bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative Glutamine Metabolism in Tobacco Callus and Leaf Tissues1
Authors: Lazar M. D. , Collins G. B. 
Published: July 2010

Tobacco (Nicotiana tabacum L.) callus tissue was found to contain at least a thirty‐fold higher concentration of free glutamine than leaves from greenhouse‐grown plants of the same genotype. The most important factor contributing to the observed difference in glutamine pool size was exogenous ammonium concentration. Also, the specific activities in cell‐free extracts of the ammonium assimilating enzymes, glutamine synthetase and glutamate dehydrogenase assayed at nonlimiting substrate concentrations were maximal in both tissues at exogenous ammonium concentrations of approximately 0.1 to 0.3 mM for glutamine synthetase and 10.0 to 30.0 mM for glutamate dehydrogenase. Labeling callus tissue with 14C‐glutamate allowed the calculation of approximate rates of in vivo transfer of carbon skeletons from glutamate to glutamine which were consistent with the effects of in vivo ammonium concentration on enzyme activities observed in cell‐free extracts.The results indicate that under conditions of ammonium limitation in either tissue, the glutamine synthetase/glutamate synthase pathway is important to ammonium assimilation. The data suggest that in vivo activities of glutamlne synthetase, glutamate synthase and glutamate dehydrogenase in both leaf and callus tissues are regulated by ammonium concentration.
Variability of Seedling Growth Characteristics among Oat Genotypes1
Authors: Murphy C. F. , Long R. C. , Nelson L. A. 
Published: July 2010

The objectives of this investigation were to (i) estimate the range of variability present for the oat (Avena sativa L.) seedling characteristics, including shoot length and weight and root length, weight, and volume; and (ii) to determine how these characters vary among groups of cultivars representing different breeding eras.Fifty‐two cultivars were chosen to represent a wide range of genetic backgrounds and breeding eras. The cultivars were classified as belonging to one, or more, of the following categories: I—spring‐sown, II—fall‐sown, III—sources of crown rust resistance, IV—earliest introductions, V—early selections, VI—early hybrid selections, VII—intermediate hybrid selections, VIII—modern hybrid selections, IX—sources of straw strength, X—diploid, XI—dwarfs, and XII—very tall. Comparisons were made between cultivar categories.Ranges in cultivar means expressed as a percentage of the grand mean for the five characters were: shoot length, 101.9 % ; root length, 81.5%; root volume, 81.8%; shoot weight, 113.3%; and root weight, 75.0%. Simple correlations were relatively high among all characters, ranging from 0.48 for shoot length and root volume to 0.84 for root volume and root weight (determined over all 52 cultivar means).The spring‐sown genotypes gave consistently higher values for the five growth characters than did the fall‐sown genotypes. Lines that are sources of crown rust resistance were genetically inferior in their seedling growth responses. The effects of selection pressure (for other characters) during the time progression from the earliest introductions to the modern hybrid selections were pronounced. The most obvious trend was toward greater root development in the modern selections. Shoot lengths were slightly reduced over the time span.
Genotypic Differences in Leaf Osmotic Potential Among Grain Sorghum Cultivars Grown Under Irrigation and Drought1
Authors: Shackel K. A. , Foster K. W. , Hall A. E. 
Published: July 2010

Osmotic potential of leaves may have relevance to turgor maintenance and adaptation of plants to water‐limited environments. Studies were conducted to determine whether it is possible to detect genotypic differences in leaf osmotic potential in the field and the conditions where screening for this character would be most effective.Consistent genotypic diffences in osmotic potential of sap expressed from frozen‐thawed leaf tissue were found during a 3‐year field trial which included 10 sorghum [Sorghum bicolor] (L.) Moench genotypes in the first year. Measurements were taken during periods of minimum and maximum water stress (predawn and midafternoon, respectively) under both frequently irrigated and water‐limited conditions. Despite highly significant genotype × environment and genotype × treatment interactions, the ranking of sufficiently contrasting genotypes was similar throughout all conditions with ‘Dwarf Redlan’ maintaining the highest and ‘M35‐1’ maintaining the lowest leaf osmotic potential.Seasonal changes in osmotic and total water potential (pressure chamber technique) indicated progressively increasing levels of predawn turgor potential for both frequently irrigated and water‐limited treatments but progressively decreasing levels of midafternoon turgor potential. Maintenance of turgor under water‐limited relative to frequently irrigated conditions was exhibited at predawn, but not midday. The low osmotic potentials of M35‐1 resulted in higher leaf turgor, compared with Dwarf Redlan, at predawn under frequent irrigation.It is proposed that differences in leaf osmotic potential may be used to select sorghum genotypes that exhibit contrasting water relations. Selection may be more effective under frequently irrigated conditions and during grain filling than under water‐limited environments or during early stages of growth.
Inheritance of Resistance to Stem Rust in a Selection of the Wheat Cultivar ‘Waldron’1
Authors: Williams N. D. , Miller J. D. 
Published: July 2010

The hard red spring wheat (Triticum aestivum L.) cultivar ‘Waldron’ is resistant to North American strains of stem rust (Puccinia graminis f. sp. tritici). The inheritance of resistance in a selection of Waldron (Wdr‐sel) was studied to determine the number of genes affecting reaction to 15 cultures of the stem rust fungus. F2 plants from Wdr‐sell/‘Little Club’ were progeny tested by inoculating families of F3 seedlings. Infection types were used to classify each F2 family into homozygous susceptible (S), segregating resistant and susceptible seedlings in a monogenic ratio (Seg), and inseparable (I). Segregation ratios were tested by chi‐square for goodness of fit to ratios of 4n‐2n‐1 (1):2n(Seg):l(S), where n is the number of segregating genes for resistance. Wdr‐sel had one gene for reaction to culture A‐14NW (race 29, HNH) and two genes for reaction to cultures 72‐14‐5 (race 11‐32‐113, RPQ), 72‐41spl (race 15B, TLM), WM‐1 (race 18, LBC), Gb121 (race 121, DCM), 370c (race 151, QFL), Or9e (race 9, JBC), Orllc (race 151, QBC), 41‐21spl (race 15, TBC), 72.00 (race 11‐32‐113, RTQ), A‐1 (race 151, QSH), A‐5 (race 156, MBC; one F1 family), and 75‐86spl (race 151, QSH; one F1 family). One F1 family gave trigenic segregations with cultures WM‐1, Or9e, Orllc, 41‐21sp1, and A‐5. Data for reactions to culture A‐15 (race 17, HNQ) were a poor fit to a digenic ratio and were inconclusive; however, the data were a better fit to a digenic ratio than to a monogenic or trigenic ratio. Wdr‐sel had four genes for resistance to culture 111‐SS2 (race 111, LCB).Paired comparisons of reactions to the different cultures were inconclusive but were consistent with the hypothesis that the gene for resistance to culture A‐14NW also conditioned resistance to the other cultures, and that the same two genes conditioned resistance to 13 of the cultures.
Strain and Within‐Season Variability of Various Allelochemics Within A Diverse Group of Cottons1
Authors: White W. H. , Jenkins J. N. , Parrott W. L. , McCarty J. C. , Collum D. H. , Hedin P. A. 
Published: July 2010

Several secondary plant metabolites are alleged to confer resistance of cotton, Gossypium hirsutum L., to various insects. The effects of these compounds on the insects, variability among cotton strains, and inheritance have been studied by various workers. Research on seasonal variability and on geotype × environment interactions is sparse. These findings prompted our research to determine the effects of within‐season environment and cotton strains on allelochemics alleged to be important in repelling the tobacco budworm, Heliothis virescens (F.).Data were recorded on samples collected at 10 dates from 20 cotton strains in replicated field plots. The following allelochemics were quantified: total phenolics, gossypol and its analogs, a flavonoid‐anthocyanin mixture, and three tests for condensed tannins (tannin, El,l, and catechin). Significant differences among cotton strains, sample dates, and significant interaction between these main effects were detected. However, the interaction components were small relative to the main effects. These results suggest that differences in the levels of allelochemics are inherited and that genetic effects among cotton strains should be manageable in breeding programs.
A Comparison of Seed Quality and Seedling Vigor in Birdsfoot Trefoil
Authors: McKersie B.D. , Tomes D.T. 
Published: July 2010

Seed quality, seedling vigor and field establishment were estimated in seed lots of three forage legumes, birdsfoot trefoil (Lotus corniculatus L.), alfalfa (Medicago sativa L.) and red clover (Trefolium pratense L.) in 1979 and in birdsfoot trefoil in 1980. Birdsfoot trefoil showed greater variability for germination than either red clover or alfalfa. Among 49 seed lots of birdsfoot trefoil tested in 2 years, 18 had less than 75% germination with a range of germination from 19 to 100%. Seed lots with poor germination generally had poor seedling vigor as measured by electrical conductivity, speed of germination and rate of seedling elongation. The maximal values of seedling vigor in birdsfoot trefoil were comparable to minimal values observed in alfalfa, except for electrical conductivity measurements which were similar between species. Quality measurements which were significantly correlated (p=0.01) with field establishment of birdsfoot trefoil (1980 data) were germination (r2=.66), electrical conductivity (r2=.59), speed of germination (r2=.66) and rate of seedling elongation (r2=.25). Seed weight was not significantly correlated with field establishment. Electrical conductivity had the highest correlation with establishment when measured after 24 hours soaking, compared to 1 and 6 hours soaking periods.In seed lots of birdsfoot trefoil with over 75% germination, field establishment was still significantly different between lots. Some of this variability can be accounted for by differences among the cuitivars Leo, Empire, Maitland and Viking. For example, the cultivar Leo had superior speed of germination and field establishment compared to Empire. Seed size was not a reliable indicator of seedling vigor between seed lots of the same variety. Electrical conductivity was not reliable for comparisons among cultivars. Germination, speed of germination, seed size, electrical conductivity, and other unidentified factors contributed to successful field establishment, but the most limiting factor varied among seed lots. Thus, the prediction of a seed lot's field establishment based on only one measure of seed quality is tenuous.
Pink Bollworm Resistance, Lint Yield, and Lint Yield Components of Okra‐Leaf Cotton in Different Genetic Backgrounds1
Authors: Wilson F. Douglas 
Published: July 2010

The two leaf (L) types, Okra leaf [2(L02)] and normal leaf, from seven genetic backgrounds (G) of cotton, Gossypium hirsutum L., were subjected over two seasons (Y) to natural populations of pink bollworm (PBW), Pectinophora gossypiella (Saunders), at Tempe, AZ. In other experiments, one of the seven Okra‐leaf strains and an Okra‐leaf cultivar, ‘Gumbo 500’, were compared with ‘Stoneville 213’, a normal‐leaf cultivar, for one to three seasons. Objectives of this study were to determine whether (i) L interacted with G or Y for seed damage caused by PBW, for lint yield, or for earliness; and (ii) yield of Okra‐leaf strains could be increased by selecting for improved yield components. An important goal is to determine whether PBW‐resistant, Okra‐leaf cottons will yield as much lint as normal‐leaf cottons in stressful environments. In the leaf shape‐genetic background experiments, significant L ✕ G and Y ✕ G interactions were detected for seed damage by PBW, but not for lint yield or earliness. Mean yield per plant and percent seed damage for the seven normal‐leaf cultivars were significantly higher than those of the Okra‐leaf strains, 36.0 vs. 30.7 g/plant, and 17 vs 14%, respectively. Okra‐leaf strains were not significantly earlier than normal‐leaf cultivars. Examination of lint yield components suggested that selection for lint per seed, a highly heritable trait, should increase lint yields of some Okra‐leaf cottons. However, bolls per plant, expected to have low heritability, was the main yield component that limited tint yield of most of those cottons. The Okra‐leaf strains and cultivar, when compared to Stoneville 213, generally had less seed damage and yielded less lint. An exception was in 1985, when Gumbo 500 did not yield significantly less lint than Stoneville 213. In a preliminary experiment in 1985, two Okra‐leaf advanced breeding stocks outyielded the normal‐leaf counterparts by 23 and 18%, respectively.Results thus show that Okra‐leaf breeding stocks in certain genetic backgrounds have a modest level of resistance to PBW and also may yield as much or more lint than do normal‐leaf cultivars. However, the inconsistent response of some Okra‐leaf cottons emphasizes the importance of comparing those cottons with normal‐leaf cultivars over a range of environments.
Daylength and Sowing Date Responses of Soybean Lines with “Juvenile” Trait1
Authors: Parvez A. Q. , Gardner F. P. 
Published: July 2010

Daylength limits adaptation of soybean [Glycine max (L.) Merr.] genotypes to a narrow range of latitudes and sowing dates by affecting vegetative and reproductive growth and development. Photoperiod and sowing‐date experiments were conducted in Gainesville, FL (29.38°N) during 1984 and 1985 to assess the vegetative and reproductive growth of soybean genotypes previously observed to differ in sensitivity to change in latitude and sowing date. ‘Kirby’ and ‘Improved Pelican’ and two breeding lines, F82‐7656 and F84‐1220, selected for adequate vegetative development under short days (“juvenile” trait), were used. Photoperiods included 14‐h, 18‐h, and natural‐winter daylengths between 22 Jan. and 30 Mar. 1984 in a greenhouse experiment, and 10‐h (covered 14 h) and natural‐summer days in 1985 in a field experiment (Jonesville Taxajunct Soil classified as loamy, mixed, thermic Arenic Hapludalf). Sowing dates in the 1984 and 1985 field experiments were monthly from 1 April through 1 August. Improved Pelican, Kirby, F82‐7656, and F84‐1220 ranged from highly to only moderately responsive to the photoperiod and sowing date treatments. In 1984, under natural‐winter days and 14 h, all plants averaged the R1 stage at 30 and 60 days after planting (DAP), respectively. Plants under 18 h were vegetative at 68 DAP, the termination date. Under 10 h in the 1985 field experiment, Kirby, F82‐7656, Improved Pelican, and F84‐1220 were in the R1 stage in 48, 52, 54, and 57 DAP, respectively. Plant height, node number, and DAP to R1 for F84‐1220 were most constant over the range of photoperiods and sowing dates, indicating efficacy of the juvenile trait in extending adaptability.Improved Pelican in the April and May sowings grew excessively tall (2 m) and aborted its flowers and pods, which indicated not only pre‐, but also postflowering daylength effects. Kirby and F82‐7656 at the August sowing date flowered too early, resulting in severe reduction of vegetative growth and pod number. In the 1 April and 1 August sowings and the 10‐h photoperiod, F84‐1220 was near optimum height and produced more branches, racemes, and pods than the other genotypes. We conclude that the juvenile trait, as demonstrated in line F84‐1220, can improve climatic adaptation of soybean cultivars by buffering photoperiod effects incident to suboptimal latitudes and/or sowing dates.
Post–Green Revolution Trends in Yield Potential of Temperate Maize in the North‐Central United States
Authors: Duvick D. N. , Cassman K. G. 
Published: July 2010

ABSTRACTThis paper addresses the question of whether there has been an increase in yield potential of maize (Zea mays L.) hybrids released in the north‐central United States since the advent of the “Green Revolution” that began in the late 1960s. Because there are few published data about hybrid growth rates and yield‐determining plant traits when grown at yield potential levels, we attempt to address this issue indirectly by evaluation of maize breeding efforts, changes in plant traits of commercial hybrids, and by comparison of statewide average yield trends and yield trends in sanctioned yield contests. On the basis of these sources of information and a definition of yield potential as the yield that can be achieved with an adapted hybrid when grown without obvious stress of any kind, we found that there is conflicting evidence to support the hypothesis that maize yield potential has increased. We recommend experimental approaches to quantify and investigate the determinants of maize yield potential in the north‐central United States and for use in breeding hybrids with greater yield potential.
Influence of Nitrogen Availability on Seed Nitrogen Accumulation in Pea
Authors: Lhuillier‐Soundélé Annabelle , Munier‐Jolain Nathalie G. , Ney Bertrand 
Published: July 2010

ABSTRACTThe final seed nitrogen concentration (the ratio of seed N and dry matter content) is highly variable in pea (Pisum sativum L.) and N remobilization during seed filling may limit yield by restricting the seed filling period. This study was conducted to determine how seed N accumulation is regulated in pea. The effect of N availability and distribution on individual seed N accumulation rate at different nodes was investigated in three genotypes grown in the field and glasshouse under various levels of N fertilizer, depodding, and defoliation. The N content of vegetative plants parts (stems, leaves, podwalls) and seeds from three mainstem nodes were regularly recorded. Plant N available to the seeds at a given time was assessed as the sum of the amount of N still available for remobilization in vegetative parts and the amount of N accumulated by the plant. The results indicate that the N available in a plant at a given time can be considered as one common pool accessible to all seeds and equitably divided among them. Thus, the rate of individual seed N accumulation was unaffected by intra‐plant position of seeds. This rate increased with the amount of N available per seed until a maximum rate of individual seed N accumulation (43 μg seed−1 degree‐day−1) was reached. The relationship established between the rate of individual seed N accumulation and the plant N available per seed will be useful to improve models simulating yield and final seed N concentration in legumes.
Regrowth of White Clover after Chilling: Assimilate Partitioning and Vegetative Storage Proteins
Authors: Corbel G. , Robin Ch. , Frankow‐Lindberg B. E. , Ourry A. , Guckert A. 
Published: July 2010

ABSTRACTUnder temperate climates, grassland species are subjected to overwintering which may significantly influence their early spring growth capacity. In white clover (Trifolium repens L.), it is known that overwintering capacity can differ among cultivars. Ability of this forage legume to recover from winter damage will, therefore, have a great influence on its persistence in grass–clover associations. Experiments were undertaken with two different white clover cultivars (Huia and AberHerald). Leaf appearance rate, dry matter distribution, 14C assimilate partitioning, and vegetative storage protein accumulation were determined in plants subjected to a 4‐wk chilling period (5/0°C, day/night) and subsequent warmer temperatures (15/10°C), and compared with control plants (20/15°C). Chilling treatment decreased leaf appearance rate, with AberHerald producing more leaves than Huia. This can be considered as a major aspect of cold adaptation strategy because leaf appearance rate controlled carbon acquisition. Low temperature increased dry matter partitioning to below‐ground tissues. AberHerald allocated more assimilates to stolons than Huia. Accumulation of a 17.3‐kDa protein, believed to act as a vegetative storage protein, also increased after the chilling treatment. Regrowth was characterized by rapid mobilization of the 17.3‐kDa protein in stolons and by preferential carbon allocation to stolon apices. AberHerald showed a higher regrowth potential than Huia in view of its morphological and physiological characters which include carbon acquisition and assimilate partitioning patterns, favoring shoot regrowth and acquisition of stolon reserves.
Reproductive‐Stage Heat Tolerance, Leaf Membrane Thermostability and Plant Morphology in Cowpea
Authors: Ismail Abdelbagi M. , Hall Anthony E. 
Published: July 2010

ABSTRACTHigh night temperatures during reproductive development can reduce yields of cowpea [Vigna unguiculata (L.) Walp.]. Screening whole plants for degree of flowering and pod set in hot environments has been effective in breeding for heat tolerance, but suitable screening environments often are not available. An indirect screening technique was evaluated involving relative electrolyte leakage from leaf tissue sampled at the end of the dark period with incubation at temperatures that are hot for night‐time conditions. This technique was tested with four different pairs of cowpea lines with similar genetic backgrounds but different heat sensitivities during reproductive development. Plants were grown in growth chambers at optimal temperatures. Additional tests were conducted with plants grown in moderately hot and extremely hot field environments. Three sets of three genotypes were used that are either heat susceptible during both early flowering and pod set or heat tolerant during early flowering and heat susceptible during pod set or heat tolerant during both early flowering and pod set. Similar genotypic differences in electrolyte leakage were obtained from plants grown in the growth chamber or field environments. Genotypes with heat tolerance during flowering and pod set had less leaf electrolyte leakage than either genotypes with heat susceptibility during flowering and pod set or genotypes having heat tolerance only during early flowering. Leaf electrolyte leakage, as a measure of leaf membrane thermostability, may provide an efficient indirect screening technique for reproductive‐stage heat‐tolerance genes that can be used with plants grown in a range of field nursery environments.