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  • Articles  (223)
  • Oryza sativa  (222)
  • Animals
  • Chemical Engineering
  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (223)
  • 1
    ISSN: 1432-0789
    Keywords: Key words Fallow ; Legumes ; Nitrogen fixation ; Oryza sativa ; Côte d'Ivoire
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Improving fallow quality in upland rice-fallow rotations in West Africa through the site-specific use of leguminous cover crops has been shown to sustain the productivity of such systems. We studied the effects of a range of residue management practices (removal, burning, mulching and incorporation) on fallow biomass and N accumulation, on weed biomass and yield response of upland rice and on changes in soil physical and chemical characteristics in 2-year field trials conducted in three agroecological zones of Côte d'Ivoire. Across fallow management treatments and agroecological zones, rice yields were on average 20–30% higher in legume than in natural fallow plots. Weed biomass was highest in the savanna zone and lowest in the bimodal forest and tended to be less following a legume fallow. Regardless of the type of fallow vegetation and agroecological zone, biomass removal resulted in the lowest rice yields that varied from 0.5 t ha–1 in the derived savanna zone to 1.5 t ha–1 in the Guinea savanna zone. Burning of the fallow vegetation significantly increased yield over residue removal in the derived savanna (0.27 t ha–1, P〈0.05) and bimodal forest zones (0.27 t ha–1, P〈0.01), but not in the Guinea savanna. In both savanna environments, residue incorporation was superior to the farmers' practice of residue removal and rice yield increases were related to amounts of fallow N returned to the soil (r 2=0.803, P〈0.01). In the forest zone, the farmers' practice of residue burning produced the highest yield (1.43 t ha-1 in the case of legumes) and resulted in the lowest weed biomass (0.02 t ha–1). Regardless of the site, improving the quality of the fallow or of its management had no significant effects on either soil physical or soil chemical characteristics after two fallow cycles. We conclude that incorporation of legume residues is a desirable practice for rice-based fallow rotation systems in savanna environments. No promising residue management alternatives to slash-and-burn were apparent for the forest zone. Determining the possible effects on soil productivity will require longer-term experiments.
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  • 2
    ISSN: 1432-0789
    Keywords: Key words Acid soil ; Brazilian Amazonia ; N use efficiency ; Priming effect ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The objective of this study was to determine the efficiency of two N fertilizers, (NH4)2SO4 and urea, for rice (Oryza sativa L.) and rye-grass (Lolium multiflorum L.) cultivated in an Ultisol of central Amazonia using 15N as a tracer. Rice was cultivated in the field, while rye-grass was grown in a phytotron. Fertilization with (NH4)2SO4 caused a 16% increase in the yield of rice grains and urea a 36% increase. In both crops total N uptake and N use efficiency of the fertilizers were higher for urea than for (NH4)2SO4. The low values for N derived from fertilizer showed that the fertilizers contributed little to the total N absorbed by the plants. The "priming effect" or positive added N interaction (ANI) between the fertilizer N and soil organic N was observed, especially with urea. Immobilization by soil microorganisms was greater in the presence of urea, while losses were always higher with the (NH4)2SO4 treatments. These losses were significant, and their reduction should allow more efficient use of this N fertilizer. It is possible that the N use efficiency was higher for urea due to a pH increase, caused by urea hydrolysis, which in turn may have favoured the activity of nitrifying bacteria in this extremely acid soil.
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  • 3
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    Springer
    Nutrient cycling in agroecosystems 58 (2000), S. 141-159 
    ISSN: 1573-0867
    Keywords: methane ; rice ; Oryza sativa ; anaerobic ; model ; simulation ; carbon dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The development of the MERES (Methane Emissions in Rice EcoSystems) model for simulating methane (CH4) emissions from rice fields is described. The CERES-Rice crop simulation model was used as a basis, employing the existing routines simulating soil organic matter (SOM) decomposition to predict the amount of subsrate available for methanogenesis. This was linked to an existing submodel, described elsewhere in this volume (Arah & Kirk, 2000), which calculates steady-state fluxes and concentrations of CH4 and O2 in flooded soils. Extra routines were also incorporated to simulate the influence of the combined pool of alternative electron acceptors in the soil (i.e., NO3 −, Mn4+, Fe3+, SO4 2−) on CH4 production. The rate of substrate supply is calculated in the SOM routines of the CERES-Rice model from (a) the rate of decomposition of soil organic material including that left from the previous crop and any additions of organic matter, (b) root exudates (modified from the original CERES-Rice model using recent laboratory data), and (c) the decomposition of dead roots from the current crop. A fraction of this rate of substrate supply, determined by the concentration of the oxidized form of the alternative electron acceptor pool, is converted to CO2 by bacteria which outcompete the methanogenic bacteria, thereby suppressing CH4 production. Any remaining fraction of the substrate supply rate is assumed to be potentially available for methanogenesis. The CH4 dynamics submodel uses this potetial methanogenesis rate, along with a description of the root length distribution in the soil profile supplied by the crop model, to calculate the steady-state concentrations and fluxes of O2 and CH4. The reduced form of the alternative electron acceptor pool is allowed to reoxidize when soil pores fill with air if the field is drained. The MERES model was able to explain well the seasonal patterns of CH4 emissions in an experiment involving mid- and end-season drainage and additions of organic material at IRRI in the Philippines.
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  • 4
    ISSN: 1573-0867
    Keywords: methane ; rice ; Oryza sativa ; anaerobic ; model ; simulation ; carbon dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The MERES (Methane Emissions from Rice EcoSystems) simulation model was tested using experimental data from IRRI and Maligaya in the Philippines and from Hangzhou in China. There was good agreement between simulated and observed values of total aboveground biomass, root weight, grain yield, and seasonal methane (CH4) emissions. The importance of the contribution of the rice crop to CH4 emissions was highlighted. Rhizodeposition (root exudation and root death) was predicted to contribute about 380 kg C ha−1 of methanogenic substrate over the season, representing 37% of the total methanogenic substrate from all sources when no organic amendments were added. A further 225 kg C ha−1 (22%) was predicted to come from previous crop residues, giving a total of around 60% originating from the rice crop, with the remaining 41% coming from the humic fraction of the soil organic matter (SOM). Sensitivity analysis suggested that the parameter representing transmissivity to gaseous transfer per unit root length (λr) was important in determining seasonal CH4 emissions. As this transmissivity increased, more O2 was able to diffuse to the rhizosphere, so that CH4 production by methanogens was reduced and more CH4 was oxidized by methanotrophs. These effects outweighed the opposing influence of increased rate of transport of CH4 through the plant, so that the overall effect was to reduce the amount of CH4 emitted over the season. Varying the root-shoot ratio of the crop was predicted to have little effect on seasonal emissions, the increased rates of rhizodeposition being counteracted by the increased rates of O2 diffusion to the rhizosphere. Increasing the length of a midseason drainage period reduced CH4 emissions significantly, but periods longer than 6–7 d also decreased rice yields. Organic amendments with low C/N were predicted to be more beneficial, both in terms of enhancing crop yields and reducing CH4 emissions, even when the same amount of C was applied. This was due to higher rates of immobilization of C into microbial biomass, removing it temporarily as a methanogenic substrate.
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  • 5
    ISSN: 1573-5036
    Keywords: mechanical impedance ; Oryza sativa ; rice ; roots ; screening ; wax layers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The development of a wax layer method for screening the ability of rice (Oryza sativa L.) roots to overcome mechanical impedance is described. Wax layers (3 mm thick) made of mixtures of white soft paraffin and paraffin wax were installed 50 mm deep in tubes of sand. The sand was watered with nutrient solution and planted with 3-d old rice seedlings. The numbers of root axes per plant that had penetrated the wax layers 24 d after planting were counted. The ratio of penetrated to total root axes per plant gave a misleading measure of root penetration ability, as rice varieties differed in the ratio of penetrated to total axes in a low impedance (3% wax) control. In non-flooded conditions, a 60% wax layer decreased root penetration (number of roots penetrating the wax layer per plant) to a mean of 74% of the low impedance control, whereas an 80% wax layer decreased mean root penetration to 31% of the control. The best measure of root penetration in non-flooded conditions was the number of axes penetrating an 80% wax layer. Flooding decreased root penetration of a 60% wax layer to a mean of 26% of the low impedance control. The best measure of root penetration in flooded conditions was the number of axes penetrating a 60% wax layer.
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  • 6
    ISSN: 1573-5060
    Keywords: genetic transformation ; japonica rice cultivar ; mature embryo ; Oryza sativa ; plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To establish a plant regeneration system from embryogenic callus derived from mature rice embryos, the addition of aminoacids and the effect of two macronutrient solutions MSD and N6D to the basal callus induction medium was tested in three Spanish varieties, Senia, Tebre and Bahia. Aminoacids enhanced the production of embryogenic callus in Tebre and Senia whereas in the case of Bahia, embryogenic callus, which gave rise to a high rate of differentiated shoots, was induced without aminoacids. The macronutrient solution had also to be adjusted for each variety. Pre-regeneration treatment with ABA significantly improved the regeneration rate in all media tested, independently of the media in which the embryogenic callus were induced. In a comparison of growth regulators, BA yielded more shoots than Kin in all varieties whereas the effect of the auxins NAA or IAA was dependent on the variety. Transgenic plants from the three varieties were obtained via an Agrobacterium tumefaciens transformation system, using the optimised culture media.
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  • 7
    ISSN: 1573-5060
    Keywords: gamete abortion ; Oryza sativa ; pollen ; wide compatibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Utilization of the pronounced heterosis of indica-japonica hybrids in rice had been difficult due to panicle sterility caused by male and female gamete abortion in such hybrids. But the female gamete abortion in the most indica-japonicahybrids has been solved by using an abortion-neutral gene S-5 n called as wide compatibility gene. On the other hand, the problem of pollen sterility remains to be solved for such hybrids. This study was conducted to identify abortion-neutral genes for pollen that may be utilized to alleviate pollen sterility in distant crosses. Some cultivars like Ketan Nangka (KN) and Dular, which are known as wide compatibility variety (WCV), were tested to find whether they possess neutral alleles for segregation distortion of marker genes. The distorted segregation of markers as well as normal segregation were confirmed among progeny lines of three-way crosses, WCV/indica//japonica and japonica//indica/WCV. Neutral alleles for segregation distortion were identified at two gamete gene loci (ga), i.e., ga-14(t) on chromosome 3 and ga-11 on chromosome 7. A new locus ga-14(t) was identified in between Pgi-1 and bc-1 and independent of ga-3 on chromosome 3. The neutral alleles at the two loci may be used to solve pollen sterility in indica-japonica hybrids.
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  • 8
    ISSN: 1573-5060
    Keywords: grain yield ; leaf K/Na ratio ; Oryza sativa ; salinity ; screening tools ; yield reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Salinity is a major constraint to irrigated rice production, particularly in semi-arid and arid climates. Irrigated rice is a well suited crop to controlling and even decreasing soil salinity, but rice is a salt-susceptible crop and yield losses due to salinity can be substantial. The objective of this study was to develop a highly predictive screening tool for the vegetative growth stage of rice to estimate salinity-induced yield losses. Twenty-one rice genotypes were grown over seven seasons in a field trials in Ndiaye, Senegal, between 1991 and 1995 and were subjected to irrigation with moderately saline water (3.5 mS cm-1, electrical conductivity) or irrigation with fresh water. Potassium/sodium ratios of the youngest three leaves (K/NaLeaves) were determined by flame photometry at the late vegetative stage. Grain yield was determined at maturity. All cultivars showed strong log-linear correlations between K/NaLeaves and grain yield, but intercept and slope of those correlations differed between seasons for a given genotype and between genotypes. The K/NaLeaves under salinity was related to grain yield under salinity relative to freshwater controls. There was a highly significant correlation (p 〈 0.001) between K/NaLeaves and salinity-induced grain yield reduction: the most susceptible cultivars had lowest K/NaLeaves and the strongest yield reductions. Although there were major differences in the effects of salinity on crops in both the hot dry season (HDS) and the wet season, the correlation was equally significant across cropping seasons. The earliest possible time to establish the relationship between K/NaLeaves under salinity and grain yield reduction due to salinity was investigated in an additional trial in the HDS 1998. About 60 days after sowing, salinity-induced yield loss could be predicted through K/NaLeaves with a high degree of confidence (p 〈 0.01). A screening system for salinity resistance of rice, particularly in arid and semi-arid climates, is proposed based on the correlation between K/NaLeaves under salinity and salinity-induced yield losses.
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  • 9
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    Plant growth regulation 30 (2000), S. 151-155 
    ISSN: 1573-5087
    Keywords: ascorbate peroxidase ; catalase ; glutathione reductase ; glycolate oxidase ; hydrogen peroxide ; Oryza sativa ; peroxidase ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of NaCl stress on H2O2 metabolismin detached rice leaves was studied. NaCl (200 mM)treatment did not cause the accumulation ofH2O2 and resulted in no increase in lipidperoxidation and membrane leakage of leaf tissues. The activities of peroxidase, ascorbate peroxidase,superoxide dismutase, and glutathione reductase wereobserved to be greater in NaCl-stressed rice leavesthan in control leaves. However, glycolate oxidasewas lower in NaCl-treated rice leaves than in thecontrol leaves. There was no difference in catalaseactivity between NaCl and control treatments. Theseresults suggest that some antioxidant enzymes can beactivated in response to oxidative stress induced byNaCl.
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  • 10
    ISSN: 1573-5087
    Keywords: auxin binding isotherm ; auxin receptor ; dose response curve ; H+-ATPase ; iIndole-3-acetic acid ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An auxin receptor protein, isolated from the soluble fractionsof rice shoots and roots, was characterised in terms of the affinity andspecificity for IAA and the modulating effect onH+-ATPase of plant plasma membrane. The receptor proteingives a biphasic binding isotherm for IAA, indicating the existence ofthe primary and secondary binding sites. The predominant isoform of thereceptor in roots shows much higher affinity to IAA compared with thatin shoots. Being monomeric protein with about the same molecular mass(57–58 kDa) and showing a similar chromatographic behaviour, bothisoforms mediate IAA-induced modulation of the plasma membraneH+-ATPase in the respective IAA concentration rangesseparated by ca. 3 orders of magnitudes(10-10–10-7 M vs.10-7–10-4 M). Analysis of kinetic data ofthe H+-ATPase activity revealed that the receptor perse functions as an effector of the enzyme, causing a decrease inKm and an increase in Vmax through protein-proteininteraction at a 1:1 ratio. Further, it appeared that, while IAAdoes not affect by itself the kinetic parameters of theH+-ATPase, the auxin exerts its effect via thereceptor, biphasically regulating the efficiency of the effectormolecule probably by inducing two-phase conformational changes thatinvolve IAA binding to two separate binding sites. It was also foundthat other active auxins examined, such as indole-3-propionic acid,1-naphthalene acetic acid and 2,4-dichlorophenoxyacetic acid, do notwork together with the receptor to elicit the same response of theH+-ATPase as seen with IAA.
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  • 11
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    Plant growth regulation 30 (2000), S. 139-144 
    ISSN: 1573-5087
    Keywords: ammonium ; methionine sulfoximine ; Oryza sativa ; proline accumulation ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ammonium accumulation in relation to prolineaccumulation in detached rice leaves under stressconditions was investigated. Ammonium accumulation indark-treated detached rice leaves preceded prolineaccumulation. Ammonium accumulation caused by waterstress coincided closely with proline accumulation indetached rice leaves. Exogenous NH4Cl andmethionine sulfoximine (MSO), which caused anaccumulation of ammonium in detached rice leaves,increased proline content. It was found that prolinein NH4Cl- or MSO-treated rice leaves is lessutilized than in water-treated rice leaves (controls). These results are in agreement with the observationthat a decrease in proline utilization contributes tothe accumulation of proline in dark-treated and waterstressed rice leaves. Although ammonium contentincreased in Cd- and Cu-treated rice leaves, theincrease in ammonium content was only observed afterthe increase in proline content.
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  • 12
    ISSN: 1573-5036
    Keywords: cadmium ; membrane permeability ; Oryza sativa ; respiration ; transmembrane electrical potential difference (Em)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Among other detrimental effects of the heavy metal Cd2+, a decrease in the plant content of essential mineral nutrients is known. In this study, the effect of Cd2+ on different physiological activities of rice roots involved in nutrient acquisition has been studied. Upon addition of 0.1 or 1 mM Cd2+ to the experimental solution, root cell membranes depolarized in few minutes, reaching very low Em values. This effect was transient and the initial membrane potential recovered totally within 6–8 h. Only the highest concentration used had an inhibitory effect on root respiration. Significant respiratory inhibition appeared after 2 h of exposure to Cd2+ and lasted for at least 4 h. In turn, membrane permeability increased in the presence of Cd2+ for at least 8 h, inducing K+ efflux from the roots. The relationship between these parameters and their possible involvement in lowered nutrient content in Cd2+-treated plants is discussed.
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  • 13
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    Plant and soil 218 (2000), S. 1-10 
    ISSN: 1573-5036
    Keywords: dry matter reduction ; leaf chlorophyll content ; leaf sodium uptake ; Oryza sativa ; photosynthesis ; salinity ; season effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Salinity is a major yield-reducing factor in coastal and arid, irrigated rice production systems. Salt tolerance is a major breeding objective. Three rice cultivars with different levels of salt tolerance were studied in the field for growth, sodium uptake, leaf chlorophyll content, specific leaf area (SLA), sodium concentration and leaf CO2 exchange rates (CER) at photosynthetic active radiation (PAR)-saturation. Plants were grown in Ndiaye, Senegal, at a research station of the West Africa Rice Development Association (WARDA), during the hot dry season (HDS) and the wet season (WS) 1994 under irrigation with fresh or saline water (flood water electrical conductivity = 3.5 mS cm-1). Relative leaf chlorophyll content (SPAD method) and root, stem, leaf blade and panicle dry weight were measured at weekly intervals throughout both seasons. Specific leaf area was measured on eight dates, and CER and leaf sodium content were measured at mid-season on the first (topmost) and second leaf. Salinity reduced yields to nearly zero and dry-matter accumulation by 90% for the susceptible cultivar in the HDS, but increased leaf chlorophyll content and CER at PAR- saturation. The increase in CER, which was also observed in the other cultivars and seasons, was explained by a combination of two hypotheses: leaf chlorophyll content was limited by the available N resources in controls, but not in salt-stressed plants; and the sodium concentrations were not high enough to cause early leaf senescence and chlorophyll degradation. The growth reductions were attributed to loss of assimilates (mechanisms unknown) that must have occurred after export from the sites of assimilation. The apparent, recurrent losses of assimilates, which were between 8% and 49% according to simulation with the crop model for potential yields in irrigated rice, ORYZA S, might be partly due to root decomposition and exudation. Possibly more importantly, energy-consuming processes, such as osmoregulation, interception of sodium and potassium from the transpiration stream in leaf sheaths and their subsequent storage, drained the assimilate supply.
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  • 14
    ISSN: 1573-5036
    Keywords: drought ; Heterodera sacchari ; nematode ; Oryza glaberrima ; Oryza sativa ; plant water status ; rice ; West Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study was undertaken to examine the influence of cyst nematodes (Heterodera sacchari) and drought stress, in isolation and combination, on the water status and growth of rice in Côte d'Ivoire. Drought is considered one of the main yield-limiting factors to upland rice in West Africa, while H. sacchari is emerging as a potentially serious pest. A field study conducted during 1997 at the West Africa Rice Development Association (WARDA) showed that under low water availability in sandy soil, damage to a nematode susceptible Oryza sativa (cv IDSA6) is significant. Visual drought score and physiological parameters were significantly affected (P≤0.01) in plots with a mean population density of 39.4 H. sacchari eggs ml-1 soil at 81 days after sowing, compared to plots with a mean density of 1.2 eggs ml-1. Stomatal conductance, leaf water potential and relative water content were lower, leaf chlorophyll content was greater, and near total yield losses were observed in higher nematode density plots. In 1-l pots following 5 days of imposed drought, the H. sacchari-resistant and drought-resistant O. glaberrima (cv CG14) showed a reduction in stomatal conductance of 73% and in leaf water potential by 0.96 MPa (54%). The effect of H. sacchari (473 eggs l-1 soil) inoculated as cysts to soil before sowing was similar but less severe. The combination of both stresses had similar but yet more pronounced effects than the single stresses on stomatal conductance, leaf water potential and leaf dry weight in CG14. IDSA6 responded in a similar manner to CG14, but less acutely to both stresses. Only the combined stresses resulted in a significant (P≤0.05) reduction in osmotic potential and root dry weight compared with the control, for either CG14 or IDSA6. It is suggested that H. sacchari increased the effects of drought and drought-related losses. This may give a false impression of drought susceptibility in field screening for cultivars, and complicate models which predict crop damage caused by nematodes.
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  • 15
    ISSN: 1573-8248
    Keywords: biological control ; Oryza sativa ; rice sheath blight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bacterial formulations, produced using both Bacillus megaterium andB. pumilus individually with pharmaceutical technology, were testedunder both greenhouse and field conditions. In the greenhouse testing,some bacterial formulations, for instance For 7 minus Lac and For 16 minusLac, performed as well as freshly prepared bacterial antagonists insuppress sheath blight disease. In the field testing, For 16 minus Lac wasnot effective in suppressing sheath blight development. Failure of the For16 minus Lac to suppress sheath blight disease in the field trial may be dueto the dilution and inactivation of antibiotics produced by B.megaterium in the aquatic environment in the rice field and climaticconditions during the formulation application.
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  • 16
    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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  • 17
    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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  • 18
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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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  • 19
    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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  • 20
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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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  • 21
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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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  • 22
    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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  • 23
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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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  • 24
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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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  • 25
    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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  • 26
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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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  • 27
    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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  • 28
    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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  • 29
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    Agroforestry systems 42 (1998), S. 107-120 
    ISSN: 1572-9680
    Keywords: erosion ; Gliricidia sepium ; Oryza sativa ; Paspalum conjugatum ; Penisetum purpureum ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Farming systems that minimize the rate of soil degradation and optimize food crop yields are needed to sustain soil productivity on sloping, acid, infertile soils in the humid tropics. Research was conducted on two Oxisols with slopes ranging from 22 to 30% to evaluate the performance of several contour hedgerow systems, with and without the addition of 60 kg N ha−1 per crop, on rice (Oryza sativa) and maize (Zea mays L.) production. Contour hedgerows were double rows of the tree legume Gliricidia sepium (G); Gliricidia and the native grass Paspalum conjugatum (GPas); Gliricidia and an exotic fodder grass Penisetum purpureum (GPen); double rows of Penisetum (Pen); and a conventional open field (C) farming system without hedgerows. Gliricidia prunings and all crop residues were applied to the soil surface in the alleys, but Penisetum was harvested. Food crop yields in all hedgerow treatments tended to be less than the Control for the first two years, presumably due to the displacement of land planted to the food crop. In the third and the fourth years, the rice and maize yields of Treatments G and GPas exceeded the Control, most consistently when N was not applied. Penisetum reduced food crop yields regardless of N application presumably due to nutrient removal in the fodder. The results indicate that Gliricidia in a contour hedgerow increases food crop yield on strongly acid Oxisols by recycling nutrients and partially supplementing the N demand by the food crops.
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  • 30
    ISSN: 1573-5036
    Keywords: growth parameters ; methane flux ; N-fertilization ; Oryza sativa ; root porosity ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Influence of urea application on growth parameters (shoot height, and weight, root volume, weight and porosity; number of tillers; grain yield) and their relationship with methane (CH4) flux was investigated in Oryza sativa (var. Pant Dhan-4) under flooded soil condition. The study design consisted of (a) fertilized vegetated, (b) control vegetated, (c) fertilized bare, and (d) control bare plots. Crop growth and CH4 flux measurements were conducted from 9 to 115 days of rice transplanting at regular intervals of 10 days. Results showed that there were significant differences due to days (dates of measurement) and fertilization in all growth parameters except shoot height. Day × fertilization interaction was significant for all growth parameters. CH4 fluxes ranged from 0.4 to 20.2, 0.1 to 11.9, 0.09 to 2.2 and 0.004 to 1.5 mg m-2 h-1 under treatments (a), (b), (c) and (d), respectively. Maximum CH4 flux was recorded at the flowering stage. All the growth parameters, including number of tillers, showed strong positive relationship with total methane flux. Root porosity was also strongly correlated with total CH4 emission. It was concluded that CH4 emission was substantially influenced by crop phenology and growth, and fertilization. The study emphasizes the substrate production and conduit effects of rice plants on CH4 flux.
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    Plant growth regulation 24 (1998), S. 17-21 
    ISSN: 1573-5087
    Keywords: leaf senescence ; lipid peroxidation ; methyl jasmonate ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Lipid peroxidation in relation to MJ-promoted senescence of detached rice leaves was investigated. Lipid peroxidation seems to be involved in the regulation of MJ-promoted senescence of detached rice leaves. This conclusion was based on the observations that (a) methyl jasmonate, which was found to promote senescence, increases the level of lipid peroxidation, (b) linolenic and linoleic acid, precursors of the biosynthesis of jasmonic acid, promoted senescence and increased lipid peroxidation level, (c) benzyladenine, a synthetic cytokinin, counteracted MJ-promoted senescence and reduced the increase in lipid peroxidation level, (d) calcium chloride effectively reduced MJ-promoted senescence and at the same time reduced MJ-promoted lipid peroxidation. Free radical scavengers (reduced glutathione and sodium benzoate) and an iron chelator (2, 2′-bipyridine) prevented MJ-promoted senescence, suggesting that lipid peroxidation induced by MJ is mediated through free radicals.
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  • 32
    ISSN: 1573-5060
    Keywords: heterosis ; heterosis × environment interaction ; Oryza sativa ; rice ; standard heterosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Moderate to high heterosis for yield and ten related characters was studied in 45 crosses involving six indica (I) and four tropical japonica (J) varieties of rice under three (E1-optimum sowing and high fertility, E2-both optimum sowing and fertility and E3- late sowing and high fertility) environments. Trends of magnitude of heterosis for grain yield and plant height were I/J 〉 I/I 〉 J/J and for days to 50% flowering I/J 〉 J/J 〉 I/I hybrids. Estimates of standard heterosis (%) for grain yield were –64.5 to 146.1 in E1, –70.4 to 82.2 in E2 and –67.2 to 63.8 in E3. Environment E1 seemed to be more favorable for higher heterosis expression than others. Higher heterosis in yield also accompanied heterosis in panicle number, dry matter and spikelet and grain number per panicle. Most estimates for days to flower were negative. Heterotic I/J hybrids also recorded maximum heterosis for earliness. Moderate to low standard heterosis for plant height across environments (2.0 to 13.7%) was recorded. Hybrids were identified in specific environments for direct exploitation in hybrid breeding. Hybrids B4116 / Sarjoo 52, B4122 / Pant Dhan 4 and B4122 / Narendera 359 were more stable than others over three environments.
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    Plant growth regulation 25 (1998), S. 165-169 
    ISSN: 1573-5087
    Keywords: ammonium ; leaf senescence ; Oryza sativa ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ammonium accumulation in relation to water stress-promoted senescence of detached rice leaves was investigated. The effect of water stress on the senescence of detached rice leaves is associated with the accumulation of ammonium. The accumulation of ammonium in detached rice leaves by water stress is attributed to a decrease in glutamine synthetase activity. Ammonium accumulation in detached rice leaves, induced by water stress, was accompanied by an increase in tissue sensitivity to ethylene which, in turn, accelerated leaf senescence.
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  • 34
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    Plant growth regulation 26 (1998), S. 63-66 
    ISSN: 1573-5087
    Keywords: ammonium ; calcium ; leaf senescence ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The possible involvement of calcium in the regulation of ammonium-promoted senescence of detached rice leaves was investigated. Calcium effectively reduced ammonium-promoted senescence of detached rice leaves. The effect of ammonium on the senescence was also significantly reduced by the calcium ionophore A23187. Ammonium-promoted senescence of detached rice leaves may be mediated through blocking the entrance of calcium ions into the cytosol.
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  • 35
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    Plant growth regulation 25 (1998), S. 11-15 
    ISSN: 1573-5087
    Keywords: ascorbate peroxidase ; glutathione reductase ; Oryza sativa ; peroxidase ; senescence ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The possible role of H2O2 metabolism on light-regulated senescence of detached rice leaves was investigated. Light retards senescence but at the same time accumulates more H2O2. Light treatment resulted in an increase in malondialdehyde level in detached rice leaves but no membrane leakage was observed in light-treated detached leaves. It seems that there was no direct relationship between lipid peroxidation and deterioration in membrane integrity. The results obtained suggest that retardation of senescence by light is closely related to high activities of superoxide dismutase and ascorbate peroxidase.
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  • 36
    ISSN: 1573-5036
    Keywords: agar ; agarose ; gels ; mechanical impedance ; Oryza sativa ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agar and agarose gels were evaluated as systems to mechanically impede roots of rice (Oryza sativa L.). Two-layer gels were used so that seedlings established in a layer of weak gel (0.35% weight/volume) and then grew downwards to encounter a treatment gel of up to 5.0% (w/v). Agarose gels were stronger than agar gels of the same concentration, reaching a maximum penetrometer resistance of 1.2 MPa at a concentration of 5.0%, compared to 0.3 MPa with agar. The 5.0% agar gel stimulated elongation of the seminal axis by 40% in seedlings of variety TN1 (compared with elongation in the 0.2% gel), but decreased it by 15% in the variety Lac 23. Although increasing agarose concentration decreased seminal axis elongation in both varieties, the seminal axis did not reach the lower layer of treatment gel when the concentration of the treatment gel was greater than 2.0%. The decreased root elongation was therefore a non-mechanical inhibition. In experiments conducted using a different batch of agarose, these inhibitory effects were not seen and strong agarose gels stimulated seminal axis elongation. It was concluded that the agar and agarose gel systems studied were unsuitable for studying the effect of mechanical impedance on the elongation of rice roots and that great care should be taken in interpreting the results of experiments using gels as a growth medium.
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    Genetic resources and crop evolution 45 (1998), S. 399-406 
    ISSN: 1573-5109
    Keywords: internal transcribed spacer sequences ; nuclear ribosomal RNA genes ; molecular phylogeny ; Potamophila parviflora ; Oryza sativa ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Potamophila parviflora is a wild relative of rice from Eastern Australia. The species was found in the Richmond, Clarence, Macleay and Hastings River systems of northern New South Wales. Existing populations had wider leaves (10–15 mM) than those previously reported (4–6 mM). This species and North American wild rice, Zizania palustris were investigated as genetic resource for rice improvement. Both species, Potamophila , and Zizania , occur in colder climates than rice (Oryza sativa). Sequencing of the ITS1 of the ribosomal genes of these two species indicated that Zizania and Potamophila were more closely related to each other than either was to Oryza sativa. Potamophila has a similar number of chromosomes (n=12) and a greater sequence homology to rice and may thus be a better source of useful genes for rice improvement.
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  • 38
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    Euphytica 102 (1998), S. 151-161 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; head rice ; seeding date ; rice ; rough rice yield ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The rice (Oryza sativa L.) crop in Arkansas is seeded from late March through early June each year. Farmers need new rice cultivars that not only produce both high rough rice yields and high head rice across this range of seeding dates but do so consistently. Thus, a seeding date study was conducted during 1994 and 1995 at Stuttgart, Arkansas, to study seeding date effects on rough rice yield and head rice and selection for stability. Fourteen rice cultivars were seeded at five dates ranging from late March through mid-June. Kang's yield-stability statistic was used to select cultivars for both high rough rice yields and high head rice as well as stability for both traits. Plant stands from March seedings of each year were significantly lower than for the later seeding dates. Maturity (days to 50 percent heading) was extended at the early seeding dates. Some rice cultivars, such as ‘LaGrue’, had lower and more variable head rice when seeded early. In the June seeding dates each year, ‘Kaybonnet’ produced rough rice yields that were more consistent with yields when planted at the earlier planting dates. ‘Bengal’, ‘Cypress’, ‘Kaybonnet’, and ‘Newbonnet’ were cultivars selected by Kang's stability statistic, which was targeted to select cultivars with stable, high rough rice yields and stable, high head rice. The validity of using Kang's yield-stability statistic for cultivar selection is also evident empirically by the adaptation and wide use of these four cultivars by southern U.S. rice producers. These results indicate that seeding date studies and stability analyses would be useful tools for rice breeders to identify cultivars that will be readily adapted and grown by rice producers.
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  • 39
    ISSN: 1573-5060
    Keywords: unpollinated ovary culture ; callus induction ; plant regeneration ; chilling pretreatment ; development stage ; medium composition ; rice ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A simple and efficient technique for in vitro unpollinated ovary culture in rice which is also applicable for indica genotypes was developed for breeding and genetic studies. Sampling explants at the auricle distance of 7–12 cm between the two uppermost leaves of a tiller, providing a chilling pretreatment and ovaries with 1/3 of the hulls intact gave optimum response to culture. For callus induction with the spontaneous breaking of ovaries, N6 media supplemented with NAA (2 mg/l) and DMSO (0.6–0.8%) gave a mean PCI value of 3.8% and range of 0.8–12.5% among genotypes. Media combining 2,4,5-T or 2,4-D with NAA in N6 medium also has reasonably good callus induction. For calli induced inside, 2,4-D (0.2–0.5 mg/l), NAA (2 mg/l) and KT (1 mg/l) contained media were superior. The maximum green plant regeneration (PPR) of 77.3% was found with the medium containing NAA 0.25 mg/l, IAA 0.5 mg/l and KT 2.0 mg/l. Significant genotype, medium and their interaction effects for per cent ovary survival and callus induction were observed.
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  • 40
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    Biology and fertility of soils 24 (1997), S. 70-75 
    ISSN: 1432-0789
    Keywords: Flooded rice soil ; Soil-trapped CH4 and C02 ; δ13C values of CH4 and C02 ; Greenhouse effect ; CO2 flux ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pot experiments were conducted to monitor the changes in compositions and δ13C values of soil-trapped CH4 and C02 in flooded rice soil with and without rice plants or rice straw. Incorporation of rice straw increased the concentration of CH4 and C02 accumulated in soil, and the quantities of emitted CH4 to the atmosphere. Rice plants reduced the concentration of soil-trapped CH4 and CO2, and the decreased portion of CH4 was replaced by N2. A significantly negative correlation was found between soil-trapped CH4 and N2. The presence of rice plants increased the δ13C values of CH4. The δ13C values of CH4 tended to increase toward the end of the growing season and were positively correlated with concentration of soil-trapped CH4. A positive correlation between δ13C values of CH4 and C02, and between the δ13C values of CH4 and its concentration, were observed. The CH4 in the rice stems was 4–14% enriched in13C relative to soil-trapped CH4. In contrast, CO2 in rice plant stems was 1–9% lighter in13C relative to soil-trapped C02. These results are discussed in relation to the precursor pools and pathways of methanogenesis.
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    Biology and fertility of soils 24 (1997), S. 261-265 
    ISSN: 1432-0789
    Keywords: Key words Methane ; Wetland rice soils ; Oryza sativa ; Methane oxidation ; Acetylene Propylene oxide ; Methanotrophs ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Acetylene up to 500 μl l–1 did not affect methane formation in anoxic soil up to 12 h, but further incubation for 1 week showed strong inhibition of methanogenesis. To ascertain the extent of the oxidation of methane produced from rice-planted pots, the effect of acetylene on methane emission was studied. Two rice varieties (Toyohatamochi and Yamahikari) were grown in a greenhouse in submerged soil in pots. At about maximum tillering, heading, and grain-forming stages, methane fluxes were measured. Flux measurement was performed for 3 h from 6 pm, then acetylene at 100 μl l–1 was added to some of the pots. At 6 a.m. the following day, methane fluxes were again measured for 3 h. Only at maximum tillering stage of the variety Toyohatamochi was a significant increase (1.4 times) in methane flux caused by acetylene observed, whereas in the other treatments no significant increase in methane fluxes by acetylene could be defected. To ascertain the activity of methane monooxygenase (MMO), propylene oxide (PPO) formation from propylene was measured with excised roots and a basal portion of stems of the rice plants grown on the submerged soil. A level of 0.1–0.2 μmol PPO h–1 plant–1 was recorded. The roots showed the highest PPO formation per gram dry matter, followed by basal stems. Methane oxidation was roughly proportional to PPO formation. Soluble MMO-positive methanotroph populations were measured by plate counts. The number of colony-forming units per gram dry matter was 106–105 in roots, and 104–103 in basal stems. These results indicate the possibility of methane oxidation in association with wetland rice plants.
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  • 42
    ISSN: 1432-0789
    Keywords: Cyanobacteria ; Soil inoculation N ; transformation ; Inorganic N ; Easily oxidizable N ; Hydrolysable N ; Non-hydrolysable N ; Wetland rice Farmyard manure ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field experiment was conducted with wetland rice (Oryza sativa cv. IR-36) in a sandy clay loam soil (Entisol) to study the effect of inoculation with a soil-based mixed culture of four diazotrophic cyanobacteria,Aulosira fertilissima, Nostoc muscorum, N. commune andAnabaena spp., on the N-flux in inorganic NH4 ++NO3 −+ NO2 −), easily oxidizable, hydrolysable and non-hydrolysable forms of N in soil during vegetative growth periods of the crop. Effects on grain and straw yield and N uptake by the crop were estimated. The effects of applying urea N and N as organic sources, viz.Sesbania aculeata, Neem (Azardirachta indica) cake and FYM, each at the rate of 40 kg N ha−1, to the soil were also evaluated. Inoculation significantly increased the release of inorganic N, evidenced by its increased concentrations either in soil or in soil solution. However, such increases rarely exceeded even 4% of total N gained in different froms in the soil system by inoculation during the vegetative growth stages of the rice plant, when the nutritional requirement of the plants is at a maximum. Most of the N2 fixed by cyanobacteria remained in the soil as the hydrolysable form (about 85%) during this period. Inoculation caused an insignificant increase in grain (8%) and straw (11%) yield, which was, however, accompanied by a significant increase in N uptake by the grain (30%) and an increase in total uptake of 15.3 kg N ha 1. Such beneficial effects of inoculation varied in magnitude with the application of organic sources, with farmyard manure (FYM) being the most effective. Application of urea N, on the other hand, markedly reduced such an effect.
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  • 43
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    Biology and fertility of soils 25 (1997), S. 285-289 
    ISSN: 1432-0789
    Keywords: Key words Methane emission ; Wetland soils ; Greenhouse gases ; Inceptisol ; Vertisol ; Rice ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a greenhouse study, methane emissions were measured from two diverse Indian rice-growing soils planted to five rice cultivars under similar water regimes, fertilizer applications and environmental conditions. Significant variations were observed in methane emitted from soils growing different cultivars. Total methane emission varied between 8.04 and 20.92gm–2 from IARI soil (Inceptisol) and between 1.47 and 10.91gm–2 from Raipur soil (Vertisol) planted to rice. In all the cultivars, emissions from IARI soil were higher than from Raipur soil. The first methane flux peak was noticed during the reproductive phase and the second peak coincided with the grain-ripening stage of the rice cultivars.
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  • 44
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rice ; aluminium-resistance ; selection ; stress ; in vitro ; hydroponic cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A selection procedure is described that isolated Al-resistant individuals from a sensitive rice (Oryza sativa L.) genotype. Somaclonal variation was used as the only source of variability and selection pressures were applied at both callus and regenerated plant levels. When 10 week-old, embryo-derived calli were submitted to different Al stresses for a period of 20 weeks. After this in vitro stress period, selected calli were grown during 18 weeks, without selection pressure, on regeneration media. Selection pressures were applied on regenerated plants (R0), and 9 R0 plants which produced seeds were selected. The transmission of the Al-resistant character to the R1, R2, R3 and R4 generations was then investigated, and three plant lines which had an increased percentage of Al-resistant plants till the fourth generation of self-pollination, were identified. One was from a callus maintained on an Al-free medium. The efficiency of in vitro selection pressures was therefore debated.
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  • 45
    ISSN: 1573-5060
    Keywords: isozyme ; differentiation ; Oryza sativa ; rice ; upland rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two rice ecotypes, the so-called lowland and upland populations, which carry different isozyme genotypes mostly at a single locus, are cultivated in Japan. The aim of this study was to examine the origin and the mechanism for keeping these genetic differences. The upland population is cultivated in upland fields and carries a different allele for a particular isozyme gene, Pgd-1, which has never been found in the lowland population. RFLP markers showed a weak trend for genetic differentiation between the two ecotypes. On the other hand, morphological, and physiological traits showed marked differences between the two ecotypes. Furthermore, based on the genotypic difference, two Japonica subgroups are defined in the upland population. Subgroup I is the minor group and carries key lowland characters, including the genotype for PGD. Subgroup II carries different traits and the genotype for PGD of the alternative subgroup. As an allelic difference for Pgd-1 is known to occur between the two ecospecies, Tropical (Tr) and Temperate (Tm) Japonicas, upland cultivars can be classified by diagnostic characters which distinguish a variety into Tr or Tm type. The upland population consists of three types of cultivars, Tr-, Tm- and intermediate-type. In contrast, the lowland population consists of a uniform Tm type Japonicas. As Japanese upland cultivars still have an isozyme allele specific to the Tr type, the upland population has a rather complex constitution which is presumably now being introgressed by lowland genetic material, but still represents a major difference at some genetic levels. Upland rice carries several stress-resistant genes which would be useful for lowland rice breeding. The genetic difference would be efficient for tagging upland specific traits by upland specific genetic markers.
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  • 46
    ISSN: 1573-5060
    Keywords: fertility restoration ; hybrid rice ; linkage analysis ; Oryza sativa ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Hybrid varieties developed by making use of the wild abortive cytoplasmic male sterility system account for 90% of hybrid rice produced. Previous inheritance studies have established that the fertility restoration in this system is controlled by two major loci, but the chromosomal locations of the fertility restorer (Rf) loci have yet to be resolved. In this study we determined the genomic locations of the two Rf loci by their linkage to molecular markers. The Rf gene containing regions were identified by surveying two bulks, made of 30 highly fertile and 46 highly sterile plants from a large F2 population of the cross between Zhenshan 97A and Minghui 63, with RFLP markers covering the entire rice genome. The survey identified two likely Rf gene containing regions, located on chromosomes 1 and 10 respectively. This was confirmed by ANOVA using a large random sample from the same F2 population and also with a genome-wide QTL analysis of a test-cross population. The results also showed that both loci have major effects of almost complete dominance on fertility restoration and the effect of the locus on chromosome 10 is larger than the one on chromosome 1. The two loci acted as a pair of classical duplicate genes; a single dominant allele at one of the two loci would suffice to restore the fertility to normal or nearly normal. Closely linked markers identified in this study may be used for marker assisted selection in hybrid rice breeding programs.
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  • 47
    ISSN: 1573-5060
    Keywords: hybrid sterility ; anther indehiscence ; spikelet sterility ; pollen grain fertility ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Hybrid sterility of the cross between Silewah, an Indonesian native variety and Hayakogane, a Hokkaido rice variety in Japan was confirmed to be caused by anther indehiscence, based on a lot of spikelets with fewer numbers than 3 of dehiscent anthers and fewer numbers of pollens poured onto stigma per spikelet in Silewah/Hayakogane F1. In Silewah/Hayakogane//Hayakogane BC1F1, spikelet fertility was correlated with mean number of dehiscent anthers per spikelet. So, genic analyses for hybrid sterility by anther indehiscence were conducted by scoring spikelet sterility in F2, BC1F1s and triple cross. As a result, it was concluded that the hybrid sterility was controlled by complementary action of three dominant genes. Silewah has one of the three genes and Hayakogane has the other two. It was presumed that the two genes which Hayakogane possesses were derived from those of Aikoku, an old native variety in Japan.
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  • 48
    ISSN: 1573-5060
    Keywords: ‘contig lines’ ; interspecific hybridisation ; genetic resources ; molecular markers ; Oryza glaberrima ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the past, utilisation of African cultivated rice, Oryza glaberrima, in O. sativa breeding was hampered by high sterility in interspecific F1 and in early progenies. Recent development of mapped molecular markers provides the opportunity to rationalise and to monitor introgressions between the two cultivated rice species. Development of such introgressed lines through interspecific hybridisation and backcrossing represents high potential to create new genetic and transgressive variation. We are initiating an original marker-aided backcross program with the aim of producing a set of 100 ‘contig lines’, each one bearing an alien O. glaberrima chromosomal fragment of around 20 cM in the O. sativa genetic background. As a preliminary step, we are now developing a genetic linkage map based on STS and RAPD markers, using an interspecific backcross between O. sativa and O. glaberrima. BC1 plants will then be selected to expedite the production of ‘contig lines’ exhibiting only the target fragment. The interspecific polymorphism is anticipated to be large enough to make this methodology feasible. Many advantages are expected from this approach, such as: (i) systematic assessment of the useful genetic resources displayed by O. glaberrima, (ii) improved and simplified detection of QTLs and (iii) comparative analysis of genomic organisation of O. glaberrima vs. O. sativa. Current work on evaluation of STS and RAPD polymorphism between parents and development of the BC1 population is presented.
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  • 49
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    Plant growth regulation 21 (1997), S. 1-6 
    ISSN: 1573-5087
    Keywords: ammonium ; cell growth ; medium pH ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The possible involvements of a decrease in medium pH and accumulation of ammonium in ammonium-inhibited growth of rice cells were investigated. Ammonium, applied at concentrations ranging from 20 to 50 mM, markedly inhibited cell growth and decreased medium pH. The accumulation of ammonium in rice cells was observed only when ammonium concentration was 40 mM or higher. Ammonium-inhibited growth was alleviated when medium pH was buffered with MES [2-(N-morpholino)-ethanesulfonic acid]. However, no difference in ammonium level was observed between buffered and unbuffered ammonium-fed rice cells. Succinic acid, α-ketoglutaric acid, glutamic acid and glutamine were found to be effective in reversing ammonium-inhibited growth of rice cells and reducing a fall in pH in the ammonium-fed medium. Succinic acid, α-ketoglutaric acid and glutamic acid decreased the level of ammonium in ammonium-fed rice cells. However, glutamine was unable to decrease the ammonium level in ammonium-fed rice cells. The current results suggest that a decrease in medium pH is a factor responsible for growth inhibition of ammonium-fed rice cells.
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  • 50
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    Plant growth regulation 21 (1997), S. 37-42 
    ISSN: 1573-5087
    Keywords: abscisic acid ; growth ; methyl jasmonate ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of abscisic acid (ABA) and methyl jasmonate (MJ) on growth of rice seedlings were compared. The lowest tested concentration of ABA and MJ that inhibited seedling growth was found to be 4.5 and 0.9 µM, respectively. Growth inhibition by ABA is reversible, whereas that by MJ is irreversible. GA3 was found to be more effective in reversing inhibition of shoot growth by ABA than by MJ. KCl partially relieved MJ-inhibited, but not ABA-inhibited, growth of rice seedlings. The beneficial effect of K+ on growth of rice seedlings in MJ medium could not be replaced by Li+, Na+ or Cs+. MJ treatment caused a marked release of K+ into the medium. In order to understand whether cell wall-bound peroxidase activity was inversely related to rice seedling growth, effects of ABA and MJ on cell wall-bound peroxidase activity were also examined. Results indicated that both ABA and MJ increased cell wall-bound peroxidase activity in roots and shoots of rice seedlings. Although MJ (4.5 µM) was less effective in inhibiting root growth than ABA (9 µM), MJ was found to increase more cell wall-bound peroxidase activity in roots than ABA.
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  • 51
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    Plant growth regulation 21 (1997), S. 195-201 
    ISSN: 1573-5087
    Keywords: abscisic acid ; ammonium ; benzyladenine ; leaf senescence ; methionine sulfoximine ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The relationship between ammonium accumulation and senescence of detached rice leaves was investigated. Ammonium accumulation in detached rice leaves coincided closely with dark-induced senescence. Exogenous NH4Cl and methionine sulfoximine, which caused an accumulation of ammonium in detached rice leaves, promoted senescence. Treatments such as light and benzyladenine, which retarded senescence, decreased ammonium level in detached rice leaves. Abscisic acid, which promoted senescence, increased ammonium level in detached rice leaves. The current results suggest that ammonium accumulation may be involved in regulating senescence. Evidence was presented to show that ammonium accumulated in detached rice leaves increases tissue sensitivity to ethylene. The accumulation of ammonium in detached rice leaves during dark-induced senescence is attributed to a decrease in glutamine synthetase activity and an increase in reduction of nitrate.
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  • 52
    ISSN: 1573-5060
    Keywords: Oryza sativa ; japonica rice cultivar ; mature embryo ; primary calli ; protoplasts ; green plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A plant regeneration system from rice protoplasts using calli derived from mature embryos was established for the two Brazilian modern rice cultivars IAC-201 and IAC-165. After 30 to 40 days of in vitro culture it was possible to obtain on average 6 million protoplasts per gram of callus. Microscopic selection of embryogenic calli was a key step for protoplast isolation. The production of embryogenic calli increased when L-proline and casein hydrolysate were used in the callus induction medium. The Oc or IR52 nurse cell lines were essential for protoplast division. Different regeneration media were studied and 139 plants were regenerated which set seed. Some of the regenerated plants showed morphological variation such as the presence of awns in spite of the short time of the in vitro culture.
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  • 53
    ISSN: 1573-5060
    Keywords: Oryza rufipogon ; Griff ; Oryza sativa ; interspecific hybrid ; hybrid swarms ; cytological abnormalities ; evolution and rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The morphology and cytology of selected hybrid swarms of wild and cultivated rices were studied following natural hybridization between the native species Oryza rufipogon Griff and exotic species Oryza sativa L. (var. Thaothabi and Moirangphoe). Similar studies were also conducted on populations developed through artificial hybridization of those two species. The morphological variation in plant height, anthocyanin pigmentation, Kernel and husk colour, sterility, presence of awns and grain shattering habits were similar in both natural (hybrid swarms) and artificially derived populations of interspecific hybrids. The cytological abnormalities such as quadrivalant formation at metaphase I, delayed separation, laggards and bridge formation, unequal separation and chromosomal elimination were also observed in both populations. These results indicated that the evolution of intermediate types had occurred due to genetic introgression from cultivated species to wild species. A systematic extinction of founder population was also noticed due to sudden ecological changes like deep submergence to medium submergence and human interference by growing cultivated species O. sativa L. in the area where wild species were being grown.
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  • 54
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    Euphytica 95 (1997), S. 253-258 
    ISSN: 1573-5060
    Keywords: rice ; Oryza sativa ; widely compatible restorer ; fertility restoration ability ; anther culture ; inheritance ; Indica-japonica heterosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Following anther culture of various F1 hybrids of indica restorer (R) lines/wide compatible varieties (WCVs) and japonica R lines/WCVs, the homozygous diploid plants (2n) generated were test-crossed with indica WA type cytoplasmic-genetic male sterile (CMS) line Zhanshan 97A (WA), indica testers Nanjing 11 and Nante, japonica BT CMS line Hanfeng A (BT), and japonica testers Balilla and Akihikari to identify widely compatible restorer lines. The results of this study showed that among the diploid pollen plants generated from F1 hybrids of indica R lines/WCVs, 36.7% and 64.7% possessed normal fertility restoration ability (rate of seed-setting 〉 80%) to Hanfeng A and Zhanshan 97A, respectively. 71.3% and 32.3% had normal fertility restoration ability to Hanfeng A and Zhanshan 97A, respectively, in diploid pollen plants derived from the japonica R lines/WCVs F1's anther culture. Several widely compatible R lines were selected from anther culture of F1 hybrids of indica R lines/WCVs and japonica R lines/WCVs. These widely compatible R lines derived from diploid pollen plants showed good wide compatibility and restoration ability both to WA and BT type CMS lines. Strong standard heterosis of major agronomic traits and yield traits was observed in F1 test-crosses of widely compatible R lines with Hanfeng A and Zhanshan 97A. The wide compatibility in widely compatible R lines H17, H158 and H281 was studied by a set of three-way crosses. Segregation of the fertile plants with seed-setting rate 〉 70% and semi-fertile plants with seed-setting rate 〉 69.9% agreed with a ratio of 1:1, indicating that wide compatibility in these widely compatible R lines is governed by a pair of major genes.
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  • 55
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    Euphytica 95 (1997), S. 301-307 
    ISSN: 1573-5060
    Keywords: gene location ; heading time ; Oryza sativa ; photoperiod sensitivity ; rice ; trisomic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Recent genetic analyses on heading-time of rice indicated that almost all the well-adapted varieties in the temperate zone carry a strong photoperiod-sensitivity gene E1, a dominant allele of E1 locus. In order to identify the chromosome on which E1 is located, a trisomic analysis was made using two primary trisomic series originating from the japonica varieties, Nipponbare and Kinmaze, respectively. The Nipponbare and Kinmaze series were crossed with heading-time tester lines, EG0 and EG3, respectively, both of which did not carry the E1. The F2 populations for chromosome 1, 2, and 3 could not be analyzed due to lack of seed. All the other F2 populations showed distinct segregation into early-type and late-type plants caused by the E1 locus segregation, which suggested that the trisomic analysis for E1 locus could be efficiently made. Both disomic and trisomic groups in the F2 population from the cross of the trisomic line for chromosome 7 × EG0 showed a segregation ratio significantly different at the 1% level from a ratio of 1 [e1e1; early]: 3 [E1e1, E1E1; late]. This suggested that E1 was located on chromosome 7. Subsequently, the linkage analysis was made using three morphological marker genes on chromosome 7. It was recognized that E1 was linked to rfs (rolled fine strip gene) and slg (slender glume gene) with recombination values of 16.3 ± 5.88 and 9.1 ± 4.72%, respectively. From these results, it can be concluded that E1 is most likely to be located on chromosome 7.
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  • 56
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    Euphytica 96 (1997), S. 135-142 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; chilling tolerance ; in vitro selection ; rice ; somaclonal variation ; field performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Embryo-derived calli of four rice varieties cultivated at high altitude in Burundi — Facagro 57, Facagro 76, Kirundo 3 and Kirundo 9 — were submitted to different temperature regimes. The percentage of regenerating calli greatly varied depending on variety, length of culture and callus temperature treatment. The reduction of regeneration percentages induced by low temperature was more pronounced in the more sensitive varieties. Regenerated plants (R0) and their progenies in R1, R2 and R3 were cold-screened together with control plants. In all varieties, significantly higher survival rates were obtained in R3 with in vitro plants than with control plants. Such chilling tolerance improvement was not obtained following a massal selection applied during 3 successive generations onto the control plants. In vitro plants regenerated from calli cultivated either at 25 °C, either at 4 °C, were cultivated at different altitudes in Burundi during two successive generations. For most observed traits, the in vitro plants were characterized by lower means, larger variation and higher maximum values than the control plants. The most chilling-tolerant somaclonal families were most usually characterized by extensive differences in fatty acid composition, chilling-induced electrolyte leakage and chlorophyll fluorescence, compared to the varieties they derived from.
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  • 57
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    Plant growth regulation 22 (1997), S. 163-168 
    ISSN: 1573-5087
    Keywords: Oryza sativa ; paraquat ; putrescine ; spermidine ; spermine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The protective effect of polyamines against paraquat (PQ) toxicity of rice (Oryza sativa) leaves was investigated. PQ treatment resulted in a higher putrescine (PUT) and lower spermidine (SPD) and spermine (SPM) levels in rice leaves. Pretreatment with SPD and SPM, which resulted in a 10- and 20-fold increase in endogenous level of SPD and SPM, respectively, reduced PQ toxicity (30%). Limited reduction of PQ toxicity by exogenous SPD and SPM is most likely due to the fact that they are not readily transported in rice leaf cells and localized to those areas along the cut edges of detached rice leaves [4]. PUT pretreatment did not increase endogenous SPD and SPM levels and had no effect on reducing PQ toxicity. It was found that 1,10-phenanthroline, an iron chelator, treatment reduced the toxicity of PQ (35%) and increased the levels of SPD (27%). The results indicate that reduction of PQ toxicity by SPD and SPM is due to increased activities of catalase (18%) and peroxidase (40%).
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  • 58
    ISSN: 1573-5060
    Keywords: Oryza sativa ; photoperiod sensitive genic male-sterile rice (PSGMR) ; inheritance ; anther culture ; pollen plant ; polyploidy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The fertility segregations of F1, F2, BCF1 descended from crosses between PSGMR and japonica varieties, and F1's anther cultured homozygous diploid pollen plant populations (H2) were studied to reveal the genetic mechanism of photoperiod sensitive genic male sterility in PSGMR under natural daylight length at Shanghai. Rate of bagged seed-setting was used as an indicator of fertility. Fifteen F1 showed complete fertility similar to their parents. The ratio of completely sterile plants to fertile plants in fifteen F2 and four BCF1 was 1:15 and 1:3, respectively. The ratio of completely sterile to fertile diploid pollen plants in nine diploid populations (H2) was 1:3. These results demonstrated that the photoperiod sensitive genic male sterility in PSGMR was governed by two pairs of independent major recessive genes. There were no significant fertility segregations in hybrids F1 and selfed F2 between Nongken 58S and its derivatives 7001S, 5088S, 5047S and M105-9S, indicating that the photoperiod sensitive genic male-sterile genes in Nongken 58S were allelic to those in its derivatives. Several photoperiod sensitive genic male-sterile diploid pollen lines were bred from anther cultured homozygous diploid populations (H2) in about a three-year period. Most of these diploid lines showed significant fertility transformation and stable complete sterility from 5 August to 5 September, excellent agronomic traits and high resistance to blast and bacterial leaf blight.
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  • 59
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    Euphytica 97 (1997), S. 25-29 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; amylograph viscosity characteristics ; inheritance ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Southern United States long grain rice (Oryza sativa L.) is a unique market type characterized by intermediate amylose content, gelatinization temperature, and amylograph viscosity profile characteristics. Rice breeders sometimes use long grain germplasm with differing amylograph viscosity profiles. The inheritance of rice amylograph viscosity profiles has not been ascertained and, thus, was the objective of this study. A six parent diallel (parents plus F1 hybrids) was evaluated at Stuttgart, AR during 1994 and 1995. In 1994, 65 F2 plants from the ‘L-202’ × ‘Newrex’ and L-202 × ‘Katy’ crosses were space planted, and in 1995, the 65 F2:3 lines were planted as hill plots. The inheritance of amylograph viscosity profiles appeared to be controlled by a single locus with genes with additive effects. The results of the diallel analysis also support control by a single locus with genes with additive effects because GCA effects were significant and SCA effects nonsignificant for peak, hot paste, and cool paste viscosities. Intermediate amylose content and intermediate amylograph viscosity profiles were strongly correlated. Selection first for intermediate amylose content followed by reselection for intermediate hot paste viscosities would identify long grain genotypes with southern United States long grain cooking quality in progeny from crosses between southern United States long grain rice genotypes and softer cooking long grain genotypes.
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  • 60
    ISSN: 1573-5060
    Keywords: Oryza sativa ; Aus ; rice ; hybrid sterility ; isozomes ; varietal diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Magnitudes of genetic variation within each of major varietal groups of cultivated rice were surveyed in terms of isozyme polymorphism and allelic differentiation of hybrid sterility loci, both of which are considered to have litt le selective value. Allelic differences for 20 isozyme loci were examined in a total of 337 accessions, including Indica and Japonica rices. Aus cultivars from India, Javanica cultivars and both landraces and cultivars from China. Eleven out of the 20 isozyme loci were polymorphic. The Aus cultivars contained more alleles per locus than others. The hybrid sterilities in the crosses among Chinese cultivars, Indica and Japonica cultivars were mainly controlled by locus S-5, whereas the hybrid sterilities of Aus cultivars, when they were crossed to Indica, Japonica or Javanica cultivars, were found to be controlled by allelic interaction at hybrid sterility loci S-5, S-7, S-9 and S-15. Also in terms of the number of alleles at S-5 and S-7, Aus cultivars contained more alleles than others. While the Aus group showed an extreme diversity for both hybrid sterility alleles and isozymes, modern cultivars from the south of YangZi River in China were classified into Indica type and those from the north were into Japonica, which were almost the same as those in Japan. On the basis of the measured polymorphism the Indica-Japonica differentiation was explained by founder effects, i.e., through selection and distribution of two original sources each with a unique set of markers. Contrastingly, the continuous and pronounced diversity in the Aus group was attributed to the absence of such a process. The intermediate groups in Yunnan province and Tai-hu Lake region of China are considered to be isolated from such founder effects, retaining an intermediate diversity in terms of isozymes and hybrid sterility genes. Since hybrid sterility hampers the exchange of genes between cultivars of different groups, the understanding of its genetic basis will be important in rice breeding, particularly in hybrid rice breeding.
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  • 61
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    Euphytica 95 (1997), S. 45-48 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; non-allelic ; segregation ; semidwarfism ; sd1 gene ; dwarf ; mutations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The mode of inheritance of five semidwarf (SD) mutants and allelic relationship with DGWG (sd1) locus was studied. The five SD mutants viz., Basmati 370 (SD1), Basmati 370 (SD2), Basmati 370 (SD3), TCA 2 (SD) and TCA P2-5 (SD) when crossed with their tall parents exhibited monogenic inheritance of 3 tall: 1 semidwarf in the F2 progenies. The SD mutants were also crossed with semidwarf varieties (DGWG and Bala) possessing sd1 gene. Crosses between Basmati 370 (SD1) × Bala, Basmati 370 (SD3) × Bala and TCA 2 (SD) × DGWG produced tall F1 hybrids and in F2 generation, modified dihybrid ratios (9 : 6 : 1 and 9 : 7) were observed indicating that the mutants Basmati 370 (SD1), Basmati 370 (SD3) and TCA 2 (SD) are non-allelic to sd1 gene. Whereas, the mutants Basmati 370 (SD2) and TCA P2-5 (SD) when crossed with Bala produced semidwarf F1 hybrids and in F2 generation, segregation for plant height was not observed indicating that these mutants are allelic to sd1 gene. The three non-allelic SD mutants identified in the present study can be used in rice breeding as alternative gene sources for semidwarfism.
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  • 62
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    Journal of agricultural and environmental ethics 10 (1997), S. 249-267 
    ISSN: 1573-322X
    Keywords: Animals ; Asia ; consciousness ; Australia ; Hong Kong ; India ; Israel ; Japan ; New Zealand ; The Philippines ; Russia ; Singapore ; Thailand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract The interactions between humans, animals and the environment have shaped human values and ethics, not only the genes that we are made of. The animal rights movement challenges human beings to reconsider interactions between humans and other animals, and maybe connected to the environmental movement that begs us to recognize the fact that there are symbiotic relationships between humans and all other organisms. The first part of this paper looks at types of bioethics, the implications of autonomy and the value of being alive. Then the level of consciousness of these relationships are explored in survey results from Asia and the Pacific, especially in the 1993 International Bioethics Survey conducted in Australia, Hong Kong, India, Israel, Japan, New Zealand, The Philippines, Russia, Singapore and Thailand. Very few mentioned animal consciousness in the survey, but there were more biocentric comments in Australia and Japan; and more comments with the idea of harmony including humans in Thailand. Comparisons between questions and surveys will also be made, in an attempt to describe what people imagine animal consciousness to be, and whether this relates to human ethics of the relationships.
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  • 63
    ISSN: 1572-9788
    Keywords: DNA markers ; genetic linkage map ; marker-assisted breeding ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We have developed an RFLP framework map with 146 RFLP markers based on a doubled haploid population derived from a cross between an indica variety IR64 and a japonica variety Azucena. The population carries 50.2% of IR64 loci and 49.8% of Azucena loci, indicating an equal amount of genetic materials from each parent has been transmitted to the progenies through anther culture. However, some markers show segregation distortion. These distorted marker loci are located on 10 chromosomal segments. Using this map we were able to place 8 isozymes, 14 RAPDs, 12 cloned genes, 1 gene for brown planthopper (BPH) resistance, and 12 QTLs for grain length, grain width and length/width ratio onto rice chromosomes. The major gene for BPH resistance was mapped on chromosome 12 near RG463 and isozyme Sdh-1. Most of the QTLs identified for the three grain characters were closely linked on chromosomes 1, 2, 3 and 10. We concluded that the RFLP framework map presented here will be useful for mapping other genes segregating in this doubled haploid population. Thus rapid generation of doubled haploid lines and their unbiased segregation make it very attractive for gene mapping.
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  • 64
    ISSN: 1572-9788
    Keywords: diversity ; genetic mapping ; Oryza sativa ; RAPDs ; rice ; inter-simple sequence repeats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Genetic variation between samples of Oryza sativa from 19 localities in Bangladesh and Bhutan was assessed using two PCR-based molecular marker systems: RAPD (random amplification of polymorphic DNA) and ISSR-PCR (inter-simple sequence repeat polymerase chain reaction). Employing RAPD, a set of 14 decanucleotides of arbitrary sequence directed the amplification of 94 reproducible marker bands, 47 (50%) of which were polymorphic. In addition, a set of 9 ISSR primers were used to direct amplification of 71 PCR products, 40 (56%) of which were polymorphic. Multivariate analyses of the two PCR-based molecular marker data sets provided evidence that the patterns of variation correspond with the classification described by Glaszmann [9] using isozyme analysis. Subtle differences in the relationships revealed between rice groups using the two types of PCR-based marker led to investigations of their map positions using an intraspecific doubled haploid mapping population. The observation that the chromosomal locations of markers can influence diversity assessments is presented and the significance of this is discussed.
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  • 65
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    European journal of plant pathology 103 (1997), S. 747-750 
    ISSN: 1573-8469
    Keywords: Appressoria ; fungitoxicity ; Magnaporthe grisea ; Oryza sativa ; partial resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 66
    ISSN: 1432-0789
    Keywords: Key words Cyanobacteria ; Soil inoculation ; N-transformation ; Inorganic N ; Easily oxidizable N ; Hydrolysable N ; Non-hydrolysable N ; Wetland rice ; Farmyard manure ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field experiment was conducted with wetland rice (Oryza sativa cv. IR-36) in a sandy clay loam soil (Entisol) to study the effect of inoculation with a soil-based mixed culture of four diazotrophic cyanobacteria, Aulosira fertilissima, Nostoc muscorum, N. commune and Anabaena spp., on the N-flux in inorganic (NH4 ++NO3 –+ NO2 –), easily oxidizable, hydrolysable and non-hydrolysable forms of N in soil during vegetative growth periods of the crop. Effects on grain and straw yield and N uptake by the crop were estimated. The effects of applying urea N and N as organic sources, viz. Sesbania aculeata, Neem (Azardirachta indica) cake and FYM, each at the rate of 40 kg N ha–1, to the soil were also evaluated. Inoculation significantly increased the release of inorganic N, evidenced by its increased concentrations either in soil or in soil solution. However, such increases rarely exceeded even 4% of total N gained in different froms in the soil system by inoculation during the vegetative growth stages of the rice plant, when the nutritional requirement of the plants is at a maximum. Most of the N2 fixed by cyanobacteria remained in the soil as the hydrolysable form (about 85%) during this period. Inoculation caused an insignificant increase in grain (8%) and straw (11%) yield, which was, however, accompanied by a significant increase in N uptake by the grain (30%) and an increase in total uptake of 15.3 kg N ha–1. Such beneficial effects of inoculation varied in magnitude with the application of organic sources, with farmyard manure (FYM) being the most effective. Application of urea N, on the other hand, markedly reduced such an effect.
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  • 67
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    Biology and fertility of soils 24 (1996), S. 70-75 
    ISSN: 1432-0789
    Keywords: Key words Flooded rice soil ; Soil-trapped CH4 and CO2 ; δ13C values of CH4 and CO2 ; Greenhouse effect ; CO2 flux ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pot experiments were conducted to monitor the changes in compositions and δ13C values of soil-trapped CH4 and CO2 in flooded rice soil with and without rice plants or rice straw. Incorporation of rice straw increased the concentration of CH4 and CO2 accumulated in soil, and the quantities of emitted CH4 to the atmosphere. Rice plants reduced the concentration of soil-trapped CH4 and CO2, and the decreased portion of CH4 was replaced by N2. A significantly negative correlation was found between soil-trapped CH4 and N2. The presence of rice plants increased the δ13C values of CH4. The δ13C values of CH4 tended to increase toward the end of the growing season and were positively correlated with concentration of soil-trapped CH4. A positive correlation between δ13C values of CH4 and CO2, and between the δ13C values of CH4 and its concentration, were observed. The CH4 in the rice stems was 4–14‰ enriched in 13C relative to soil-trapped CH4. In contrast, CO2 in rice plant stems was 1–9‰ lighter in 13C relative to soil-trapped CO2. These results are discussed in relation to the precursor pools and pathways of methanogenesis.
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  • 68
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    Journal of plant growth regulation 15 (1996), S. 197-200 
    ISSN: 1435-8107
    Keywords: Ethylene ; Jasmonates ; Oryza sativa ; Senescene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The role of ethylene in jasmonate-promoted senescence of detached rice leaves was investigated. Ethylene production in methyl jasmonate-treated leaf segments of rice was lower than in the control leaves. Treatment of leaf segments with silver nitrate or/and silver thiosulfate, inhibitors of ethylene action, inhibited methyl jasmonate-, jasmonic acid-, linolenic acid-, and abscisic acid-promoted senescence of detached leaves. We suggest that an increase in ethylene sensitivity, but not ethylene level, is the initial event triggering the enhanced senescence by jasmonates of detached rice leaves.
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  • 69
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rice ; chilling ; electrolyte leakage ; chlorophyll fluorescence ; seed dormancy ; seed germination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Rice varieties were screened for chilling tolerance during germination and vegetative growth using different techniques. The effects of temperature during germination were investigated from 10 to 25°C. The screening was most effective at 10°C. Time of data collection has to be considered in order to discriminate slow germinating from chilling sensitive varieties. Chilling survival tests (10°C) applied at the 2-leaf stage revealed that different chilling durations brought complementary results: the longer treatments allowed to identify the most tolerant varieties, while shorter treatments allowed to distinguish intermediate from most sensitive rices. Results of chilling tests applied at the 2- and the 8-leaf stages showed a high correlation. Low-temperature electrolyte leakage and low-temperature fluorescence were also highly correlated to each other and to survival tests applied at the same development stage. By contrast, weak correlations were observed between low-temperature germination and plantlet chilling survival. It is concluded that low-temperature electrolyte leakage and low-temperature fluorescence are good indicators of chilling tolerance during the vegetative growth. The possibility to use a chilling screening procedure applied at this stage in order to predict the chilling tolerance at other development stages is discussed.
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  • 70
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    Euphytica 89 (1996), S. 349-354 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; quantitative trait loci ; gene mapping ; restriction fragment ; length polymorphism ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Segregation of plant height (PH), tiller number (TN), panicle number (PN), average panicle length per plant (PL), average primary branch number per panicle per plant (PBN) and 1000 grain weight (1000G) were specific in an F2 population derived from a cross of Palawan, a tall Javanica variety, and IR42, an Indica semidwarf variety. One hundred and four informative RFLP markers covering all 12 chromosomes were used for detecting putative QTLs controlling the traits. Orthogonal contrasts and interval mapping analysis were used for the analysis. QTL detected for PH on the region of chromosome 1, where semidwarfing gene sd-1 locus is located, seems to be a multiple allelic locus. An additional QTL for PH was identified on chromosome 2. Two QTLs for TN were detected on chromosomes 4 and 12. The QTL on chromosome 4 seemed also to govern the variation in PN. Four QTLs were found for the other traits, two of them for PL were located on chromosomes 6 and 2, one for PBN on chromosome 6 and the other for 1000G on chromosome 1. Additive gene actions were found to be predominant, except one QTL for PH and one QTL for PL, but partial or incomplete dominance also existed for the QTLs detected.
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  • 71
    ISSN: 1573-5087
    Keywords: cell wall polysaccharides ; deepwater rice ; floating rice ; internodal elongation ; Oryza sativa ; submergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In excised stem segments of floating rice (Oryza sativa L.), as well as in intact plants, submergence greatly stimulates the elongation of internodes. The differences in the composition of cell wall polysaccharides along the highest internodes of submerged and air-grown stem segments were examined. The newly elongated parts of internodes that had been submerged for two days contained considerably less cellulosic and noncellulosic polysaccharides than air-grown internodes, an indication that the cell walls of the newly elongated parts of submerged internodes are extremely thin. In the young parts of both air-grown and submerged internodes, the relative amounts of noncellulosic polysaccharides were equal to those of α-cellulose, whereas the relative amounts of α-cellulose were higher than those of noncellulosic polysaccharides in the upper, old parts. In the cell-elongation zones of both air-grown and submerged internodes, glucose was predominant among the noncellulosic neutral sugars of cell wall. The relative amount of glucose in noncellulosic neutral sugars decreased toward the upper, old parts of internodes, whereas that of xylose increased.
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  • 72
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    Euphytica 91 (1996), S. 285-288 
    ISSN: 1573-5060
    Keywords: anther culture ; breeding ; doubled haploids ; Oryza sativa ; rice ; salt tolerant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A haploid breeding program was initiated to develop doubled haploid salt tolerant rice breeding line via anther culture. Two sensitive breeding lines BR4608-R1-R2 and BR4909-R1-R2 were crossed with a salt tolerant line IR13146-13-3-3 to transfer its salt tolerant character to the doubled haploids. Anther from confirmed F1s of the two crosses were cultured in defined medium for callus induction and eventual plant regeneration. Fifteen doubled haploid (DH) lines were obtained from two crosses. Test for salt tolerance were done in vitro. Five out of 15 lines were found tolerant at the level of 8–10 decisiemens/m (ds/m) while the rests were sensitive to that level of salinity. Field experiment was conducted to evaluate the doubled haploids under saline and non saline soil. Five salt tolerant lines produced comparable yield with the resistant control (BR 23) under saline condition, whereas these lines yielded even higher in non saline soil under irrigated condition when evaluated with other 10 sensitive DH lines
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  • 73
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    Plant growth regulation 18 (1996), S. 161-164 
    ISSN: 1573-5087
    Keywords: ethylene production ; Oryza sativa ; vanadate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of vanadate on ethylene biosynthesis in detached rice leaves was investigated. Vanadate at pH 5.0–7.0 effectively enhanced ethylene production within 3 h of its application. It promoted the conversion of ACC to ethylene. Treatment with vanadate did not decrease ACC level until late stage of incubation, i.e. at 12 h after incubation. Molybdate, an inhibitor of phosphatase had no or much less stimulatory effect on ethylene production than did vanadate at comparable concentrations. Azide, an inhibitor of F1-ATPase, inhibited ethylene production in detached rice leaves. FC and vanadate were observed to be synergisticly increased ethylene production in detached rice leaves. In conclusion, plasma membrane H+-ATPase does not seem to be involved in ethylene biosynthesis in detached rice leaves.
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  • 74
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    Euphytica 88 (1996), S. 1-7 
    ISSN: 1573-5060
    Keywords: rice ; Oryza sativa ; hybrid rice ; thermosensitive genic male sterility (TGMS) ; rice genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Inheritance of thermosensitive genic male sterility (TGMS) in Norin PL12 and IR32364TGMS and their allelic relationship were studied from F1, F2 testcross (TC) and F3 generations of the crosses made with the two mutants and several fertile tester parents. F2, TC and F3 segregation behavior for pollen and spikelet fertility indicated that the TGMS trait in the two mutants was controlled by a single recessive gene. Allelic relationship studies indicated that TGMS genes of the two mutants were different. Since TGMS gene in Norin PL12 has been designated as tms 2 , the TGMS gene present in IR32364TGMS is tentatively designated as tms 3 (t) until allelic test is done with another TGMS gene (tms 1 ) reported from China in a line 5460S seeds of which were not available.
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  • 75
    ISSN: 1573-5060
    Keywords: Oryza sativa ; cytoplasmic male sterility (CMS) ; fertility-restoring reversion ; radiation mutation ; genetic analysis, rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A male fertile revertant was isolated from M1 of a cytoplasmic male sterile indica rice line II-32A, the dry seeds of which were treated with 60Co-γ rays at a dose of 290 Gy. The acquired revertant T24 was morphologically and agronomically similar to II-32B, the maintainer of II-32A. Testcrosses of the revertant with II-32A and Zhenshan 97A showed that the revertant was able to restore the fertility of CMS lines. Genetic analysis of the progenies between T24 and II-32A, Zhenshan 97A XieqingzaoA and DZhenshan 97A, which have different cytoplasms, showed that the fertility restoration of four CMS lines by T24 involved one nuclear gene, indicating that T24 was a result of the mutation of one nuclear gene. The mechanism of the restoration of CMS line by T24 was obviously different from other restorers such as Minghui 63 and 20964, which were shown to behave in two gene mode in fertility restoration. The discovery of the revertant T24 contributes to the understanding of CMS and fertility restoration of CMS in rice. The T24 and its parent II-32A may constitute a pair of near isogenic lines for the restoring gene, which should be valuable materials for molecular genetic analysis of CMS.
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  • 76
    ISSN: 1573-5060
    Keywords: heading time ; gene analysis ; Oryza sativa ; photoperiod insensitivity ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The release of extremely early maturing varieties has made it possible to cultivate rice in Hokkaido (NL45-42°) in Japan, the northern limit region of paddy rice cultivation. Until then, rice cultivation in this region has been impracticable due to the climate condition, especially short summer and long-day more than 15 hours during summer. Experiment results confirmed that the success of rice cultivation in this area depends on raising photoperiod insensitivity varieties with short basic vegetative growth period. Moreover, in this study, the genetic factors controlling the photoperiod insensitivity of Hokkaido varieties were analyzed by using 8 kinds of tester lines for three loci, E1, E2, and E3, controlling photoperiod sensitivity. It was found out that all the varieties examined carry el, a photoperiod insensitivity allele of E1 locus, but as for the other loci, E2 and E3, the existence of plural alleles were recognized. We have already clarified that almost all the japonica-type varieties grown in Japan (except Hokkaido) and Taiwan carry E1 bringing about strong photoperiod sensitivity. Accordingly, it can be concluded that el is the gene essential to Hokkaido varieties: the interchange of E1 with e1 enabled rice cultivation under long-day condition.
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  • 77
    ISSN: 1573-5060
    Keywords: Oryza sativa ; inter-varietal cross ; spikelet fertility ; genetic basis ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary There is much interest in the inter-varietal fertility of Asian cultivated rice. In this study, we analyzed the fertility of hybrids in a diallel set of 210 crosses involving 21 parents representing a broad range of the cultivated rice germplasm including landraces, primitive cultivars, modern elite cultivars and parents of hybrid rice. The materials were also carefully selected with respect to indica-japonica classification including typical indica/japonica, more or less intermediate and wide compatibility varieties. The level of hybrid fertility varied widely among the crosses from almost completely sterile to fully fertile. In general, hybrid fertility of intra-subspecific crosses, i.e., indica by indica (I×I) and japonica by japonica (J×J), is much higher than inter-subspecific crosses (I×J or J×I). The fertility varied widely in hybrids involving wide compatibility varieties and also in inter-subspecific crosses not involving wide compatibility varieties. An analysis of variance showed that both the main effects of indica and japonica parents and the interaction between the parents are highly significant in determining hybrid fertility. We speculate that, in addition to wide compatibility, the overall genetic difference between the indica and japonica parents, that may involve a series of minor mutations, play an important role in determining the hybrid fertility. There are also genes of sizable effect that influence fertility in hybrids resulting from specific combinations of the parents.
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  • 78
    ISSN: 1573-5036
    Keywords: anaerobic soil ; flooded soils ; intensive cropping ; long term experiments ; lowland rice ; nitrogen mineralization ; nitrogen uptake ; on-farm research ; organic carbon ; organic matter ; Oryza sativa ; plant nitrogen ; soil nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil organic matter (SOM) has been proposed as an index of N supply in paddy soils although field validations are few. We evaluated the relationship between the indigenous N supply (N i ) of the soil-floodwater system and soil organic carbon (SOC) or total N (N t ) in surface soil of long-term fertility experiments (LTFEs) at 11 sites, in 42 farmer's fiels with similar soil type, and in the same field in ten consecutive rice (Oryza sativa L.) crops. The N i was estimated by crop N uptake from plots without applied N (N o plots) under otherwise favorable growth conditions. There was a tight linear correlation between yields and N uptake in N o plots and tremendous variation in both parameters among LTFE sites, farmer's fields, and in the same field over time. Correlation between N i and SOC or N t explained little of this variation. Factors likely to contribute to the poor correlation were: (1) inputs of N from sources other than N mineralization of SOM in surface soil, (2) degree of congruence between soil N supply and crop demand, which is sensitive to soil drying, length of fallow, crop rotation, and residue management, and (3) differences in SOM quality related to intensive cropping in submerged soil. Better understanding of the processes governing the N i of tropical lowland rice systems would contribute to the development of crop management practices that optimize utilization of indigenous N resources.
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  • 79
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    Nutrient cycling in agroecosystems 41 (1995), S. 145-150 
    ISSN: 1573-0867
    Keywords: Eppawala Rock Phosphate ; selectively mined Eppawala Rock Phosphate ; primary apatite ; secondary phosphate matrix ; acid soils ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Apatite in Sri Lanka is mined from Eppawala (Eppawala Rock Phosphate or ERP). The finely ground product is used as a direct application fertilizer for tea, rubber and coconut. ERP is an indiscriminate mixture of more soluble primary crystals and a less soluble secondary phosphate matrix rich in ferruginous and aluminous compounds with an average P2O5 content of 30%. The primary crystals can easily be separated from the groundmass by mechanical separation to produce selectively mined primary crystals (SERP) which has higher P2O5 (35 to 42%) and lower R2O3 contents (around 1%) than the matrix. The ground SERP shows promise, as measured using yield and bicarbonate-extractable soil P, as fertilizer for rice grown in lowland and midland acid soils. In the second crop residues of SERP produced larger yields and bicarbonate-extractable P than Triple super phosphate (TSP) for the first crop. TSP is imported and its price is four times that of SERP. Therefore SERP is a potentially more profitable alternative fertilizer for TSP for rice on Sri Lankan acid soils.
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  • 80
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    Nutrient cycling in agroecosystems 41 (1995), S. 11-17 
    ISSN: 1573-0867
    Keywords: Oryza sativa ; grain yield ; agronomic and physiological P efficiencies ; harvest index ; rooting depth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus (P) deficiency is one of the major limiting factor for crop production in highly weathered soils in the humid tropics. Field experiments were conducted for two years (1992 and 1993) to determine P response and efficiencies of upland rice cultivars in an Ultisol, low in available P, in the forest zone of Cote d'Ivoire. The rice cultivars tested were selected from a large number of entries tested earlier for acidity tolerance. Grain yields of the cultivars were significantly increased by P application. There was little further response in grain yield at higher rates than 60 kg P ha−1. The rice cultivars differed in agronomic and physiological P efficiencies and the efficiencies were higher at lower rates of P. The rooting depths of the cultivars were increased by application of P at the lowest application rate (30 kg P ha−1).The results suggest that P fertilization of soil acidity-tolerant upland rice cultivars can significantly improve the productivity of the Ultisols.
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    Euphytica 82 (1995), S. 17-23 
    ISSN: 1573-5060
    Keywords: induced mutations ; Oryza sativa ; phytochrome ; pollen fertility ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Low pollen fertility mutants in the M7 generation were identified in the field from ethyl methane sulfonate-treated material of the rice cultivar M-201. M7 plants exhibited low pollen fertility levels (2%–28%) with mean values 7.5-fold less than M-201. Pollen fertility increased 3 to 44-fold when the M7 field plants were ratooned and grown in a growth chamber with a 12 hr daylength. High fertility of all F1's was observed in crosses with normal and pollen sterile lines. Chi squared analyses of five F2 populations indicated that, depending on the cross, pollen fertility was governed by one to three recessive nuclear genes. Transgressive segregation for both low and high fertility was observed in all but one cross. A 19% to 66% increase in fertility of late tillers over main stems was observed in mutants under field conditions. Interruption of the dark period with 5 minute treatments of red or far-red light resulted in altered fertility levels and suggested involvement of phytochrome in regulation of pollen fertility.
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    Euphytica 86 (1995), S. 83-85 
    ISSN: 1573-5060
    Keywords: gene-mapping ; microsatellite ; Oryza sativa ; rice ; waxy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A polymorphic microsatellite locus has been located closely linked to the Waxy gene of rice. Primers were designed to allow detection of the microsatellite by utilising the polymerase chain reaction. In screen of 13 commercial rice varieties, four different alleles were found, demonstrating the potential of this marker in commercial rice breeding for starch quality.
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  • 83
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    Plant growth regulation 17 (1995), S. 15-20 
    ISSN: 1573-5087
    Keywords: NaCl ; Oryza sativa ; polyamine ; seedling growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The role of endogenous polyamines in the control of NaCl-inhibited growth of rice seedlings was investigated. Putrescine, spermidine and spermine were all present in shoots and roots of rice seedlings. NaCl treatment did not affect spermine levels in shoots and roots. Spermidine levels in shoots and roots were increased with increasing concentrations of applied NaCl. NaCl at a concentration of 50 mM, which caused only slight growth inhibition, drastically lowered the level of putrescine in shoots and roots. Addition of precursors of putrescine biosynthesis (L-arginine and L-ornithine) resulted in an increase in putrescine levels in NaCl-treated shoots and roots, but did not allow recovery of the growth inhibition of rice seedlings induced by NaCl. Pretreatment of rice seeds with putrescine caused an increase in putrescine level in shoots, but could not alleviate the inhibition effect of NaCl on seedling growth. The current results suggest that endogenous polyamines may not play a significant role in the control of NaCl-inhibited growth of rice seedlings.
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  • 84
    ISSN: 1573-5060
    Keywords: rice ; Oryza sativa ; cytoplasmic male sterility ; fertility restoration ; chromosomal gene location ; primary trisomics ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Identification and location of fertility restoring genes facilitates their deployment in a hybrid breeding program involving cytoplasmic male sterility (CMS) system. The study aimed to locate fertility restorer genes of CMSWA system on specific chromosomes of rice using primary trisomics of IR36 (restorer), CMS (IR58025A) and maintainer (IR58025B) lines. Primary trisomic series (Triplo 1 to 12) was crossed as maternal parent with the maintainer line IR58025B. The selected trisomic and disomic F1 plants were testcrossed as male parents with the CMS line IR58025A. Plants in testcross families derived from disomic F1 plants (Group I crosses) were all diploid; however, in the testcross families derived from trisomic F1 plants (Group II crosses), some trisomic plants were observed. Diploid plants in all testcross families were analyzed for pollen fertility using 1% IKI stain. All testeross families from Group I crosses segregated in the ratio of 2 fertile: 1 partially fertile+partially sterile: 1 sterile plants indicating that fertility restoration was controlled by two independent dominant genes: one of the genes was stronger than the other. Testcross families from Group II crosses segregated in 2 fertile: 1 partially fertile+ partially sterile: 1 sterile plants in crosses involving Triplo 1, 4, 5, 6, 8, 9, 11 and 12, but families involving triplo 7 and triplo 10 showed significantly higher X2 values, indicating that the two fertility restorer genes were located on chromosome 7 and 10. Stronger restorer gene (Rf-WA-1) was located on chromosome 7 and weaker restorer gene (Rf-WA-2) was located on chromosome 10. These findings should facilitate tagging of these genes with molecular markers with the ultimate aim to practice marker-aided selection for fertility restoration ability.
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  • 85
    ISSN: 1573-5060
    Keywords: Oryza sativa ; indica rice ; shoot proliferation ; micropropagation ; cytokinins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Week old seedlings of indica rice variety Jaya obtained on basal MS medium and further sub-cultured on agar solidified MS medium supplemented with cytokinins, sucrose (3% w/v) and mannitol (1% w/v) lead to development of multiple shoot buds. Shoot cultures were maintained and multiplied in liquid medium containing BAP 5 mg l-1, sucrose (3% w/v) and mannitol (1% w/v). Profuse rooting was obtained on transfer to MS liquid medium containing IBA 1 mg l-1 and sucrose (3% w/v). Complete plants were successfully transferred to soil and grown to maturity.
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  • 86
    ISSN: 1573-5060
    Keywords: Oryza sativa ; hybrid rice ; early maturity ; genetic analysis ; high yielding capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A distant cross between a maintainer Zhenshan 97B and an early maturing F2 palnt of O. longistaminata x O. rufipogon was made in 1985, and a new CMS line Zaoxian A was bred in 1989 through continuous backcross of new maintainer plants derived from the distant cross to the leading CMS line Zhenshan 97A. Several experiments were carried out in Sichuan during 1990–1992, to analyze the inheritance of earliness of Zaoxian A and its application value to hybrid rice production. The results showed that Zaoxian A was as early-maturing as Zhenshan 97A, the earliness of Zaoxian A was incompletely dominant to the lateness of restorer lines, and was different from the earliness of Zhenshan 97A which was suppressed by the lateness of restorer lines. The F1 hybrids between Zaoxian A and late maturing restorers combined the early maturity and high yielding capacity, and significantly outyielded the provincial and national checks with same or longer growth duration, because the larger genetic distance between early and late maturing ecotypes remained unchanged and the new earliness could express in F1 generation. Therefore, the new dominant earliness character of Zaoxian A could enhance the regional and seasonal adaptability of rice. It is also valuable to hybrid rice production and the formation of new cropping systems with high yielding capacity and high economical profit.
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  • 87
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    Euphytica 86 (1995), S. 103-110 
    ISSN: 1573-5060
    Keywords: Korean weedy rice ; Oryza sativa ; RFLP ; classification ; weedy rice ; genetic similarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The genetic characteristics and classification of 24 strains of Korean weedy rice, two strains of foreign red rice, three Japonica cultivars, one Tongil cultivar and one Indica cultivar (Oryza sativa L.) were investigated at the DNA level using the restriction fragment length polymorphism (RFLP) method. Eighty-three random combinations between six restriction enzymes and forty genomic DNA probes (RG# and KR#) were assayed. Thirty-seven (92.5%) out of the forty probes used showed polymorphisms among the 31 accessions assayed. A high level of polymorphism was found between short and long grain type Korean weedy rices, whereas fewer polymorphisms were presented among strains within each grain type. A dendrogram summarizing genetic similarity coefficients among thirty-one accessions was constructed based on their DNA polymorphisms. The Korean weedy rice strains were classified into two groups identical to the short and long grain types classified by morphological and physiological characters. From the RFLP analysis, it was deduced that the short grain strains of Korean weedy rice belonged to Japonica, while the long grain strains were closer to Indica than to Japonica, and were differentiated into a local ecotype surviving in the growth conditions in the southern part of the Korean peninsula.
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  • 88
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    Plant growth regulation 17 (1995), S. 67-71 
    ISSN: 1573-5087
    Keywords: cadmium ; Oryza sativa ; peroxidase ; proline ; root growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of Cd on changes in proline level and peroxidase activity in roots of rice seedlings were investigated. CdCl2 was effective in inhibiting root growth and in accumulating proline in roots. The inhibition of root growth by Cd is reversible. The reduction of root growth induced by Cd is closely associated with accumulation of proline in roots. External application of proline markedly inhibited root growth of rice seedlings in the absence of Cd. Ionically bound, but not soluble, peroxidase activity in roots was increased by CdCl2. Proline treatment also resulted in an increase in ionically bound peroxidase activity in roots. The relationship between growth inhibition of roots induced by Cd and changes of proline level and peroxidase activity is discussed.
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  • 89
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    Euphytica 86 (1995), S. 227-231 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rachis branch ; rice ; varietal variation ; vascular bundle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The capacity of vascular bundle system transporting assimilates from source to sink is one of the limiting factors for rice (Oryza sativa L.) yield. Genetic variation in vascular bundle system should be investigated for improvement of transporting efficiency. A total of 531 Asian rice cultivars were studied for vascular bundles in the peduncle and its relation to spike morphology. A few difference was detected for the number of primary rachis branches of the spike among the cultivars from various countries. However, the number of vascular bundles significantly differed among the cultivars; those from Nepal, Bangladesh and India bore more vascular bundles than those from Japan. Therefore, the ratio of vascular bundles to rachis branches (V/R ratio) was nearly 1.0 in cultivars from Japan, while those from Nepal, Bangladesh and India ranged from 1.3 to 2.2. Chinese and Indonesian cultivars incuded two types of high and low V/R ratios. Cultivars with high V/R ratio showed positive reactions to the phenol solution, while those with low V/R ratio were negative reactions, suggesting that the former cultivars are of Indica type and the latter of Japonica type. It was concluded that the relationship between vascular bundles and rachis branches differentiated among the ecotypes of Asian cultivated rice.
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  • 90
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    Plant and soil 174 (1995), S. 181-194 
    ISSN: 1573-5036
    Keywords: green manure ; lowland rice ; nitrogen fertilizer ; nitrogen fixation ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The growing concern about the sustainability of tropical agricultural systems stands in striking contrast to a world-wide decline in the use of soil-improving legumes. It is timely to assess the future role that soil-improving legumes may play in agricultural systems. This paper reviews recent progress, potential, and limitations of green manure technology, using lowland rice cropping systems as the example. Only a few legume species are currently used as green manures in lowland rice. Sesbania cannabina is the most widely used pre-rice green manure for rice in the humid tropics of Africa and Asia. Astragalus sinicus is the prototype post-rice green manure species for the cool tropics. Stem-nodulating S. rostrata has been most prominent in recent research. Many green manure legumes show a high N accumulation (80–100 kg N ha-1 in 45–60 days of growth) of which the major portion (about 80%) is derived from biological N2 fixation. The average amounts of N accumulated by green manures can entirely substitute for mineral fertilizer N at current average application rates. With similar N use efficiencies, green manure N is less prone to loss mechanisms than mineral N fertilizers and may therefore contribute to long-term residual effects on soil productivity. Despite a high N2-fixing potential and positive effects on soil physical and chemical parameters, the use of green manure legumes for lowland rice production has declined dramatically world-wide over the last 30 years. Land scarcity due to increasing demographic pressure and a relatively low price of urea N are probably the main determining factors for the long-term reduction in pre-rice green manure use. Post-rice green manures were largely substituted for by high-yielding early-maturing grain legumes. Unreliability of green manure performance, non-availability of seeds, and labor intensive operations are the major agronomic constraints. The recognition and extrapolation of niches where green manures have a comparative advantage may improve an often unfavorable economic comparison of green manure with cash crop or fertilizer N. Socio-economic factors like the cost of land, labor, and mineral N fertilizer are seen to determine the cost-effectiveness and thereby farmers' adoption of sustainable pre-rice green manure technology. Hydrology and soil texture determine the agronomic competitiveness of a green manure with N fertilizers and with alternative cash crops. In general, the niches for pre-rice green manure are characterized by a relatively short time span available for green manure growth and a soil moisture regime that is unfavorable for cash crops (flood-prone rainfed lowlands with coarse-textured soils). Given the numerous agronomic and socio-economic constraints, green manure use is not seen to become a relevant feature of favourable rice-growing environments in the foreseeable future. However, in environments where soil properties and hydrology are marginal for food crop production, but which farmers may be compelled to cultivate in order to meet their subsistence food requirements, green manures may have a realistic and applicable potential.
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  • 91
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    Plant and soil 173 (1995), S. 239-250 
    ISSN: 1573-5036
    Keywords: fertility ; Oryza sativa ; pollen viability ; rice ; salinity ; seed set ; stigma ; stigmatic receptivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of salinity on the reproductive physiology of five rice genotypes (IR54, IR26, IR2153-26-3-5-2, IR15324-117-3-2-2 and BR6), was investigated by treatment from panicle initiation with sodium concentrations of 20, 35 or 50 mol m-3 in an ‘artificial seawater’. In an experiment conducted in a glasshouse, plant height and dry weight were little affected by the treatments. There was, however, genotypic variation in the extent of the sodium accumulation, with IR15324-117-3-2-2 containing the highest and IR2153-26-3-5-2 the lowest concentrations: sodium concentrations were higher in older than younger leaves. Salinity delayed flowering, reduced the number of productive tillers, the number of fertile florest per panicle, the weight per grain and the grain yield: effects on grain yield were very much more severe than on vegetative growth. Panicle length was also reduced as was the number of primary branches in a panicle: again there was genotypic variation in the response of these characters to salinity, with the number of branches in IR2153-26-3-5-2 being particularly sensitive. The concentration of sodium increased in the pollen, stigmas, lemmas and paleas with each increment of external salinity. The highest concentrations of sodium in pollen and stigmas was recorded in IR54 and IR15324-117-3-2-2. Pollen viability, whether tested with the tetrazolium salt thiazolyl blue (3-{4,5-dimethylthiazolyl-2}-2,5-diphenyl monotetrazolium bromide or MTT), germination on stigmas, growth through the stylar tissue or F1 seed set, was reduced particularly in those genotypes accumulating most sodium. At all three salt levels, a genotype which accumulated more Na in its pollen produced less-viable pollen than those with less Na in their pollen. Since the amount of Na in the pollen was highly correlated with the Na in the flag leaf, assessment of flag leaf Na should prove a useful indicator of the likely pollen viability. Stigmatic receptivity was also reduced, when estimated either from germination of viable pollen on stigmas of salt-grown plants, its growth through the stylar tissue or F1 seed set. The reduction of seed set in crosses suggested that the overall consequences of salinity are dominated by effects on panicle development, stigmas and grain filling rather than on pollen. Analysis of the data suggests that genotypic variation exists in the extent to which salinity affects aspects of the plants reproductive physiology and development: this variation might be used in attempts to enhance the resistance of rice to salinity.
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  • 92
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    Nutrient cycling in agroecosystems 42 (1995), S. 165-174 
    ISSN: 1573-0867
    Keywords: Anabaena ; cropping systems ; fertilizer management ; integrated nitrogen management ; 15N ; nitrogen balance ; Oryza sativa ; urea ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract By the year 2020, an additional 300 million tons of rice are needed annually to meet the demands of a growing population. If our natural resource base is to be preserved, intensification strategies should rely on integrated nutrient management, making full use of biological nitrogen fixation. TheAzolla-Anabaena complex is amongst the most effective systems of fixing nitrogen. In this paper we present evidence from greenhouse studies on the potential ofAzolla to curb the volatilization of NH3 following the application of urea to a mixedAzolla-rice culture, providing a new incentive for developing ways of integratingAzolla in intensive rice cultivation systems. The results of a series of short term greenhouse experiments show that a full cover ofAzolla can significantly reduce losses of applied urea-N from 45 and 50% to 20 and 13% for the 30 and 60 kg N ha−1 treatments, respectively. About one-quarter of the applied N was tied up in theAzolla biomass. The applied N inhibitedAzolla growth as well as the amount of N fixed. Inoculation with smaller quantities ofAzolla allowing for more vigorousAzolla multiplication was equally effective in reducing NH3 volatilization and doubled the amount of15N tied-up byAzolla. The reduction in NH3 volatilization is largely related to the depression byAzolla of the floodwater pH, which in its absence may reach values between 9 and 10 as a result of algal activity. Early rice growth responded positively to urea as well as the large quantities of appliedAzolla and increased the yield potential of the crop. Smaller quantities ofAzolla alone were not effective in this regard. The conservation of fertilizer N byAzolla, particularly when it fully covered the water, was reflected in a synergistic effect on rice dry matter production, amounting to 9% at the 30 kg N rate and 16% at the 60 kg N rate. In all likelihood this interaction is attributable to the higher efficiency of the applied N. The benefits ofAzolla in conserving basal urea-N even in small quantities (200-500 kg fresh material ha−1), outweighed competition for the applied N and may be as important as its BNF. The most promising integratedAzolla/rice management systems emerging from our studies should be given further attention under field conditions.
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  • 93
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    Molecular breeding 1 (1995), S. 133-142 
    ISSN: 1572-9788
    Keywords: genetic distance ; heterosis ; Oryza sativa ; restriction fragment length polymorphism (RFLP) ; simple sequence repeat (SSR)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study was undertaken to determine the relationship between genetic distance of the parents based on molecular markers and F1 performance in a set of diallel crosses involving eight commonly used parental lines in hybrid rice production. The F1s and their parents were measured for five traits including heading date, plant height, straw weight, grain yield and biomass. The parental lines were assayed for DNA polymorphisms using two classes of markers: 140 probes for restriction fragment length polymorphisms (RFLPs) and 12 simple sequence repeats (SSRs), resulting in a total of 105 polymorphic markers well spaced along the 12 rice chromosomes. SSRs detected more polymorphism than RFLPs among the eight lines. A cluster analysis based on marker genotypes separated these eight lines into three groups which agree essentially with the available pedigree information. Correlations were mostly low between general heterozygosity based on all the markers and F1 performance and heterosis. In contrast, very high correlations were detected between midparent heterosis and specific heterozygosity based on the markers that detected significant effects for all the five traits; these correlations may have practical utility in predicting heterosis. The analyses also suggest the existence of two likely heterotic groups in the rice germplasm represented by these eight lines.
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  • 94
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    Euphytica 76 (1994), S. 139-143 
    ISSN: 1573-5060
    Keywords: bacterial brown sheat rot ; germination ; Oryza sativa ; Pseudomonas fuscovaginae ; rice ; screening for toxin tolerance ; seedling growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of a Pseudomonas fuscovaginae toxin, on germination, root formation and seedling elongation, after soaking rice grains in the toxin prior to sowing, was investigated. The toxin enhanced germination, but had no apparent effect on the number of roots of the seedlings. It induced a drastic inhibition of seedlings elongation correlated to varieties susceptibility to the disease in the rice field. After denaturation of the bioactive compounds of the extract, all the previously observed effects were lost. Using the toxin and the present test, could be a reliable tool for screening genotype susceptibility to P. fuscovaginae disease.
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  • 95
    ISSN: 1573-5060
    Keywords: gametogenesis ; mutagenesis ; radiosensitivity ; mutation frequency ; X-ray irradiation ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Developmental stages during gametogenesis of rice were histologically examined in the period from differentiation of reproductive organs to anthesis. Plants were exposed to acute X-rays of 20 Gy. Radiosensitivity and mutation frequency were investigated in relation to the developmental stages of reproductive organs. The most radiosensitive stage, as measured by reduction of the M1 pollen-and seed-fertilities, was the last premeiotic interphase. Mutations induced at different developmental stages were scored in M3 strains. Sterility mutants and short-culm mutants were most frequently observed. Grain shape, panicle morphology, heading-date and endosperm character mutants were induced at a relatively low frequency. The overall mutation frequency varied with the developmental stage at the time of irradiation. The highest overall mutation frequency was observed when radiation was applied 10 days before anthesis, the late tetrad stage of microspores. Radiation exposure of florets at the late tetrad stage was found to be a more efficient method of inducing a large number of mutations than radiations applied to seeds and fertilized egg cells.
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  • 96
    ISSN: 1573-5060
    Keywords: linkage ; molecular markers ; morphological mutant markers ; Oryza sativa ; rice RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The classical genetic map and molecular map of rice chromosome 11 were oriented to facilitate the use of these maps for genetic studies and rice improvement. Three morphological markers (d-27, z-2, and la) were crossed to a rice breeding line, IRBB21, which has the Xa-21 gene for bacterial blight resistance. Three F2 populations were analyzed with RFLP markers known to be located on chromosome 11. Segregation analysis of molecular markers and morphological markers was used to construct an RFLP map for each population. The recombination frequency between markers varied from population to population although the marker order on the maps was the same for all three populations. Based on a common set of markers mapped in the three populations, an integrated map was generated consisting of both RFLP and morphological markers. The genetic distance between markers on this map was determined by taking a weighted average of the data from the three populations. The oriented map serves as a bridge to understand the relationship between the classical and molecular linkage maps. Based on this information, the location of several genes on the classical map can be approximated with respect to RFLP markers without having to map them directly.
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  • 97
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    Plant growth regulation 15 (1994), S. 125-128 
    ISSN: 1573-5087
    Keywords: rice ; Oryza sativa ; phloem sap ; polyamine ; abscisic acid ; auxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Putrescine, spermidine, spermine and cadaverine have been identified and quantified in rice phloem sap and shoot extracts by HPLC. It is suggested that diamines, putrescine and cadaverine, easily migrate into the phloem, while movement of a triamine, spermidine, and a tetramine, spermine, tend to be restricted. Spermine especially seems to be the most immobile among polyamines. Thus it is indicated that movement of polyamines into phloem is decreased with increasing number of amino groups. Indole-3-acetic acid and abscisic acid in rice phloem sap were also analyzed by HPLC and it is suggested that indole-3-acetic acid is transported freely into phloem, while abscisic acid is much more actively exuded into phloem.
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  • 98
    ISSN: 1573-5087
    Keywords: abscisic acid ; cadmium ; gibberellic acid ; mineral nutrition ; nickel ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rice plants accumulate high quantities of Cd and Ni when grown for 10 days in a medium containing these heavy metals. Accompanying Cd and Ni uptake, a decrease in shoot and root length was observed, though dry matter accumulation was not affected accordingly. Metal treatments also induced a decrease in K, Ca and Mg contents in the plants, particularly in the shoots, indicating that Cd and Ni interfered not only with nutrient uptake but also with nutrient distribution into the different plant parts. Addition of abscisic acid (ABA) or gibberellic acid (GA3) to the external solution could not overcome the depressing effects of the metals on nutrient acquisition, and even induced a further decrease of Ca content in Ni-treated plants. Both hormones also reduced, significantly, heavy metal incorporation into the plants. Additionally, hormonal applications affected the transport of Cd and Ni to the shoots, resulting in a higher percentage of the metals taken up remaining in the roots.
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  • 99
    ISSN: 1573-5060
    Keywords: DNA fingerprint ; Lactuca sativa ; Oryza sativa ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Thirty-five rice (Oryza sativa L.) varieties, including 18 japonica, 5 javanica and 12 indica subspecies and 12 lettuce (Lactuca sativa L.) varieties were identified taxonomically, using PCR with originally designed 21 RAPD (Random Amplified Polymorphic DNA) primers and 8 sequence-specific primers, used for amplifying four specific DNA fragments. Use of these primers revealed polymorphisms among varieties in rice and lettuce and facilitates DNA fingerprinting. Dendrograms of both species based on polymorphisms were constructed and genetical relationships were established. In rice, half the number of amplified bands were polymorphic and almost all varieties differentiated. However, differentiation of minor genetic alterations among somaclonal variants or mutants and their mother varieties was not feasible. In L. sativa, 47% of the amplified fragments were polymorphic and all 12 varieties were differentiated. Some of the PCR fragments were variety or type specific, which could be used for indicators for type-selection. The dendrogram obtained showed differentiated clusters of crisphead, leaf and butterhead type, findings in good accord with the classification based on the genetic background.
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  • 100
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    Euphytica 76 (1994), S. 89-96 
    ISSN: 1573-5060
    Keywords: Indica rice ; Oryza sativa ; radiation mutagenesis ; thermo-sensitive male sterility ; pollen ; vigour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Male-sterile mutants were isolated from M2 and M3 generations of indica rice variety 26 Zhaizao, dry seeds of which had been exposed to 60Co-γ rays at a dose of 290 Gy. The mutants were planted in early season and ratooned in late season for two successive years for identification of fertility conversion in different growing seasons. One of the mutant lines was further observed in a growth chamber and in the field. Results showed that daily average temperature might be the major factor conditioning the male fertility conversion at a moderate daylength. The critical temperature for the male fertility conversion of the mutant grown under 12.5 h and 14.0 h daylength is about 23°C, below which the plant becomes completely male sterile. Its male fertility conversion character differs from other EGMS lines so far developed. The performance of the hybrids between the mutant and some other indica varieties demonstrated its good combining ability and its potential value in hybrid rice production. The obtained mutant line still sheds KI-stainable pollen grains under male sterilizing conditions. Nevertheless, pollen grains shed from the male sterile plants were much more vulnerable than from normal plants. At sucrose concentration below 1.5 M, the pollen grains from the mutant grown under male sterilizing conditions almost completely broke down, while above 1.5 M they became plasmolysed and shrunken. This is indicative of poor development of the membrane and walls of the pollen grains from the male sterile mutant, causing the pollen grains to be unfunctional. NBT test also clarified the abortion of the pollen grains from the mutant, which were formed in the male sterilizing environment.
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