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  • Articles  (223)
  • maize  (64)
  • biological control  (59)
  • Solanum tuberosum L.  (54)
  • Oryza sativa  (47)
  • 2015-2019
  • 1995-1999  (64)
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  • 1915-1919
  • 1999  (64)
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  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (223)
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  • Articles  (223)
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  • 2015-2019
  • 1995-1999  (64)
  • 1990-1994  (159)
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  • 1
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    Springer
    Nutrient cycling in agroecosystems 55 (1999), S. 175-185 
    ISSN: 1573-0867
    Keywords: fertilizer recommendation ; maize ; soil mineral nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fifteen field trials were conducted to evaluate soil mineral N measurement as a means for quantifying the total N supply to forage maize and so to form the basis for fertilizer recommendations on a crop-specific basis. In every trial, 4 rates of cattle manure N (nominally 0, 80, 160, 240 kg N per ha) and 4 rates of ammonium nitrate (0, 50, 100, 150 kg N per ha) were factorially combined. Soil mineral N measurements were made before manure application, at the time of maize drilling, 7-10 weeks after drilling and after harvest. Measurements on control treatments which received no manure or ammonium nitrate showed extensive net mineralisation of soil N (mean 140 kg N per ha) in the 7-10 weeks after drilling followed by a decrease due to crop uptake, and probably net immobilisation, of approximately the same amount by harvest. This net mineralisation was probably the reason why only one trial showed a significant dry-matter yield response to ammonium nitrate. Results indicated that , to be useful for N recommendations, soil mineral N measurements should be taken 7-10 weeks after drilling. Only if the amount of mineral N at this time is less than expected crop N offtake should fertilizer N be applied. A mean of around 64% of the N applied in ammonium nitrate could be accounted for in soil mineral N after harvest of the maize, although this was reduced to 24% in the single trial where a dry-matter response to ammonium nitrate was recorded.
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  • 2
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    Nutrient cycling in agroecosystems 55 (1999), S. 95-105 
    ISSN: 1573-0867
    Keywords: cover crops ; savanna ; N fertilizer ; maize ; cowpea ; N fertilizer replacement value
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Integrated soil management with leguminous cover crops was studied at two sites in the northern Guinea savanna zone of northern Nigeria, Kaduna (190 day growing season) and Bauchi (150 days). One-year planted fallows of mucuna, lablab, and crotalaria were compared with natural grass fallow and cowpea controls. All treatments were followed by a maize test crop in the second year with 0, 30, or 60 kg N ha−1 as urea. Above ground legume residues were not incorporated into the soil and most residues were burned early in the dry season at the Kaduna site. Legume rotation increased soil total N, maize growth in greenhouse pots, and dry matter and N accumulation of maize. Response of maize grain yield to 30 kg N ha−1 as urea was highly significant at both sites and much greater than the response to legume rotation. The mean N fertilizer replacement value from legume rotation was 14 kg N ha−1 at Kaduna and 6 kg N ha−1 at Bauchi. W ith no N applied to the maize test crop, maize grain yield following legume fallow was 365 kg ha−1 higher than natural fallow at Bauchi and 235 kg ha−1 higher at Kaduna. The benefit of specific legume fallows to subsequent maize was mostly related to above ground N of the previous legume at Bauchi, where residues were protected from fire and grazing. At Kaduna, where fallow vegetation was burned, maize yield was related to estimated below ground N. The results show that legume rotation alone results in small maize yield increases in the dry savanna zone.
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  • 3
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    Integrated pest management reviews 4 (1999), S. 127-143 
    ISSN: 1572-9745
    Keywords: wheat ; stored-grain ; integrated pest management ; aeration ; biological control ; grain sampling ; insect monitoring ; modeling ; area-wide IPM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Management of stored-grain insect pests by farmers or elevator managers should be based upon a knowledge of the grain storage environment and the ecology of insect pests. Grain storage facilities and practices, geographical location, government policies, and marketing demands for grain quality are discussed as factors influencing stored-grain insect pest management decisions in the United States. Typical practices include a small number of grain samples designed to provide grain quality information for segregation, blending and marketing. This low sampling rate results in subjective evaluation and inconsistent penalties for insect-related quality factors. Information on the efficacy of insect pest management practices in the United States, mainly for farm-stored wheat, is discussed, and stored-grain integrated pest management (IPM) is compared to field-crop IPM. The transition from traditional stored-grain insect pest control to IPM will require greater emphasis on sampling to estimate insect densities, the development of sound economic thresholds and decision-making strategies, more selective use of pesticides, and greater use of nonchemical methods such as aeration. New developments in insect monitoring, predictive computer models, grain cooling by aeration, biological control, and fumigation are reviewed, their potential for improving insect pest management is discussed, and future research needs are examined.
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  • 4
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    Integrated pest management reviews 4 (1999), S. 21-37 
    ISSN: 1572-9745
    Keywords: carrot weevil ; IPM ; Anaphes spp. ; biological control ; ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The carrot weevil, Listronotus oregonensis (LeConte) (Coleoptera: Curculionidae) is a major pest of carrots in northeastern North America. The females oviposit in the leaf petiole and the developing larvae make tunnels in the carrot roots. Exclusive reliance on chemical control and the poor control obtained, prompted, in the early 1980s, research on the ecology and physiology of the pest and its natural enemies. Carrot weevil females start their oviposition by 147±9 DD7°C but they oviposit only in carrots past the 4 true-leaf-stage. As a result, oviposition is delayed, and damage reduced, in late-sown carrots. Monitoring carrot weevil adults in the spring with either carrot root sections or wooden plate traps enables growers to apply control treatments only if the population density justifies it. Egg parasitoids of the genus Anaphes (Hymenoptera: Mymaridae) are the most important natural enemies and they account, in untreated plots, for up to 80% mortality. Their effectiveness could be improved by managing field borders to establish secondary host species. An IPM programme was developed in the 1980s based on the research results obtained and, through regular monitoring, has achieved a substantial decrease in pesticide use.
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  • 5
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    Integrated pest management reviews 4 (1999), S. 39-52 
    ISSN: 1572-9745
    Keywords: Scapteriscus ; Neocurtilla ; Gryllotalpa ; biological control ; turf ; pastures ; vegetables
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract There are at least 70 species of mole crickets (Orthoptera: Gryllotalpidae). Some are rare, others are innocuous, and a few are important pests. These soil-dwelling pests damage underground parts of a long list of cultivated plants. Although tillage and flooding are used successfully in some situations to bring these pests to the soil surface and expose them to vertebrate and other predators, chemical pesticides are widely used against them. Knowledge of their life history is used to time application of chemical treatments to save money, but is not used as widely as it might be. Classical biological control has been used against immigrant mole crickets in Hawaii, Puerto Rico, and the southern USA. In Florida, three Scapteriscus species from South America cause major damage to pastures and turf and are targets of a classical biological control program. Population levels of two of the pest species have been reduced substantially in Florida by establishment of a tachinid fly (Ormia depleta) and a steinernematid nematode (Steinernema scapterisci) from South America. The nematode also functions as a biopesticide. Managers of pastures and turf in Florida have thus far derived benefit from these classical biological control agents without understanding their function: use of chemicals is reduced when mole cricket populations are lower due to action of these organisms. Future enhancement of the action of O. depleta and of a sphecid wasp (Larra bicolor, which also was introduced from South America) probably will demand deliberate planting of nectar sources for adults of these biological control agents, and the advantage will be to managers who adopt such a strategy. Chemical pesticide use is strongly promoted by a large chemical industry, whereas biopesticidal use has thus far been little promoted and sales have been few. Even managers who do not change their simple strategy of pesticide use in response to damage by mole crickets, and have no knowledge of the differing life cycles of the three Scapteriscus species or of the presence and action of the classical biological control agents, will derive benefit as these biological control agents (and a predatory beetle which has not yet been released) increase their distribution.
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  • 6
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    Integrated pest management reviews 4 (1999), S. 97-126 
    ISSN: 1572-9745
    Keywords: agriculture ; biological control ; campaign ; chemosterilent ; commensal ; control methods ; economics ; environmental and cultural methods ; horticulture ; India ; pest management ; pre- and post-harvest crop losses ; poultry farms ; rodent ; rodenticide ; South Asia ; trapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Eighteen species of rodents are pests in agriculture, horticulture, forestry, animal and human dwellings and rural and urban storage facilities in India. Their habitat, distribution, abundance and economic significance varies in different crops, seasons and geographical regions of the country. Of these, Bandicota bengalensis is the most predominant and widespread pest of agriculture in wet and irrigated soils and has also established in houses and godowns in metropolitan cities like Bombay, Delhi and Calcutta. In dryland agriculture Tatera indica and Meriones hurrianae are the predominant rodent pests. Some species like Rattus meltada, Mus musculus and M. booduga occur in both wet and dry lands. Species like R. nitidus in north-eastern hill region and Gerbillus gleadowi in the Indian desert are important locally. The common commensal pests are Rattus rattus and M. musculus throughout the country including the islands. R. rattus along with squirrels Funambulus palmarum and F. tristriatus are serious pests of plantation crops such as coconut and oil palm in the southern peninsula. F. pennanti is abundant in orchards and gardens in the north and central plains and sub-mountain regions. Analysis of the information available on the damage and economic losses caused by rodents in rice, wheat, sugarcane, maize, pearl millet, sorghum, oil seed, legume and vegetable crop fields, horticulture and forestry, poultry farms, and rural and urban dwellings and storage facilities clearly shows that chronic damage ranging from 2% to 15% persists throughout the country and severe damage, sometimes even up to 100% loss of the field crop, is not rare. Several traditional and modern approaches and methods of rodent control are being used. The existing knowledge of the environmental, cultural, biological, mechanical and chemical methods of rodent control in India is reviewed. Considerable variations exist in the susceptibility of the pest species to different methods, particularly to rodenticides and trapping, their field applicability, efficacy and economics in different crops, seasons and geographical regions, behavioural responses of the pest species to these methods in different ecological conditions and their adoption by farmers in different regions of India. Environmental and cultural techniques, such as clean cultivation, proper soil tillage and crop scheduling, barriers, repellents and proofing which may reduce rodent harbourage, food sources and immigration have long lasting effects but are seldom adopted. However, their significance in relation to normal agricultural practices, intensification and diversification are discussed. Rodenticides, which provide an immediate solution to the rodent problem, form the major component of rodent control strategies in India. Poison baiting of rodents with zinc phosphide and burrow fumigation with aluminium phosphide are common in agricultural fields and recently Racumin (coumatetralyl) and bromadiolone have been introduced for the control of both agricultural and commensal rodent pests in India. Methods and timings of campaigns and successes and problems in implementation of rodent control are also reviewed.
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  • 7
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    Integrated pest management reviews 4 (1999), S. 307-312 
    ISSN: 1572-9745
    Keywords: microbial control ; biological control ; biopesticide ; mycopesticide ; Metarhizium ; Beauveria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microbial control agents generally kill insects more slowly than chemical pesticides, and fast-moving migratory pests may not at first sight appear to offer the most promising targets for microbial control. Operators responsible for control may need to have recourse to chemical control agents. Nevertheless, there are many occasions when pests breed and feed outside the crop and a microbial control agent can be used. Similarly, immature stages may cause little damage and early treatment in the crop can avoid damage. Microbial control agents are particularly likely to be favoured if the pest breeds in a conservation area, and if a publicly-accountable agency is responsible for control. Other key points of importance are the IPM context, in particular detection, planning and forecasting of outbreaks and the role of natural enemies. With these points in mind, we identify several locust and grasshopper systems where microbial control is becoming established; additionally, Sunn pest of wheat and Armyworm are identified as promising situations forbreak microbials.
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  • 8
    ISSN: 1871-4528
    Keywords: Solanin ; Chaconin ; Magnesium ; Kalium ; Stickstoff ; Solanum tuberosum L. ; Phytophthora infestans ; Feldversuch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary Field experiments were carried out for three years to study the effect of various magnesium, potassium and nitrogen fertilization rates on two medium-early edible potato cultivars. Additionally, one of the experimental areas was sprayed againstPhytophthora infestans to ascertain the effect of fungicides on the content of total glycoalkaloids (TGA) in potato tubers after harvest and after six months of storage. The applied fungicide treatments increased total glycoalkaloids (TGA) of potato tubers (Fig. 4). Fertilization with mineral nitrogen caused different reactions in both cultivars. There was a tendency for cv. Beryl to accumulate more glycoalkaloids with increasing nitrogen fertilization rates, while the opposite was observed for cv. Mila (Fig. 7). Fertilization with potassium and magnesium did not affect the results. On the basis of these results there was no conclusive evidence that the TGA content in the tubers was dependent on cultivar or on the weather during the growing season (Figs 1,2 and 3). The TGA content increased during storage, independently of previous treatments, (Figs 4–7).
    Notes: Zusammenfassung Es wurden Feldversuche in drei Jahren mit zwei Speisekartoffelsorten, verschiedenen Mengen an Mineraldüngern und der Anwendungen eines Pflanzenschutzmittelns gegenPhytophthora infestans angelegt. Die Knollen wurden direkt nach der Ernte sowie nach einer sechsmonatigen Lagerung auf Glykoalkaloidgehalt untersucht. Zwischen den Sorten treten statistisch gesicherte Unterschiede im Gehalt an Glykoalkaloiden auf. Die Anwendung von Pflanzenschutzmitteln während der Vegetation erhöht den Gesamtgehalt an Glykoalkaloiden (TGA) in den Kartoffelknollen kurz nach der Ernte. Eine variierte Mineraldüngung hat keinen statistisch signifikanten Einfluss auf den TGA-Gehalt in den Proben kurz nach der Ernte, N- und K-Düngung verändern diesen jedoch im Laufe der Lagerung. Unabhängig von den übrigen Bedingungen erhöht sich der TGA-Gehalt in diesem Versuch während der Lagerung im Mittel von 5,8 auf 7,7 mg/100g Frischsubstanz.
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  • 9
    ISSN: 1871-4528
    Keywords: growth regulator ; sucrose ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Ancymidol-induced in vitro tuberisation under different photoperiodic regimes (dark, SD=8 h, LD=16 h) and sucrose concentrations (2, 4, 6 and 8%) in cv. Jaerla (early) and cv. Baraka (late) was studied. Tuberisation was scored after 4 (dark) or 8 (light) weeks. Ancymidol significantly increased tuberisation under LD-SD for any sucrose concentration in both cultivars. Ancymidol also significantly increased tuberisation under LD-dark for 6% sucrose in both cultivars. Tuberisation in cv. Jaerla was significantly higher than in cv. Baraka for any photoperiodic treatment in the presence or absence of ancymidol with 4, 6 or 8% sucrose. The photoperiod SD-SD resulted in the higher level of tuberisation for any combination of sucrose, cultivar and ancymidol. The possible role of ancymidol is discussed.
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  • 10
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    Potato research 42 (1999), S. 611-617 
    ISSN: 1871-4528
    Keywords: dormancy ; potato ; losses ; Solanum tuberosum L. ; seed potato production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Microtubers can be stored longer, transported and handled easier than plantlets, but they have some disadvantages related to long dormancy. Dormancy, number of sprouts per tuber and loss of microtubers under different storage temperatures were studied. Microtubers of four genotypes originated from different tuberization treatments (photoperiod combinations) were observed. We found that dormancy depended on cultivar and — in some cases — on the photoperiod treatment applied during tuberization. Generally, the dormacy was long and was greatly elongated by low storage temperature. One of the photoperiod treatments shortened while the other treatment prolonged the rest-period compared to the control, maybe due to a change in temperature accompanying the change in daily light (photoperiod combination). Besides, these treatments affected the number of sprouts per tuber. There was no significant difference in duration of dormancy between different tuber-size groups, but the loss increased significanctly with a decrease in tuber size. Based on this information we can use microtubers more effectively in the seed potato production programme.
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  • 11
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    Potato research 42 (1999), S. 101-105 
    ISSN: 1871-4528
    Keywords: late blight ; testing methods ; electrolyte leakage ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The resistance of ten potato cultivars (Agria, Ajax, Désirée, Liseta, Kennebec, Majestic. Monalisa, Prima, Spunta and Tonda di Berlino) toPhytophthora infestans was analyzed in vitro using 8 fungal strains. An assay based on electrolyte leakage was used for screening leaves and tuber tissues with fungal culture filtrates. With almost all cultivars the resistance of leaves did not correlate with the resistance of tubers. Cv. Ajax appeared the least susceptible in both leaf and tuber tests, while the cv. Prima was the most susceptible in tuber tests.
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  • 12
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    Potato research 42 (1999), S. 229-240 
    ISSN: 1871-4528
    Keywords: earliness ; planting season ; Mediterranean area ; off-season production ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In Italy, the early potato cultivars of greatest economic significance are those grown off-season, in a cycle which is generally much earlier than the typical spring-summer cycle. Of the area given over to early potatoes in Italy, more than 90% is in the southern regions. The economic value of this production is due to its extraseasonality, which allows much of the early potato harvest to be sold on foreign markets. In Sicily, more than 5000 ha of potato are grown, with a high frequency of potato crops on small plots. Early potatoes are often rotated with various fruits and vegetables, and the length of the cycle is variable, from 100 to 140 days. Choosing the most suitable cultivar is the most complex aspect of early potato growing. Of the criteria used, tuber growth rate has shown most validity. In Sicily two cultivars are mainly grown: Sieglinde and the more recent but well-established Spunta. Agricultural techniques used for early potato cultivation vary depending on the area. An overview of the agronomic practices used in different areas is given in this paper.
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  • 13
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    Potato research 42 (1999), S. 381-395 
    ISSN: 1871-4528
    Keywords: agronomy ; breeding ; pathology ; physiology ; Solanum tuberosum L. ; storage ; utilisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This contribution presents highlights of the oral and poster presentations in the various sessions of the 14th Triennial Conference of the European Association for Potato Research, held in Sorrento, Italy, May 1999. It is based on the reports of the session chairpersons and the book of abstracts. The paper reports the progress made in many aspects of potato research, but also stresses the need for further collaborative work, especially in the fields of molecular physiology, marker assisted breeding, control of late blight, potato tuber moth and other pests and diseases, stress physiology and stress resistance, and sustainable cropping systems with both short and long cycle potato crops.
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  • 14
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; tuberisation ; extensin ; acyl carrier protein thioesterase ; high mobility group protein ; gene expression ; plant development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In screening to isolate a full-length copy of a previously isolated cDNA clone, a further three cDNAs were also isolated from a library prepared from sub-apical swelling-stolon tissue of potato (Solanum tuberosum L.). Sequence analysis showed these clones to be similar to extensin-like protein genes, acyl carrier protein thioesterase genes and high mobility group protein genes, respectively. A further cDNA, isolated by subtractive hybridisation, was similar to a tomato cDNA previously isolated on the basis of its down-regulation following nematode infection. While all the newly isolated genes were expressed in swelling stolons, for most, maximal expression was seen to be in stem tissue. Possible roles for these genes in the development of potato plants are discussed, as is the significance of gene expression in stems and stolons to the process of tuberisation.
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  • 15
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    Potato research 42 (1999), S. 89-93 
    ISSN: 1871-4528
    Keywords: analysis ; HPLC ; β-glucoside ; 1,2-dihydro-3,6-pyridazinedione ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The method of Vadukul (1991) for determining maleic hydrazide (MH) was modified and gave recoveries of free MH of 89%±4%. The values recorded on individual tubers ranged from 2–14 mg kg−1. Maleic hydrazide was evenly distributed throughout the tuber (peel, outer and inner flesh) but concentration increased slightly as tuber size increased. The concentration of free MH decreased from 7 to 3 mg kg−1 over the storage period of 5 1/2 months. Acid hydrolysis released substantial amounts of MH particularly from older potatoes (13 mg kg−1) compared with 6 mg kg−1 from new potatoes, implying that free MH is gradually converted to a bound form with time after treatment. No evidence was found for the presence of a β-glucoside of MH.
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  • 16
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    Potato research 42 (1999), S. 241-264 
    ISSN: 1871-4528
    Keywords: global distribution ; prospects ; diversification ; specialization ; price risk ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We examine the changing character of supply and demand for potatoes over time and space with an eye towards implications for agricultural research. Diversification in consumption and specialization in production are our organizing themes. The foundation for comparative analysis is a map of the global distribution of potato growing area. We highlight the adverse impact of price risk on specialization and discuss several sources of uncertainty that condition the size but not the direction of major trends.
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  • 17
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    Potato research 42 (1999), S. 499-504 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; microtuber ; liquid medium ; temporary immersion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary CIRAD developed a new apparatus for plant tissue culture, using temporary immersion in a liquid medium. This apparatus was adapted to the microtuber production in potato. The procedure is as follows: single node cultivation on MS medium containing 30 g/l sucrose in the light for 2 weeks, induction of microtuberisation with 80 g/l sucrose over a 2 week period in the light, followed by a further 6 weeks in the dark. All experiments were performed at 20 °C. The basic vessel had a capacity of approximately 11;30 nodes were cultivated per vessel. Depending on the cultivars tested (Bintje, Ostara and Désirée) 47 to 115 microtubers were harvested per vessel. Between 30 and 60% of the microtubers weighted over 0.5 g and between 10 and 40% over 0.8 g. Sprouting is still under investigation. Preliminary results indicate that the dormancy period was relatively short and several stems were obtained per microtuber. These results seem to be better than those usually reported. Only one simple protocol has been tested and further improvements are probably easy to obtain.
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  • 18
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    Potato research 42 (1999), S. 585-591 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; microtubers ; acetic acid ; propionic acid ; asscorbic acid ; salicylic acid ; acetylsalicylic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potato microtubers are usually induced in media containing growth regulatory, typically cytokinins and growth retardants. However, since these substances may imbalance the physiology of the cultured explants and cause adverse carry-over effects on the subsequent performance of the microtubers, the potential acid-induction of in vitro-mass tuberization was investigated as an alternative. For this purpose, a range of explant types (stolons, single-node or apex-containing multinodal sections), organic acids (acetic, propionic, ascorbic, acetylsalicylic or salicylic acid), and photoperiods (continuous dark, 8 or 16 h photoperiod) were established. Gellified medium or raft membranes on liquid medium were also tested. Although variations due to explant type, photoperiod, organic acid supplemented, and medium type were found, all organic acids tested under the different experiments caused tuberization. Multiple tuber formation or bigger tubers did not develop on multinodal explants. In terms of tuberization rate and mean tuber weight, gellified medium performed better than liquid medium with rafts. The recently established role of the salicylic and acetylsalicylic acids on tuberization is corroborated by our system. The results with the acetic, propionic and ascorbic acids show that in vitro hormone-free tuberization can be easily and rapidly achieved.
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  • 19
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    Potato research 42 (1999), S. 73-78 
    ISSN: 1871-4528
    Keywords: growth parameters ; K+/Na+ ratio ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Increased potassium (K) fertilization of saline soils has been implicated in alleviating salt stress in plants. We examined whether varying K concentrations in Murashige & Skoog (MS: 1962) basal medium could affect salt (NaCl) stress in micropropagated potatoes. Plantlets of cvs Sierra and Russet Burbank were evaluated after 1 month of growth in a medium containing 0. 40, or 80 mM NaCl and 6,20, or 30 mMK. The medium K was adjusted using KNO3 while total nitrogen was kept constant using NH4NO3. Growth parameters were less affected in Sierra than Russet Burbank, and roots were less affected than shoots, as the medium salinity increased. Tissue Na levels were greater when the medium K was 6 mM compared with 20 mM MS control. The medium K concentration 50% greater than MS control did not promote growth and did not limit tissue Na levels. While this should be confirmed by field assessment, our results suggest that while K deficiency promotes salt damage, its addition beyond the usual fertilizer recommendations is not beneficial in alleviating salinity stress.
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  • 20
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    Potato research 42 (1999), S. 607-610 
    ISSN: 1871-4528
    Keywords: seed production ; Greece ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Large scale, commercial production of potato minitubers, cvs Spunta, Jaerla and Kennebec, has been carried out in VITRO HELLAS S.A. since 1995, according to protocols based on in vitro methods. Apical meristems were cultured on MS medium supplemented with 1 μM IBA, 20 g/l sucrose and 6 g/l agar (pH 5.8). Subculture was carried out every 15 days. Multiplication rate was 4–5 per cycle. Self-rooted microplants were transferred into screen houses (200 plants/m2) in a mixture of peat and perlite 1∶1 (v/v). Cultivation period was 15 August to 15 November each year. During the period 1995–1997, the number of minitubers produced/plant was 2.07 for cv. Spunta, 1.85 for cv. Jaerla and 2.52 for cv. Kennebec and their average weights were 10.8 g, 10.9 g and 9.8 g, respectively. The percentage of minitubers〈10 mm in diameter was 2%, 50.1% were 10–20 mm and 47.9% were〉20 mm.
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  • 21
    ISSN: 1871-4528
    Keywords: cultivar ; virus diseases ; nematodes ; ground cover ; physiological age ; seed production ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In Argentina, different areas are suitable for seed potato production: however, each has particular problems, mainly related to different pest and diseases. Tierra del Fuego Island is well isolated from traditional potato growing areas. Therefore, it was tested for its potential for seed production. The cultivars Achatt. Mailén INTA. Pampeana INTA and Spunta were grown in Río Grande, San Pablo and Ushuaia from 1991–1994. Nematode presence and aphid population dynamics were recorded. Average tuber yield ranged from 20.1–37.6 t ha−1. After three years PVY and PLRV remained low (0–1% for different cultivars and locations). Moreover, seed tubers obtained were physiologically young. Long days, early frosts and strong winds may limit tuber yield in some years. The island can be considered as an ecological “safe haven” and is very suitable to obtain healthy and physiologically adequate seed potatoes.
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  • 22
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    Potato research 42 (1999), S. 25-29 
    ISSN: 1871-4528
    Keywords: chlorpropham ; particulates ; dusts ; solvents ; ignition source ; explosive limits ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary An appraisal was undertaken of the key factors involved in explosion and combustion processes mainly associated with the fogging of chlorpropham formulations into potato stores. The key factors considered are source of ignition, solvents, explosive limits of solvents, the presence and atmospheric concentrations of particulate clouds and the role of particulate material in dust explosions. Also the sequence of events that takes place in a dust explosion, including critical concentrations of dust required to initiate the reactions involved and the particular relevance of the above events to the behaviour of chlorpropham fogs both at the time of application and when distributed throughout a store. The relevance of fine dust already present in the store to the initiation of explosions, particularly secondary explosions, which are considered to be a major cause of concern due to their severity, is also emphasised.
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  • 23
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    Potato research 42 (1999), S. 95-99 
    ISSN: 1871-4528
    Keywords: analysis ; HPLC ; filter paper model ; Diels-Alder reaction ; 1,2-dihydro-3,6-pyridazinedione ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A method used for estimating extractable maleic hydrazide (MH) concentrations in fresh potato material, concentration range 5–17 mg kg−1, was found not to be suitable for processed potato products (10–33% recoveries) although, boiling potato pieces enhanced recovery by 20%. Each step of the determination was examined and a modified procedure developed with particular emphasis on the extraction of MH from the dried potato matrix, and the quality of the HPLC column used. Potato slices and model systems based on filter papers plus additives were used. Recoveries from fried potato slices were 74±6%. Based on the effect of glucose in reducing extractable MH recoveries, it is suggested that the remainder of the MH (20–25%) is converted into a conjugated structure on reaction with dehydrated sugar (Diels-Alder reaction).
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  • 24
    ISSN: 1871-4528
    Keywords: bioassay ; biological control ; blackleg ; green crop harvesting ; haulm killing ; skin damage ; wound protection ; Solanum tuberosum L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Green crop lifting (GCL) for haulm killing was developed in The Netherlands and offers ideal conditions for controlling the blackleg pathogenErwinia carotovora subsp.atroseptica (Eca) by antagonists. Based on the use of mini-tubers or young tubers from field crops, two bioassays for wound protection were developed. GCL was simulated by artificially skinning or wounding tubers, inoculating the damaged skin with Eca, treating with antagonists and incubating in either potting compost or outside in field soil. Mainly fluorescent pseudomonads, pre-screened for in vitro antagonistic activity on agar and high soft rot reducing ability on tuber slices, were tested in the mini-tuber bioassay. Strains giving the highest degree of wound protection were further tested individually and in combination under field conditions in the young tuber bioassay. One individual strain and two combinations, resulting in reduction of contamination levels on skinned surfaces of 85% and between 60% and 70%, respectively, show good potential for biological control of blackleg.
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  • 25
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    Potato research 42 (1999), S. 215-221 
    ISSN: 1871-4528
    Keywords: potato virus Y ; strain differentiation ; RFLP ; potato tuber necrotic ringspot disease ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A procedure for differentiating PVYNTN from PVYN is described and is based on the unique cleavage of their respective PCR products with strain specific restriction endonucleases. The PCR products corresponding to the 5′ end of the N and NTN strains of PVY were cloned and sequenced, and a restriction map was constructed which included common enzymes that were used for the differentiation of PVYNTN. Unique, single cleavage of PCR products derived from the 5′ end of the PVYNTN genome by Nco I, and that of the N-strain of PVY by Bgl II restriction endonuclease were demonstrated. The specific digestion patterns in polyacrylamide gel were used for the unequivocal differentiation between the N and NTN strains of the virus. Both single and mixed infections were detected in field samples of potatoes using this procedure.
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  • 26
    ISSN: 1871-4528
    Keywords: wild species ; gene introgression ; heat stress ; drought stress ; frost stress ; biotic stresses ; off-season production ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In the Mediterranean area the potato is a very important crop and can be cultivated throughout the year. However, tuber yields are generally much lower than those in Northern European countries. This is because the environmental and agro-economic conditions are different from those of Northern countries where most cultivars were developed. We feel that the objective for the “new Mediterranean potato” must be the availability of potato cultivars for each environment and for each planting season. Breeding programmes should focus on improving potato production within a specific agro-ecological Mediterranean area rather than improving crop production across areas. This paper reports aspects of potato breeding and physiology related to resistance to stress conditions in the Mediterranean area, with particular emphasis given to resistance to abiotic (heat, drought and frost) as well as biotic stresses. We also discuss the potential to produce seed tubers suitable for potato cultivation in the Mediterranean area.
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  • 27
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    Potato research 42 (1999), S. 279-282 
    ISSN: 1871-4528
    Keywords: late blight ; mating types ; sexual recombination ; Solanum tuberosum L. ; diversification ; aggressiveness ; migration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Since the early 1980s and continuing through the end of the 20th century, potato late blight caused byPhytophthora infestans has become noticeably more problematic throughout the world. Exotic strains of the pathogen are largely responsible for the increased problems. The new strains were initially detected in Europe, but subsequently they have been detected in Asia, the Middle East, South America and North America. Populations in the Middle East and South America may represent secondary migrations from Europe. Several independent migrations have occurred such that migrant populations in North America are very different from those in Europe. Also, population structures ofP. infestans are different in different worldwide locations. In some locations the migrant strains are resistant to metalaxyl, but in other locations either migrant or indigenous strains may be resistant. In most locations, the migrant strains are more aggressive than the previous indigenous strains.
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  • 28
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    Potato research 42 (1999), S. 489-498 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; microtubers ; nodal cuttings ; in vitro tuberization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A tissue culture technique is described in which nodal cuttings ofSolanum tuberosum L. are induced to form usable microtubers in order to produce high health status of the seed potato genotypes cultivated in Switzerland.
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  • 29
    ISSN: 1871-4528
    Keywords: genes ; transgenic plants ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Continuing study of the potato plant's response to stressful conditions has led to the identification of a large number of plant genes whose expression, is regulated by external stimuli. Stress-induced genes can be broadly divided into functional or regulatory genes. To the first category belong genes encoding proteins or enzymes of plant metabolic pathway, of molecules involved in repairing cellular damages and/or indispensable for restoring a new cellular homeostasis compatible with the external conditions. The other class includes genes primarily involved in the perception and/or intracellular transduction of the stress signal, such as kinases, phosphatases or transcription, factors. The research objectives in the field of plant stress tolerance has recently evolved from a mere cloning and description of stress-induced genes to the design of the best strategy of producing transgenic plants tolerant to environmental constraints. It is well known that stress tolerance is a complex trait, requiring the coordinated regulation of a network of genes that act synergistically and additively. At best, manipulation of one single down-stream gene may contribute only partially to the tolerance of the transgenic plants. Recent studies have shown that it is feasible to regulate the level of expression of many down-stream stress-induced genes in a coordinated fashion by regulating the expression of genes encoding transcription factors able to bind DNA motifs in the promoter of stress-induced genes. However, the constitutive high level of expression of transcription factors often causes detrimental phenotypic effects. This drawback could be bypassed by putting genes for transcription factors under the control of inducible promoters. In this way, endogenous tolerance genes are activated only when the stress event occurs, minimizing the negative pleiotropic effect. Novel technology (reverse genetics, DNA microarrays, mRNA differential display, T-DNA tagging, complementation and over-expression of plant cDNA in yeast as model for cellular stress tolerance), improvement of genetic transformation techniques (multiple gene transfer, gene targeting by homologous recombination) as well as a better efficiency of foreign gene expression (discovery of plant promoters with cell-specific, tissue-specific, developmental stage-specific, and/or inducible patterns of expression) will give a tremendous impulse to produce stress tolerant commercial cultivars of the main crops through genetic engineering.
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  • 30
    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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  • 31
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    European journal of plant pathology 105 (1999), S. 123-137 
    ISSN: 1573-8469
    Keywords: Aureobasidium pullulans ; biological control ; Cryptococcus albidus ; grey mould ; Trichoderma harzianum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The efficacy of Trichoderma harzianum T39 and the yeasts Aureobasidium pullulans and Cryptococcus albidus against Botrytis cinerea in cucumber and tomato was compared with chemical control. Four experiments were conducted in cucumber grown under different climatic conditions in The Netherlands, and two experiments were done in tomato both in the Netherlands and in Israel. T. harzianum and A. pullulans showed the most consistent control of B. cinerea, reducing stem lesions and death of plants by 40–100% in most cases. Control of stem lesions and subsequent wilting was generally better than control of symptoms on fruits. In some cases, the biocontrol agents were more effective than the broad-spectrum fungicide tolylfluanid and the selective fungicide iprodione. The climatic conditions did not strongly influence the efficacy of the biocontrol agents, but regression analysis showed that high temperature during the day and high vapour pressure deficit during the night reduced biocontrol efficacy. From the results, prospects for biocontrol of B. cinerea in greenhouse vegetables appear good under a range of conditions.
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  • 32
    ISSN: 1573-8469
    Keywords: ear rot ; leaf blight ; mid-altitude ; maize ; Stenocarpella macrospora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inheritance of resistance to Stenocarpella macrospora (Earle) Sutton (syn. Diplodia macrospora Earle) ear rot of maize was studied among selected maize populations in the mid-altitude (1280 m) agro-ecological zone of Nigeria. Diallel analysis among the populations showed significant values for general combining ability (GCA) and specific combining ability (SCA) effects at 5% and 1% levels respectively. Variance components of GCA and SCA on Stenocarpella ear rot were 0.019 and 0.627 respectively, indicating that non-additive genes play major roles in the inheritance of Stenocarpella ear rot resistance. The GCA and SCA effects were relatively dependent on the materials involved in the evaluations. Generation mean analysis was used on five selected parent inbreds (2 resistance and 3 susceptible crossed to give P1, P2, F1, BC1, BC2 and F2 generations). Estimates of the six parameters on ear rot indicate that dominance gene effects made the major contribution to variation in ear rot of maize in the crosses studied. The magnitude and significance of the estimates for digenic effects in the crosses suggest that epistatic gene effects are present and important in the basic mechanism of Stenocarpella ear rot inheritance in the populations studied. Additive effects have only minor importance in the total variation.
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  • 33
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    European journal of plant pathology 105 (1999), S. 95-101 
    ISSN: 1573-8469
    Keywords: bacteria ; biological control ; Chryseobacterium ; Flavobacterium ; grey mold ; Pseudomonas ; strawberries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Most potential fungal antagonists have been identified only after exhaustive non-selective screening. Bacteria antagonistic to Botrytis cinerea were selected using a simple method based on techniques developed for trace enrichment studies, where a crude cell wall preparation from B. cinerea was used as a selective substrate and bacteria were isolated based on growth on cell wall agar media. Most of the 52 bacterial isolates that were obtained from the surface of ‘organically grown’ strawberry fruit and could grow on B. cinerea wall media in culture showed some ability to inhibit the growth of the fungus. Potato dextrose agar seeded with B. cinerea spores (104 ml−1) were challenged with each of these bacterial isolates at concentrations of 109 and 106 colony forming units ml−1. Eleven of the 52 isolates initially recovered, subsequently demonstrated strong antagonism in vitro and were selected for additional screening tests on strawberry fruit. All 11 isolates reduced grey mold rot incidence on fruit in storage. Three of the best isolates were tested in limited field trials, and also reduced grey mold rot on fruit under field conditions.
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  • 34
    ISSN: 1573-8469
    Keywords: in vitro interactions ; biological control ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fusarium wilt diseases, caused by the fungus Fusarium oxysporum, lead to significant yield losses of crops. One strategy to control fusarium wilt is the use of antagonistic, root-colonizing Pseudomonas spp. It has been demonstrated that different strains of these bacteria suppress disease by different mechanisms. Therefore, application of a mixture of these biocontrol strains, and thus of several suppressive mechanisms, may represent a viable control strategy. A prerequisite for biocontrol by combinations of biocontrol agents can be the compatibility of the co-inoculated micro-organisms. Hence, compatibility between several Pseudomonas spp. strains, that have the ability to suppress fusarium wilt of radish, was tested in vitro on KB agar plates. Growth of P. fluorescens strain RS111 was strongly inhibited by Pseudomonas spp. strains RE8, RS13, RS56 and RS158, whereas a mutant of strain RS111 (RS111-a) was insensitive to inhibition by these strains. Strains RS111 and RS111-a only slightly inhibited some other strains. Suppression of fusarium wilt of radish in a potting soil bioassay by the incompatible combination of RE8 and RS111 was comparable to the effects of the single strains. However, disease suppression by the compatible combination of RE8 and RS111-a was significantly better as compared to the single strains. In contrast, the incompatible combination of RS56 with RS111 resulted in enhanced disease suppression as compared to the single strains. Increased disease suppression by combinations of RS13 or RS158 with RS111 or RS111-a was not observed. This indicates that specific interactions between biocontrol strains influence disease suppression by combinations of these strains.
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  • 35
    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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  • 36
    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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  • 37
    ISSN: 1573-5036
    Keywords: maize ; matric water potential ; rhizosphere ; soil:root adhesion ; soil:root contact ; soil surface properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study was designed to investigate the strength of attachment of plant seedling roots to the soil in which they were grown. The study also assessed the effects of differing soil textures and differing soil matric potentials upon the strength of the root:soil attachment. A device for growing roots upon a soil surface was designed, and was used to produce roots which were attached to the soil. In order to quantify root:soil adhesion, roots of maize seedlings, grown on the soil surface, were subsequently peeled off using a universal test machine, in conjunction with simultaneous time-lapse video observation. To clarify the partitioning of energy in the root:soil peeling test, separate mechanical tests on roots, and on two adherent remoulded topsoil balls were also carried out. The seedling root was characterised by a low bending stiffness. The energy stored in bending was negligible, compared to the root:soil adhesion energy. The mechanical properties of two adherent remoulded topsoil balls were a decrease of the soil:soil adhesion energy as the soil:soil plastic energy increased. These two parameters were therefore interdependent. Using a video-camera system, it was possible to separate the different processes occurring during the root:soil peeling test, in particular, the seed:soil adhesion and the root:soil soil adhesion. An interpretation of the complex and variable force:displacement curves was thus possible, enabling calculation of the root:soil interfacial rupture energy. At a given suction (10 kPa), the results of the peeling test showed a clear soil texture effect on the value of the root:soil interfacial rupture energy. In contrast, for the same silty topsoil, the effect of the soil water suction on the value of the interfacial rupture energy was very moderate. The root:soil interfacial rupture energy was controlled mainly by a product of microscopic soil specific surface area and the macroscopic contact surface area between the root and the soil. Biological and physical interactions contributing to root:soil adhesion such as root:soil interlocking mechanics were also analysed and discussed.
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  • 38
    ISSN: 1573-5036
    Keywords: calcite ; goethite ; maize ; phosphate ; H+ release ; Brassica napus L. ; Zea Mays L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In calcareous soils the dynamics of phosphorus is controlled by calcite and iron oxides such as goethite which strongly retain P and consequently maintain low P concentrations in soil solution. Plants can drastically change chemical conditions in the rhizosphere, in particular by releasing H+ or OH− or by excreting organic anions. By modifying the dissolution/precipitation and desorption/adsorption equilibria, roots can influence the mobility of soil P. The aim of this work was to test whether H+ or OH− release can induce the mobilization of P in the rhizosphere of maize and rape supplied with NO3-N or NH4-N and grown on synthetic phosphated calcite or goethite as sole source of P. With P-calcite, the mobilization of P was generally related to the acidification of the rhizosphere. With P-goethite, rhizosphere acidification induced some increase of DTPA-extractable Fe and hence dissolution of goethite. Rhizosphere P was concomitantly depleted but the mechanisms involved are less clear. The difference in behavior of the two species is discussed.
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  • 39
    ISSN: 1573-5036
    Keywords: agroforestry ; Gliricidia sepium ; inorganic nitrogen ; maize ; nitrogen mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Many soils of southern Africa are severely N deficient, but inorganic fertilizers are unaffordable for most subsistence farmers. Rotations and intercrops of legumes with crops may alleviate N deficiency through biological N2 fixation and redistribution of subsoil N to the surface. We monitored soil inorganic N dynamics for two seasons in a gliricidia [Gliricidia sepium (Jacq.) Walp.] – maize (Zea mays L.) intercrop in the unimodal rainfall area of southern Malawi. One maize crop per year was grown with or without interplanted gliricidia, in factorial combination with three rates of N (0, 24 or 48 kg N ha-1). Application of gliricidia prunings increased (p 〈 0.001) topsoil (0 to 20 cm) inorganic N at the end of the dry season and during the early rains. Differences between plus and minus gliricidia treatments were less when total inorganic N to 1-m depth was summed. A greater proportion of the total inorganic N to 1-m depth occurred in the topsoil (0 to 20 cm) when gliricidia was present, suggesting that redistribution of subsoil N to the surface accounted for part of the N increase by gliricidia. Gliricidia lowered (p 〈 0.05) subsoil water content during drier periods. Gliricidia plots accumulated more (p 〈 0.01) ammonium-N during the dry season. Nitrate-N remained constant during the dry season but rose rapidly in gliricidia plots after the onset of rains. A 2-factor model including preseason inorganic N and anaerobic N mineralization potential accounted for 84% of the variability in maize yields for the two seasons' data combined. The combination of preseason inorganic N and potential N mineralization appears to provide a good estimate of N supply to maize in systems receiving both organic and inorganic sources of N.
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  • 40
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    Euphytica 108 (1999), S. 145-150 
    ISSN: 1573-5060
    Keywords: maize ; North Carolina model 2 ; salinity tolerance ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The genetic basis of salt tolerance was examined in selected salt tolerant and sensitive material from a sample of accessions previously assessed for variability in salinity tolerance. The North Carolina Model 2 Design and analysis was followed, tolerance being assessed in 10-day-old seedlings grown in salinized solution culture at control (0 mM), 60 mM and 80 mM NaCl concentrations). Salinity tolerance was shown to be under the control of genes with additive and non-additive effects, with broad and narrow sense heritability estimates being approximately 0.7 and 0.4 over all treatments.
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  • 41
    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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  • 42
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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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  • 43
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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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  • 44
    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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  • 45
    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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  • 46
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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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  • 47
    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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  • 48
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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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  • 49
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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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  • 50
    ISSN: 1573-0867
    Keywords: applied N and P ; crop residue ; maize ; Residual N and P ; Typic Pellustert ; Typic Ustorthent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Field trials were conducted on two soil types for seven years (1988–1994) to investigate grain yield response of maize to crop residue application as influenced by varying rates of applied and residual N and P fertilizers. Yearly application of N and P fertilizers at both one-half and full recommended rates resulted in grain yield increases of more than 500 and 1100 kg ha-1, respectively over application of only crop residue. Moreover, grain yield responses due to residual N and P fertilizers applied only during the first year were found to be comparable to the yearly applications of these fertilizers. Rainfall and soil type have exerted considerable influences on the grain yield response obtained in this study. Grain yield exhibited a corresponding decrease with decreasing rainfall. Grain yield increases on Typic Pellustert were relatively higher than on Typic Ustorthent.
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  • 51
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    Agroforestry systems 47 (1999), S. 67-91 
    ISSN: 1572-9680
    Keywords: cover crops ; farmer innovation ; land tenure ; maize ; nutrient cycling ; velvetbean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In many parts of Central America long fallow periods are no longer feasible due to increasing land pressures. Farmers in northern Honduras have developed and diffused from farmer-to-farmer a maize cropping system using velvetbean (Mucuna spp.) as a short-term fallow. High total annual rainfall in a bimodal distribution is favorable to the system because it allows the completion of two rainfed cropping cycles annually. The first season is dedicated to the production of the mucuna crop and the second season is dedicated to maize. Soil pH and exchangeable Ca were not reduced during a 15-year period of continuous mucuna use. Soil organic matter, infiltration, and porosity increased with continuous mucuna use. Maize yields in fields with continuous rotation of mucuna were on average double those obtained without mucuna. The mucuna system was more profitable than the existing alternative bush-fallow system due to higher returns to land and labor resulting from higher yields, lower weeding and land preparation costs, and reduced risk of drought stress. The relative profitability of the mucuna system was also enhanced by seasonally high maize prices during the second season when maize is harvested in the mucuna system. Relatively easy access to land through inexpensive land ownership and land rental markets has made it possible for even small-scale farmers to dedicate land to the mucuna system. Land-use intensity is increasing in the region, however, as land is converted to pastures for cattle production. The opportunity costs of keeping land in the mucuna system, while also accessing land for first-season maize and other crops, are also increasing. These experiences remind us that a viable livelihood is the primary factor in farmers' decision making about adoption particular components of farming systems.
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  • 52
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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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  • 53
    ISSN: 1573-8469
    Keywords: Alternaria brassicae ; biological control ; cross infection ; disease management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Resistance in susceptible mustard cv. PR-15 against the highly virulent A. brassicae isolate A (AbA) and moderately virulent isolate C (AbC) was induced using an avirulent Alternaria brassicae isolate D (AbD). The induction of resistance due to AbD against AbA or AbC resulted in significant reduction in disease severity. The A. alternata (Aa) failed to induce resistance against AbA and AbC, on the contrary it induced susceptibility against them.
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  • 54
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    European journal of plant pathology 105 (1999), S. 177-189 
    ISSN: 1573-8469
    Keywords: biological control ; grey mould ; mechanisms ; pathogenicity enzymes ; proteolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The role of protease of Trichoderma harzianum in the biocontrol of Botrytis cinerea was examined. Two isolates of T. harzianum were compared for their ability to produce protease in liquid culture medium and on the surface of bean leaves. The biocontrol agent T. harziaum T39 produced 58 mU/ml of protease and T. harzianum NCIM1185 produced 54 mU/ml on the 5th day of growth in liquid culture medium. On bean leaves, combinations of B. cinerea and T. harzianum isolates were examined for the synthesis of protease. The protease activities were 0.9 and 0.6 mU/ml for T. harzianum T39 and NCIM1185, respectively, and 0.5 mU/ml for B. cinerea alone after 48 h of incubation. In the presence of T. harzianum T39 culture liquid containing protease, a 55% reduction in B. cinerea germination and a 80% reduction in the germ tube length were observed after 17 h of incubation in vitro. When T. harzianum isolates were added to B. cinerea on bean leaves, increased synthesis of protease was observed (1.0 and 1.2 mU/ml for T39 and NCIM1185, respectively). In the presence of T. harzianum NCIM1185 protease, although the rate of germination was reduced, B. cinerea attained 98% germination after 17 h of incubation. The hydrolytic enzymes produced by B. cinerea, endo-polygalacturonase (PG) and exoPG were partially deactivated by protease from the T. harzianum isolates. Carboxymethyl cellulase was deactivated only by protease of NCIM1185. On the surface of bean leaves, the protease (obtained from liquid culture medium of T. harzianum isolates) resulted in 56–100% reduction of disease severity. The culture liquid containing protease synthesized on the surface of bean leaves treated with B. cinerea and with T. harzianum was collected and added to fresh leaves infected by B. cinerea. There was 56–100% and 30–75% reduction of disease severity with liquid droplet collected from the leaves treated with T. harzianum T39 and NCIM1185, respectively. Increased control of disease was obtained by combining the conidia of T. harzianum isolates with protease obtained from culture media. Protease inhibitors, trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane (E64), antipain hydrochloride, and a mixture of inhibitors, but not pepstatin A, fully or partially nullified the biocontrol effect of T39. T39 was found to be a poor producer of chitinase and β-1,3-glucanase in vitro. These enzymes were not detected on leaves treated with T39. Involvement of protease in biocontrol of B. cinerea is suggested.
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  • 55
    ISSN: 1573-8248
    Keywords: Acari ; biological control ; generalist ; intraspecific predation ; multiple species release ; predatory mites ; specialist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We examined intra- and interspecific predation of adult females and immature stages of the generalist Neoseiulus californicus and the specialist Phytoseiulus persimilis. Adult females and immatures of both predators exhibited higher predation rates on larvae than on eggs and protonymphs. N. californicus fed more inter- than intraspecifically. Predation on P. persimilis by N. californicus was more severe than vice versa. P. persimilis had higher predation rates on conspecifics than heterospecifics and was more prone to cannibalism than N. californicus. When provided with phytoseiid prey, P. persimilis suffered higher mortality than N. californicus. When held without food, adult females and protonymphs of N. californicus survived longer than the corresponding stages of P. persimilis. N. californicus females were able to sustain oviposition when preying upon P. persimilis, whereas cannibalizing females did not lay eggs. Females of P. persimilis were not able to sustain oviposition, irrespective of con- or heterospecific prey. Immatures of both predators were able to reach adulthood when provided with either con- or heterospecifics. Juvenile development of N. californicus was shorter with heterospecific vs. conspecific larvae; mortality of P. persimilis immatures was less when feeding on conspecific vs. heterospecific larvae. Different behavioral pattern in intra- and interspecific predation are discussed in regard to their feeding types (generalist vs. specialist).
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  • 56
    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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  • 57
    ISSN: 1573-8248
    Keywords: Anaxipha longipennis ; biological control ; Gryllidae ; Metioche vitatticollis ; parasitism ; predation ; Trichogramma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Egg mortality of rice leaf folders Cnaphalocrocis medinalisand Marasmia patnalis was studied in unsprayed irrigated rice fields in Laguna Province, the Philippines. Mortality was assessed by field exposure of laboratory-laid eggs for two days and by monitoring of field-laid eggs. Egg disappearance, the major mortality factor, was low in the first four weeks after transplanting and then increased. Egg parasitism by Trichogrammajaponicum was highest at the start of the crop and decreased to a low level towards crop maturity. Non-hatching of eggs was of minor importance. Over the total duration of the egg stage, the average disappearance of exposed laboratory-laid eggs was40%, and of field-laid eggs 46%. Egg mortality due to parasitism averaged 15% and 18%, respectively. The potential impact of egg parasitism is probably partly obscured by the disappearance of parasitized eggs. Mortality rates were highly variable between egg cohorts, but with multiple regression analysis several factors were identified that statistically explained a significant part of this variation. The results suggest that the predatory crickets Metiochevittaticollis and Anaxipha longipennis play a major role in egg disappearance, and that egg parasitism is positively dependent on the overall density of host eggs of Trichogramma in the field.
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  • 58
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    BioControl 44 (1999), S. 159-169 
    ISSN: 1573-8248
    Keywords: biological control ; Euphorinae ; species identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four parasitoids of the subfamily Euphorinae are common in New Zealand pasture. These are Microctonus aethiopoides, M. hyperodae, M. zealandicus and Dinocampus coccinellae. There is overlap in these parasitoids' host ranges and, although adults of these species can be identified morphologically, their larval stages have not yet been compared. This contribution provides morphological descriptions of the head capsules of 1st instar larvae that enable the four parasitoid species to be distinguished. Diagnostic characteristics are the shape of the mandible and the pattern of sclerotisation on the hypopharynx. Post 1st instar larvae can be identified by retrieving the shed 1st instar head capsule from the host abdomen.
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  • 59
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    BioControl 44 (1999), S. 347-367 
    ISSN: 1573-8248
    Keywords: Aphidiidae ; biological control ; Chrysopidae ; Coccinellidae ; entomopathogens ; Hemerobiidae ; Syrphidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sixteen cohorts of the brown citrus aphid, Toxoptera citricida, were followed from colony initiation to maturation/extinction in citrus groves at two sites in Puerto Rico and nine sites in Florida, USA. Infested citrus terminals were sampled repeatedly in a non-destructive manner and data recorded on the recruitment of natural enemies and the fate of aphid colonies. Coccinellidae were the most efficient predators of T. citricida, primarily Cycloneda sanguinea, and Coelophora inaequalis (Puerto Rico), C. sanguinea, Harmonia axyridis (Florida). Coccinellids were abundant in citrus year-round in Puerto Rico, but in Florida citrus their abundance peaked in spring and declined thereafter. Syrphid flies were other important predators, especially Pseudodorus clavatus (Florida and Puerto Rico) and Ocyptamus fuscipennis (Puerto Rico). Syrphids increased in abundance from spring to fall in both regions. Other predators included Cereaochrysa lineaticornis, Chrysoperla rufilabris (Chrysopidae) and Micromus posticus (Hemerobiidae). The parasitoid Lysiphlebus testaceipes was ubiquitous in T. citricida cohorts, but its impact on colony survival was usually low. The fungal pathogen Verticillium lecanii was a significant source of colony mortality at one site in Puerto Rico, but was not observed on T. citricida in Florida.
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  • 60
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    BioControl 44 (1999), S. 291-299 
    ISSN: 1573-8248
    Keywords: biological control ; cerambycid ; Coleoptera ; pine wood borer ; poplar wood borer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Artificial diets for the colydiid beetle, Dastarcus helophoroides, a predator of cerambycid beetles and xylocopid bees, were evaluated. Hatched larvae were reared on artificial diets composed of silkworm pupa-powder, dry yeasts, yeast extract, sucrose, peptone, squid liver oil, preservatives and distilled water, but their emergence rate was very low. If larvae were fed paralyzed cerambycid larvae till they became approximately 8 mm in body length and then reared on artificial diet, emergence rates were high. Using the latter method, mass-production of this colydiid beetle is feasible.
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  • 61
    ISSN: 1573-8248
    Keywords: bacterial antagonists ; biological control ; Pantoea agglomerans ; pseudosclerotia ; Sclerotiniaceae ; Vaccinium macrocarpon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bacteria inhibitory to Moniliniaoxycocci, the cranberry cotton ball pathogen, were identified. Eighty-three bacteria isolated from a cranberry marsh and Erwinia herbicola C9-1,which is being developed elsewhere for the biological control of fire blight of pome fruits, were tested fortheir ability to inhibit radial growth and conidial germination of M. oxycocci in vitro. IsolateBA35 from cranberry (tentatively identified as Pseudomonas syringae pv. morsprunorum) and E. herbicola C9-1 completely inhibited radial growth of M. oxycocci. BA35 and C9-1 were among the most effective of 21 bacteria tested for inhibition of conidial germination. Growth of bacteria in sclerotial extracts of M. oxycocci and Sclerotinia sclerotiorum was determined in order to select isolates that might be successful in degradingsclerotia, thereby reducing the viability of M.oxycocci. Populations of isolates 62 and S-18(identities unknown), and S-19 (tentatively identified as Micrococcus luteus), increased approximately3.0--5.0 log10 units in all extracts within 24 h. Populations of isolate S-10 increased by about 3.5log10 units in all sclerotial extracts within 48 h. Populations of isolate S-49 (identity unknown)were lower in extracts of M. oxycocci than S. sclerotiorum after 48-h. In buffer controls, bacterial populations remained stable or decreased over the 48-h period.
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  • 62
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    BioControl 43 (1999), S. 441-456 
    ISSN: 1573-8248
    Keywords: agroecosystems ; biological control ; Carabidae ; carabid community ; Coleoptera ; generalist predators ; natural enemy abundance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Generalist natural enemies such as carabid beetles have the potential to maintain a variety of pests below outbreak levels in annual crops. To assess the relationship between carabid beetle abundance and field rates of prey removal, we created plots surrounded by different boundaries that selectively affected dispersal of edaphic arthropods, primarily carabids. Three treatments were established: (1) naturally occurring communities, (2) augmented communities using ingress boundaries, and (3) reduced communities using egress boundaries. Selective boundaries altered carabid communities with minimal habitat alteration and without use of insecticides. Three times during the growing season, a fixed number of onion fly pupae were placed in plots to evaluate the impact of carabid abundance on predation rates. A combination of vertebrate and invertebrate exclosures allowed us to evaluate prey removal by invertebrates alone. In comparison to the no boundary treatment, carabids increased 54.2% and decreased 83.1% in plots surrounded by ingress and egress boundaries respectively. Predation rates were positively correlated with carabid abundance (r2 = 0.70, p 〈 0.0001). Significantly more pupae were removed from exclosures allowing access to invertebrates alone than from total exclosures, suggesting that invertebrates represented an important group of predators. Laboratory trials tested the feeding potential of the four most abundant carabid species and showed that they readily consumed onion fly pupae, supporting our hypothesis that carabids were the main predators in field tests. This study corroborates and extends previous observations of the importance of carabid beetles as generalist predators of insect pests in agricultural fields.
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  • 63
    ISSN: 1573-8248
    Keywords: Acari ; biological control ; cannibalism ; generalist ; interspecific predation ; multiple predators release ; predatory mites ; specialist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Discrimination between and predation preference for con- or heterospecific larvae was examined for adult females of P. persimilis and N. californicus in plexiglass cages with and without their primary prey T. urticae. Rates of intra- and interspecific predation on larvae were measured for females held on leaves and provided with excess amounts of spider mites. Females of the generalist N. californicus distinguished con- and heterospecific larvae and preferred to prey upon the latter. Females of the specialist P. persimilis appeared to lack discrimination ability and fed equally on con- and heterospecifics. When spider mites and phytoseiids were offered simultaneously, all P. persimilis females chose to first attack T. urticae, whereas N. californicus females attacked both tetranychids and heterospecific phytoseiids. Females of both predators preyed upon phytoseiid larvae when held on leaves with surplus T. urticae: while P. persimilis fed on both con- and heterospecifics, N. californicus attacked larvae of P. persimilis but avoided cannibalizing larvae. The different behaviors of P. persimilis and N. californicus are discussed with regard to different predation types (generalists vs. specialists) and the possible consequences of mixed release for biological control of spider mites in greenhouses.
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  • 64
    ISSN: 1573-8248
    Keywords: biological control ; kaolin ; mycoherbicide ; preservation ; weed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Different solid substrates were investigated as spore production methods for Stagonospora convolvulistrain LA39, a potential bioherbicide for field bindweed (Convolvulusarvensis L.). Up to 4 × 108 spores/g of substratewere yielded on cous-cous (cracked hard wheat). Thespores were as pathogenic as those grown on artificial medium (V-8-juice agar). The air-drying on kaolin and storage at 3 °C kept spores viable and pathogenic for 180 days. Spore germination exceeded70% for the first 140 days and then declined to 50%after 175 days. Less than 5% of spores were still viable after 17 months. The preservation of stock cultures in 10% glycerine at −80 ° C and in liquid nitrogen did not affect viability orpathogenicity of the spores.
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  • 65
    ISSN: 1573-0867
    Keywords: animal manure ; leaching ; maize ; nitrification inhibitor ; nitrogen recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Field experiments with silage maize during eight years on a sandy soil in The Netherlands, showed that dicyandiamide (DCD) addition to autumn-applied cattle slurry retarded nitrification, thus reducing nitrate losses during winter. Spring-applied slurry without DCD, however, was on average associated with even lower losses and higher maize dry matter yields. Economically optimum supplies of mineral N in the upper 0.6 m soil layer in spring (EOSMN), amounted to 130–220 kg ha−1. Year to year variation of EOSMN could not be attributed to crop demand only. According to balance sheet calculations on control plots, apparent N mineralization between years varied from 0.36 to 0.94 kg ha−1 d−1. On average, forty percent of the soil mineral N (SMN) supply in spring, was lost during the growing season. Hence, the amounts of residual soil mineral N (RSMN) were lower than expected. Multiple regression with SMN in spring, N crop uptake and cumulative rainfall as explanatory variables, could account for 79 percent of the variation in RSMN. Postponement of slurry applications to spring and limiting N inputs to economically optimum rates, were insufficient measures to keep the nitrate concentration in groundwater below the EC level for drinking water.
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  • 66
    ISSN: 1572-9680
    Keywords: Erythrina ; Gliricidia ; alley cropping ; maize ; competition ; nitrogen availability ; Costa Rica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize growing next toErythrina hedgerows had 44% lower biomass (p〈0.01) and 35% lower N content (p〈0.1) than maize growing in the middle of the alleys. Maize growing next toGliricidia hedgerows had the same biomass but 56% higher N content (p〈0.1) than maize growing in the middle of the alleys. However these differences did not develop until 2 months after sowing of the maize. Spatial variability in soil nitrogen mineralization and mulch nitrogen release did not explain any of the differences in growth or N uptake of the maize with respect to distance from the trees. It is hypothesized that the slower growth of the maize next to theErythrina trees after 2 months is due to increasing light and/or nutrient competition from the trees as the trees recover from pollarding. The apparent lack of competition fromGlirigidia may be due to different rates of regrowth or different shoot and root architecture. A theoretical model is described demonstrating that if a crop is to take advantage of the higher nutrient availability under alley cropping it must complete the major part of its growth before the trees recover significantly from pollarding, and start competing strongly with the crop.
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  • 67
    ISSN: 1572-9680
    Keywords: alley cropping ; maize ; nitrogen ; organic matter ; soil fertility ; Leucaena leucocephala ; Flemingia congesta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A detailed study of the soil chemical and physical properties in seven-year-old alley cropping trial containingLeucaena leucocephala andFlemingia congesta in Northern Zambia is described. There was a strong correlation between the maize yield and the total amount of nitrogen applied, both from prunings and fertiliser, suggesting that a major reason for the observed benefit from alley cropping, particularly withLeucaena, was due to an improvement in nitrogen supply.Leucaena produced significantly more biomass, and its leaves had higher concentrations of nitrogen, phosphorous and potassium and lower C/N and C/P ratios than did those ofFlemingia. There was also evidence that the trees had a beneficial effect on other soil chemical properties; under the hedgerows, particularly those ofLeucaena, there were higher levels of organic carbon, Mg, K and ECEC, and pH values were also highest. It is suggested that higher levels of organic carbon in the alley crop treatments were responsible for the improvements observed in soil physical properties. Lower bulk density, lower penetration resistance, and a higher infiltration rate and pore volume fraction were measured in the alley crops, although there was no significant change in the soil water release parameters. A deteriorating effect of constant applications of nitrogen fertiliser on soil fertility was observed; as the level of urea application increased, there were significant decreases in Mg, K and pH, increases in Al and soil acidity, and higher penetrometer resistance. These results highlight the urgent need for further research on biological methods of maintaining soil fertility.
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  • 68
    ISSN: 1432-0789
    Keywords: Nitrogenase activity ; Acetylene reduction activity ; ARA ; Cyanobacteria ; Soil inoculation ; Wetland rice ; Root system ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A greenhouse experiment was conducted with wetland rice (Oryza sativa cv. IR-50) in a clay-loam soil (Fluventic Eutrochrept) to study the effect of cyanobacterial inoculation a mixed culture of Aulosira fertilissima, Nostoc muscorum, Nostoc spp., and Anabaena spp., applied at the rate of 0.15 g (dry weight pot-1 or 43 kg ha-1) on acetylene reduction activity in soil and the root system (excised root), and the grain and straw yield. The effects of applying P (40 kg ha-1), N (60 kg ha-1), and P+N to the soil were also evaluated. Cyanbacterial inoculation significantly increased (more than 200% on average) photo-dependent acetylene reduction activity in soils, particularly where the indigenous activity was considerably low, i.e. under unfertilized and N-fertilized conditions. The effect of inoculation was prominent at the maximum tillering and grain formation stages of the crop. This inoculation benefit was, however, marginal in P-applied soils (P and P+N), where the indigenous activity was stimulated more than threefold. The inoculation led to a remarkable increase in root-associative acetylene reduction activity after the maximum tillering stage of the crop, particularly with applied N but for other treatments this inoculation effect was not significant. Cyanobacterial inoculation also increased the grain and straw yield of the crop when N was not applied. The grain and straw yield was significantly correlated with the acetylene reduction activity in flooded soils and in the root system during the tillering and maximum tillering stages of rice growth, respectively.
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  • 69
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    Biology and fertility of soils 16 (1993), S. 151-153 
    ISSN: 1432-0789
    Keywords: Triple cereal cropping ; Barley ; double-cropped rice ; Oryza sativa ; Wetland rice soils ; Stable grain yield ; Organic manuring ; Sustainability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Triple cereal cropping is an important grain production pattern which has been adopted on a vast area of paddy fields in Southern China. A long-term triple cereal cropping (barely with double-cropped rice) experiment has been conducted for 18 years (1974–1991) in paddy fields on the southern coastal plain of Zhejiang. The results showed that long-term triple cereal cropping has a high and stable grain yield level if certain improved crop varieties are used. Furthermore, the use of organic manure to reduce yield fluctuations and promote N-use efficiency was evaluated.
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  • 70
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    Potato research 36 (1993), S. 35-42 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; disease screening ; maturity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Fourteen genotypes of potato were assessed for resistance toAlternaria solani Sor., both in the glasshouse at the Scottish Crop Research Institute in Scotland and in the field in the Negev, Israel. Glasshouse assessments agreed well with field results, identifying the most resistant and susceptible genotypes. The effects on the glasshouse test of plant age, inoculum concentration, and length of time plants were kept damp after inoculation, were examined. The best agreement with field results was shown by plants inoculated at flowering, and the best discrimination between genotypes was achieved by keeping the foliage damp for 24 h after inoculating with a spore suspension containing 2.5×103 spores/ml.
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  • 71
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    Potato research 36 (1993), S. 283-292 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; rapid multiplication ; seed production ; non-destructive harvest ; physiological age ; cultivar ; stem number
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Minitubers of cultivars Agria and Liseta were harvested from the same plantlets on three dates. After each harvest, tubers were dried (1 day), cured (13 days) and cold stored at 2 °C in darkness and 80 % RH. Their performance was studied 65, 128, 191, 254, 317, 380, 443, 506 and 569 days after harvest. Minitubers (1–2 g) were planted in pots and grown for 8 weeks in a controlled environment. After 191 days of storage their growth was still extremely poor. In both cultivars, tallest plants and largest leaf areas per plant were observed in plants from tubers from the second and third harvests that had been stored for 317 days. Highest stem numbers, yields (total dry matter, tuber fresh weight) and harvest indices were achieved with 443 days storage with cv. Agria and 569 days storage with cv. Liseta. Tubers from the first harvest behaved slightly differently.
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  • 72
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    Potato research 36 (1993), S. 143-151 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; Warmlagerung ; Keimintensität ; Schwund ; Aufgangsverspätung ; Bestandesdichte ; Ertrag
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary Seed tubers were stored at above optimal temperatures. Mean temperatures varied during test years from 16 to 29.5°C (in 1988–1990 tubers desprouted before planting; in 1991 chitted tubers as in control; Table 1). This procedure of physiological ageing of seed tubers resulted in reduced plant density and lower yield compared to the chitted control in every year of the test period (average of 25 cultivars). The emergence was significantly delayed as compared to the control in all years (Table 2). Assessed for yield, the cultivars Désirée, Sanetta, Astilla and Andra showed a significantly higher degree of tolerance to warm storages (〉80%, when compared to the control) than the cultivars Arkula, Dorisa, Karlena and Koretta (〈25%; Table 3). Between these two extremes there was a large number of intermediate levels of tolerance, a result of fluctuating reactions of various cultivars to changing conditions in the years of the test period (Fig. 1). No correlation could be found between the cultivars' reactions and their maturity group or their sprouting behaviour. There was, however, for each cultivar a significant negative correlation between loss in weight through transpiration and respiration and plant density and yield (r=−0.55 and −0.54; Table 4). Plant density and yield were closely correlated (Table 4). The regressions between loss of plants and reductions in yields show that after seed tuber storage at higher temperatures a reduced yield must be expected even when plant density is not reduced (loss of plant 0%; Fig. 2). With complete stands, the use of physiologically aged seed tubers that were desprouted before planting (1988–1990) resulted in a reduction of yield of 17–20%; when old seeds were chitted as in control a loss in yield of 15% was calculated.
    Notes: Zusammenfassung Die physiologische Alterung der Pflanzknollen durch Lagerung bei überoptimalen Temperaturen (jahresunterschiedlich 16–29,5°C, 1988–90 vor dem Pflanzen abgekeimt, 1991 vorgekeimt wie Kontrolle) führte im Vergleich zur vorgekeimten Kontrolle im Mittel von 25 Sorten in allen Versuchsjahren zu einer Verminderung der Bestandesdichte und des Ertrages. Eine Gruppe von Sorten erwies sich in allen Jahren als relativ tolerant gegen die Alterung, eine andere als signifikant empfindlicher, dazwischen lag ein breites Mittelfeld mit zum Teil erheblichen Schwankungen in den Jahren. Die Reaktion der Sorten zeigte keine Beziehung zu ihrer Reifegruppe und ihrer Keimintensität, dagegen war die sortentypische Ertragsdepression nicht sehr eng, aber signifikant mit dem Schwund während der Lagerung korreliert.
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  • 73
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; Phytophthora infestans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of the moisture level of potting compost at harvest on the susceptibility of tubers of three cultivars to late blight was investigated in the glasshouse in three successive years. Three moisture regimes (dry, moist, wet) were imposed at flowering time, the tubers harvested 3 weeks later and immediately dipped in a zoospore suspension ofPhytophthora infestans. Tubers from dry compost were significantly more susceptible than those from wet or moist compost, which showed similar levels of susceptibility.
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  • 74
    ISSN: 1871-4528
    Keywords: culture filtrate ; resistant variants ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Cells of seven potato cultivars were selectedin vitro with culture filtrate (CF) ofPhytophthora infestans (Mont.) de Bary. Regenerated plants were tested for late blight resistance. The aim of the study was to check the efficacy of CF in the selection of potatoes for resistance to late blight and to evaluate the effects of additive factors on general resistance. One selection cycle, applied to a cell culture system, selected cells resistant to toxic metabolites of CF.In vivo screening of clones regenerated from selected cells was done in two steps: on whole plants, assessing foliage late blight, and on detached leaves, assessing single factors of horizontal resistance. In general, the frequency of resistant variants selected with CF did not differ from that of resistant somaclonal variants. Nevertheless, high concentrations of CF in the growth medium seemed to induce an improvement of some partial resistance factors as compared with the source plants.
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  • 75
    ISSN: 1871-4528
    Keywords: foliage blight ; tuber blight ; Phytophthora infestans ; breeders' preference score ; specific combining ability ; potato ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Screening tests to detect resistance to late blight in both foliage and tubers were done on glasshouse-grown seedling progenies in parallel with visual assessments by three experienced potato breeders of the yield and quality of glasshouse-grown tubers of the same progenies. There were large differences between the parents of the progenies in their general combining ability (GCA) for both foliage and tuber blight, despite some variation due to specific combining ability for foliage blight. There were also differences between parents in their GCAs for visual preference scores, but these GCAs and those for blight resistance were not correlated. The blight-resistant cv. Stirling had the best combination of high GCAs for all three attributes. The use of these and other seedling progeny tests in a multitrait genotypic recurrent selection scheme is discussed.
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  • 76
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; seed size ; rapid multiplication ; seed production ; non-destructive harvest ; water loss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Storage losses were studied in minitubers of cvs Agria and Liseta, using five fresh weight classes (〈0.50 g, 0.5–0.99 g, 1.00–1.99 g, 2.00–2.99 g, ≥3.00 g), and three successive harvests of the same plantlets. After each harvest, tubers were dired at room temperature (1 day), curred at 18 °C (13 days) and stored at 2 °C (540 days). Two kinds of storage losses were considered: (a) losses of entire tubers because of deterioration, and (b) fresh weight losses of the other tubers. Both kinds of losses were higher in cv. Liseta, in tubers with lower fresh weights and in tubers from the first harvest. Almost all minitubers ≥0.5 g from later harvests and from both cultivars survived storage for 1.5 years. Deterioration occurred mainly from 6 to 12 months of storage. Tubers which deteriorated during cold storage had already shown high weight losses during curing.
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  • 77
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    Potato research 36 (1993), S. 365-372 
    ISSN: 1871-4528
    Keywords: gametophytic selection ; reciprocal differences ; GA ; dwarfs ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A selected clone ofSolanum tuberosum Group Andigena PI 347773 (clone Adg 11.1) and the cultivar Superior had previously been shown to be heterozygous at a gibberellin related dwarfing locus, ga1. Experiments were conducted to test for gametophytic selection for alleles at the ga1 locus in reciprocal crosses and for the effect of genotype on tuber yield. The genotypes of individuals from superior-Adg 11.1 reciprocal F1 families were determined by test crossing. Genotypic classes could be distinguished by the percentages of dwarf seedlings in their test cross progeny. No differences were found in the genotypic distributions of the reciprocal families, which indicates gametophytic selection at this locus is not the cause of reciprocal yield differences. Superior-Adg 11.1 individuals classified by ga1 locus genotype were evaluated for tuber yield. Tuber yields were highly correlated with genotype in both reciprocal families. Yields followed the pattern of simplex〉duplex〉triplex, indicating that the recessive mutant ga1 allele exhibited a dose effect stimulating yield.
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  • 78
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; seed size ; rapid multiplication ; seed production ; non-destructive harvest ; cold treatment ; sprouting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Dry-matter concentration and dormancy were studied in minitubers of cvs Agria and Liseta, using five fresh weight classes (〈0.50 g, 0.50–0.99 g, 1.00–1.99 g, 2.00–2.99 g and ≥3.00 g) and three successive harvests of the same plantlets. The average dry-matter concentration increased with tuber weight for tubers from the second and third harvests. In minitubers ≥0.5 g, dry-matter concentration was higher in tubers from later harvests. The dormant period (days from harvest to 50% sprouting) was longer in minitubers with lower than higher weights, and longer in tubers from the first harvest than from later harvests. A cold-storage period of 6 weeks, starting 14 days after harvest, reduced the dormant period by an average of 11 days.
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  • 79
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    Potato research 36 (1993), S. 359-364 
    ISSN: 1871-4528
    Keywords: glutamine ; arginine ; valine ; histidine ; asparagine ; proline ; tyrosine ; methionine mixture ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Amino acids and sugars were removed from slices of potato of the cultivar Record. The slices were then soaked in solutions of the amino acids and various concentrations of glucose to study their effect on the fry colour of crisps. Glutamine was an important amino acid in the development of fry colour intensity at low glucose concentrations and also contributed to the dark fry colour when combined with glucose concentrations above 0.15%. The basic amino acid arginine had a similar but lesser effect and other amino acids used gave the same effect at glucose concentrations above 0.45%. Asparagine could play an important role in the development of fry colour quality and may decrease the grey colour intensity developed by the mixture of amino acids.
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  • 80
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    Potato research 36 (1993), S. 55-61 
    ISSN: 1871-4528
    Keywords: rapid multiplication ; Solanum tuberosum L. ; stem length ; underground tubers ; variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The formation of above-ground tubers on stem cuttings of eight potato cultivars was studied over three seasons. To promote tuber formation in the leaf axils, stems grown from single node cuttings were exposed to short day conditions. Tuber formation underground was reduced by covering the soil with a plastic sheet and by using single node cuttings planted with the leaf axils several centimetres above the soil surface. With all cultivars except Alpha, which produced mis-shapen tubers in all experiments, an average of 11 (maximum 40) tubers per cutting were harvested. Significant cultivar × year interactions were observed.
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  • 81
    ISSN: 1871-4528
    Keywords: ELISA ; hybridoma ; closterovirus ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two monoclonal antibodies (McAbs) which react specifically with potato virus T (PVT) were produced and tested for cross reactivity with potato viruses (A, S, X, Yo, YN, leaf roll), apple stem grooving virus (ASGV) and against healthy sap. They were found to be highly specific for PVT. These two McAbs form the basis of an enzyme-linked immunosorbent assay (ELISA) for the detection of PVT in infected plant material which is of key significance for potato quarantine.
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  • 82
    ISSN: 1871-4528
    Keywords: ELISA ; enzyme amplification ; feeding behaviour ; field resistance ; honeydew excretion ; Myzus persicae ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The acquisition of potato leafroll virus (PLRV) byMyzus persicae nymphs from the top leaves of potato plants was studied throughout a growing season in relation to the antigen titre in those leaves and the feeding behaviour of the aphid. Secondarily-infected plants of eight potato genotypes with different levels of field resistance served as virus sources. Early in the growing season, plants were efficient sources for virus acquisition. The amount of viral antigen detected inM. persicae nymphs fed on the top leaves was strongly correlated with the titres of viral antigen in these leaves. Virus acquisition from the top leaves of older potato plants was markedly impaired and could not be correlated with their virus titre. With increasing age of the potato plants and the development of virus symptoms, the virus titre in the leaves declined and the initial weak correlation between the virus titre and field resistance ratings disappeared. Thus, screening secondarily-infected potato plants for field resistance to PLRV based on the concentration of viral antigen in leaves or in aphids fed on them should be avoided later in the growing season. The feeding rate ofM. persicae, measured by the number of honeydew droplets excreted, did not account for the reduced uptake of virus from older plants since it was not influenced by the age of the plant. Throughout the growing season, the feeding rate ofM. persicae nymphs on PLRV-infected plants was higher on genotypes with low levels of field resistance to PLRV than on genotypes with high ones.
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  • 83
    ISSN: 1871-4528
    Keywords: PVY ; plant breeding ; progeny tests ; genetics ; resistance ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary For potato breeding or genetical research purposes, the number of copies of a dominant major gene for resistance to potato virus Y in a parent clone can be determined by test-crossing with a susceptible parent and observing the segregation ratio of resistant to susceptible seedlings in the progeny. In a comparison of different susceptible cultivars for use in test-crosses for this purpose, their progenies differed in the clarity of symptoms and parental phenotype proved an unreliable guide. Cvs Maris Piper, Arran Peak and Dr MacIntosh were found to be suitable tester parents, Pentland Squire less so and cv. Désirée was confirmed as having a major gene conferring incomplete resistance. It was found advisable to test-cross with more than one susceptible parent.
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  • 84
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    European journal of plant pathology 99 (1993), S. 197-203 
    ISSN: 1573-8469
    Keywords: Pyricularia ozyzae ; Oryza sativa ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect ofPyricularia oryzae, the causal organism of leaf blast in rice, on photosynthesis characteristics of rice leaves was measured in two greenhouse experiments. Leaf blast reduced photosynthesis not only through a reduction in green leaf area, but also through an effect on photosynthesis of green leaf tissue surrounding the lesions. The assimilation rate at light saturation (P max ) was more affected than the initial light use efficiency (∈). Dark respiration (R d ) increased as a result of infection. The experimental data were used to derive relations between leaf blast severity andP max , ∈ andR d .
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    European journal of plant pathology 99 (1993), S. 323-334 
    ISSN: 1573-8469
    Keywords: Pyricularia oryzae ; Oryza sativa ; crop loss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rice crops grown under irrigated conditions were inoculated withPyricularia oryzae during early growth stages to study the effect of leaf blast on yield formation. The inoculations led to severe epidemics of leaf blast around maximum tillering, characterized by the presence of typical blast lesions and an accelerated senescence of heavily infested leaf tissue. Leaf blast led to a prolonged tillering and a delay in flowering and maturity. Crop growth rate and leaf area formation declined sharply during establishment of the disease and continued to be reduced till maturity. This resulted in a marked reduction of total dry matter production and grain yield. Dry matter distribution was not affected. Leaf blast reduced spikelet number, 1000 grain weight, and the fraction filled grains. From this last observation it was concluded that the reduction in grain yield was exclusively source determined. Nitrogen uptake of the inoculated crops before flowering was reduced compared to the N uptake of the control crop, but shoot N content of the inoculated crops at flowering was higher. Uptake of nitrogen after flowering was negligible in both healthy and inoculated crops. Redistribution from vegetative tissue was therefore the main source of N for grain growth. The higher N content of the shoot organs in the inoculated crops during ripening led to the conclusion that the reduced N uptake was not responsible for the yield reduction observed. Consequently, the reduction in grain yield was solely determined by a reduced carbohydrate supply.
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  • 86
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    European journal of plant pathology 99 (1993), S. 205-217 
    ISSN: 1573-8469
    Keywords: Pyricularia oryza ; Oryza sativa ; simulation model ; respiration ; vertical distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect ofPyricularia oryzae, the causal organism of leaf blast in rice, on photosynthetic rate of a rice crop was determined with mobile equipment in the field. Canopy CO2 exchanges rate (CER) was significantly reduced in plots inoculated withP. oryzae. The experimentally obtained data were used to evaluate the performance of a model for the effects of leaf blast on canopy photosynthesis. The model comprised photosynthesis and respiration routines of a mechanistic crop growth model, extended with submodels for effects of leaf blast on both processes. Canopy photosynthesis and the effect of leaf blast on CER were accurately simulated with the model. Analysis showed that the reduction in canopy photosynthesis was mainly due to an adverse effect of lesions on leaf photosynthetic rate and to shading by dead leaf are resulting from disease induced senescence. A sensitivity analysis demonstrated the importance of the vertical distribution of the disease in the canopy. This implies that disease monitoring for crop loss assessment should consider vertical disease distribution.
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  • 87
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    Plant foods for human nutrition 43 (1993), S. 87-95 
    ISSN: 1573-9104
    Keywords: maize ; bran ; niacin ; thiamin ; pantothenic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of the project was to determine the bioavailability of selected B vitamins (niacin, pantothenic acid and thiamin) to humans from wet and dry milled maize brans which were coarsely or finely ground. Using a double cross-over design, the nine subjects were fed laboratory controlled diets containing unsupplemented bread or bread supplemented with finely ground, wet milled maize bran; coarsely ground, wet milled maize bran; finely ground, dry milled corn bran; or coarsely ground, dry milled maize bran. Subjects made complete collections of urine throughout the study which were analyzed for contents of the test vitamins. Although varying somewhat among vitamins, in general, better apparent bioavailability was achieved with the finely ground, dry milled maize bran than with the other test brans.
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  • 88
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    Plant and soil 155-156 (1993), S. 99-102 
    ISSN: 1573-5036
    Keywords: field bean ; maize ; plasmalemma ATPase ; proton motive force ; retrieval mechanism ; root exudates ; sugar/proton cotransport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The re-uptake of sugars driven by the proton gradient was studied in sugar net-release and net-uptake experiments using roots of intact maize (Zea mays cv. Blizzard) and field bean (Vicia faba L. cv. Alfred) plants. The net release of sugars into the root medium (0.1 mM CaSO4) was stimulated by: the protonophore CCCP (10 μM); the sulfhydryl reagent NEM (300 μM); the specific inhibitor of plasmalemma ATPase vanadate (0.5 mM); and the inhibitor of the glucose carrier phlorizin (2 mM). Net uptake of glucose, fructose and arabinose from 10 μM external concentrations was also inhibited by these substances. Surprisingly fusicoccin, a stimulator of net proton release did not effect net sugar uptake. Medium pH values only influenced sugar net uptake if the pH was above 7. It is concluded that a degradation of the proton gradient across the plasmalemma stimulates net sugar release because of disturbed re-uptake of sugars (in particular glucose) via a proton/sugar cotransport system. Thus, the retention of sugars by root cells not only depends on the plasmalemma permeability but also on the electro-chemical proton gradient. If an electro-chemical proton gradient is established by plasmalemma ATPase activity the re-uptake of sugars by proton/sugar cotransport minimizes the release of sugars into the rhizosphere.
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  • 89
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    Plant and soil 155-156 (1993), S. 87-90 
    ISSN: 1573-5036
    Keywords: amino acids ; maize ; rhizosphere ; root exudates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The aim of the study was to investigate the ability of Zea mays L. roots to regulate the amount of free amino acids present in the rhizosphere. The active uptake of amino acids was shown to conform to Michaelis-Menten kinetics. Comparison of amino acid-N and NO3-N kinetic parameters and soil solution concentrations showed that root uptake of free amino acids from soil may contribute significantly to a plant's N budget. The influx of amino acids also helps to minimize net C/N losses to the soil, and is therefore important in regulating the size of the rhizosphere microbial population. Experimental data and a computer simulation model of amino acid influx/efflux in a sterile solution culture, showed that roots were capable of re-sorping over 90% of the amino acids previously lost into solution as a result of passive diffusion.
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  • 90
    ISSN: 1573-5036
    Keywords: autoradiography ; freeze-cutting ; maize ; P-accumulation ; P-depletion ; phytate-P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Autoradiographs of soil slices mapping the distribution of phytate-derived33P around the primary root of 6-day-old maize seedlings were used to investigate the uptake of phytate by the root. Analysis of the autoradiographs with a laser densitometer and processing of the data with image analysing software resulted in a resolution of 40 μm. The effect of33P-crossfire was corrected by analysis of the apparent33P-gradient around a phosphate-impermeable teflon tube that was inserted into the labeled soil as a standard. In spite of the high resolution achieved, a significant depletion zone could not be detected when the soil was equilibrated with33P-phytate. However, with33P-inorganic phosphate, 2 concentric zones were obvious. Within the inner zone, P was accumulated by about 20%, while in the outer zone a corresponding depletion of P could be detected. The accumulation zone coincided with the extension of the root hair cylinder, whereas the depleted area was clearly beyond the range of the root hairs.
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  • 91
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    Plant and soil 151 (1993), S. 97-104 
    ISSN: 1573-5036
    Keywords: aluminium ; ammonium ; induction ; maize ; nitrate ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments with two maize (Zea mays L.) hybrids were conducted to determine (a) if the inhibition of nitrate uptake by aluminium involved a restriction in the induction (synthesis/assemblage) of nitrate transporters, and (b) if the magnitude of the inhibition was affected by the concurrent presence of ambient ammonium. At pH 4.5, the rate of nitrate uptake from 240 μM NH4NO3 was maximally inhibited by 100 μM aluminium, but there was little measurable effect on the rate of ammonium uptake. Presence of ambient aluminium did not eliminate the characteristic induction pattern of nitrate uptake upon first exposure of nitrogen-depleted seedlings to that ion. Removal of ambient aluminium after six hours of induction resulted in recovery within 30 minutes to rates of nitrate uptake that were similar to those of plants induced in absence of aluminium. Addition of aluminium to plants that had been induced in absence of aluminium rapidly restricted the rate of nitrate uptake to the level of plants that had been induced in the presence of aluminium. The data are interpreted as indicating that aluminium inhibited the activity of nitrate transporters to a greater extent than the induction of those transporters. When aluminium was added at initiation of induction, the effect of ambient ammonium on development of the inhibition by aluminium differed between the two hybrids. The responses indicate a complex interaction between the aluminium and ammonium components of high acidity soils in their influence on nitrate uptake. ei]{gnA C}{fnBorstlap}
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  • 92
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    Plant and soil 155-156 (1993), S. 45-55 
    ISSN: 1573-5036
    Keywords: compartmentation ; cytoplasm ; 39K NMR ; maize ; nitrogen ; 14N NMR ; 15N NMR ; pea ; phosphorus ; potassium ; 31P NMR ; vacuole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The cytoplasmic and vacuolar pools of ammonium, inorganic phosphate and potassium can be studied non-invasively in plant tissues using high resolution nuclear magnetic resonance spectroscopy. The techniques that allow these pools to be discriminated in vivo are described and their application to plants is reviewed with reference to the phosphorus, nitrogen and potassium nutrition of root tissues.
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  • 93
    ISSN: 1573-5036
    Keywords: autoradiography ; freeze-cutting ; maize ; P-accumulation ; P-depletion ; phytate-P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Autoradiographs of soil slices mapping the distribution of phytate-derived 33P around the primary root of 6-day-old maize seedlings were used to investigate the uptake of phytate by the root. Analysis of the autoradiographs with a laser densitometer and processing of the data with image analysing software resulted in a resolution of 40 μm. The effect of 33P-crossfire was corrected by analysis of the apparent 33P-gradient around a phosphate-impermeable teflon tube that was inserted into the labeled soil as a standard. In spite of the high resolution achieved, a significant depletion zone could not be detected when the soil was equilibrated with 33P-phytate. However, with 33P-inorganic phosphate, 2 concentric zones were obvious. Within the inner zone, P was accumulated by about 20%, while in the outer zone a corresponding depletion of P could be detected. The accumulation zone coincided with the extension of the root hair cylinder, whereas the depleted area was clearly beyond the range of the root hairs.
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  • 94
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    Plant and soil 152 (1993), S. 261-267 
    ISSN: 1573-5036
    Keywords: gravitropism ; growth angle ; maize ; nodal roots ; soil water content ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The direction of root growth is an important factor that determines the spatial distribution of roots in the soil. The influence of soil water content on the direction of growth of maize nodal roots was studied both in the field and in the greenhouse. In the field experiment, the one plot was regularly irrigated (I-plot) and the other non-irrigated (N-plot). In the greenhouse experiment, three water treatments were conducted on plants grown in pots: continuously wet (CW), early drying (ED), and late drying (LD). The direction of root growth was quantified by the angle from the vertical, measured at 1 cm intervals for 10 cm from the first five internodes. Nodal roots grew more vertically in the N-plot and ED treatment than those in the I-plot and CW treatment. This was due to the decrease of the initial angle and/or the liminal angle. It is therefore thought that two events regulate the growth direction of nodal roots under dry soil conditions: gravitropic bending at root emergence from the stem and the later establishment of the angle of growth. Nodal roots appearing after rewatering in the ED treatment grew in a similar direction as those in the CW treatment. It follows from this that the water content of the surrounding soil has a direct effect on the direction of growth. Nodal roots that emerged in rapidly drying soil in the LD treatment ceased growing after showing negative gravitropism. The possible mechanisms determining the growth direction of nodal roots in drier soils are discussed.
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  • 95
    ISSN: 1573-5036
    Keywords: alfisols ; maize ; mulch quality ; nutrient uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of application of prunings of three woody species (Acioa barteri, Gliricidia sepium and Leucaena leucocephala), maize (Zea mays L.) stover and rice (Oryza sativa L.) straw as mulch on maize were studied on an Alfisol in southern Nigeria in 1990 and 1991. Maize dry matter and grain yield were higher with applications of plant residues and N fertilizer in both years. Addition of Leucaena prunings gave the highest maize grain yield in both years. Compared to the 1990 results, Acioa showed the least grain yield decline among the mulch treatments in 1991. Nutrient uptake was enhanced by applications of plant residues. Leucaena prunings had the highest effect in both years and increased the mean N, P, and Mg uptake by 96%, 84%, and 50%, respectively, over the control. Addition of Acioa prunings increased K and Ca uptake by 59% and 92%, respectively, over the control. ‘High quality’ (low C/N ratio and lignin level) plant residues enhance crop performance through direct nutritional contributions, whereas ‘low quality’ (high C/N ratio and lignin level) plant residues do so through mulching effects on the microclimate. ‘Intermediate quality’ plant residues have no clear effects on crop performance.
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  • 96
    ISSN: 1573-5036
    Keywords: bioavailability ; maize ; myo-inositol ; phosphorus ; phytase ; phytin ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of adding phytase to the root medium of maize plants on the P-availability of added myo-inositol hexaphosphate (phytin) has been studied in pot experiments. When 40 mM phytin-P in nutrient solution was incubated in quartz-sand for 15 days in the absence of plants, 80% of it could be recovered from the solution as soluble organic P. Maize plants growing on this mixture assimilated P from phytin at rates comparable to those from inorganic phosphate (Pi). At a lower addition rate (2 mM phytin-P) only 10% was recovered in the soil solution, and plant growth was severely limited by P. At this low phytin level, the addition of phytase (10 enzyme units per kg sand) increased the plants' dry weight yield by 32%. The relative increases of the Pi concentration in the solution and of the amount of P in the plants were even higher, indicating that the observed growth stimulation was due to an increased rate of phytin hydrolysis. The enzyme-induced growth stimulation was also observed with plants growing in pots filled with soil low in P, when phytin was added. However, on three different soils the addition rates of phytin and phytase necessary for obtaining a significant phytase effect were both about 10 times higher than those required in quartzsand. It is concluded that the P-availability from organic sources can be limited by the rate of their hydrolytic cleavage.
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  • 97
    ISSN: 1573-5060
    Keywords: Oryza sativa ; thermo-sensitive genic male sterile rice (TGMSR) ; critical temperature ; sensitive panicle development stage ; fertility change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of a 1–5 day low temperature treatment applied at different stages during panicle development on the male sterility of 5460S, a thermo-sensitive genic male sterile rice line (TGMSR), was studied. Before and after the period of low temperature treatments the plants were continuously grown under 14.75 h daylength and 29.6° C average temperature (max. 33° C/min. 29° C) in growth chambers in order to avoid any other possible influences on the male sterility. The results indicate that the plant responses to low temperature was dependant on the developmental stage of the young panicle. The stages from formation of pollen mother cell to late uninucleate of pollen grains were the most sensitive to temperature. It is concluded that the critical temperature for the fertility change from male sterile to partially fertile in ‘5460S’ is about 28.5° C in the sensitive panicle development stages under the condition studied.
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  • 98
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    Euphytica 70 (1993), S. 105-111 
    ISSN: 1573-5060
    Keywords: maize ; genotype × environment interaction ; stability analysis ; cultivar testing ; YSi statistic ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Genotype × environment (GE) interaction complicates selection of superior genotypes across environments. The main objective of this study was to select maize (Zea mays L.) genotypes via a new yield-stability (YSi) statistic in yield trials conducted in Albania. Another objective was to estimate contribution of environmental index (% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]·j − % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\].., where % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]·j is mean of all genotypes in the jth environment and % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]is mean of all genotypes across all environments), minimum temperature, maximum temperature, preseason rainfall, rainfall during the growing season, and relative humidity to GE interaction by determining heterogeneity (nonadditivity) attributable to each of these environmental factors. In five of eight trials, heterogeneity due to environmental index was significant. Heterogeneity due to the other environmental factors was not significant in any trial. A comparison of δ i 2 (stability-variance statistic derived from total GE interaction) and s i 2 (stability-variance statistic derived from residual GE interaction following removal of heterogeneity due to encovariate) helped identify genotypes that performed stably or unstably because of a linear effect of environmental index. In three of the five trials showing significant heterogeneity due to environmental index, the YSi statistic selected a reduced number of unstable genotypes as compared with selection based solely on yield. However, the circumstances or conditions under which YSi and solely yield-based method select the same or different genotypes are not fully understood.
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  • 99
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    Euphytica 72 (1993), S. 87-94 
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; pollen storage ; pollen grain viability ; pollen enzymes ; pollen physiology ; enzyme cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Maize pollen quality was investigated after long-term storage both in a refrigerator and in liquid nitrogen by a combination of viability tests and cytochemical methods. Determination of the activities of a number of enzymes involved in important metabolic pathways was carried out. Quinone formation was also studied, as some products of secondary metabolism affect pollen grain viability. One year of pollen storage in liquid nitrogen had little effect on the activities of oxidoreductases and hydrolases and had no significant effect on pollen grain viability evaluated by acetocarmine, neutral red and acridine organe. Only the FCR test showed slightly decreased viability. After one and two years of storage in a refrigerator, pollen grain viability, tested using acetocarmine, neutral red and acridine orange, did not change substantially. Simultaneously the FCR test showed a considerable decrease in pollen grain viability. Long-term storage in a refrigerator resulted in the loss of cytochrome oxidase activity and rise of alcohol dehydrogenase, lactate dehydrogenase, peroxidase and polyphenoloxidase activities as well as of quinone formation.
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  • 100
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    Plant and soil 152 (1993), S. 187-199 
    ISSN: 1573-5036
    Keywords: aeration ; aerenchyma ; carnation ; cucumber ; gerbera ; maize ; oxygen stress ; oxygen transport ; redox dye ; rice ; rose ; sugar beet ; sweet pepper ; tomato ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The development of gas-filled root porosity in response to temporary low oxygen supply was tested for a range of edible and ornamental crops: rice, maize, wheat, sugar beet, tomato, cucumber, sweet pepper, carnation, gerbera and rose. In a first experiment, the roots of tomato, maize and gerbera had a higher gas-filled root porosity, Ep (% v/v), when grown permanently in a non-aerated instead of aerated solution. The Ep of roots increased during two weeks when half the root system of a young plant was transferred to a non-aerated solution; in older plants this response was not seen. Carnation had a negligible gas-filled porosity in all treatments. In a second experiment, a comparison was made between high (20 kPa) and low (about 2 kPa) O2 partial pressure in a recirculating nutrient solution. Half of the root system was transferred to low O2 at various growth stages. In most species older plants did not increase Ep on exposure to low O2. For tomato, sweet pepper and rose, Ep was normally in the range 3–8% (v/v). Young plants of cucumber, wheat and sugar beet also had an Ep in that range, but in older plants values ranged from 1 to 3%. Transverse root sections examined by light microscopy showed, on average, 60% more intercellular spaces in the root cortex than the measurements of gas-filled porosity, probably because some gaps and spaces in the cortex were not gas-filled. This effect was most pronounced in tomato. A negative pressure in the cortex may be needed for gaps to be gas-filled. An exodermis may increase the effectiveness of gas spaces in the cortex by closing the gas channels and, by offering some resistance to water uptake, allowing a negative pressure head in the cortex which keeps gaps gas-filled. A redox dye method was developed to study the length of root which is effectively supplied with oxygen, as a function of Ep. Results indicated that for every percent Ep the root can remain aerated over at least 1 cm in a non-aerated medium under the conditions of the test.
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