions ; Manure ; Soybean-wheat rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Soil P availability and efficiency of applied P may be improved through an understanding of soil P dynamics in relation to management practices in a cropping system. Our objectives in this study were to evaluate changes in plant-available (Olsen) P and in different inorganic P (Pi) and organic P (P0) fractions in soil as related to repeated additions of manure and fertilizer P under a soybean-wheat rotation. A field experiment on a Typic Haplustert was conducted from 1992 to 1995 wherein the annual treatments included four rates of fertilizer P (0, 11, 22 and 44 kg ha–1 applied to both soybean and wheat) in the absence and presence of 16 t ha–1 of manure (applied to soybean only). With regular application of fertilizer P to each crop the level of Olsen P increased significantly and linearly through the years in both manured and unmanured plots. The mean P balance required to raise Olsen P by 1 mg kg–1 was 17.9 kg ha–1 of fertilizer P in unmanured plots and 5.6 kg ha–1 of manure plus fertilizer P in manured plots. The relative sizes of labile [NaHCO3-extractable Pi (NaHCO3-Pi) and NaHCO3-extractable P0 (NaHCO3-P0)], moderately labile [NaOH-extractable Pi (NaOH-Pi) and NaOH-extractable P0 (NaOH-P0)] and stable [HCl-extractable P (HCl-P) and H2SO4/H2O2-extractable P (resisual-P)] P pools were in a 1 : 2.9 : 7.6 ratio. Application of fertilizer P and manure significantly increased NaHCO3-Pi and -P0 and NaOH-Pi, and -P0 fractions and also total P. However, HCl-P and residual-P were not affected. The changes in NaHCO3-Pi, NaOH-Pi and NaOH-P0 fractions were significantly correlated with the apparent P balance and were thought to represent biologically dynamic soil P and act as major sources and sinks of plant-available P.
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  • 6
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    Nutrient cycling in agroecosystems 55 (1999), S. 7-14 
    ISSN: 1573-0867
    Keywords: fertiliser formulation ; nutrients ; phosphorus ; relative humidity ; soil moisture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus lost in runoff from agricultural land leads to the enrichment of surface waters and contributes to algal blooms. Fertilisers are one source of this P. To compare the water available P of different fertiliser formulations in the laboratory it is necessary to control environmental conditions, temperature, relative humidity and soil water content, prior to simulating rainfall. Two chambers were designed in which relative humidity and soil water content were controlled using salt solutions. An initial design comprising a sealed chamber with three layers of soil samples over a salt bath was found to be inferior to a single layer design. The changes in water content of soil samples were used to test the single layer chamber in a constant temperature environment (15 °C) using a saturated KCl solution (90% relative humidity). Based on the final soil water content of the samples, the spatial variation within the chamber was within tolerable limits. The single layer chamber was used for a simulation experiment comparing the water available P of two commercial fertilisers. Using a saturated resorcinol solution (95% relative humidity) soil samples were equilibrated at 15 °C for 21 days, fertiliser added, and the water available P measured up to 600 h after fertiliser application. The results indicate that the amount of water available P was related to the fertiliser compound and exponentially related to the time since fertiliser application. It was concluded that the single layer chamber is suitable for controlling relative humidity and soil water content in trials such as these where the water available P of fertilisers are being compared.
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  • 7
    ISSN: 1573-0867
    Keywords: dairy systems ; feeds ; fertilizers ; phosphorus ; P surplus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inputs of phosphorus (P) above requirements for production on dairy farms lead to surplus P with increased risk of P transfer in land run-off to surface waters causing eutrophication. The impact of reducing surplus P inputs in purchased feeds and fertilizers on milk and forage production was investigated in a comparison of three dairy farm systems on chalkland soils in southern England over a 3-year period. In accordance with current commercial practice, no attempt was made to regulate P inputs in system 1, which accumulated an average annual surplus of 23 kg P ha-1. Progressive reductions in purchased feed and/or fertilizer inputs into systems 2 and 3 decreased surplus P to 17 and 3 kg ha-1, respectively, without apparently limiting either milk or herbage dry matter production. The estimated reduction in faecal P output from system 3 cows fed a low P diet compared to system 1 cows fed a high P diet was 26%. Milk P concentrations significantly (P 〈0.001) increased in systems 2 and 3 which included maize in the diet. Output of P in milk and meat products, as a proportion of the total dietary P inputs, increased from 28% in system 1 to 36% in system 3. Surplus P was greatest in continuous maize fields receiving both dairy manure and starter P fertilizer. Withholding P fertilizer in system 3 did not reduce P offtake in cut herbage on soils of moderate P fertility. Total annual losses of P in storm run-off and leaching were no greater than annual inputs of P from the atmosphere (0.5 kg ha-1). The results indicate there is scope to reduce surplus P on commercial dairy farms without sacrificing production targets at least in the short term. Purchased feeds are the largest of the P inputs on intensive dairy farms, yet these are rarely quantified on commercial holdings.
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  • 8
    ISSN: 1573-0867
    Keywords: leaching ; phosphorus ; poultry litter ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To determine P loadings, added through poultry litter, sufficient to cause downward movement of P from the cultivated layer of a sandy soil, six rates of poultry litter were applied annually for four years to a site in central England. (total loading 0 – 1119 kg P ha-1). A single extra plot also received an extra 1000 kg ha-1 as triple superphosphate (TSP; total loading 2119 kg P ha-1) and three other treatments received 200 – 800 kg ha-1 P as TSP only. Annual soil sampling in 30-cm increments to 1.5-m depth provided information on P build-up in the topsoil and P movement to depth. There were strong linear trends between P balance (P applied – P removed in crops) and total P, Olsen bicarbonate extractable P and water-soluble P in the topsoil. Phosphorus from TSP and poultry litter fell on the same regression lines, suggesting that both would be equally effective as fertilizer sources. We calculated that 100 kg ha-1 surplus total P would increase the Olsen extractable P content by c. 6 mg kg-1 and the water-soluble P by c. 5 mg kg-1. Thus, relatively large amounts of P would need to be applied to raise soil P status. We found some evidence of P movement into the soil layers immediately below cultivation depth. However, neither soil sampling nor soil solution extracted through Teflon water samplers showed evidence of movement into the deep subsoil (1 m) despite large P loadings.
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  • 9
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    Nutrient cycling in agroecosystems 54 (1999), S. 259-266 
    ISSN: 1573-0867
    Keywords: bahiagrass ; manure ; pasture fertilization ; phosphorus ; phosphorus cycling ; Spodosol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bahiagrass (Paspalum notatum Flugge) pasture fertilization recommendations have traditionally been based upon clipping studies. Inclusion of P from manure, not originally considered when P recommendations were developed for pastures, may minimize the need for P fertilization without reducing bahiagrass production or P uptake. The objective of this research was to determine if manure contributes greatly to the P crop nutrient requirement. A 2-year field study utilized a factorial arrangement of 0 and 6.9 Mg air-dried manure ha-1 with 0, 17, 34, 51, and 68 kg inorganic P ha-1 from triple superphosphate to evaluate bahiagrass yield, root distribution, and P uptake response on a Myakka fine sand (sandy, siliceous, hyperthermic Aeric Alaquod). Because air-dried manure was used in the field study, a greenhouse study was employed to confirm that there were no differences in bahiagrass yield or P uptake from either air-dried or fresh cattle (Bos spp.) manure sources. There were no manure or manure by P interaction effects on yield or P uptake of bahiagrass indicating that manure source did not effect grass production in the greenhouse. In the field study, bahiagrass roots were distributed into the Bh horizon, and the Bh horizon had at least four times more Mehlich-1 extractable P than that of the Ap horizon. This horizon was most likely acting as a main source for P-uptake by the grass. This observation was further confirmed by no yield response to levels of inorganic P application in 1989. A linear-response-and-plateau (R2=0.196) relationship with a critical point of 15.4 kg P ha-1 was found in 1990. Bahiagrass yield and P uptake were not dependent on P fertilization, either from manure or inorganic P, due to the availability of P from the Bh horizon.
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  • 10
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    Potato research 42 (1999), S. 471-481 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum ; S. andigena ; S. demissum ; hormones ; regulation ; starch accumulation ; tuber formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The evidence for a role of gibberellins in the regulation of potato tuber formation is reviewed. Endogenous gibberellin levels in plants are high under non-inducing conditions and decrease under inducing conditions. Exogenously applied gibberellins inhibit tuber formation, whereas applying inhibitors of gibberellin biosynthesis has the opposite effect. Cellular events involved in tuberization, viz., cell division, cell enlargement and orientation of micro-tubules, are also reviewed. Based on available evidence, a major regulatory role of gibberellins is suggested. However, it is also argued that tuber formation is not simply regulated by gibberellins acting as the sole signal between above-ground and below-ground parts, since stolon tips are able to synthesize their own gibberellins, and the phenotype of phytochrome B-antisense plants cannot be explained only by altered levels of GAs.
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  • 11
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    Potato research 42 (1999), S. 569-575 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum ; micropropagation ; seed production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary An efficient and low cost modular system for the production of mini-tubers as a source for conventional seed tubers is reported. In this system, microplants are soil grown and produce minitubers of 5 to 25 mm diameter. The system is based on the use of pre-sterilized disposable plastic containers which allow micropropagation, weaning, hardening, and soil growing of micropropagated plants in the same container. Depending upon the cultivar, the modular system allows production of 2900 to 6600 mini-tubers/m2 in a glasshouse.
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  • 12
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    European journal of plant pathology 105 (1999), S. 61-76 
    ISSN: 1573-8469
    Keywords: core sampling ; foliar nutrient concentrations ; minirhizotrons ; nitrogen ; phosphorus ; potassium ; Rhizolab
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Potato-cyst nematodes (Globodera pallida) cause severe yield losses in potato. Plants infected with potato-cyst nematodes generally have reduced concentrations of nitrogen, phosphorus and potassium in the foliage. This study investigated whether reduced growth of nematode-infected potato is caused by nutrient limitation. Experiments in the field and in containers showed that phosphorus concentration correlated best with total crop biomass at early stages of growth. The role of phosphorus in nematode damage was further investigated in the field and in the Wageningen Rhizolab. The experimental field was infested with potato-cyst nematodes and two levels of nematode density were established by fumigation with a nematicide. Prior applications of calcium carbonate resulted in pHKCl levels of 4.8 and 6.1. Two levels of phosphorus fertiliser were applied: either 0 or 225 kg P ha−1. In the Wageningen Rhizolab, soil of both pH levels from the field was used after treatment with 1 MRad gamma irradiation to kill the nematodes. Subsequently, half of the soil was inoculated with cysts to give a nematode density of 30 viable juveniles per gram of soil. In the field, nine weeks after planting, the total crop biomass ranged from 107 g m−2 for the treatment with nematodes at pHKCl 6.1 without phosphorus fertiliser to 289 g m−2 for the fumigated treatment at pHKCl 4.8 with phosphorus fertiliser. The differences in total biomass for the various treatments were explained by differences in foliar phosphorus concentration. Nematodes induced or aggravated P deficiency and reduced total biomass. This was not the only damage mechanism as at high, non-limiting levels of foliar phosphorus concentration, nematodes still reduced total biomass. In the Wageningen Rhizolab, directly after planting, the number of roots visible against minirhizotrons was reduced by nematodes. However, the increase of root number in the nematode treatment continued longer than in the control, until root number was higher than that of the control. The compensary root growth of the nematode treatment was restricted to the top 30 cm and nematodes reduced rooting depth. High soil pH reduced growth, mainly by reducing the availability of phosphate. Both nematodes and high soil pH reduced nutrient uptake per unit root length. Our results lead us to suggest an interaction between nematodes and soil pH, with nematode damage being higher at pHKCl 6.1 than at pHKCl 4.8.
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  • 13
    ISSN: 1573-8469
    Keywords: Magnaporthe grisea ; Pseudomonas syringae pv. syringae ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rice seedlings treated with the synthetic compound benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester (BTH) acquired resistance to subsequent attack by the rice blast fungus Magnaporthe grisea (Hebert) Barr. BTH (trade name Bion™) has been released to the market as a plant protecting agent for rice. Here, we analysed the pattern of expressed genes in rice plants treated with BTH, and compared this pattern with those induced by the formerly discovered resistance inducer 2,6-dichloroisonicotinic acid (INA) and by Pseudomonas syringae pv. syringae, a non-host pathogen inducing a hypersensitive response. Both INA and BTH induced similar patterns of genes, suggesting that these compounds are functional analogues. In contrast, the patterns induced by the chemical inducers and by P. syringae were clearly dissimilar.
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  • 14
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    European journal of plant pathology 105 (1999), S. 753-760 
    ISSN: 1573-8469
    Keywords: hypersensitive-like response ; Phytophthora infestans ; potato ; proteases ; Solanum tuberosum ; zoospores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The proteolytic activity present in the extracellular preparation (ECP) from suspension media of infective structures of the late blight pathogen Phytophthora infestans was partially characterized. The proteolytic activity was analyzed in gelatin-containing SDS-PAGE. A discrete band of digested gelatin was visualized at approximately 45 kDa in ECPs from zoospores and germinating cysts media. Treatment of ECP with the protease inhibitor phenylmethylsulfonyl fluoride (PMSF) or incubation at 100°C for 5 min completely abolished the proteolytic activity in the zymograph assay. When microinjected in potato leaves, ECP induce localized necrosis within 24 h post inoculation. This necrosis appeared in potato and was not visible in two non-host plants. Moreover, the necrosis seems to be dependent on active host metabolism. Treatments of ECP with Proteinase K, PMSF and boiling inhibited their ability to induce the necrotic response. These results suggest a correlation between, proteolytic and necrosis-inducing activities in ECP. A preliminary characterization with protease inhibitors suggests that the ECPs contain serine protease(s).
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  • 15
    ISSN: 1573-143X
    Keywords: alevin ; Atlantic salmon (Salmo salar) ; development ; egg ; temperature ; thermal tolerance ; yolk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three embryonic stages of Atlantic salmon (Salmo salar L.) were subjected to eight constant incubation temperatures (4, 7, 10, 12, 14, 16, 19 and 22 °C) exceeding the range usually experienced in natural conditions. A change in thermal tolerance during the embryonic and larval development was registered: pre-hatching stages showed an upper thermal limit at about 16 °C, while hatched larvae survived until 22 °C. Temperature significantly affects developmental rate, resulting in a faster development and, consequently, lower yolk weight percentage at higher temperatures. We found positive relationships between incubation temperature and body size (length and weight) in the less developed stages, in which some yolk remained, but size decreased at increasing temperatures when yolk was completely exhausted.
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  • 16
    ISSN: 1573-143X
    Keywords: cyanobacteria ; microalgae ; Spirulina ; Spirulina composition ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of temperature on growth and biomass composition of two species of Spirulina, S. maxima and S. platensis used for food was studied. A 4L fermenter with temperature and agitation control was used to cultivate both species. Under continuous light, maximum cell production of 2.4 g l−1 was verified for both cultures studied at temperatures above 25 °C: S. maxima (30 °C and 35 °C) and S. platensis (25 °C and 30 °C). An accentuated lag phase was observed for all cultures at lower temperatures (15–20 °C), and a maximum biomass production of 1.5 g l−1 was achieved. It was also observed that an increase of temperature caused a marked decrease in protein content, while carbohydrate synthesis was stimulated. The concentration of γ-linolenic acid varied from 11–16% for S. maxima and from 12–14% for S. platensis, at the optimum growth temperatures. Greater culture volumes were also studied in order to compare the performance of glass and plastic containers. At optimum growth temperature, S. maxima produced the same cell growth and similar final biomass composition.
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  • 17
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    European journal of plant pathology 105 (1999), S. 509-512 
    ISSN: 1573-8469
    Keywords: tospovirus ; resistance ; Capsicum sp. ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Infection by two isolates of impatiens necrotic spot tospovirus (INSV) under temperature regimes of 25/18°C (day/night) or 33°C (continuous) was studied in Capsicum annuum (systemically susceptible to tomato spotted wilt tospovirus, TSWV), C. chinense PI 152225 and PI 159236 (reacting hypersensitively to TSWV) and Nicotiana benthamiana (systemically susceptible to both tospoviruses). At 25/18°C infection was systemic in all hosts tested. At 33°C infection in N. benthamiana was systemic whereas in C. annuum and C. chinense it was restricted to the inoculated leaves. The result differed from that reported for TSWV, where high temperature made plants more susceptible, or caused no difference. Exchanging temperature regimes 6 h to 4 days after inoculation did not affect the final results one month later, with plants being only locally infected at 33°C continuous regime, or systemically infected at 25/18°C alternate regime. The two INSV isolates were biologically and serologically stable for 5 passages in N. benthamiana held continuously at 33°C.
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  • 18
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    Plant and soil 209 (1999), S. 283-295 
    ISSN: 1573-5036
    Keywords: leaf emergence ; phosphorus ; photosynthesis ; tillering ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus (P) deficiency limits the yield of wheat, particularly by reducing the number of ears per unit of area because of a poor tiller emergence. The objectives of this work were to (i) determine whether tiller emergence under low phosphorus availability is a function of the availability of assimilates for growth or a direct result of low P availability, (ii) attempt to establish a quantitative relation between an index of the availability of P in the plant and the effects of P deficiency on tiller emergence, and (iii) to provide a better understanding of the mechanisms involved in tiller emergence in field-grown wheat. Wheat (Triticum aestivum L., cv. INTA Oasis), was grown in the field under drip irrigation on a typic Argiudol, low in P (5.5 μg P g-1 soil Bray & Kurtz I) in Balcarce, Argentina. Treatments consisted of the combination of three levels of P fertilization 0, 60 and 200 kg P2O5 ha-1, and two levels of assimilate availability, a control (non-shaded) and 65% of reduction in incident irradiance from seedling emergence until the end of tillering (shaded). Phosphorus treatments significantly modified the pattern of growth and development of the plants. Shading reduced the growth and concentration of water-soluble carbohydrates in leaves and stems. Leaf photosynthetic rate at saturating irradiance was reduced by P deficiency, but was not affected by shading. At shoot P concentrations less than 4.2 g P kg-1 the heterogeneity in the plant population increased with respect to the number of plants bearing a certain tiller. At a shoot P concentration of 1.7 g P kg-1 tillering ceased completely. Phosphorus deficiency directly altered the normal pattern of tiller emergence by slowing the emergence of leaves on the main stem (i.e. increasing the phyllochron), and by reducing the maximum rate of tiller emergence for each tiller.
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  • 19
    ISSN: 1573-5036
    Keywords: ectomycorrhizae ; Eucalyptus regnans ; forest burns ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study was conducted to compare the effects on the growth of Eucalyptus regnans seedlings of unheated soil and soil heated to different extents (as indicated by soil colour–bright red or black) in burnt logging coupes, and to separate the effects of heating of the soil on direct nutrient availability and on morphotypes and effectiveness of ectomycorrhizae. Burnt soils were collected from three logging coupes burnt 2, 14 and 25 months previously and unbumt soil from adjacent regrowth forests. Compared to unburnt soil, the early seedling growth was stimulated in black burnt soil from all coupes (burnt 2, 14 and 25 months previously). Seedling growth was generally poor in red burnt soil, especially in soil collected 2 months after burning. However, the concentration of extractable P was extremely high in red burnt soil, especially in soil collected 2 months after burning. In black burnt soil, extractable P was increased in soil 2 months after burning, but not in the soils collected 14 or 25 months after burning. However, both total P content and concentration in seedlings were increased in all collections of black burnt soil. Frequency of ectomycorrhizae was high in seedlings grown in all black burnt soils, but the mycorrhizal mantles were poorly developed in seedlings in black burnt soil collected 2 months after burning. Seedlings were also ectomycorrhizal in red burnt soil, except in soil collected 2 months after burning. Fine root inocula from seedlings grown in black burnt soils collected 14 and 25 months after burning significantly stimulated both seedling growth and P uptake compared with the uninoculated control, whereas the fine root inocula from the seedlings grown in all the other soils did not. These results suggest that, in black burnt soil, both direct nutritional changes and changes in the ectomycorrhizae may contribute to seedling growth promotion after regeneration burns. The generally poor seedling growth in red burnt soils is likely to have been due to N deficiency as the seedlings in these soils were yellow-green and the tissue concentrations of N were significantly lower than in other treatments.
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  • 20
    ISSN: 1573-5060
    Keywords: microsatellite ; Oryza sativa ; polymorphism ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ten microsatellite loci were analysed for 43 cultivars or breeding lines of rice. Polymorphism-Information-Content values ranged from 0.62 to 0.92. The microsatellite markers were found to be useful for cultivar identification and assessment of genetic relationships. Most of the cultivars could be uniquely identified by at least one microsatellite marker. Genetic heterogeneity was detected within rice samples by amplification of microsatellites from DNA extracted from multiple individual plants and also from bulked DNA preparations.
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  • 21
    ISSN: 1573-5060
    Keywords: Pisum sativum L. ; frost resistance ; floral initiation ; photoperiod ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Frost is one of the main climatic stresses which has to be overcome by a winter pea crop. Some forage lines show a delayed floral initiation, which helps them to escape the main winter freezing periods, as a higher susceptibility to frost is observed after floral initiation commences. Frost tolerant forage peas have been used in all winter pea breeding programs in France and our main purpose was to evaluate to what extent those lines and the current winter varieties are variable for the date of floral initiation in field conditions. A field experiment was carried out during two years at the INRA experimental station of Mons (northern France). Different genotypes (9 in 1995–1996 and 12 in 1996–1997) were sown at approximately monthly intervals between September and June to provide a range of photothermal conditions. The date of floral initiation was determined by destructive sampling. We observed variability for the date of floral initiation among the different genotypes and sowing dates. Our data particularly highlighted the different reactions to photoperiod. Three varieties had no detectable reaction. Six varieties exhibited a quantitative response, with varied intensities. Lastly, the three forage varieties showed a qualitative, high response to photoperiod, which indicated the presence of the Hr allele, already described in Pisum.
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  • 22
    ISSN: 1573-5060
    Keywords: doubled haploids ; genetics ; haploids ; induced variation ; Oryza sativa ; ovary culture ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plants derived from unpollinated ovary culture of ten rice genotypes showed significant variability in agro-morphological characteristics. The ovary-derived plant (H1) populations were completely haploid, doubled haploid or haploid-doubled haploid mixture. Haploids had very drastic reduction in plant height, panicle length, grain length, breadth and number and spikelet fertility (0.0%–2.1%). Doubled haploids from the hybrid of UPRI 95–121 × UPRI 95–165 were normal with fertility ranging between 69.6% and 97.7%. A genetic segregation in ratio of 1:1 was observed for five pigmentation characters in the H1 population derived from hybrid UPRI 95–122 × UPRI 95–165. Plant height showed the largest coefficient of variability (28.5%) followed by the number of spikelets per panicle (24.2%), number of grains per panicle (22.0%), percent seed set (9.2%) and panicle length (9.0%). The range of variation in the H1 population from fully fertile hybrid PMS 2A (CMS) × IR 31802 (restorer) was similar to its corresponding F2 population for plant height, spikelet fertility and number of grains/panicle. A single clone of plants from the cultivar BG 1321 exhibited complete male sterility but normal female fertility when pollinated with other varieties. Ovary-derived plants from the CMS lines PMS 2A and IR 58025A showed stable male sterility and those from thermosensitive genetic male sterile line UPRI 95–140 showed thermosensitive genetic male sterility. These lines have potential in the hybrid breeding program and are being currently exploited.
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  • 23
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    Plant and soil 214 (1999), S. 133-140 
    ISSN: 1573-5036
    Keywords: ammonium ; eucalyptus ; nitrate ; pH ; root uptake ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ammonium and nitrate uptake by roots of Eucalyptus nitens was characterised with respect to pH and temperature. Uptake of ammonium and nitrate was measured as depletion from solutions by roots of intact 11 week old solution-cultured seedlings. Uptake rates of ammonium were consistently higher than those of nitrate in all experiments. Uptake rates for ammonium were 200% higher at pH 4 than at pH 6, but for nitrate were unchanged. Uptake rates of ammonium and nitrate were both reduced to a similar extent (70%) with a decrease in temperature from 20 °C to 10 °C. For ammonium uptake, there was rapid (〈24 hr) adaptation to a reduction in root temperature. The apparent preference shown here for ammonium over nitrate could be indicative of E. nitens growing in cold, acidic forest soils where ammonium is commonly more available than nitrate. These results suggest that N uptake rates of E. nitens may be maximised under a wide variety of conditions if N is supplied predominantly in the ammonium form.
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  • 24
    ISSN: 1573-5036
    Keywords: fire ; nitrogen ; phosphorus ; soil nutrient heterogeneity ; tree effects ; tropical dry forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Individual trees are known to influence soil chemical properties, creating spatial patterns that vary with distance from the stem. The influence of trees on soil chemical properties is commonly viewed as the agronomic basis for low-input agroforestry and shifting cultivation practices, and as an important source of spatial heterogeneity in forest soils. Few studies, however, have examined the persistence of the effects of trees on soil after the pathways responsible for the effects are removed. Here, we present evidence from a Mexican dry forest indicating that stem-related patterns of soil nutrients do persist following slash-and-burn removal of trees and two years of cropping. Pre-disturbance concentrations of resin extractable phosphorus (P), bicarbonate extractable P, NaOH extractable P, total P, total nitrogen (N) and carbon (C), KCl extractable nitrate (NO3 -), and net N mineralization and nitrification rates were higher in stem than dripline soils under two canopy dominant species of large-stemmed trees with contrasting morphologies and phenologies (Caesalpinia eriostachys Benth. and Forchhammeria pallida Liebm.). These stem effects persisted through slash burning and a first growing season for labile inorganic and organic P, NaOH inorganic P, and plant-available P, and through a second growing season for labile organic P, NaOH organic P, and plant-available P. While stem effects for extractable NO3 -, net nitrification rates, total N and C disappeared after felling and slash burning, these stem effects returned after the first growing season. These results support the view that tree-influenced patterns of soil nutrients do persist after tree death, and that trees contribute to the long-term spatial heterogeneity of forest soils.
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  • 25
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    Plant and soil 212 (1999), S. 173-181 
    ISSN: 1573-5036
    Keywords: nitrogen ; phosphatase activity ; phosphorus ; protease activity ; soil microbial biomass ; substrate-induced respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Estimating in situ N and P status of the soil microbiota is complicated because microbiological features reflect potentials rather than field conditions. Complementary microbiological assays were, therefore, combined to evaluate the N and P requirement of the microbiota in seven agricultural, grassland and forest topsoils of the Bornhöved Lake district as follows: (i) the sensitivity of the substrate-induced respiration (SIR) to supplemental addition of N and P was monitored during microbial growth and (ii) soil protease and phosphatase activities were analysed and related to soil mass and microbial biomass content. Nitrogen addition increased the maximal SIR rate in all except one soil indicating that the growth of organisms is restricted by this element when easily degradable C source is present. Supplemental N (and in some cases also P) retarded the respiratory response within the first 24 h which suggests microbial sensitivity and/or greater anabolic efficiency. With additional N the maximal SIR rate was most strongly enhanced in topsoils of the beech forest and the dystric alder forest. Thus, the microbial growth in these soils that were below litter horizons seems to be mostly restricted by N. Supplemental P positively affected respiratory response of soils under monoculture, wet grassland and dystric alder forest. In the dystric alder forest soil, high rates of alkaline and unbuffered phosphatase activity were observed when activity was related to either soil mass or microbial biomass content. The data of proteolytic and phospholytic enzymes are discussed with reference to nutrient deficiency and microbial strategy for N and P adsorption.
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  • 26
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    Plant and soil 211 (1999), S. 103-110 
    ISSN: 1573-5036
    Keywords: bioavailability ; isotopic evaluation ; phosphate ion exchange ; phosphorus ; rhizosphere ; soil solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The uptake of phosphorus (P) by roots results in a depletion of phosphate ions (PO4) in the rhizosphere. The corresponding decrease in PO4 concentration in the soil solution (CP) gives rise to a replenishment of P from the solid phase which is time- and CP-dependent. This PO4 exchange which reflects the buffer power of the soil for PO4 also varies with the composition and the physico-chemical conditions of the soil. As root activity can modify these physico-chemical conditions in the rhizosphere, the question arises whether these modifications affect the ability of PO4 bound to the soil solid phase to exchange with PO4 in soil solution. The aim of the present work was to measure and compare the parameters which describe the amount of PO4 bound to soil solid phase that is capable to replenish solution P for both rhizosphere and bulk soils. The soil sample was a P-enriched, calcareous topsoil collected from a long-term fertiliser trial. Rhizosphere soil samples were obtained by growing dense mats of roots at the surface of 3 mm thick soil layer for one week. Three plant species were compared: oilseed rape (Brassica napus L., cv Goeland) pea (Pisum sativum L., cv. Solara) and maize ( Zea mays L., cv. Volga). The time- and CP-dependence of the PO4 exchange from soil to solution were described using an isotopic dilution method. The measured CP values were 0.165 mg P L−1 for bulk soil and 0.111, 0.101 and 0.081 mg P L−1 for rhizosphere soils of maize, pea and rape, respectively. The kinetics of the PO4 exchange between liquid and solid phases of soil were significantly different between rhizosphere and bulk soils. However, when changes in CP were accounted for, the parameters describing the PO4 exchange with time and CP between soil solution and soil solid phase were found to be very close for bulk and rhizosphere soils. For this calcareous and P-enriched soil, plant species differed in their ability to deplete PO4 in solution. The resulting changes in the ability of the soil solid phase to replenish solution PO4 were almost fully explained by the depletion of soil solution P.
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  • 27
    ISSN: 1573-5060
    Keywords: broad sense heritability ; genetic correlation ; glycoalkaloids ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two segregating resource populations were constructed, one of 216 clones using the tetraploid clones Cara and LT7 as parents and one of 176 clones using the tetraploid clones NT8 and LT7 as parents. The populations were used, in replicates, to estimate genetic parameters for total glycoalkaloid (TGA) content in the tubers, and for other agronomic and morphological traits such as tuber weight, dormancy and plant height. In both populations, the parental clones differed markedly in TGA-content and the progeny population was normally distributed for this trait after logarithmic transformation. Broad sense heritability estimate of TGA-content was 0.54 in Cara × LT7 and 0.50 in NT8 × LT7 and the trait proved to be inherited in a non-dominant manner. The minimum number of genes contributing to TGA-content was estimated to be between 3 and 7. None of the other traits recorded in this study showed a statistically significant genetic association with TGA-content. This suggests that tuber TGA-content may be genetically modulated without any significant adverse effects on other agronomic traits. The genetic parameters estimated in this study indicate that these populations are suitable for DNA-marker analysis for TGA-content in tubers.
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  • 28
    ISSN: 1573-5060
    Keywords: genic male-sterility gene ; mapping ; molecular markers ; Oryza sativa ; pleiotropic effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A genic male-sterility gene newly induced by chemical mutagenesis, tentatively designated as ms-h(t), was located on the molecular map of rice and tested for its effect on chalky endosperm. Bulked segregant analysis was used to determine the chromosomal location of the ms-h(t) locus by screening four to five RFLP markers per chromosome. After confirming that the gene was located on chromosome 9, twenty-four RFLP markers from chromosome 9 were surveyed for polymorphism in the parents of the mapping population. Of these, eleven markers were mapped around the ms- h(t) locus. RG451 and RZ404 flanked the ms-h(t) gene, at 2.5cM and 3.3cM, respectively. Heterozygous F2 to F4 progenies were tested for co- segregation of male-sterility and chalky endosperm and it was revealed that ms-h(t) might have a pleiotropic effect on chalky endosperm. This mutant would be a good biological material to characterize the biochemical mechanism of male sterility and related pleiotropic effects. Further studies should be needed to know the usefulness of this mutant for hybrid seed production.
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  • 29
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    Plant growth regulation 27 (1999), S. 191-194 
    ISSN: 1573-5087
    Keywords: ornithine-δ-aminotransferase ; proline accumulation ; Oryza sativa ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Proline is synthesized either from glutamate or from ornithine in plants. Relatively little is known about the contribution of the pathway from ornithine to proline biosynthesis. In this paper we investigated the contribution of ornithine-δ-aminotransterase (OAT), an enzyme responsible for ornithine pathway, to proline accumulation in water-stressed detached rice leaves. Although OAT activity increased with the increase of water stress duration, a pattern similar to that obtained for proline accumulation, the ornithine pathway in rice leaves seems to contribute little, if any, to proline accumulation under water stress condition. This conclusion was based on the observations that (a) gabaculine (50 μM), an inhibitor of OAT, inhibited about 75% OAT activity caused by water stress but reduced only 20% of proline content and (b) cycloheximide, a protein synthesis inhibitor, had no effect on OAT activity induced by water stress but significantly reduced proline accumulation.
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  • 30
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    Plant growth regulation 28 (1999), S. 17-20 
    ISSN: 1573-5087
    Keywords: abscisic acid ; ammonium ; leaf senescence ; methyl jasmonate ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Both abscisic acid (ABA) and jasmonates are known to promote leaf senescence. Since ABA and jasmonates have both chemical and physiological similarities, we are interested to know whether senescence of detached rice leaves induced by methyl jasmonate (MJ) is mediated through an increase in endogenous ABA levels. In darkness, the endogenous level of ABA in detached rice leaves remained unchanged in the first day of incubation in water and increased about 5 times its initial value in the second day. However, the pattern of senescence, as judged by protein loss, was rapid during the first day. MJ significantly promoted senescence of detached rice leaves. Contrary to our expectation, endogenous ABA levels decreased in MJ-treated detached rice leaves. Similar to the effect of MJ, endogenous ABA levels decreased in detached rice leaves which were induced to senesce by treatment with NH4Cl. These results suggest that endogenous ABA levels are not linked to MJ-induced senescence of detached rice leaves.
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  • 31
    ISSN: 1573-5087
    Keywords: 1-aminocyclopropane-1-carboxylate (ACC) oxidase ; ethylene ; Oryza sativa ; ozone ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Exposure to ozone at 1 µl l−1 for 6 h induced ethylene production in rice (Oryza sativa L. cv. Hitomebore) leaves. The stimulation of ethylene production was detectable 2 h after the start of the exposure to ozone, and lasted for 6 h after the exposure. A 429-bp cDNA fragment encoding ACC oxidase was obtained by RT-PCR from ozone-treated rice leaves. Its nucleotide sequence and deduced amino-acid sequence had 97.2% and 94.4% identity, respectively, to those of OS1A1COX, which was previously obtained from deepwater rice. The abundance of the cDNA increased in accordance with the induction of ethylene production by the exposure to ozone.
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  • 32
    ISSN: 1573-5109
    Keywords: AFLP analysis ; DNA fingerprinting ; genetic diversity ; Indian rice varieties ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To assess diversification of indica rice, fingerprinting of 42 Indian rice varieties (Oryza sativa L) and one accession of O. brachyantha Chev. et Roehr. was taken up using amplified fragment length polymorphism (AFLP). Six primer combinations of PstI and MseI were used for this purpose. On denaturing polyacrylamide sequencing gel, on average 41 scorable AFLP bands were obtained of which 81% were polymorphic. Each variety revealed a distinct fingerprint. Data were scored on the basis of presence and absence of bands and cluster analysis was performed using Dice similarity coefficients. The resultant dendrogram showed four major clusters and traits. Some varieties especially landraces revealed more polymorphism and unique loci. Such study will be a valuable tool for proper choice of parents in mapping populations or breeding programs to produce heterotic several inexplicable minor clusters. Some varieties were grouped according to parentages of the cross while some were grouped according to physiological combinations apart from providing a characteristic fingerprint.
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  • 33
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    Genetic resources and crop evolution 46 (1999), S. 13-17 
    ISSN: 1573-5109
    Keywords: F2 weakness ; reproductive barrier ; Oryza sativa ; gene distribution ; clinal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a backcrossing program to introduce the wx (glutinous endosperm) gene from a Thai upland rice cultivar, Col.No.15, to a Japanese cultivar, Sasanishiki, of Asian cultivated rice, Oryza sativa L., weak plants were observed in the BC1F1 generation. These weak plants were characterized by poor growth and discoloration at the tillering stage, though they were completely fertile. Hybrid breakdown, which is defined as hybrid weakness and sterility detected in the F2 and later inbred generations of varietal crosses, is controlled by a pair of recessive genes, hwd1 and hwd2, at unlinked loci. Two dominant genes at either the same or different loci, Hwd1/Hwd1 hwd2/hwd2, hwd1/hwd1 Hwd2/Hwd2 or Hwd1/hwd1 Hwd2/hwd2, are needed for normal growth. Using tester lines homozygous for a pair of recessive genes selected in the BC1F3 generation, the genotypes for hybrid breakdown of 100 Asian rice cultivars were determined based on the phenotype of F1 plants. Clinal variation for hybrid breakdown was observed. Cultivars with two dominant alleles at either hwd1 or hwd2 locus, were mainly found in insular Asia (Japan, Philippines and Indonesia), while the frequency of cultivars with four dominant alleles was more common in cultivars from continental Asia. Roles of hybrid breakdown in genetic differentiation of Asian cultivated rice are discussed.
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  • 34
    ISSN: 1573-5087
    Keywords: 2,6-diisopropylphenoxyacetic acid ; gibberellin ; Oryza sativa ; rice ; shoot elongation ; uniconazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract 2,6-Diisopropylphenoxyacetic acid (DIPA), a promoter of growth and flowering of Sagittaria species, was found to improve the shoot growth of rice plants treated with uniconazole, an inhibitor of gibberellin (GA) biosynthesis. In a modified micro-drop bioassay using semi-dwarf rice, Oryza sativa L. cv. Tan-ginbozu, in which uniconazole had been incorporated into the agar medium, a significant recovery from growth inhibition was observed for both the 3rd and the 4th leaf sheaths but not for the 2nd sheath. In greenhouse experiments, uniconazole-treated rice plants partially recovered from growth inhibition when DIPA was applied after uniconazole treatment, whereas DIPA applied with, or before, uniconazole treatment did not improve growth. The levels of GA1 and GA20 in the rice plants treated with uniconazole plus DIPA were almost equal to those of the untreated controls, indicating that the observed growth recovery is attributable to the restoration of GA biosynthesis by DIPA.
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  • 35
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    Plant growth regulation 29 (1999), S. 123-133 
    ISSN: 1573-5087
    Keywords: Oryza sativa ; drought resistance ; root morphology ; root growth ; osmotic adjustment ; review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The use of molecular markers in the mapping of traits of agronomic importance holds great promise for speeding the development of improved plant varieties and increasing our understanding of the physiological or molecular mechanisms behind biological phenomena. The technique is now being applied to drought resistance in rice (Oryza sativa L.). Drought is important because a considerable proportion of the world rice area is not irrigated and can be prone to water deficit. A large number of people, particular some of the poorest rice farmers, stand to gain if new varieties which combine high yield and drought resistance can be developed. Rice should be particularly useful for the molecular genetic analysis of drought resistance because of its growing role as a model monocot species and the diversity of drought resistance mechanisms which are found in the germplasm. We briefly review the traits which might be considered important in improving drought resistance in rice, before explaining the molecular mapping approach. We review progress at locating quantitative trait loci (QTLs) for individual mechanisms of drought resistance in controlled environment conditions. This includes a detailed comparison of reported QTLs related to root morphological characters. The search for QTLs associated with field performance under drought stress is analysed and the problems associated with understanding the genetic control of a complex physical and physiological phenomenon under conditions of substantial environmental variation are highlighted. We emphasise that the use of near isogenic lines in overcoming some of the problems offers considerable promise for the future.
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  • 36
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    Genetic resources and crop evolution 46 (1999), S. 587-598 
    ISSN: 1573-5109
    Keywords: diversity ; genetic resources ; GIS ; Oryza sativa ; RAPD ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A diverse set of 115 rice varieties from Bangladesh was surveyed using 35 polymorphic RAPD (randomly amplified polymorphic DNA) markers and the genetic structure of this germplasm, encompassing the principal rice ecotypes of Bangladesh (aus, aman and boro), was determined using multivariate analysis. The level of genetic diversity was evaluated and compared with the levels of diversity found within other rice growing areas of the world. Geographical information systems analysis using Atlas-GIS was employed to analyse and present the geographic distribution of genetic diversity across Bangladesh, and cluster analysis was used to test the efficiency of selection of material for a core collection.
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  • 37
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    Aquaculture international 7 (1999), S. 357-360 
    ISSN: 1573-143X
    Keywords: feed intake ; growth ; silver trevally (Pseudocaranx dentex) ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 38
    ISSN: 1573-0867
    Keywords: ammonium chloride ; ammonium sulphate ; nest placement ; nitrification ; temperature ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrification occurring in an alkaline sandy loam soil fertilized with urea, ammonium sulphate (AS) and ammonium chloride (AC) was studied in the laboratory at 20°C and 40°C for 30 days. Nitrogen fertilizers were applied as nest of sizes 0.2, 0.5, 1.0 and 2.0 g. Unfertilized control and soil mixed with 50 mg N kg-1 were also included as treatments. Nitrification in all the fertilizer treatments decreased markedly with increasing nest size. At 20°C, differences among the three N sources were not significant at 5 days after incubation but marked differences appeared thereafter. All the N was nitrified by 30 days in case of fertilizers mixed into the soil. In nest placement, nitrification ranged from 30.1 to 75.5%, 28.3 to 74.6% and 35.3 to 88.7% for urea, AC and AS, respectively. When equal amounts of fertilizers were placed in a nest, nitrification occurred at a slower rate with urea than with AC and AS. Rates of nitrification were significantly higher at 40°C than at 20°C. At 20 days, nitrification from different nest sizes ranged from 8.4 to 64.9% and from 24.9 to 87.0% at 20°C and 40°C, respectively. The difference in nitrification at two temperatures were more pronounced at higher nest sizes than at smaller nest sizes. While nitrification with the three N sources decreased linearly with increase in N concentration (nest size) in soil at 40°C, it showed a quadratic relationship at 20°C. At equal N concentration, the highest rate of nitrification occurred with urea and the lowest with AC. At the same rate of applied N (50–2000 mg kg-1), AC and AS increased electrical conductivity of soil by 1.3–9 times that of urea. Apparent mineral N recovery of applied N decreased with the increase in nest size.
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  • 39
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    Agroforestry systems 45 (1999), S. 215-244 
    ISSN: 1572-9680
    Keywords: biodiversity ; disturbance ; nitrogen ; phosphorus ; resilience ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nutrient and hydrologic cycles in harvested native forests in southern Australia are largely balanced. For example, we have little or no evidence of any decline in nutrient capital or availability in harvested forests. Short-term and small-scale reductions in evapotranspiration due to loss of leaf area after harvesting are adequately balanced at the landscape scale by large areas of regenerating or older-age forest. In contrast, agricultural systems on similar soils are a) dependent on large inputs of fertilisers to maintain growth and b) frequently subject to increasing salinity and waterlogging or other forms of degradation. The large-scale replacement of long-lived communities of perennial and often deep- rooting native species with annual crops or other communities of shallow-rooting species might be better managed within the framework of knowledge developed from studies of native plant communities. However, application of such a mimic concept to systems of low natural productivity is limited when agricultural systems require continued high productivity. Nonetheless, the mimic concept may help in developing sustainable management of agriculture on marginal lands, and contribute to the nutritional resilience of agroecosystems. Relevant characteristics for mimic agroecosystems in south western Australia include: high species diversity, diversity of rooting attributes, utilisation of different forms of nutrients (especially of N and P) in space and time, and the promotion of practices which increase soil organic matter content.
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  • 40
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    Biodegradation 10 (1999), S. 43-50 
    ISSN: 1572-9729
    Keywords: biodegradation ; nitrogen ; nutrients ; phenanthrene ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phenanthrene mineralization rates were found to vary widely among four soils; differences in soil nutrient levels was one hypothesis to explain this variation. To test this hypothesis, phenanthrene mineralization rates were measured in these soils with, and without, added nitrogen and phosphorus. Mineralization rates either remained unchanged or were depressed by the addition of nitrogen and phosphorus. Phenanthrene degradation rates remained unchanged in the soil which had the highest indigenous levels of nitrogen and phosphorus and which showed the largest increase in phosphorus levels after nutrients were added. The soils in which degradation rates were depressed had lower initial phosphorus concentrations and showed much smaller or no measurable increase in phosphorus levels after nutrients were added to the soils. To understand the response of phenanthrene degradation rates to added nitrogen and phosphorus, it may be necessary to consider the bioavailability of added nutrients and nutrient induced changes in microbial metabolism and ecology.
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  • 41
    ISSN: 1573-5060
    Keywords: Erwinia carotovora ; Solanum tuberosum ; somaclonal variation ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three somatic hybrid lines between potato (cv. While Lady line no. Ke 79, 2n = 2x = 48) + Solanum brevidens (PI 218228, 2n = 2x = 24) were evaluated using randomly amplified polymorphic DNA (RAPD) markers. The lines originated from the same callus but showed different reactions to Erwinia carotovora ssp. carotovora, the cause of potato soft rot. By the use of 48 oligomer primers producing 99 scorable bands, DNA polymorphism were detected on 7 of 12 S. brevidens chromosomes. Loss of certain DNA segments on chromosome 5, 6, 9 and 11 were observed. Some of the variations could have taken place in early callus stage of development; others may have occurred after initiation of individual shoot regeneration. The possible involvement of missing RAPD products specific to one somatic hybrid that shows decreased resistance to bacterial soft rot is discussed.
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  • 42
    ISSN: 1573-5060
    Keywords: freezing tolerance ; potato ; Solanum brevidens ; Solanum commersonii ; Solanum tuberosum ; somatic hybrids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The expression of freezing tolerance was characterized in interspecific somatic hybrids between S. tuberosum (tbr) and two cold-hardy wild species, S. brevidens (brd) and S. commersonii (cmm). The nonacclimated freezing tolerance (NA) and acclimation capacity (ACC, increase in freezing tolerance in response to low nonfreezing temperature), two main genetic components of freezing tolerance, were evaluated separately. In contrast to cmm, which exhibited excellent NA and ACC, the freezing tolerance of brd was mainly due to ACC. However, the ACC of brd was only moderately expressed in the somatic hybrids. The NA of cmm was also suppressed in combination with tbr genomes. However, with acclimation, some of the tbr (+) cmm somatic hybrids achieved freezing tolerance comparable to pure hardy species such as brd used in this study. Analysis of chloroplast DNA type by RFLP markers revealed no significant difference in ACC between somatic hybrids carrying chloroplasts from either tbr or cmm. The reasons for the reduced expression of freezing tolerance from either the brd or cmm parent and the utilization of these somatic hybrids in breeding programs are discussed.
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  • 43
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    Plant and soil 216 (1999), S. 147-153 
    ISSN: 1573-5036
    Keywords: NaCl ; Oryza sativa ; peroxidase ; root growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The changes in ionically bound peroxidase activity in roots of NaCl-stressed rice seedlings and their correlation with root growth were investigated. Increasing concentrations of NaCl from 50 to 150 mM progressively decreases root growth. The reduction of root growth by NaCl is closely correlated with the increase in ionically bound peroxidase activity. Since proline and ammonium accumulations are associated with root growth inhibition caused by NaCl, we determined the effects of proline or NH4Cl on root growth and ionically bound peroxidase activity in roots. External application of proline or NH4Cl markedly inhibited root growth and increased ionically bound peroxidase activity in roots of rice seedlings in the absence of NaCl. An increase in ionically bound peroxidase activity in roots preceded inhibition of root growth caused by NaCl, NH4Cl or proline. Mannitol inhibited root growth, but decreased rather than increased ionically bound peroxidase activity at the concentration iso-osmotic with NaCl. The inhibition of root growth and the increase in ionically bound peroxidase activity in roots by NaClis reversible and is associated with ionic rather than osmotic component.
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  • 44
    ISSN: 1573-5036
    Keywords: hydraulic conductivity ; leaf growth ; phosphorus ; Rhizoctonia ; water status ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat seedlings infected with a pure inoculum of the root-rotting fungus Rhizoctonia solani were grown in pots designed to fit in pressure chambers, to allow the effects of the Rhizoctonia infection on leaf growth to be studied while maintaining the leaves at elevated water status. Wheat was grown to the third leaf stage in soil inoculated with three different levels of Rhizoctonia, and the pots were then pressurised for seven days to maintain the leaf xylem at the point of bleeding (ie. the leaves were at full turgor). The reduction in leaf expansion caused by Rhizoctonia was not overcome by pressurisation, indicating that a reduced supply of water to the leaves was not responsible for reduced leaf growth. The addition of phosphorus to pots marginally deficient in P did not increase the leaf growth of Rhizoctonia-infected plants, despite increased P uptake to the leaves. These results indicate that a reduced supply of water to the leaves and a supply of phosphorus that was bordering on deficient was not the cause of the growth reduction in seedlings with Rhizoctonia infection. The nature of this reduced growth remains uncertain but may involve growth regulators produced by the fungus, or by the plant as a result of the infection process. The mechanism of these growth reductions is of interest as it may provide a key to the development of plant resistance mechanisms.
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  • 45
    ISSN: 1573-8248
    Keywords: Macrolophus pygmaeus ; photoperiod ; predation rate ; temperature ; predator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of temperature and photoperiod on the rate of predation of nymphs and adults of the predator Macrolophus pygmaeus was studied using Myzus persicae prey feeding on egg-plant and pepper plants. The experiments were conducted at three photoperiods (16L:8D, 12L:12D and 8L:16D), three temperatures (20, 25 and 30 °C), and at 65% r.h. The rate of predation increased with temperature. Predation rate was affected by photoperiod on pepper but not on egg-plant. Females and fifth instar nymphs were the most voracious stages followed by third and fourth instar nymphs and males. First and second instar nymphs consumed far fewer aphids. Predation rate was higher on leaves of pepper than egg-plant, especially at 30 °C. Variation in the efficacy of this predator is discussed.
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  • 46
    ISSN: 1573-8248
    Keywords: biological control ; Botrytis aclada ; Botrytis cinerea ; cyclamen ; ecological adaptation ; hydrangea ; lily ; onion ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ulocladium atrum and Gliocladium roseum are fungal antagonists capable of suppressing sporulation of Botrytis spp. on dead plant parts. The effect of temperature (3 to 36 °C) on antagonist conidial germination and mycelial growth was assessed on agar. In addition conidial germination of U. atrum was measured on dead lily leaves. The optimum temperature of both antagonists for both conidial germination and mycelial growth was between 27 and 30 °C. U. atrum was less affected by lower temperatures than G. roseum. At optimum temperature, 50% of conidia of U. atrum and G. roseum germinated within 2.6 and 10.0 hrs, respectively. At low sub-optimal temperatures (6 °C), 50% of conidia germinated within 18 and 96 hours, respectively. In bioassays on dead onion leaves, U. atrum suppressed sporulation of B. cinerea and B. aclada at all temperatures tested (6 to 24 °C) by more than 85%. On dead cyclamen leaves, G. roseum was more efficient than U. atrum at 21 and 24 °C but, in contrast to U. atrum, showed no antagonistic activity at temperatures below 21 °C. On dead hydrangea leaves, U. atrum significantly reduced sporulation of B. cinerea at temperatures as low as 3 and 1 °C. Under Dutch growing conditions, the mean air temperature during leaf wetness periods in onion and lily fields was 15 °C with temperatures only occasionally above 20 °C. In greenhouse crops of cyclamen, the mean temperature during high humidity periods was 17 °C. It is therefore concluded that U. atrum is better adapted than G. roseum to temperatures which occur in the field, in greenhouse crops such as cyclamen, or during cold storage of plant stocks.
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  • 47
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    Nutrient cycling in agroecosystems 50 (1998), S. 321-324 
    ISSN: 1573-0867
    Keywords: nutrient modelling ; leaching ; nitrogen ; phosphorus ; schematization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In context of preparing the Fourth National Policy Document on Water Management in the Netherlands effects of different scenarios of fertilizer management on nitrogen (N) and phosphorus (P) leaching from rural areas into Dutch surface waters were analyzed. The manuscript offers insight into the model instrument that is used to simulate the different scenarios. Main parts of the modelinstrument are: a procedure to schematize the Netherlands in horizontal areal units, field scale mechanistic models for water and nutrient behaviour in the soil and an empirical model for fertilizer additions.
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  • 48
    ISSN: 1573-0867
    Keywords: agriculture ; catchment ; fertilizer ; historical ; manure ; nitrate ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A suggested increase in the growth of macrophytic algae within the Ythan estuary (N.E. Scotland) over recent years has been linked to the increased amounts of nitrogen in the form of NO3–N entering the estuary from the river. The increased NO3 concentration in the river has been associated with recent changes in farming practices in this predominantly agricultural catchment. Terrestrially derived phosphorus is also considered to contribute increasingly to eutrophication of fresh waters. Historical agricultural census data together with appropriate surveys of fertilizer practice were used to calculate the total quantities of fertilizer and manure derived N and P applied annually over the wholeYthan catchment during the period 1960 – 1990. While the total agricultural land area has remained similar, significant changes in cropping practice have occurred. In particular, a greater proportion of land is given to autumn sown crops while the area of grassland has declined. These changes in farming practice are associated with differences in both the total amounts and timing of fertilizer applied. The use of inorganic N in the catchment has trebled since 1960 and is currently approximately 6400 tonnes (104 kg N/ha). The use of P has decreased by more than a quarter to 1274 tonnes (21 kg P/ha) over a similar time period. There has been no obvious change in total quantity of N and P derived from animal manures, estimated to be 44 and 11 kg per ha, respectively, when averaged over the area of agricultural land. Cattle and sheep numbers have remained relatively constant and together account for approximately 80% of the manure N and 70% of the manure P produced annually. However, poultry have declined by 70% since 1960 while pig numbers have increased six-fold. The average annual application rate of manure derived N over the whole catchment (44 kg/ha) is considerably below that proposed at the farm scale in the EC Nitrate Directive (210–170 kg/ha). However, on a local scale difficulties may arise for large manure producing concerns such as dairy or pig units.
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  • 49
    ISSN: 1572-9788
    Keywords: amylose ; antisense RNA ; endogenous allele ; Solanum tuberosum ; T-DNA insertion ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The T-DNA composition was analysed of twelve potato genotypes obtained after transforming a tetraploid cultivar with an antisense granule-bound starch synthase (GBSSI) gene. In five transformants (labelled TB50 nos.) the antisense GBSSI gene was driven by the CaMV 35S promoter, while in the remaining seven (labelled TBK50 nos.) the GBSSI promoter was used. In these twelve transformants the antisense effect on amylose production in potato tuber starch ranged from complete suppression to no discernible inhibition, and the number of T-DNA insertions ranged from one to at least fifteen. The antisense effect of individual T-DNA loci in progeny of these transformants was studied. Progeny containing a single T-DNA showed no inhibition of GBSSI activity. Only multiple, linked T-DNA insertions resulted in substantial antisense inhibition. T-DNA fragments present in duplex in selfed progeny resulted in a larger antisense effect than that in the parent (which contained the T-DNA insertions in simplex). Furthermore, the antisense effects of some T-DNA-containing linkage groups were influenced by the composition of endogenous GBSSI alleles. For practical breeding this implies that (1) the efficiency of obtaining primary potato transformants showing complete inhibition of GBSSI gene expression by antisense RNA is genotype-dependent, and (2) many transformants have to be produced per genotype to be able to select plants with maximum suppression of GBSSI and a minimum number of T-DNA loci.
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  • 50
    ISSN: 1573-5087
    Keywords: carbohydrates ; elevated CO2 ; Gossypium hirsutum L. ; interaction ; photosynthesis ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cotton (Gossypium hirsutum L., cv DPL 5415) plants were grown in naturally lit environment chambers at day/night temperature regimes of 26/18 (T-26/18), 31/23 (T-31/23) and 36/28 °C (T-36/28) and CO2 concentrations of 350 (C-350), 450 (C-450) and 700 μL L-1 (C-700). Net photosynthesis rates, stomatal conductance, transpiration, RuBP carboxylase activity and the foliar contents of starch and sucrose were measured during different growth stages. Net CO2 assimilation rates increased with increasing CO2 and temperature regimes. The enhancement of photosynthesis was from 24 μmol CO2 m-2 s-1 (with C-350 and T-26/18) to 41 μmol m-2 s-1 (with C-700 and T-36/28). Stomatal conductance decreased with increasing CO2 while it increased up to T-31/23 and then declined. The interactive effects of CO2 and temperature resulted in a 30% decrease in transpiration. Although the leaves grown in elevated CO2 had high starch and sucrose concentrations, their content decreased with increasing temperature. Increasing temperature from T-26/18 to 36/28 increased RuBP carboxylase activity in the order of 121, 172 and 190 μmol mg-1 chl h-1 at C-350, C-450 and C-700 respectively. Our data suggest that leaf photosynthesis in cotton benefited more from CO_2 enrichment at warm temperatures than at low growth temperature regimes.
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  • 51
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    Plant and soil 198 (1998), S. 185-192 
    ISSN: 1573-5036
    Keywords: colonization ; crop-rotation ; maize ; mycorrhiza ; phosphorus ; tillage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We selected three crop production practices; crop rotation, tillage and phosphorus fertilization, all known to affect arbuscular mycorrhiza (AM) development, to study early AM intraradical colonization in maize. Half of the plots were planted during the first year with either a host (maize, Zea mays L.) or a non-host (canola, Brassica napus L.) crop, and all of them with maize for the second year. Tillage and P fertilization treatments were applied to the plots in the second year. Mycorrhiza development in maize was measured in pot culture bioassays conducted before planting and after harvest of the previous and the subsequent crops, and in the field during the second crop season. Previous cropping of a soil with canola (Brassica napus L.), a non-host plant species, delayed mycorrhiza development of maize in a bioassay conducted with that soil in comparison with a previous cropping cycle with maize (Zea mays L.) or with the original plant species in the field site, bromegrass (Bromus inermis Leys.) and alfalfa (Medicago sativa L.). The delay in mycorrhiza development after cropping with canola was also observed in samples taken from the field and in a bioassay, both conducted at the beginning of the subsequent cropping cycle. Tillage had, on average, little effect on intraradical colonization either in the field or in the bioassays. Phosphorus fertilization also had little effect on mycorrhiza development in the field. Crop rotation with a non-host had the strongest effect on intraradical mycorrhiza development of the three practices studied.
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  • 52
    ISSN: 1573-5036
    Keywords: growth parameters ; methane flux ; N-fertilization ; Oryza sativa ; root porosity ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Influence of urea application on growth parameters (shoot height, and weight, root volume, weight and porosity; number of tillers; grain yield) and their relationship with methane (CH4) flux was investigated in Oryza sativa (var. Pant Dhan-4) under flooded soil condition. The study design consisted of (a) fertilized vegetated, (b) control vegetated, (c) fertilized bare, and (d) control bare plots. Crop growth and CH4 flux measurements were conducted from 9 to 115 days of rice transplanting at regular intervals of 10 days. Results showed that there were significant differences due to days (dates of measurement) and fertilization in all growth parameters except shoot height. Day × fertilization interaction was significant for all growth parameters. CH4 fluxes ranged from 0.4 to 20.2, 0.1 to 11.9, 0.09 to 2.2 and 0.004 to 1.5 mg m-2 h-1 under treatments (a), (b), (c) and (d), respectively. Maximum CH4 flux was recorded at the flowering stage. All the growth parameters, including number of tillers, showed strong positive relationship with total methane flux. Root porosity was also strongly correlated with total CH4 emission. It was concluded that CH4 emission was substantially influenced by crop phenology and growth, and fertilization. The study emphasizes the substrate production and conduit effects of rice plants on CH4 flux.
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  • 53
    ISSN: 1573-5036
    Keywords: endophyte ; Festuca arundinacea ; Neotyphodium coenophialum ; phenolics ; phosphorus ; root activity ; tall fescue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Endophyte-infected (E+) tall fescue (Festuca arundinacea Schreb.) plants grown in phosphorus (P) deficient soils accumulate more P in roots and shoots than noninfected isolines. In a growth chamber experiment, four tall fescue genotypes DN2, DN4, DN7, and DN11, infected with their naturally occurring strains of Neotyphodium coenophialum (Morgan-Jones & Gams) Glenn, Bacon & Hanlin, and their noninfected isolines (E-), were cultivated in nutrient solution at two P levels: 31 ppm (P+) and 0 ppm (P-) for 4 wk. The Fe3+ reducing activity of extracellular reductants and intact root tissues, and total phenolic concentration in roots and shoots were measured. Endophyte infection significantly increased Fe3+ reducing activity rate of extracellular reductants (9.6 × 10-3 μmol Fe3+ h-1 g-1 root FW) when compared to E- plants (3.9 × 10-3) and Fe3+ reduction rate of intact root tissues (6.16 and 4.48 μmol Fe3+ h-1 g-1 root FW, respectively for E+ and E- plants). In response to P deficiency, Fe3+ reduction rate of intact root tissues increased in E+ plants by 375% when compared to E- plants, whereas no significant differences were observed when P was provided. Total phenolic concentration was 20% greater in shoots of E+ plants than in E- plants. In response to P deficiency, total phenolic concentration significantly increased in roots of E+ plants by 7%, and decreased in roots of E- plants by 10%. The most active Fe3+ reducing zones were located along branching of secondary and tertiary roots. The Fe3+ reducing activity on the root surface and total phenolic concentration in roots and shoots increased dramatically in response to endophyte infection, especially under P limiting conditions.
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  • 54
    ISSN: 1573-5036
    Keywords: maple ; moisture ; phenology ; root growth ; soil fertility ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A two-year study was undertaken in a maple-dominated watershed of southern Québec, Canada, to examine relationships between trends in fine root growth, stem diameter growth, soil moisture, soil temperature, mineralized-N and extractable-P. Until September, soil temperature was consistently higher in 1995 than in 1994. Apart from the first sampling in mid-May, soil moisture was higher in 1994 than in 1995. In 1994, most fine roots were produced before leaf expansion, whereas in 1995, fine root production peaked in July. Annual fine root production was estimated to be 2.7 times higher in 1994 than in 1995. Stem growth was strongly associated with the seasonal and annual variation in soil temperature. Root and diameter growth were asynchronous in 1994 but not in 1995. Fine root production was associated with two groups of variables: a soil fertility (mineralized-N and extractable-P) group and a physical soil environment (moisture and temperature) group. Our results are consistent with the negative effect of high soil-N fertility on fine root production but are inconclusive as to the positive effect of high soil-P fertility. Soil conditions that are detrimental to root growth such as high N availability and anaerobiosis could modify the normal dynamics of fine root growth.
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  • 55
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    Euphytica 104 (1998), S. 143-149 
    ISSN: 1573-5060
    Keywords: potatoes ; Solanum tuberosum ; parent selection ; cross prediction ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cross prediction techniques were applied to data collected from over 600 hybrid combinations of potato (Solanum tuberosum) and analyzed to determine the potential of using early generation cross prediction techniques to identify superior parental clones. Performance of parental lines based on parameters collected in early generations were compared with the observed frequencies of desirable recombinants with a common parent in the latter stages of a breeding program. Results showed that value of parents, in their ability to produce desirable recombinants in breeding programs, can be predicted using univariate cross prediction techniques. This type of information can be available from early generation progeny trials and could easily be incorporated into a practical potato breeding scheme.
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  • 56
    ISSN: 1573-5060
    Keywords: unpollinated ovary culture ; callus induction ; plant regeneration ; chilling pretreatment ; development stage ; medium composition ; rice ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A simple and efficient technique for in vitro unpollinated ovary culture in rice which is also applicable for indica genotypes was developed for breeding and genetic studies. Sampling explants at the auricle distance of 7–12 cm between the two uppermost leaves of a tiller, providing a chilling pretreatment and ovaries with 1/3 of the hulls intact gave optimum response to culture. For callus induction with the spontaneous breaking of ovaries, N6 media supplemented with NAA (2 mg/l) and DMSO (0.6–0.8%) gave a mean PCI value of 3.8% and range of 0.8–12.5% among genotypes. Media combining 2,4,5-T or 2,4-D with NAA in N6 medium also has reasonably good callus induction. For calli induced inside, 2,4-D (0.2–0.5 mg/l), NAA (2 mg/l) and KT (1 mg/l) contained media were superior. The maximum green plant regeneration (PPR) of 77.3% was found with the medium containing NAA 0.25 mg/l, IAA 0.5 mg/l and KT 2.0 mg/l. Significant genotype, medium and their interaction effects for per cent ovary survival and callus induction were observed.
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  • 57
    ISSN: 1573-5036
    Keywords: Eucalyptus globulus ; Eucalyptus nitens ; root apical diameter ; root elongation ; shoot elongation ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Information on the growth response of a crop plant in relation to temperature can be helpful in selecting genotypes to suit local environments, scheduling favourable time of planting and forecasting growth and yield. To determine the effects of varying temperature on root and shoot elongation of eucalypt seedlings, elongation rates of roots and shoots were measured in rhizotrons for two species (Eucalyptus nitens (Deane and Maiden) Maiden, and Eucalyptus globulus Labill.) at a temperature range of 5–23 °C. Within this range of temperatures, elongation rates of roots and shoots of both species increased with an increase in temperature. Roots of E. globulus were more sensitive and shoots less sensitive to temperature than those of E. nitens. However, the threshold temperature corresponding with zero elongation rate predicted from the regression of elongation rate against temperature was similar for the roots (∼5 °C) and shoots (∼0 °C) of both species. Hysteresis did not appear to have a significant influence on root or shoot elongation of both species during warming compared with cooling. Results are discussed highlighting the importance of the interaction between development and growth of plant components.
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  • 58
    ISSN: 1573-5036
    Keywords: agar ; agarose ; gels ; mechanical impedance ; Oryza sativa ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agar and agarose gels were evaluated as systems to mechanically impede roots of rice (Oryza sativa L.). Two-layer gels were used so that seedlings established in a layer of weak gel (0.35% weight/volume) and then grew downwards to encounter a treatment gel of up to 5.0% (w/v). Agarose gels were stronger than agar gels of the same concentration, reaching a maximum penetrometer resistance of 1.2 MPa at a concentration of 5.0%, compared to 0.3 MPa with agar. The 5.0% agar gel stimulated elongation of the seminal axis by 40% in seedlings of variety TN1 (compared with elongation in the 0.2% gel), but decreased it by 15% in the variety Lac 23. Although increasing agarose concentration decreased seminal axis elongation in both varieties, the seminal axis did not reach the lower layer of treatment gel when the concentration of the treatment gel was greater than 2.0%. The decreased root elongation was therefore a non-mechanical inhibition. In experiments conducted using a different batch of agarose, these inhibitory effects were not seen and strong agarose gels stimulated seminal axis elongation. It was concluded that the agar and agarose gel systems studied were unsuitable for studying the effect of mechanical impedance on the elongation of rice roots and that great care should be taken in interpreting the results of experiments using gels as a growth medium.
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  • 59
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    Plant and soil 203 (1998), S. 269-277 
    ISSN: 1573-5036
    Keywords: fertilization ; pH ; phosphorus ; rice ; sodicity ; sodium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rice seedlings transplanted into sodic soil are exposed to an excess of potentially toxic ions as well as nutritional imbalance, both of which adversely affect their growth and yield. The present study was aimed to investigate the beneficial effects of fertilization with phosphorus and potassium on the plants at varying sodicity levels and also the response of genotypes with known variability in their tolerance to sodicity. In pot-house experiments during two seasons, the alleviating effects of P and K fertilization on three rice genotypes were examined at four sodicity levels. Seedlings of CSR13 and Jaya (both moderately tolerant to sodicity), died by 25–35 days after transplanting in sodic soils of pH 9.7–9.9 where Olsen's P was 12.5 and 14.8 kg/ha, respectively. However, there was no problem of survival or growth in these soils when Olsen's P was 17.6 and 20.8 kg/ha. Depletion in P from 12.0 kg to 10 kg resulted in some mortality of the seedlings even at pH 9.1. Sodicity tolerant genotype CSR10, did show some survival and growth even at pH 9.9 with Olsen's P at 14.8 kg/ha (without P fertilization) which suggests that differences in tolerance to sodicity which exist at genotypic level are not masked by low P. None of the three genotypes showed any survival problem at pH 8.0 and 8.1 with Olsen's P at 8.5 and 8.7 kg/ha, respectively. Seedlings in P fertilized sodic soils not only produced significantly more new roots but also higher root biomass than those in unfertilized sodic soils and these roots seem to have some control on Na uptake as reflected by low Na concentration in the shoots. Thus, P fertilization not only improved P and K status of plants but also reduced the concentration of potentially toxic Na ions in shoots, resulting in better survival, growth and yield. Although fertilization with K alone did improve shoot K content, it had no significant effect on reducing Na. So the mortality of the seedlings or grain yield in K fertilized sodic soils was as good as in control and this could be explained on the basis of lack of any significant difference in Na concentrations in shoots between these two treatments.
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  • 60
    ISSN: 1573-5036
    Keywords: grassland ; nitrogen ; nutrient competition ; phosphorus ; plant diversity ; potassium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Many studies carried out during these last few years have focused on the factors influencing plant diversity in species-rich grasslands. This is due to the fact that these ecosystems, among the most diversified in temperate climates, are extremely threatened; in some areas, they have almost disappeared. The re-establishment of these habitats implies to know the living conditions of the associations to be recreated. Very often, the typical species of these communities have become so rarefied that the seed bank or the seed rain are not sufficient to recreate the plant community. Most of the time, to achieve the restoration of these communities, they have to be totally recreated by sowing. For the restoration or the maintenance of the community, the soil chemical characteristics have also to be appropriate or if not modified. This research tends to establish a relation between some soil chemical factors and the plant diversity of a great number of stations. This research has illuminated the relationship between soil extractable phosphorus and potassium and plant diversity. Over 5 mg of phosphorus per 100 g of dry soil (acetate + EDTA extraction), no station containing more than 20 species per 100 m2 has been found. The highest number of species is found below the optimum content of the soil for plant nutrition (5–8 mg P/100 g). Concerning the potassium, the highest number of species is found at 20 mg/100, a value corresponcing to an optimum content of the soil for plant nutrition. High potassium contents, in opposition to phosphorus contents, are thus compatible with high values of diversity. Other factors (i.e. pH, organic matter, total nitrogen and calcium) do not show so clearly a relation with plant diversity. Excess of N–NO3 is known for its negative effect on the diversity of plant communities. In these environments, apart from the atmospheric deposits which can be important in some areas, N–NO3 is derived mainly from the symbiotic fixation of atmospheric nitrogen by legumes as well as from the mineralization of the organic matter of the soil. It is possible that, when in small quantities, the available soil phosphorus could be a limiting factor of the N–NO3 supply by these two sources. In this hypothesis, nitrogen would remain the main element limitating plant diversity but its availability would be controlled by phosphorus.
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  • 61
    ISSN: 1573-5036
    Keywords: climate change ; Ecotron ; microbial biomass ; microbial community structure ; soil enzymes ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We investigate the response of soil microorganisms to atmospheric CO2 and temperature change within model terrestrial ecosystems in the Ecotron. The model communities consisted of four plant species (Cardamine hirsuta, Poa annua, Senecio vulgaris, Spergula arvensis), four herbivorous insect species (two aphids, a leaf-miner, and a whitefly) and their parasitoids, snails, earthworms, woodlice, soil-dwelling Collembola (springtails), nematodes and soil microorganisms (bacteria, fungi, mycorrhizae and Protista). In two successive experiments, the effects of elevated temperature (ambient plus 2 °C) at both ambient and elevated CO2 conditions (ambient plus 200 ppm) were investigated. A 40:60 sand:Surrey loam mixture with relatively low nutrient levels was used. Each experiment ran for 9 months and soil microbial biomass (Cmic and Nmic), soil microbial community (fungal and bacterial phospholipid fatty acids), basal respiration, and enzymes involved in the carbon cycling (xylanase, trehalase) were measured at depths of 0–2, 0–10 and 10–20 cm. In addition, root biomass and tissue C:N ratio were determined to provide information on the amount and quality of substrates for microbial growth. Elevated temperature under both ambient and elevated CO2 did not show consistent treatment effects. Elevation of air temperature at ambient CO2 induced an increase in Cmic of the 0–10 cm layer, while at elevated CO2 total phospholipid fatty acids (PLFA) increased after the third generation. The metabolic quotient qCO2 decreased at elevated temperature in the ambient CO2 run. Xylanase and trehalase showed no changes in both runs. Root biomass and C:N ratio were not influenced by elevated temperature in ambient CO2. In elevated CO2, however, elevated temperature reduced root biomass in the 0–10 cm and 30–40 cm layers and increased N content of roots in the deeper layers. The different response of root biomass and C:N ratio to elevated temperature may be caused by differences in the dynamics of root decomposition and/or in allocation patterns to coarse or fine roots (i.e. storage vs. resource capture functions). Overall, our data suggests that in soils of low nutrient availability, the effects of climate change on the soil microbial community and processes are likely to be minimal and largely unpredicatable.
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  • 62
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    Plant and soil 207 (1998), S. 77-86 
    ISSN: 1573-5036
    Keywords: Cedar Creek ; Minnesota ; light ; root respiration ; Scizachyrium scorparium ; soil CO2 flux ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ecosystem studies often study soil CO2 flux as a function of environmental factors, such as temperature, that affect respiration rates by changing the rate of utilization of carbon substrates. These studies tend not to include factors, such as photosynthesis, that affect the supply of carbon substrates to roots and root-associated processes. We examined the role of decreased carbohydrate source on soil CO2 flux and root respiration in an annually-burned grassland through manipulations of light intensity and removal of above ground biomass. We also quantified the contribution of root respiration to soil CO2 flux by measuring the respiration rates of excised roots. Two days of shading caused a 40% reduction in soil CO2 flux, while clipping was associated with a 19% reduction in soil CO2 flux. Both reductions were independent of soil and air temperature at the time of measurement. The relative decrease in soil CO2 flux observed in the clipping experiment was similar in magnitude to an observed decrease in root respiration per gram of root, linking decreased root activity and soil CO2 flux. From these experiments, we conclude that variation in factors that affect carbon availability to roots can be important determinants of soil CO2 flux and should be included explicitly in studies that measure or model soil CO2 flux.
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  • 63
    ISSN: 1573-5087
    Keywords: Solanum tuberosum ; tissue culture ; jasmonic acid ; sucrose uptake ; photosynthetic pigments ; xanthophyll cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Potato (Solanum tuberosum L., cv. Sante) plantlets grown from stem node culture on medium supplemented with 90 mM sucrose accumulated lower amounts of photosynthetic pigments per mg dry weight in comparison to those grown on 30 mM sucrose. Addition of 0.1, 1 or 10 µM jasmonic acid (JA) to the medium resulted in a decrease of chlorophylls and carotenoids in the plantlets grown on either sucrose concentration. JA treatment induced de-epoxidation of violaxanthin to antheraxanthin and zeaxanthin only in those plantlets grown on a higher amount of sucrose in which hyperhydric symptoms were observed. The synergistic effect of JA and sucrose was clearly demonstrated in the plantlets grown on 90 mM sucrose and 1 µM JA. This was possibly due to overaccumulation of sucrose, the consequence of the most developed root system, and/or to stimulated water and solute transport by other mechanisms.
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  • 64
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    Genetic resources and crop evolution 45 (1998), S. 399-406 
    ISSN: 1573-5109
    Keywords: internal transcribed spacer sequences ; nuclear ribosomal RNA genes ; molecular phylogeny ; Potamophila parviflora ; Oryza sativa ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Potamophila parviflora is a wild relative of rice from Eastern Australia. The species was found in the Richmond, Clarence, Macleay and Hastings River systems of northern New South Wales. Existing populations had wider leaves (10–15 mM) than those previously reported (4–6 mM). This species and North American wild rice, Zizania palustris were investigated as genetic resource for rice improvement. Both species, Potamophila , and Zizania , occur in colder climates than rice (Oryza sativa). Sequencing of the ITS1 of the ribosomal genes of these two species indicated that Zizania and Potamophila were more closely related to each other than either was to Oryza sativa. Potamophila has a similar number of chromosomes (n=12) and a greater sequence homology to rice and may thus be a better source of useful genes for rice improvement.
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  • 65
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    Plant growth regulation 26 (1998), S. 63-66 
    ISSN: 1573-5087
    Keywords: ammonium ; calcium ; leaf senescence ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The possible involvement of calcium in the regulation of ammonium-promoted senescence of detached rice leaves was investigated. Calcium effectively reduced ammonium-promoted senescence of detached rice leaves. The effect of ammonium on the senescence was also significantly reduced by the calcium ionophore A23187. Ammonium-promoted senescence of detached rice leaves may be mediated through blocking the entrance of calcium ions into the cytosol.
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  • 66
    ISSN: 1573-0867
    Keywords: hydrology ; solute transport ; nitrate ; phosphorus ; polypedon scale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Over application of poultry litter may cause pollution of surface and ground water. Spatial variability in soil characteristics makes predictions difficult. Composting poultry litter could reduce the risk of pollution by creating more stable organic components. Three rates of poultry litter and compost (10 Mg ha-1 litter, 20 Mg ha-1 litter and 10 Mg ha-1 litter combined with 50 Mg ha-1 compost) to three watersheds under pasture. The watersheds were monitored for surface and subsurface flow. Nitrate-N concentrations in subsurface flow did not exceed the U.S. Environmental Protection Agency drinking water standard of 10 mg L-1. Soluble phosphorus concentrations in runoff were high, reaching a maximum of 8.5 mg L-1 under the compost treatment. These concentrations are generally lower than reported on smaller scale studies, which shows the need of studies at the correct scale.
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  • 67
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    Nutrient cycling in agroecosystems 51 (1998), S. 193-200 
    ISSN: 1573-0867
    Keywords: cropping systems ; inorganic fertilizer ; nitrogen ; organic carbon ; phosphorus ; potassium ; rice-wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three levels of N (40,80,120 kg N ha-1) and P (0,17.5,35 kg P ha-1), and 2 levels of K (0,33 kg K ha-1) were tested for 19 years in rice and wheat crops of a rice-wheat cropping system in a fixed layout of 3×2×2 factorial partially confounded design along with one control and 3 replications. From this trial, data of 7 treatments, i.e. 0-0-0, 40-35-33, 80-35-33, 120-35-33, 120-0-0, 120-35-0 and 120-0-33 kg ha-1 N-P-K respectively were compared for yield trends, changes in response functions, soil organic -C and available N,P,K status. Soil organic - C decreased in unfertilized plots by 62% (over initial value of 0.45%) but increased by 44, 40 and 36% in plots receiving 120-35-33, 120-35-0 and 80-35-33 kg ha-1 N-P-K respectively. Available N was also greatest in these same three treatments. Available soil P increased by about 5 fold in 15 years in treatments supplied with fertilizer P, but no significant change was detected in treatments without P addition. Yields of rice and wheat exhibited linear declining trend in all treatments. The highest rate of decline (89 kg ha-1 year-1 in rice and 175 kg ha-1 year-1 in wheat), however, was found when 120 kg ha-1 N was applied alone. The least rate of decline of 20 kg ha-1 year-1 in rice and 58 kg ha-1 year-1 in wheat was observed when 40-35-33 kg ha-1 N-P-K respectively was applied to both the crops. At currently recommended levels of NPK (120-35-33 kg ha-1), the rate of decline in yields was 25 kg ha-1 year-1 for rice and 62 kg ha-1 year-1 for wheat. Possible causes of these yield declines are discussed.
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  • 68
    ISSN: 1573-0867
    Keywords: durum wheat ; Glomus mosseae ; micronutrients ; nutrient uptake ; phosphorus ; vesicular-arbuscular ; mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of the vesicular arbuscularmycorrhizal fungus (VAMF) Glomus mosseae ongrowth, yield and nutrients' uptake of the durum wheatvariety ‘Sifnos’ was investigated in ten differentsoils. Inoculation had a positive effect on tillering,improved plant growth up to 11.6 times and increasedgrain yield up to 5.4 times as compared tonon-inoculated plants. The thousand kernels weight wasimproved by up to 60%. The analysis of shoot tissue ofthe mycorrhizal plants showed that P concentration wasincreased up to 4 fold, while the K, Ca and Mg uptakewas similar for both mycorrhizal and non-mycorrhizalplants. The concentrations of the trace elements Mn,Zn, Fe and Cu were lower in the mycorrhizal plantscompared to that of non-inoculated ones. The P and Mgconcentration of the grains produced by the inoculatedplants was increased while the Ca concentration wasdecreased. The concentration of the heavy metals waseither decreased ( Mn, Fe, Co, Cr, Ni, Pb) or remainedunchanged (Zn, Cu). The colonization in the roots ranged from 23 to 78%.
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  • 69
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    Agroforestry systems 42 (1998), S. 107-120 
    ISSN: 1572-9680
    Keywords: erosion ; Gliricidia sepium ; Oryza sativa ; Paspalum conjugatum ; Penisetum purpureum ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Farming systems that minimize the rate of soil degradation and optimize food crop yields are needed to sustain soil productivity on sloping, acid, infertile soils in the humid tropics. Research was conducted on two Oxisols with slopes ranging from 22 to 30% to evaluate the performance of several contour hedgerow systems, with and without the addition of 60 kg N ha−1 per crop, on rice (Oryza sativa) and maize (Zea mays L.) production. Contour hedgerows were double rows of the tree legume Gliricidia sepium (G); Gliricidia and the native grass Paspalum conjugatum (GPas); Gliricidia and an exotic fodder grass Penisetum purpureum (GPen); double rows of Penisetum (Pen); and a conventional open field (C) farming system without hedgerows. Gliricidia prunings and all crop residues were applied to the soil surface in the alleys, but Penisetum was harvested. Food crop yields in all hedgerow treatments tended to be less than the Control for the first two years, presumably due to the displacement of land planted to the food crop. In the third and the fourth years, the rice and maize yields of Treatments G and GPas exceeded the Control, most consistently when N was not applied. Penisetum reduced food crop yields regardless of N application presumably due to nutrient removal in the fodder. The results indicate that Gliricidia in a contour hedgerow increases food crop yield on strongly acid Oxisols by recycling nutrients and partially supplementing the N demand by the food crops.
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  • 70
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    Plant growth regulation 24 (1998), S. 17-21 
    ISSN: 1573-5087
    Keywords: leaf senescence ; lipid peroxidation ; methyl jasmonate ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Lipid peroxidation in relation to MJ-promoted senescence of detached rice leaves was investigated. Lipid peroxidation seems to be involved in the regulation of MJ-promoted senescence of detached rice leaves. This conclusion was based on the observations that (a) methyl jasmonate, which was found to promote senescence, increases the level of lipid peroxidation, (b) linolenic and linoleic acid, precursors of the biosynthesis of jasmonic acid, promoted senescence and increased lipid peroxidation level, (c) benzyladenine, a synthetic cytokinin, counteracted MJ-promoted senescence and reduced the increase in lipid peroxidation level, (d) calcium chloride effectively reduced MJ-promoted senescence and at the same time reduced MJ-promoted lipid peroxidation. Free radical scavengers (reduced glutathione and sodium benzoate) and an iron chelator (2, 2′-bipyridine) prevented MJ-promoted senescence, suggesting that lipid peroxidation induced by MJ is mediated through free radicals.
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  • 71
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    Euphytica 100 (1998), S. 95-100 
    ISSN: 1573-5060
    Keywords: genetic variation ; wheat genotypes ; nitrogen ; phosphorus ; potassium ; breeding ; low-input cultivars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nutrient efficiency in wheat is very complex. It includes two major types: nutrient acquisition efficiency and nutrient use efficiency. Various studies on wild, landraces, old, intermediate and new genotypes of cereals showed that the new varieties produced higher grain yields than the old varieties, and were also more efficient at using nutrients. Several spring wheat cultivars, representing almost all cultivars of spring wheat, released from the Federal Office for Cultivar Registration, Germany and published in the 'Descriptive List of Cultivars', were used to investigate the interactive effects between genotypes and the use efficiencies of the three macro nutrients N, P and K by the grain and straw. The results obtained in this study indicate that nutrient use efficiency of the single nutrients varies widely within recent cultivars. Some cultivars were identified as being multiple-nutrient use efficient. These are considered low-input cultivars. It appears that a special breeding programme of crop cultivars for low nutrient and stress conditions could be successful. Improved cultivar response to nutrients will help to reduce inputs and hence protect the environment.
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  • 72
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    Euphytica 102 (1998), S. 151-161 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; head rice ; seeding date ; rice ; rough rice yield ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The rice (Oryza sativa L.) crop in Arkansas is seeded from late March through early June each year. Farmers need new rice cultivars that not only produce both high rough rice yields and high head rice across this range of seeding dates but do so consistently. Thus, a seeding date study was conducted during 1994 and 1995 at Stuttgart, Arkansas, to study seeding date effects on rough rice yield and head rice and selection for stability. Fourteen rice cultivars were seeded at five dates ranging from late March through mid-June. Kang's yield-stability statistic was used to select cultivars for both high rough rice yields and high head rice as well as stability for both traits. Plant stands from March seedings of each year were significantly lower than for the later seeding dates. Maturity (days to 50 percent heading) was extended at the early seeding dates. Some rice cultivars, such as ‘LaGrue’, had lower and more variable head rice when seeded early. In the June seeding dates each year, ‘Kaybonnet’ produced rough rice yields that were more consistent with yields when planted at the earlier planting dates. ‘Bengal’, ‘Cypress’, ‘Kaybonnet’, and ‘Newbonnet’ were cultivars selected by Kang's stability statistic, which was targeted to select cultivars with stable, high rough rice yields and stable, high head rice. The validity of using Kang's yield-stability statistic for cultivar selection is also evident empirically by the adaptation and wide use of these four cultivars by southern U.S. rice producers. These results indicate that seeding date studies and stability analyses would be useful tools for rice breeders to identify cultivars that will be readily adapted and grown by rice producers.
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  • 73
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    Euphytica 102 (1998), S. 117-124 
    ISSN: 1573-5060
    Keywords: sea buckthorn ; climate ; freezing ; germination ; ice nucleators ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The main aim of the investigation was to study the effects of climate on the ice nucleation temperatures of fruit juice from sea buckthorn, Hippophaë rhamnoides L. This could provide information on possible adaptive values of ice nucleators in the fruits. It was also an aim to provide information on ice nucleation of fruit juice from different varieties of sea buckthorn. This was done to find suitable varieties for agricultural production of ice nucleator containing fruit juice. Such food grade ice nucleators can be used in the processing of food stuffs particularly where large ice crystals are desired. The ice nucleation temperatures were low in juice from unripe fruits in the summer, and peaked at − 6 °C in the autumn. There were no significant differences in nucleation temperatures in juice from fruits grown along a climatic gradient along the Trondheimsfjord. Juice from varieties originating from different parts of the world, but grown at the same fields, showed different mean nucleation temperatures, ranging from − 15.1 °C in a Swiss wild type of subsp. fluviatilis to − 6.1 °C in a Swedish wild type of subsp. rhamnoides. Varieties with very potent nucleators (− 2 °C to − 3 °C) were found, but these nucleators were present in low concentrations. Varieties with high concentration of nucleators within a small temperature range (− 6 °C to − 7 °C) were also found. No correlation between geographic origin and nucleation temperatures was found. Depending on conditions, freezing the fruits had either no, or a negative effect on the germination success. Since no adaptive benefit to the sea buckthorn could be demonstrated, the nucleating ability of the fruit juice is probably incidental.
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  • 74
    ISSN: 1573-5060
    Keywords: chromosome elimination ; pollen fertility ; RFLP markers ; Solanum acaule ; Solanum tuberosum ; somatic hybrids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Eleven somatic hybrids (2n = 68 to 74) obtained between S. tuberosum ssp. tuberosum cv. Dejima (2n = 48) and ATDH-1 (2n = 24), an anther-culture-derived dihaploid of S. acaule (Yamada et al., 1997), were characterized by nuclear RFLP markers using 49 single-copy DNA probes distributed throughout the potato genome (2 to 6 probes per chromosome). One of the somatic hybrids, DA8-2, had 72 chromosomes and all the Dejima- and ATDH-1-specific markers (124 and 103 bands, respectively), suggesting the presence of a whole set of both parental chromosomes. The other somatic hybrids lost varying numbers of markers up to seventeen. The pattern of the loss of markers indicated the elimination of five chromosomes among four somatic hybrids. A nucleolar organizer region of chromosome 2 was often eliminated in the somatic hybrids. The somatic hybrids studied here had higher frequencies of multivalent formation than the S. tuberosum parent. They had reasonably good seed set when pollinated with S. tuberosum pollen. Hence, homoeologous recombination between S. acaule and S. tuberosum chromosomes is possible and useful traits from S. acaule may be transferred to the S. tuberosum gene pool.
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  • 75
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    Euphytica 103 (1998), S. 67-74 
    ISSN: 1573-5060
    Keywords: in vitro selection ; micropropagation ; potato breeding ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effectiveness of in vitro selection for agronomic characters was studied by finding correlation coefficients between in vitro and in vivo performance of 22 potato genotypes. Evaluation was performed under eight in vitro and two in vivo conditions. Genotypic differences were highly significant for various characters under all in vitro and in vivo conditions. Error mean squares were much lower in in vitro experiments than in in vivo experiments. In vitro selection was found to be highly effective for tuber colour, stem pigment and number of eyes, and moderately effective for average tuber weight, plant vigour and foliage senescence under specific conditions. The results also indicated the possibility of in vitro selection for heat tolerance. For tuber yield and number of tubers, effectiveness of in vitro selection was low to very low, because differences in phenotypic expressions of genotypes were much enlarged under in vitro conditions compared to under in vivo conditions. Correlation coefficients for certain characters were better when in vitro conditions were closer to in vivo conditions. To improve the efficiency of in vitro selection, there is perhaps a need to simulate and identify the in vitro conditions under which genotypic differences are reflected in phenotypes more realistically as they are expressed under in vivo conditions.
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  • 76
    ISSN: 1573-5060
    Keywords: heterosis ; heterosis × environment interaction ; Oryza sativa ; rice ; standard heterosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Moderate to high heterosis for yield and ten related characters was studied in 45 crosses involving six indica (I) and four tropical japonica (J) varieties of rice under three (E1-optimum sowing and high fertility, E2-both optimum sowing and fertility and E3- late sowing and high fertility) environments. Trends of magnitude of heterosis for grain yield and plant height were I/J 〉 I/I 〉 J/J and for days to 50% flowering I/J 〉 J/J 〉 I/I hybrids. Estimates of standard heterosis (%) for grain yield were –64.5 to 146.1 in E1, –70.4 to 82.2 in E2 and –67.2 to 63.8 in E3. Environment E1 seemed to be more favorable for higher heterosis expression than others. Higher heterosis in yield also accompanied heterosis in panicle number, dry matter and spikelet and grain number per panicle. Most estimates for days to flower were negative. Heterotic I/J hybrids also recorded maximum heterosis for earliness. Moderate to low standard heterosis for plant height across environments (2.0 to 13.7%) was recorded. Hybrids were identified in specific environments for direct exploitation in hybrid breeding. Hybrids B4116 / Sarjoo 52, B4122 / Pant Dhan 4 and B4122 / Narendera 359 were more stable than others over three environments.
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  • 77
    ISSN: 1573-5036
    Keywords: leaf expansion rate ; phosphorus ; phyllochron ; plastochron ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In two simultaneous experiments we examined the effects of phosphorus (P) supply on leaf area development in wheat (Triticum aestivum L.) grown in sand with nutrient solutions. In Experiment 1 we studied leaf emergence, leaf elongation, tiller emergence, shoot growth, and P uptake under four levels of P supply (mM) 0.025 (P1), 0.05 (P2), 0.1 (P3), and 0.5 (P4), and. In Experiment 2 there were two levels of P supply, P1 and P4, and we examined the effects of P on leaf primordia differentiation and leaf emergence. The phyllochron was calculated as the inverse of the rate of leaf emergence calculated from the regression of number of leaf tips (PHY-Ltip), Haun index (PHY-Haun), and as the cumulated thermal time between the emergence of two consecutive leaves (PHYtt). The plastochron was calculated from the inverse of the rate of leaf primordia initiation in the apex. P deficiency delayed the emergence of leaves on the main stem and on the tiller 1. Phosphorus deficiency increased the time from emergence to double ridge and anthesis. The final number of leaves was not affected by P. The effects of P on the value of the phyllochron were attributed to both a reduced rate of leaf primordia initiation, and to a reduced leaf elongation rate. P deficiency delayed or even suppressed the emergence of certain tillers. In this work a phosphorus deficiency that reduced shoot growth by 25% at 44 days after emergence significantly modified the structure of the plants by increasing the value of the phyllochron and delaying tillering. These results suggest that any attempt to simulate leaf area development and growth of wheat plants for P-limited conditions should include the effects of the deficiency on leaf emergence.
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  • 78
    ISSN: 1573-5036
    Keywords: leaf expansion rate ; modelling ; phosphorus ; photosynthesis ; sunflower
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Reductions in leaf area and plant growth as a consequence of phosphorus (P) limitations have been attributed both to direct effects of P shortage on leaf expansion rate and to a reduced production of assimilates required for growth. Canopy assimilation and leaf area expansion are closely interrelated processes. In this work we used experimental and simulation techniques to identify and study their importance in determining leaf area on sunflower (Helianthus annuus L.) growing under P-deficient conditions. Experiment 1 was done outdoors, in Buenos Aires, Argentina, and Experiment 2 in a glasshouse in Wageningen, The Netherlands. In both experiments we studied the effects of soil P addition on leaf appearance, leaf expansion, dry matter accumulation, and leaf photosynthesis of non-water stressed plants grown in pots containing a P-deficient soil. Before sowing the equivalent amounts of 0–600 kg of super phosphate ha-1 were added to the pots. Phosphorus deficiency delayed leaf appearance increasing the value of the phyllochron (PHY) up to 76%, the rate of leaf area expansion during the quasi-linear phase of leaf expansion (LER) was reduced by up to 74%, with respect to high P plants. Phosphorus deficiency reduced by up to 50% the rate of light saturated photosynthesis per unit of leaf area (AMAX) in recently expanded leaves, while at low levels of leaf insertion in the canopy, AMAX was reduced by up to 85%, when compared to that in high P plants. Phosphorus deficiency also reduced the duration of the quasi-linear phase of leaf expansion by up to eight days. The values of LER were related (r = 0.56, P 〈 0.05) to the mean concentration of P in all the leaves (Leaves P%) and not to the concentration of P in the individual leaf where LER was determined (r = 0.22, P 〈 0.4) suggesting that under P deficiency individual leaf expansion was not likely to be regulated by the total P concentration at leaf level. The values of AMAX of individual leaves were related (r = 0.79, P 〈 0.01) to the concentration of total P in the corresponding leaf (Leaf P%). LER showed a hyperbolic relationship with Leaves P% (R2 = 0.94, P 〈 0.01, n = 13) that saturate at 0.14%. AMAX showed a hyperbolic relationship with Leaf P% (R2 = 0.73, P 〈 0.01, n = 53) that saturated with values of Leaf P% higher than 0.22. A morphogenetic model of leaf area development and growth was developed to quantify the effect of assimilate supply at canopy level on total leaf area expansion, and to study the effects of model parameters on the growth of sunflower plants under P-deficient conditions. With this model we identified the existence of direct effects of P deficiency on individual leaf area expansion. However, we calculated that under mild P stress conditions up to 83% of the reduction in the observed leaf area was explained by the particular effects of P% on the rate of leaf appearance, on the duration of the linear period of leaf expansion, and on the value of AMAX. We also calculated that the effects of P deficiency on the value of AMAX alone, explained up to 41% of the observed reductions in total leaf area between the highest and the intermediate P level in Experiment 2. Possible mechanisms of action of the direct effects of P on individual leaf expansion are discussed in this paper.
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  • 79
    ISSN: 1573-5036
    Keywords: acid soils ; endophyte ; ergot alkaloids ; Festuca arundinacea ; Neotyphodium coenophialum ; phosphorus ; tall fescue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tall fescue (Festuca arundinacea Schreb.) plants infected by the fungal endophyte Neotyphodium coenophialum (Morgan-Jones & Gams) (Glenn et al., 1996) often perform better than noninfected plants, especially in marginal resource environments. There is a lack of information about endophyte related effects on the rhizosphere of grasses. In a greenhouse experiment, four endophyte-infected (E+) tall fescue clones (DN2, DN4, DN7, DN11) and their endophyte-free (E−) forms were grown in limed (pH 6.3) Porter soil (low fertility, acidic, high aluminum and low phosphorus content, coarse-loamy mixed mesic Umbric Dystrochrept) at three soil P levels (17, 50, and 96 mg P kg-1 soil) for five months. Excluding the genotype effect, endophyte infection significantly increased cumulative herbage DM yield by 8% at 17 mg P kg-1 soil but reduced cumulative herbage DM yield by 12% at 96 mg P kg-1 soil. With increased P availability in the soil, shoot and root DM, and root/shoot ratio in E+ plants were significantly less when compared to E− plants. Endophyte infection increased specific root length at 17 and 50 mg P kg-1soil. At soil P level of 17 mg P kg-1soil, E+ plants had significantly higher P concentrations both in roots and shoots. Similar relationships were found for Mg and Ca. E+ plants had significantly higher Zn, Fe, and Al concentration in roots, and lower Mn and Al concentration in shoots when compared to E− plants. Ergot alkaloid concentration and content in shoot of E+ plants increased with increasing P availability in the soil from 17 to 50 mg P kg-1 but declined again at 96 mg P kg-1 soil. Ergot alkaloid accumulation in roots increased linearly with P availability in the soil. Results suggest that endophyte infection affects uptake of phosphorus and other mineral nutrients and may benefit tall fescue grown on P-deficient soils. Phosphorus seems also to be involved in ergot alkaloid accumulation in endophyte-infected tall fescue.
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  • 80
    ISSN: 1573-5036
    Keywords: carbon ; cultivation ; deforestation ; nitrogen ; phosphorus ; tropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The study area, within the Simlipal National Park, India, provides a rare variety of soil sampling sites. These include virgin forests in the proximity of several cultivated areas (where no chemical fertilizers or any modern technology has been used and where periods of cultivation vary from 5 to a little over 100 yr); samples from evergreen forests, deciduous forests and natural grasslands could also be obtained. The availability of numerous such samples made it possible to use statistical methods to evaluate the changes. This study showed that deforestation and cultivation result in statistically significant (P0.05) reduction in organic C, total N and C:N ratios but no significant changes in total and available P levels; C:P and N:P ratios are also reduced. Loss of organic C and N occurs rapidly in the first 15 yr of cultivation and reaches quasi-steady state values around 1–2% organic C and 0.1–0.2% total N; extent of reduction is not related to initial levels. Significant reduction in C:N, C:P ratios following cultivation suggest that mineralisation losses of C are higher than loss of N whereas loss of P is lowest. Lack of significant correlation between organic C and P levels in all types of soils, suggests that the bulk of the P is in the inorganic form. Highest levels of organic C and N were observed in evergreen forests followed by deciduous forests, grasslands and cultivated areas in that order; total and available P levels, however, showed no significant differences. Evergreen vegetative cover appears to provide the ideal environment for organic matter accumulation.
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  • 81
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    Plant and soil 199 (1998), S. 177-186 
    ISSN: 1573-5036
    Keywords: colonization ; crop rotation ; harvest index ; maize ; mycorrhizae ; phosphorus ; tillage ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We conducted a field experiment to test the hypothesis that improved phosphorus nutrition occurs in maize plants with rapid arbuscular (AM) mycorrhizae development at early developmental stages and that this also is reflected in dry matter allocation and final yield. A split-split plot design was used with previous crop (Zea mays L.-maize and Brassica napus L.-canola), tillage practices (no-tillage or conventional tillage) and P fertilization (5 levels) as factors chosen to modify mycorrhizae development at early developmental stages of maize. Previous cropping with canola resulted in decreased shoot-P concentration and shoot growth of maize at early stages. No-tillage resulted in higher shoot-P concentration but lower shoot weight than conventional tillage. Greater shoot-P uptake was related to a rapid intraradical development of mycorrhizae (previous crop of maize) or rapid connection to a mycorrhizal mycelium network (no-tillage treatments). Maize yield and harvest index were lower after cropping with canola. The yield for conventional tillage was higher than that for no-tillage but the harvest index was lower. The hypothesis was supported at early stages of maize growth by the effect of previous crop but not by results of tillage, because an unknown factor reduced growth in the no-tillage system. The hypothesis was supported at maturity by increased biomass allocation to grain relative to total shoot weight in treatments with greater shoot-P concentration at early stages.
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  • 82
    ISSN: 1573-5036
    Keywords: leaf expansion rate ; modelling ; phosphorus ; photosynthesis ; phyllochron ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Under phosphorus deficiency reductions in plant leaf area have been attributed to both direct effects of P on the individual leaf expansion rate and to a reduced availability of assimilates for leaf growth. In this work we use experimental and simulation techniques to identify and quantify these processes in wheat plants growing under P-deficient conditions. In a glasshouse experiment we studied the effects of soil P addition (0–138 kg P2O5 ha-1) on tillering, leaf emergence, leaf expansion, plant growth, and leaf photosynthesis of wheat plants (cv. INTA Oasis) that were not water stressed. Plants were grown in pots containing a P-deficient (3 mg P g-1 soil) sandy soil. Sowing and pots were arranged to simulate a crop stand of 173 plants m-2. Experimental results were integrated in a simulation model to study the relative importance of each process in determining the plant leaf area during vegetative stages of wheat. Phosphorus deficiency significantly reduced plant leaf area and dry weight production. Under P-deficient conditions the phyllochron (PHY) was increased up to a 32%, compared to that of high-P plants. In low-P plants the rate of individual leaf area expansion during the quasi-linear phase of leaf expansion (LER) was significantly reduced. The effect of P deficiency on LER was the main determinant of the final size of the individual leaves. In recently expanded leaves phosphorus deficiency reduced the photosynthesis rate per unit leaf area at high radiation (AMAX), up to 57%. Relative values of AMAX showed an hyperbolic relationship with leaf P% saturating at 0.27%. Relative values of the tillering rate showed an hyperbolic relationship with the shoot P% saturating at values above 0.38%. The value of LER was not related to the concentration of P in leaves or shoots. A morphogenetic model of leaf area development and growth was developed to quantify the effect of assimilate supply at canopy level on total leaf area expansion, and to study the sensitivity of different model variables to changes in model parameters. Simulation results indicated that under mild P stress conditions up to 80% of the observed reduction in plant leaf area was due to the effects of P deficiency on leaf emergence and tillering. Under extreme P-deficient conditions the simulation model failed to explain the experimental results indicating that other factors not taken into account by the model, i.e. direct effects of P on leaf expansion, must have been active. Possible mechanisms of action of the direct effects of P on individual leaf expansion are discussed in this work.
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  • 83
    ISSN: 1573-5060
    Keywords: wheat quality ; temperature ; heat shock ; polymeric protein ; nitrogen application ; breadmaking quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In southern Europe, the Mediterranean climate offers a unique opportunity for the production of high quality wheats, which are lacking in the European Economic Union. It is also responsible for the remarkable variability in both wheat yield and quality from year to year and from location to location. In this paper, the effects (in recent years) of the Mediterranean climate in Italy on grain yield and quality of bread and durum wheats are summarised with particular regard to high temperatures. Nitrogen fertilisation rate and timing were investigated in five cultivars grown at six sites. The impact of high temperature was evaluated in open field and pot experiments by imposing different temperature regimes during grain filling. Viscoelastic properties were evaluated with the Chopin alveograph for field experiments and with a Promylograph T3 apparatus for pot experiments. Protein composition was evaluated by SE-HPLC (size exclusion high performance liquid chromatrography). Agronomic trials indicated that high quality wheats can be obtained in a wide range of growing conditions. Viscoelastic properties were significantly affected by the temperature treatments. Short episodes of daily maximum temperatures above 35 °C caused a 'weakening' in both durum and bread wheat. High temperatures seemed to affect mainly the composition of the polymeric fraction (soluble/insoluble polymers) without influencing their synthesis.
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  • 84
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    Euphytica 103 (1998), S. 83-88 
    ISSN: 1573-5060
    Keywords: chlorophyll ; lethal ; marker gene ; photosynthesis ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A light green mutant was found in a population of adapted cultivated diploid potatoes. Genetic analysis indicates that this trait is controlled by a single nuclear gene. The gene symbol lg is proposed. The segregation ratios fit a pattern which strongly suggest that there is a close linkage between the Lg allele and a locus which confers lethality in its homozygous recessive state. Some crossing over between the lg locus and the lethal was found to occur but LgLg genotypes were not observed in progenies from sib-matings. The lg locus mapped to the potato linkage group VI between the restriction fragment length polymorphism (RFLP) loci CP18 and GP24.
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  • 85
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    Plant growth regulation 25 (1998), S. 165-169 
    ISSN: 1573-5087
    Keywords: ammonium ; leaf senescence ; Oryza sativa ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ammonium accumulation in relation to water stress-promoted senescence of detached rice leaves was investigated. The effect of water stress on the senescence of detached rice leaves is associated with the accumulation of ammonium. The accumulation of ammonium in detached rice leaves by water stress is attributed to a decrease in glutamine synthetase activity. Ammonium accumulation in detached rice leaves, induced by water stress, was accompanied by an increase in tissue sensitivity to ethylene which, in turn, accelerated leaf senescence.
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  • 86
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    Plant growth regulation 25 (1998), S. 11-15 
    ISSN: 1573-5087
    Keywords: ascorbate peroxidase ; glutathione reductase ; Oryza sativa ; peroxidase ; senescence ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The possible role of H2O2 metabolism on light-regulated senescence of detached rice leaves was investigated. Light retards senescence but at the same time accumulates more H2O2. Light treatment resulted in an increase in malondialdehyde level in detached rice leaves but no membrane leakage was observed in light-treated detached leaves. It seems that there was no direct relationship between lipid peroxidation and deterioration in membrane integrity. The results obtained suggest that retardation of senescence by light is closely related to high activities of superoxide dismutase and ascorbate peroxidase.
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  • 87
    ISSN: 1572-9788
    Keywords: comparative mapping ; database ; genetic linkage ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An AFLP marker catalogue is presented for gene mapping within cultivated potato. The catalogue is comprised of AFLP fingerprint images of 733 chromosome-specific AFLP markers which are mapped relative to 220 RFLP loci, isozyme loci, morphological characteristics and disease resistance traits. Use of the catalogue is based on identification of common AFLP markers which are visually recognized on autoradiogram images as co-migrating bands in fingerprints generated from different genotypes. Images of AFLP fingerprints combined with detailed information on the genomic location of all AFLP markers are available at URL: http://www.spg.wau.nl/pv/aflp/catalog.htm. It is demonstrated that the comparison of autoradiogram images and subsequent identification of common AFLP markers solely are efficient means for alignment of linkage groups and mapping target genes.
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  • 88
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    Journal of applied electrochemistry 27 (1997), S. 1198-1206 
    ISSN: 1572-8838
    Keywords: alloy ; amorphous ; anomalous ; hydrogen ; iron ; nickel ; phosphorus ; plating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this study we have investigated the electrodeposition of amorphous iron–nickel–phosphorus alloys from a sulfate electrolyte. Fe-Ni alloys are known to exhibit an ’anomalous‘ type of plating behaviour in which deposition of the less noble metal is favoured. We have found that the codeposition of phosphorus from hypophosphite in the electrolyte led to a reversal to a ’normal‘ behaviour. This reversal was due both to the suppression of iron and enhancement of nickel partial currents. The overall deposition process is dominated by the hydrogen evolution reaction. This is exacerbated by the low pH needed to codeposit sufficient phosphorus to achieve an amorphous structure.
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  • 89
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    Journal of applied electrochemistry 27 (1997), S. 1328-1332 
    ISSN: 1572-8838
    Keywords: metal hydride ; capacity ; temperature ; performance ; enthalpy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The effect of temperature on the performance of a LaNi4.76Sn0.24 metal hydride electrode was investigated in the temperature range of 0 to 50°C. The electrode showed a maximum discharge capacity at 25°C. The total resistance increases with a decrease of temperature from 50°C to 0°C. The apparent activation enthalpies at different states of charge were determined by evaluating the polarization resistance at different temperatures. It was found that the apparent activation enthalpy is an indicator of the relative reaction rate of the charge-transfer reaction and hydrogen absorption.
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  • 90
    ISSN: 1432-0789
    Keywords: Cyanobacteria ; Soil inoculation N ; transformation ; Inorganic N ; Easily oxidizable N ; Hydrolysable N ; Non-hydrolysable N ; Wetland rice Farmyard manure ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field experiment was conducted with wetland rice (Oryza sativa cv. IR-36) in a sandy clay loam soil (Entisol) to study the effect of inoculation with a soil-based mixed culture of four diazotrophic cyanobacteria,Aulosira fertilissima, Nostoc muscorum, N. commune andAnabaena spp., on the N-flux in inorganic NH4 ++NO3 −+ NO2 −), easily oxidizable, hydrolysable and non-hydrolysable forms of N in soil during vegetative growth periods of the crop. Effects on grain and straw yield and N uptake by the crop were estimated. The effects of applying urea N and N as organic sources, viz.Sesbania aculeata, Neem (Azardirachta indica) cake and FYM, each at the rate of 40 kg N ha−1, to the soil were also evaluated. Inoculation significantly increased the release of inorganic N, evidenced by its increased concentrations either in soil or in soil solution. However, such increases rarely exceeded even 4% of total N gained in different froms in the soil system by inoculation during the vegetative growth stages of the rice plant, when the nutritional requirement of the plants is at a maximum. Most of the N2 fixed by cyanobacteria remained in the soil as the hydrolysable form (about 85%) during this period. Inoculation caused an insignificant increase in grain (8%) and straw (11%) yield, which was, however, accompanied by a significant increase in N uptake by the grain (30%) and an increase in total uptake of 15.3 kg N ha 1. Such beneficial effects of inoculation varied in magnitude with the application of organic sources, with farmyard manure (FYM) being the most effective. Application of urea N, on the other hand, markedly reduced such an effect.
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  • 91
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    Biology and fertility of soils 25 (1997), S. 285-289 
    ISSN: 1432-0789
    Keywords: Key words Methane emission ; Wetland soils ; Greenhouse gases ; Inceptisol ; Vertisol ; Rice ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a greenhouse study, methane emissions were measured from two diverse Indian rice-growing soils planted to five rice cultivars under similar water regimes, fertilizer applications and environmental conditions. Significant variations were observed in methane emitted from soils growing different cultivars. Total methane emission varied between 8.04 and 20.92gm–2 from IARI soil (Inceptisol) and between 1.47 and 10.91gm–2 from Raipur soil (Vertisol) planted to rice. In all the cultivars, emissions from IARI soil were higher than from Raipur soil. The first methane flux peak was noticed during the reproductive phase and the second peak coincided with the grain-ripening stage of the rice cultivars.
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  • 92
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    Biology and fertility of soils 24 (1997), S. 70-75 
    ISSN: 1432-0789
    Keywords: Flooded rice soil ; Soil-trapped CH4 and C02 ; δ13C values of CH4 and C02 ; Greenhouse effect ; CO2 flux ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pot experiments were conducted to monitor the changes in compositions and δ13C values of soil-trapped CH4 and C02 in flooded rice soil with and without rice plants or rice straw. Incorporation of rice straw increased the concentration of CH4 and C02 accumulated in soil, and the quantities of emitted CH4 to the atmosphere. Rice plants reduced the concentration of soil-trapped CH4 and CO2, and the decreased portion of CH4 was replaced by N2. A significantly negative correlation was found between soil-trapped CH4 and N2. The presence of rice plants increased the δ13C values of CH4. The δ13C values of CH4 tended to increase toward the end of the growing season and were positively correlated with concentration of soil-trapped CH4. A positive correlation between δ13C values of CH4 and C02, and between the δ13C values of CH4 and its concentration, were observed. The CH4 in the rice stems was 4–14% enriched in13C relative to soil-trapped CH4. In contrast, CO2 in rice plant stems was 1–9% lighter in13C relative to soil-trapped C02. These results are discussed in relation to the precursor pools and pathways of methanogenesis.
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  • 93
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    Biology and fertility of soils 24 (1997), S. 261-265 
    ISSN: 1432-0789
    Keywords: Key words Methane ; Wetland rice soils ; Oryza sativa ; Methane oxidation ; Acetylene Propylene oxide ; Methanotrophs ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Acetylene up to 500 μl l–1 did not affect methane formation in anoxic soil up to 12 h, but further incubation for 1 week showed strong inhibition of methanogenesis. To ascertain the extent of the oxidation of methane produced from rice-planted pots, the effect of acetylene on methane emission was studied. Two rice varieties (Toyohatamochi and Yamahikari) were grown in a greenhouse in submerged soil in pots. At about maximum tillering, heading, and grain-forming stages, methane fluxes were measured. Flux measurement was performed for 3 h from 6 pm, then acetylene at 100 μl l–1 was added to some of the pots. At 6 a.m. the following day, methane fluxes were again measured for 3 h. Only at maximum tillering stage of the variety Toyohatamochi was a significant increase (1.4 times) in methane flux caused by acetylene observed, whereas in the other treatments no significant increase in methane fluxes by acetylene could be defected. To ascertain the activity of methane monooxygenase (MMO), propylene oxide (PPO) formation from propylene was measured with excised roots and a basal portion of stems of the rice plants grown on the submerged soil. A level of 0.1–0.2 μmol PPO h–1 plant–1 was recorded. The roots showed the highest PPO formation per gram dry matter, followed by basal stems. Methane oxidation was roughly proportional to PPO formation. Soluble MMO-positive methanotroph populations were measured by plate counts. The number of colony-forming units per gram dry matter was 106–105 in roots, and 104–103 in basal stems. These results indicate the possibility of methane oxidation in association with wetland rice plants.
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  • 94
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    Journal of nondestructive evaluation 16 (1997), S. 91-100 
    ISSN: 1573-4862
    Keywords: LASER ultrasound ; anisotropic material ; group velocity ; stiffness coefficients ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Ultrasonic waves are generated through a composite material by means of a noncontact technique. It uses a Nd:Yag LASER for the generation and an interferometric probe for the detection of acoustic waveforms. From a suitable set of experimental data, an inversion scheme is used for the recovering of four stiffness coefficients. They characterize the elasticity in a principal plane of symmetry of the material which exhibits an orthorhombic symmetry. The measurements are performed at various temperatures, elevated by steps up to 300°C for two specimen. The sensitivity of the method appears convenient to measure the temperature induced stiffness changes. The anisotropic degradation of the material properties are then pointed out.
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  • 95
    ISSN: 1871-4528
    Keywords: skin resistance ; temperature ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Chambers were designed to simulate environmental conditions present in commercial potato stores and were used to introduce condensation to tubers infected with silver scurf (Helminthosporium solani). The electrical resistance measured across the skin of tubers from the top of the chambers was consistently lower than that from the bottom of the chamber, and this was reflected in an increased number ofH. solani spores produced by the top tubers. An increase in the length of the condensation period resulted in the skin resistance remaining lower for a longer period and also resulted in higher number of spores. Tubers held at relatively high ambient temperatures (15 °C) required a shorter period of condensation to cause an increase in spore count. This investigation highlighted the need for close monitoring of store environments so that condensation events can be quickly identified and the tubers dried.
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  • 96
    ISSN: 1871-4528
    Keywords: light ; temperature ; stolon growth medium ; below ground nodes ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Five experiments studied the effects of shading, temperature and stolon growth medium on stolon and tuber formation. The lowest numbers of stolons and tubers were produced at the higher and lower nodes. Numbers of primary stolons and tubers were relatively stable across nodes and treatments and variation in total numbers was largely due to changes in numbers of lateral and branch stolons. In the field, 70% shading reduced numbers of stolons and tubers by reducing lateral and branch stolons, while in hydroponics, 45% shading and temperatures at initiation had no effect on tuber numbers. In both environments later planting tended to reduce numbers of stolons and tubers. There were large effects of the physical environment, with compost producing three times as many tubers as dry vermiculite. The potential number of tubers may be determined by the number of stolons and the environmental conditions affecting stolon formation and development.
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  • 97
    ISSN: 1871-4528
    Keywords: Solanum tuberosum ; Spongospora subterranea ; thermal inactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary 23 potato cultivars were grown in fields infested with potato mop-top virus and spraing was assessed on tubers at harvest and after storage. Large differences in spraing susceptibility were found between cultivars. Compared with other countries, spraing in Denmark is characterised by a high incidence at harvest, a low increase during storage and a very low proportion of superficial spraing. Decrease in spraing during storage was recorded in two cultivars. DASELISA tests for PMTV in tubers revealted a high reliability. Mapping of PMTV in important Danish potato growing areas showed that the virus is widespread. Occurrence of spraing did not influence total yield or dry matter content. Soil acidity did not influence incidence of spraing but it was more common on coarse-grained soil than on finer sandy soils. PMTV in viruliferous resting spores ofSpongospora subterranea was inactivated by heating to 90°C for 15 minutes.
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  • 98
    ISSN: 1572-9788
    Keywords: diversity ; genetic mapping ; Oryza sativa ; RAPDs ; rice ; inter-simple sequence repeats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Genetic variation between samples of Oryza sativa from 19 localities in Bangladesh and Bhutan was assessed using two PCR-based molecular marker systems: RAPD (random amplification of polymorphic DNA) and ISSR-PCR (inter-simple sequence repeat polymerase chain reaction). Employing RAPD, a set of 14 decanucleotides of arbitrary sequence directed the amplification of 94 reproducible marker bands, 47 (50%) of which were polymorphic. In addition, a set of 9 ISSR primers were used to direct amplification of 71 PCR products, 40 (56%) of which were polymorphic. Multivariate analyses of the two PCR-based molecular marker data sets provided evidence that the patterns of variation correspond with the classification described by Glaszmann [9] using isozyme analysis. Subtle differences in the relationships revealed between rice groups using the two types of PCR-based marker led to investigations of their map positions using an intraspecific doubled haploid mapping population. The observation that the chromosomal locations of markers can influence diversity assessments is presented and the significance of this is discussed.
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  • 99
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    European journal of plant pathology 103 (1997), S. 643-651 
    ISSN: 1573-8469
    Keywords: chlorophyll ; nitric oxide ; Phytophthora infestans ; plant-pathogen interactions ; reactive oxygen species ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitric oxide (NO) is a bioactive molecule involved in many physiological processes. Among its biological function, NO has been proved to be cytotoxic against microorganisms in cells of the immune response, thus preventing infection. We have specifically studied the effect of a NO donor, sodium nitroprusside (SNP), on the chlorophyll content in potato leaves infected with the pathogenic fungus Phytophthora infestans (Pi). Fifteen days after infection, chlorophyll content strongly decayed in water-treated potato leaf sections. SNP was able to partially revert that loss in a dose-dependent manner, being the effective SNP concentrations between 10 µM and 100 µM. NaNO2 and NaNO3, the SNP-derived residual products, were unable to prevent the chlorophyll loss. Treatments with SNP did not affect the survival of Pi and the fungus was able to grow in a V8-agar medium containing 100 µM SNP. Both the amount and the extent of germination of Pi sporangia resulted similar in the absence and in the presence of SNP. Respiratory inhibitors of the cyanide-sensitive and cyanide-resistant pathways, 2,4-dinitrophenol and salicylhydroxamic acid respectively, did not change the chlorophyll levels in infected potato leaves, suggesting that NO effect should not be on mitochondrial respiration. These results indicate that NO could be a protective molecule, either preserving the chloroplast membrane of infected leaf sections against the toxicity of reactive oxygen species or being directly involved in any step of the chlorophyll metabolic pathway.
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  • 100
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    European journal of plant pathology 103 (1997), S. 573-580 
    ISSN: 1573-8469
    Keywords: Pisum sativum ; host plant exudates ; light ; temperature ; infection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of host plant exudates, light and temperature on germination of oospores of Peronospora viciae f.sp. pisi in vitro were investigated. Seed and root exudates did not increase percentage germination, whereas light inhibited germination. The first germ tubes appeared after 4, 7, and 14 days of incubation at 15, 10 and 5 °C, respectively. The eventual level of germination was highest and had similar values at 5 and 10 °C. At 20 °C germination was poor and at 25 °C no germination was observed. Oospores placed on membrane filters were incubated on soil. When oospores were retrieved from the membrane filters after six days and placed in water at 10 °C, they germinated within 2 days. On soil significantly less oospores germinated than in water. Germinability of oospores stored in the dark at 5 or 20 °C at 30 or 76% RH was studied over a two-year period. Germinability generally increased over time, but fluctuations were observed indicating the occurrence of secondary dormancy. Time courses of germinability were generally similar for oospores stored at several temperatures and humidities. No effect of light on time course of germinability was found when oospores were exposed to alternating light-dark periods or stored in continuous dark for 140 days. Percentage germination observed in a germination assay was correlated with percentage infection determined in a bioassay.
    Type of Medium: Electronic Resource
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