bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frost Tolerance in Soybeans1
Authors: Hume D. J. , Jackson Ann K. H. 
Published: July 2010

Additional frost tolerance in soybeans (Glycine max (L.) Merr.] would be a useful trait. Our research was conducted to test the effects of prefrost temperatures, stages of plant development, and genotype on frost tolerance in soybeans. In one experiment, 30 genotypes were tested for frost tolerance. Plants were grown in controlled environments at prefrost day/night temperatures of 15/9, 20/14, and 25/19 C, then subjected to advective white frosts of − 2, − 2.5, and − 3 C. at the cotyledon, unifoliolate, or first trifoliolate leaf stage in a factorial design, for a total of 27 treatments. Lower frost temperatures caused a greater percentage of the tissue to be damaged and a greater percentage of plant kill. Plants grown at 25/19 C before frost exhibited more damage than plants grown at lower temperatures. Frosts at the cotyledon stage killed fewer plants (P<0.1) than at the unifoliolate leaf stage, with plants at the first trifoliolate leaf stage intermediate in susceptibility to frost. Most plants grown to the cotyledon stage at 15/9 C could survive frosts of − 3 C. Significant (P<0.05) differences were measured in frost tolerance among genotypes, but the temperatures tolerated varied only about 0.2 C.In a second experiment, 40 genotypes collected in the People's Republic of China were grown at 25/19 C and subjected to − 2.5 and − 3 C at the first trifoliolate leaf stage. No differences in frost tolerance were detected among genotypes. The results suggest that little variability exists among genotypes of G. max for frost tolerance.
Temperature Effects on in vitro Kernel Development of Maize1
Authors: Jones R. J. , Gengenbach B. G. , Cardwell V. B. 
Published: July 2010

This study was conducted to ascertain the effects of temperature extremes on kernel characteristics, respiration, starch synthesis, soluble sugar, and protein content during grain filling in maize (Zea mays L.). Kernels cultured in vitro on a defined media at 15, 30, and 35 C were compared to kernels from ears developed in the field. Kernels cultured for 7 days at 35 C had higher dry weights than kernels from other treatments; however, their growth ceased by the 14th day. High soluble sugar content of aborted kernels suggests that inhibition of starch synthesis may have caused kernel abortion at 35 C. Respiration was higher for kernels from field‐grown ears. During the linear phase of dry matter accumulation, kernel growth rates were 0.65, 6.26, and 5.26 mg kernel‐1 day ‐1 for 15 C, 30 C, and field control treatments, respectively. The higher rate of kernel growth at 30 C was negated by a pronounced shortening of the duration of the grain filling period. Relative to the 30 C treatment, a three‐fold increase in duration of grain filling at 15 C was not adequate to compensate for the 90% reduction in kernel growth rate that occurred. Cool temperatures that occurred in the field or that were maintained in vitro caused soluble sugar levels to remain high and deposition of starch in the endosperm to lag several days behind that observed at 30 C.Cool temperatures did not affect the synthesis of proteins in general or cause differential synthesis of an individual or specific class of protein in the zein fraction. These data show that kernel abortion and shortening of the grain filling period at higher than optimum temperatures and severe reduction in kernel growth rates at lower than optimum temperatures are possible mechanisms by which temperature may mediate kernel growth and development and ultimately grain yield of maize.
Environmental Controls on the Growth and Yield of Okra. I. Effects of Temperature and CO2 Enrichment at Cool Temperature1
Authors: Sionit Nasser , Strain B. R. , Beckford H. A. 
Published: July 2010

Growth and yield responses of okra (Abelmoschus esculentus (L.) Moench, cv. Clemson Spineless) to 6 different day/night temperature regimes and 3 CO2 concentrations were studied in controlled environment chambers of the Duke University Phytotron. The objective of these experiments was to characterize the effects of temperature and CO2 concentrations on vegetative growth and fruit yield of okra. The day/ night temperature regimes in the greenhouses at ambient light and CO2 concentration (350 ppm) were: 17/11, 20/14, 23/17, 26/20, 29/23 and 32/26 C, and the CO2 concentration in the growth chambers at 20/14 C were 450, 675, and 1,000 ppm.In the experiments at ambient CO2 concentration, no plants survived at temperatures below 26/20 C. The plants grown at 26/20 C and higher temperatures in the greenhouses grew to maturity and produced fruits. Under CO2 enrichment in growth chambers, however, the plants survived to maturity at 20/14 C. Thus at the suboptimal temperature of 20/14 C, CO2 enrichment compensated for the adverse effects of cool temperature on the growth of okra. The chamber grown plants at 20/14 C produced the maximumd ry weight in 1,000 ppm CO2. The greenhouse grown plants under ambient CO2 and light produced the greatest dry weight at 32/26 C.The results demonstrate why okra is not a productive crop at mean temperature of 26/20 C or below in ambient CO2 concentration. However, at increasing atmospheric CO2 levels okra becomes much more vigorous and productive at low temperature and therefore may spread into cooler areas if the global atmospheric CO2 concentration continues to increase.
Description of Sunflower Growth Stages1
Authors: Schneiter A. A. , Miller J. F. 
Published: July 2010

A standardized, accurate, and easy system is needed to describe sunflower (Helianthus annuus L.) plant development. The objective of this study was to develop and describe stages of sunflower plant development in a manner which is simple but accurate.Plants were divided into either Vegetative (V) or Reproductive (R) stages of plant development. Vegetative development is divided into two phases, emergence and true leaf development. The latter stages are determined by the number of true leaves in excess of 4 cm in length. The number of vegetative stages is dependent upon the number of true leaves formed by the plant, making the method flexible but accurate. The reproductive development was divided into nine stages based on the development of the inflorescence from its initial appearance through anthesis to physiological maturity of the seed. This method of describing the stages of development in sunflower is rapid, accurate, greatly simplifies current methods, and can be used to determine plant development for either single or branched inflorescence sunflower.
Nitrogen Volatilization from Rice Leaves. II. Effects of Source of Applied Nitrogen in Nutrient Culture Solution1
Authors: da Silva P. R. F. , Stutte C. A. 
Published: July 2010

The objective of this study was to determine the effects of source of N applied in nutrient media on the rate of volatile N lost from leaves of two rice (Oryza saliva L) cultivars in conjunction with the transpirational water vapors. The water‐soluble, non‐elemental N in the condensate was analyzed by pyro‐chemiluminescence.The N source in the nutrient culture solution did not significantly affect the rate of volatile N loss from the ‘Y’ and third leaves at tillering and panicle initiation. However, at heading the Y leaf of ‘Labelle’ and the third leaf of ‘Lebonnet’ grown in nitrate medium lost N at a lower rate than the corresponding leaves of plants supplied with ammonia. The percentage of N lost in oxidized form(s) was not affected by source of N applied in the nutrient solution at any of the three stages examined. The relative amounts of reduced and oxidized forms of volatile N loss varied with the growth stage; at heading the percentage of N lost in oxidized form(s) was lower than that at tillering and panicle initiation regardless of cultivar, leaf position, and N source applied. The percentage of N lost in oxidized form(s) varied from 8 to 28% of the total loss. For both cultivars the transpiration rates were not statistically affected by N source, but transpiration rate of the Y leaf was higher than that of the third leaf from the top at panicle initiator! and heading.
Comparison of Agronomic and Morphologic Characters in Sorghums Having Different Cytoplasms1
Authors: Lenz M. C. , Atkins R. E. 
Published: July 2010

Grain sorghum (Sorghum bicolor L. Moench) crossesdiffering in source of their cytoplasms were compared for agronomic performance in two environments. None of the male‐sterility‐inducing cytoplasms possessed by the lines KS34 through KS39 differed significantly from the milo sterility‐inducing cytoplasm for their effects on grain yield, the primary components of yield, and most other plant characteristics. For those traits for which significance (P > 0.05) was indicated, the differences in performance were small and seemed of little practical consequence. The cytoplasms possessed by the KS lines seem to provide suitable alternatives to the milo cytoplasm for use in hybrid seed production.Comparisons of the performance of entries produced by using seven male‐sterility‐inducing cytoplasms with that of entries with nonsterility‐inducing cytoplasm often were significant (P > 0.05). Generally, the nonsterility‐inducing cytoplasm seemed associated with a slightly more vigorous and productive plant. If additional studies support this conclusion, greater emphasis for research on alternative methods of hybrid seed production in sorghum may be warranted.
Variation and Correlations of Proline Accumulation in Spring Wheat Cultivars1
Authors: Tan B. H. , Halloran G. M. 
Published: July 2010

Water‐stressed plants accumulate considerable amounts of free proline in their leaf tissues. The physiological significance of this metabolic response to water deficit is, however, contentious.Proline accumulation in in vitro‐stressed seedling leaf segments and its associations with a number of physiological responses induced by water deficit was studied in 14 wheat (Triticum aestivum L.) cultivars with known drought resistance rankings. The cultivars differed (at P <0.05) in their capacity to accumulate proline, which was also intercorrelated with increases in total catabolic amino acids and sugars during stress.The study did not corroborate the purported association of high proline concentration in stressed leaf tissues with drought resistance, severity of leaf firing, or post‐stress recovery. High relative growth rate of seedlings subjected to moderate water stress was found to be strongly correlated with drought susceptibility.
Recurrent Selection for Percent Protein in Soybean Seed — Indirect Effects on Plant N Accumulation and Distribution1
Authors: Carter T. E. , Burton J. W. , Brim C. A. 
Published: July 2010

Six cycles of recurrent selection in two soybean [Glycine max (L.) Merr.] populations increased percent protein in the seed 1.2 and 3.3 percentage units (2). We subsequently evaluated seasonal accumulatioann dd istribution in these populationsto relate changes in N accumulationw ith the observedc hangesi n seed percent protein. Cycles 0, 2, 4, and 6 of selection were tested in 2 years, two locations, with four or five replications per environment. Plants were separated into leaves, petioles, stems, roots, and pods at 70, 91, 105, 118, and 133 days after emergence for Kjeldahl N and dry weight determination.In Population I, selection indirectly increased total N accumulation in vegetative parts. This increase was primarily the result of increased N accumulationin the leaves. Leaf area index, total stem N, total petiole N, and percent N in the petioles also increased with selection while seed yield changed little. The increase in leaf N with selection increased the amount of N potentially available for translocation to the seed and was the apparenct ause for the increase in percent protein in seed.In Population I, selection indirectly decreased total vegetative N accumulation. This decrease resulted from decreased N accumulation in leaves. Number of leaves, leaf area index, and seed yield also decreased with selection while percent N in the petioles increased. The decrease in leaf N with selection decreased the amount of, N potentially available for translocation to the seed, and thus did not explain the increase in seed percent protein. Carbon supply to the seed, althoughn ot directly measured, may have been reduced by genetic changes in leaf N accumulation and leaf area index to bring about increased seed protein percent and decreased seed yield.The observed changes in N accumulation and distribution with selection show that morphological‐physiological traits can be genetically related to percent protein of seed and seed yield. Such relationships may have use in breeding program
Design of Experiments in Growth Chambers — Uniformity Trials in the North Carolina State University Phytotron1
Authors: Lee Chong‐soon , Rawlings J. O. 
Published: July 2010

Experiments conducted in growth chambers frequently are deficient with respect to one or more aspects of experimental design, primarily, proper use of randomization and replication. To provide information with which to counter the usual arguments associated with the failure to use proper designs and to improve the efficiency of growth chamber experiments, extensive uniformity trials (using soybeans) were conducted in the North Carolina State University Phytrotron in three sizes of chambers.The results confirmed the existence of sizeable, patterned plantto‐plant variation within chambers and among chambers of all sizes. Patterns of plant growth within chambers tended to be characteristic of chamber type and to persist over time. Both chamber and time effects were very important.Correlations among spatially related observations confirmed the potential for serious bias in estimates of both treatment effects and experimental error in experiments which ignore either randomization or proper replication. Properly designed experiments are as important in growth chambers as in greenhouse or field experiments. Proper blocking both within chambers (for within‐chamber experiments) and with respect to time and/or chambers (for between‐chamber experiments) appears to be effective in controlling a major portion of the variation.
Disruption of Leaf Tissues by Rumen Microorganisms: An Approach to Breeding Bloat‐safe Forage Legumes
Authors: Howarth R. E. , Goplen B. P. , Brandt S. A. , Cheng K. J. 
Published: July 2010

To develop the basic knowledge for breeding a bloat‐safe alfalfa (Medicago saliva L.) cultivar, the extent of leaf tissue disruption by rumen microbes was measured using a modified nylon bag technique. Only green leaf fragments were retained for determination of undigested dry matter. Among six legume forages, the relative rates of leaf tissue disruption were: alfalfa = red clover (Trifolium pratense L.) = white clover (Trifolium repens L.) > birdsfoot trefoil (Lotus corniculatus L.) = cicer milkvetch (Astragalus cicer L.) > sainfoin (Onobrychis viciifolia Scop.). Thus the bloat‐causing legumes (alfalfa, red clover, and white clover) were disrupted more rapidly than the bloat‐safe legumes (birdsfoot trefoil, cicer milkvetch, and sainfoin). These results are consistent with the cell rupture theory of legume pasture bloat.Six alfalfa cultivars (‘DuPuits’, ‘Ladak’, ‘Lahontan’, ‘Ranger’, ‘Vernal’, ‘Uinta’) had similar rates of leaf tissue disruption, and there were no differences between high‐ and low‐saponin strains of these cultivars. However, consistent differences were detected among 11 clones (genotypes) of ‘Beaver’ alfalfa. This finding encourages further development of nylon bag digestion as a method for breeding a bloat‐safe alfalfa cultivar by selection for low leaf tissue disruption. A 25 to 30% reduction in dry matter loss at 6 to 8 hours of digestion would be required to reach the bloat‐safe threshold.
Resistance in Soybeans to the Southern Green Stink Bug1
Authors: Gilman D. F. , McPherson R. M. , Newsom L. D. , Herzog D. C. , Williams C. 
Published: July 2010

The southern green stink bug [Nezara viridula (L.)] is a pest soybean [Glycine max (L.) Merr.] in many areas of the Southern U.S., particularly in Louisiana and other Gulf Coast states, as well as in other countries where soybeans are grown. To identify resistance to the southern green stink bug, 894 plant introductions and 26 cultivars of Maturity Groups V through VIII were evaluated in replicated single row field plots during 1975 to 1979 at Baton Rouge, LA. Damage ratings were made by classifying 100 seeds selected at random from each sample into four categories (none, light, medium, and severe) on the basis of visual damage.Stink bug damage was associated with plant maturity, with earlier maturing genotypes generally having less damage than later maturing genotypes. Significant differences in stink bug damage were detected among cultivars within Maturity Group VI. There were no differences in damage among cultlvars within Groups V, VII, or VIII. However, all cultivars had in excess of 60% damage and were highly susceptible to stink bug feeding.Highly significant differences in damage were obtained among plant introductions. Of the 894 strains evaluated, 67 had significantly less damage than the most resistant cultivar of similar maturity, and appeared to have resistance. These strains were from fairly diverse geographical locations and may represent different sources of resistance. There were no differences in damage among the more resistant strains within Maturity Groups V, VII, or VIII. However, the Group VI strain PI 171444 had significantly less damage than the other more resistant Group VI strains. This strain had the lowest stink bug damage rating in the test during all years, and appeared to have a high level of southern green stink bug resistance.
Selection for Grain Protein, Grain Yield, and Nitrogen Partitioning Efficiency in Hard Red Spring Wheat1
Authors: Löffler C. M. , Busch R. H. 
Published: July 2010

Progeny from three crosses of adapted hard red spring wheats (Triticum aestivum L. em Thell.) and a common exotic parent, ‘Rageni 15’, were grown in replicated field experiments for 3 years in Minnesota. Agronomic and physiologic traits were measured to evaluate Rageni 15 as a source of high grain protein and to appraise selection criteria for the combination of grain yield and grain protein percentage.The comparison of actual vs. predicted grain protein percentage, based on the linear regression of grain protein percentage on grain yield, indicated the Rageni 15 had low yield and grain protein percentage, and did not contribute higher grain protein to its progeny.Grain yield and grain protein percentage were negatively correlated (r = −0.48), and no single selection criterion proved of value in improving both traits simultaneously. Improvement of grain protein percentage with reduction of grain yield was obtained upon selection for high deviants from the linear regression of grain protein percentage on grain yield, protein content per kernel, and grain protein percentage. Selection for grain protein per se was most effective in improving this trait.Nitrogen harvest index and harvest index were correlated (r = −0.54) and both were positively correlated with grain yield. Grain protein percentage was negatively correlated with harvest index (r = −0.54), but it was not correlated with N harvest index (r 0.00). Therefore, N harvest index could prove useful as a selection criterion to improve grain yield while maintaining grain protein percentage
Effects of Accelerated Aging Treatments on Six Cotton Cultivars1
Authors: Bourland F. M. , Ibrahim Adly A. L. 
Published: July 2010

The objectives of this study were to determine if cotton (Gossypium hirsutum L.) cultivars having different genetic backgrounds would respond to accelerated aging as predicted by Bird and Reyes' seed quality curve and to determine the resistance to seed deterioration of the cultivars. The seed quality curve predicts seed germination to increase with low exposure to aging, reach a peak then decrease rapidly with addition exposure. Mold growth on seed is expected to increase linearly with exposure to aging.Acid‐delinted seed of each cultivar having minimum preharvest deterioration were exposed to accelerated aging for varying periods of time then evaluated in laboratory tests at 13.3 and 18.3 C and in field tests. Germination percentages in all tests tended to respond to accelerated aging as predicted with variation accentuated in the 13.3 C test. When removed from the aging chamber, molds growing on the seed in proportion to the length of the aging period were observed. When the 13.3 C test was initiated the same day seed were removed from the chamber, mold growth increased linearly with length of aging period but when initiation was delayed, mold growth on seed did not respond to aging as expected. A strain (TXORMAR‐S‐2) selected for resistance to seed deterioration consistently was the least sensitive to the effects of accelerated aging; ‘Deltapine 61,’ ‘CAMD‐E,’ and ‘Stoneville 213’ were intermediate; and ‘Delcot 277J’ and ‘DES 56’ were the most sensitive.Variation for resistance to seed deterioration exists among cotton cultivars. Absence of mold growth on seed can be an indicator of high seed quality. However, precautions should be taken to validate relationships involving mold growth before it is used as a selection criterion in a breeding program.
Adaptability of Crop Plants to High Temperatures Stress1
Authors: Chen Hwei‐Hwang , Shen Zheng‐Yan , Li P. H. 
Published: July 2010

The ability of crop plants to adapt to heat stress is potentially an important component of tolerance to heat stress under field conditions. Two genotypes each of bean, potato, and soybean and tomato, with known differences in heat sensitivity as evaluated by their yield and fruit set under high temperature conditions, were used in a study of adaptability of leaf tissues to heat stress. Heat tolerance was measured by 2,3,5‐triphenyl tetrazolium chloride (TTC) reduction and conductivity tests; both methods gave similar results. The degree of heat tolerance could be expressed by either the heat killing temperature or the heat killing time, the latter being the more sensitive indicator.Heat tolerant and susceptible genotypes did not differ in heat killing time when the plants were grown at 20/15 C day/night temperature; however, the differences became dramatic after the plants were acclimated at temperatures above 30 C for 24 hours. Heat killing time was a function of the acclimating temperature with the optimum acclimating temperature found to be 35 to 37 C. Rate of heat acclimation was very fast, and a continuous high temperature treatment appeared to be necessary to retain the high level of heat tolerance. Heat tolerance of leaves was not affected by age when the plants were grown under 20/15 C condition. At 35/35 C, however, the heat tolerance of leaves was lower at the earlier stages and reached a level similar to fully grown plants after 30 days growth.The results suggest that I) the TTC reduction test in addition to the conductivity test can be used to test heat tolerance in crop plants, and 2) screening genotypes that perform well in high temperature environments is feasible at the early stage of growth by testing leaf tissue heat tolerance after the plants have been subjected to a high acclimation temperature, such as 35 C for 12 to 24 hours.