bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationships of Different Histochemical Types of Lignified Cell Walls to Forage Digestibility1
Authors: Akin Danny E. , Burdick Donald
Published: July 2010

Cell walls of leaf blades of several grasses were examined both for their reactions with lignin stains and for their digestibility by rumen microorganisms. Thin sections were tested for lignin with acid phloroglucinol and chlorine‐sulfite stains. Cell wall digestion was determined by incubation (in vitro) of leaf blades with rumen microorganisms and examination with electron microscopy. In general, the rigid and supportive cell walls of the vascular bundles (i.e., inner bundle sheath and xylem cells) that stained positive for lignin with acid phloroglucinol were totally undergraded by rumen microorganisms. Sclerenchyma tissue was degraded only at the periphery by normal, adhering rumen microorganisms; however, occasionally digestion was extensive and was associated with an unusual or filamentous bacterium. When treated with chlorinesulfite, sclerenchyma cell walls of all grasses showed a definitive positive reaction for lignin. However, chlorine‐sulfite stain also revealed the presence of lignin in cell walls of certain living cells in some grasses. Included were cell walls of the parenchyma bundle sheath of bermudagrasses [Cynodon dactylon (L.) Pers.] and the parenchyma sheath, mesophyll (occasionally) and abaxial epidermis of tall fescue (Festuca arundinacea Schreb.) These tissues in leaf blades from similar or the same harvests were only slowly or partially degraded after 24 to 72 hours. Further examination of Coastal bermudagrass revealed that portions of the parenchyma bundle sheath resisted in vitro digestion for 8 days, and also were present in the fecal residue along with the xylem and sclerenchyma tissues. In these studies, the extent of forage digestion appeared to be determined by the rigid, acid phloroglucinol‐positive cell walls of the vascular bundles, the sclerenchyma (except for cells at the periphery and those cells degraded by the filamentous bacterium), and variable amounts of cell walls of living tissues which often gave a positive chlorine‐sulfite reaction.
Selection for High CO2 Exchange Rate among Inbred Lines of Maize1
Authors: Crosbie T. M. , Pearce R. B. , Mock J. J.
Published: July 2010

Photosynthesis is a primary trait to be improved in a selection program designed to improve yield potential of maize (Zea mays L.). Previous studies have suggested that selection for high CO2 exchange rate (CER) among inbred parents would be effective. We conducted experiments to evaluate the effectiveness of selection for high CER among inbred lines of maize. Actual advance for one cycle of selection among inbred lines was 2.5 (4.7%) and 2.3 (5.7%) mg CO2 dm−2 hour−1 during vegetative growth and during mid‐grain filling, respectively. Realized heritabilities for CER were 0.33 and 0.26 for vegetative and grain‐filling growth stages.
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.
Tests for a Diffusable Compound Endowing rj1‐incompatible Strains of Rhizobium japonicum with the Ability to Nodulate the rj1rj1 Soybean Genotype1
Authors: Devine T. E. , Breithaupt B. H. , Kuykendall L. D.
Published: July 2010

The nodulation restrictive genotype of soybeans [Glycine max (L.) Merr.] rj1 rj1 is nodulated by some strains of Rhizobium japonicum. Inoculation with mixed cultures of rj1‐compatible and rj1‐incompatible strains has shown that the presence of an rj1‐compatible strain facilitates nodulation of rj1rj1 plants by an rj1‐incompatible strain. This study was undertaken to determine whether rj1‐compatible strains of R. japonicum produce a diffusable product capable of endowing rj1‐incompatible strains with the ability to nodulate the rj1rj1 genotype. An rj1‐incompatible strain remained unchanged in ability to nodulate rj1rj1 plants when: (a) grown in culture filtrates of rj1‐compatible strains, (b) cultured in U‐tubes across a 0.08 mμ pore size polycarbonate membrane from rj1‐compatible strains, or (c) cultured in dialysis tubing suspended in broth cultures of an rj1‐compatible strain. It was concluded that the rj1‐compatible strains tested apparently do not produce a diffusable compound in vitro capable of endowing rj1‐incompatible strains with the ability to nodulate the rj1rj1 genotype. The rj1‐compatible Rhizobium appear to exert their effect, in close proximity to the nodulation site.
Effect of Environment and Genotype on Alfalfa Sprout Production1
Authors: Hesterman O. O. B. , Teuber L. R. , Livingston A. L.
Published: July 2010

Alfalfa (Medicago sativa L.) sprouts are rapidly increasing in popularity in salads and sandwiches in the USA. Methods for growing sprouts are nearly as varied as the number of growers. We examined genetic and environmental influences on germination of alfalfa seed for human consumption. Six cultivars representing a broad range in fall dormancy were germinated under varying environmental conditions including temperature, light duration, amount and frequency of water application, and number of days to harvest. Sprouts were evaluated for fresh weight (yield), nutritional value, and taste acceptability. On a dry weight basis, sprouts were higher in percentage protein than ungerminated seed. Total protein, however, decreased as the seed sprouted. Fresh weight and percentage protein were negatively correlated. Cultivars differed significantly in yield and quality. Sprouts grown for high nutritional value provided a greater percentage of the Recommended Dietary Allowance (RDA) than sprouts grown for high fresh weight. Considering the relatively small nutritional difference between sprouts grown for high fresh weight and high quality, it may be sufficient for sprout growers to concentrate solely on improving fresh weight yield rather than nutritional quality of alfalfa sprouts. Favorable environments are recommended for producing sprouts of either high nutritional quality or high fresh weight.
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.
Plants from Ethionine‐Resistant Alfalfa Tissue Cultures: Variation in Growth and Morphological Characteristics1
Authors: Reisch B. , Bingham E. T
Published: July 2010

Diploid alfalfa, Medicago sativa L. (HG2‐2x), was used to select variant cell lines resistant to growth inhibition caused by ethionine. Plants from 23 of 91 mutagenized HG2‐2x cell lines grown on 0.02 mM DL‐ethionine were morphologically different from the original plant. Plants with multifollolate leaves, elongated petiolules, compact growth habit, jagged leaf margins, and appendage‐like leaflets were identified. Several diploid and tetraploid plants outyielded HG2‐2x (2n = 16) and HG2‐4x (2n = 32), respectively, replicated study of spared plants. Variation also occurred for plant height, length of the longest shoot, and number of primary branches after 7 weeks. Most of the 91 cell lines produced diploid plants (66) whereas the remainder produced tetraploid (20), aneuploid (4), hexaploid (1) plants. Aneuploidy (2n = 33 and 2n 31) was concomitant with morphological abnormalities. Few variants were observed among plants regenerated from mutagenized cultures which were not treated with ethionine. Therefore,. the mutagenic effects of ethionine may be responsible for the appearance of a high frequency of variants. The possibility that useful variation might be obtained from alfalfa tissue cultures is discussed.
Progress in the Selection for Altered Fatty Acid Composition in Soybeans1
Authors: Wilson Richard F. , Burton J. W. , Brim C. A.
Published: July 2010

Progress in the selection for altered unsaturated fatty acid composition in soybeans [Glycine max (L.) Merr.] was evaluated. N78‐2245, an experimental line developed through recurrent selection methodology contained 51% oleic acid (18:1), 31.9% linoleic acid (18:2), and 4.2% linolenic acid (18:3). In comparison ‘Dare,’ a representative cultivar, contained 21.4% 18:1, 55.6% 18:2, and 8.9% 18:3. This investigation has demonstrated that both soybean fatty acid composition and glycerolipid fatty acid composition were influenced by genetic manipulation.
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.
Inheritance of Papery Glume and Cleistogamy in Sorghum1
Authors: Merwine N. C. , Gourley L. M. , Blackwell K. H.
Published: July 2010

Cleistogamous spikelets in sorghum [Sorghum bicolor (L.) Moench] form when the inner glume is rolled, clasping the internal flower structures and preventing normal opening of the glumes. Cleistogamy is controlled by two independently‐inherited genes. Indurate (hard) glume is dominant to papery glume. The rolled glume condition is dominant to unrolled. Indurate glume is epistatic to rolling, and only papery glumes can exhibit rolling. The F2 ratios from the cross (indurate glume × cleistagamous) show a good fit to a 12:3:1 ratio of induratercleistogamous (papery‐rolled): papery‐unrolled. This cleistogamy cannot be used to breed hybrids resistent to sorghum midge because one parent would be cleistogamous and prevent production of hybrid seed.
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.
Yield and Plant Growth Responses of Mononychellus Mite Resistant and Susceptible Cassava Cultivars under Protected vs. Infested Conditions
Authors: Byrne D. H. , Guerrero J. M. , Bellotti A. C. , Gracen V. E.
Published: July 2010

Root yield, propagation material yield, and growth responses to Mononychellus mite (Acari:Tetranychidae) populations, and foliage damage ratings of resistant and susceptible cultivars (previously determined by foliage damage ratings) were compared in protected and unprotected plots to confirm the level of resistance, to relate foliage damage estimates with economic yield reductions, and to study the general effectof mite attacks on cassava. On the average, cassava cultivars selected as susceptible had larger reductions in leaf size, leaf life, leaf formation rate, plant height, root yield, yield of propagation material, root weight, root number, and percent marketable roots than did the resistant cultivars when compared to their respective performance in protected plots. The average yield loss for susceptible cultivars was 73% for roots and 67% for propagation material; the respective losses for the resistant cultivars were 15 and 19%. Our selection criterion for resistance (i.e., foliage damage ratings) was correlated with mite density and associated with the percent yield loss caused by the mites indicating this criterion's potential value in future breeding efforts, although exceptions exist due to the presence of tolerance.
Effects of Recessive Alleles for Low Alkaloid Content on Chemical and Agronomic Characteristics of Burley Tobacco1
Authors: Miller R. D. , Collins G. B. , Davis D. L.
Published: July 2010

Conventional and doubled haploid derived alkaloid lines were studied to determine the effects of recessive alleles for low alkaloid content on chemical and agronomic characteristics of hurley tobacco (Nicotiana tabacum L.). Statistically significant differences were detected among genotypes for total alkaloids, total‐N,.protein‐N, and total volatile nitrogenous bases (TVNB). Levels of total‐N and TVNB were higher in high alkaloid lines, but, in general, protein‐N was higher in low alkaloid lines. Dominant alleles at both the A and B alkaloid loci were associated with higher levels of total alkaloids, total‐N, and TVNB, but lower levels of protein‐N, than were recessive alleles. Significant differences in nitrate‐N concentrations were not detected between dominant and recessive alleles at either locus. Although significant genotypic differences were detected for several agronomic characteristics, no consistent ranking of genotypes was evident. Conventional lines contained significantly higher concentrations of total alkaloids and TVNB and lower concentrations of protein‐N than did doubled haploid‐derived lines. Conventional lines had larger bottom leaves, greater yield, and earlier maturity dates than did haploid derived lines.
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.
Efficiency of Yield Selection in Cassava Populations under Different Plant Spacings1
Authors: Kawano Kazuo , Tiraporn Charn , Tongsri Somsak , Kano Yoshiaki
Published: July 2010

Cassava (Manihot esculenta Crantz) genotypes were evaluated in a high productivity environment for single‐plant root yield and harvest index (proportion of root weight to total plant weight) in segregating populations and single‐row trials at different plant spacings and for unit‐area yield in a replicated large‐plot trial to assess efficiency of selection. Broad‐sense heritability for single‐plant yield in segregating populations was much higher than that for harvest index irrespective of spacing. The correlation of single‐plant yield in segregating populations with unit‐area yield was invariably lower than that of harvest index with unit‐area yield. Thus, harvest index is a better selection criterion than single‐plant yield in segregating populations or in single‐row trials when the final selection objective is unit‐area yield. Intergenotypic competition appeared to be the major cause for a low correlation between single‐plant yield and unit‐area yield. Spacing of 1 × 2 m in segregating populations and a distance of 2 m between rows in single‐row trials were more efficient than other spacings.
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
Effect of Barley Yellow Dwarf Virus Infection on Winter Survival and Other Agronomic Traits in Barley1
Authors: Grafton K. F. , Poehlman J. M. , Sechler D. T. , Sehgal O. P.
Published: July 2010

Four cultivars and four experimental lines of winter barley (Hordeum vulgare L.), varying in resistance to barley yellow dwarf virus (BYDV), were grown during 1978‐79 and 1979‐80 in four treatments: (a) caged to exclude natural aphid vectors, (b) caged inoculated with viruliferous Rhopalosiphum padi, (c) exposed to natural aphid vectors, (d) exposed and inoculated with R. padi. Overall, BYDV infection reduced winter survival, plant height, number of spike‐bearing tillers, total dry weight, grain yield, and seed size. The reduction was related to the amount of BYDV injury. In Post, the entry with the least BYDV injury, none of the traits were reduced significantly. In Harrison and Durra, the entries with the largest BYDV injury, all of the traits were reduced severely by the viral infection. The remaining entries were intermediate in their reaction to BYDV and also in the expression of the agronomic traits. The data confirm that fall infection by BYDV predisposes winter barley to winter injury and reduces height, tillering, grain yield, and seed size, and that entries selected for this experiment vary in response to BYDV infection.
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.
Non‐destructive Estimation of 14C in Soybeans Immediately After Labelling1
Authors: Pearen J. R. , Hume D. J.
Published: July 2010

Accurate measurement of 14C initially taken up in photosynthesis would allow estimation of respiratory losses from disappearances of 14C between labelling and subsequent harvests. Also, distribution of the photo‐assimilates could be determined. This experiment was conducted to evaluate a nondestructive technique for estimating 14C in soybeans [Glycine max (L.) Merrill] immediately after labelling. Plants were grown in the field in buckets with nutrient solutions containing low N, NO3 ‐ or NH4*. Leaflet areas were measured prior to labelling with 14CO2 at five different growth stages. Leaf discs removed immediately after labelling and leaf areas were used to estimate how much 14C was in each plant. In plants harvested immediately, the technique accounted for 81 to 97% of the variability in 14C contents at the five growth stages with the poorest precision occurring during seed‐filling. The leaf disc technique allowed estimation of initial 14C in other plants left for later harvests.
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.
Pollen Shedding and Combining Ability for High Temperature Tolerance in Rice1
Authors: Mackill D.J. , Coffman W.R. , Rutger J.N.
Published: July 2010

High temperature‐induced sterility in rice (Oryza sativa L.) has not been an important problem in traditional cropping patterns. High temperature tolerance will become an important breeding objective as irrigation systems for dry season cropping are developed and rice production in semi‐arid countries expanded. A study was made to ascertain the prospects for breeding heat tolerant cultivars.

A diallel cross experiment was conducted in the phytotron at the International Rice Research Institute to determine the combining ability of six rice lines for high temperature tolerance at anthesis. Control plants were kept under a 29/.21C temperature regime. The treated plants were subjected to 38/27 C for 10 days during anthesis. A heat tolerance index was calculated by dividing the percentage of filled grains of the treated plants by that of the control plants. General and specific combining ability effects for this index were highly significant. The tolerant lines, N22, IR2006 and IET4658, had general combining ability effects of 6.80, 4.08 and 3.02, respectively. The susceptible lines, IR28, IR1561 and IR52, had general combining ability effects of —3.40, —4.92 and —5.58, respectively.

The amount of pollen shed on the stigma was studied for the six diallel parents and two F~ hybrids under the two temperature regimes (29/21 and 38/27 C). Tolerant cultivars shed more pollen grains on the stigma under both temperature regimes. In the susceptible genotypes, there was a marked reduction in the amount of pollen shed on the stigma at the high temperature. Pollen germination in the cultivar IET4658 was reduced under the 38/27 C temperature regime. Percentage fertility was positively correlated with the amount of pollen on the stigma at 38/27 C. The large amount of pollen on the stigma in tolerant genotypes appeared to compensate for reduced pollen growth under high temperature. Observations of pollen shedding under field conditions corresponded well with the phytotron results.
A New Method to Determine the Number of Genes for Resistance to Maize Dwarf Mosaic in Maize1
Authors: Scott Gene E. , Rosenkranz Eugen
Published: July 2010

Information on the number of genes conditioning resistance to maize dwarf mosaic (MDM) will assist maize (Zea mays L.) breeders to choose the most appropriate breeding system for using these genes in their breeding program. Our objectives were (a) to devise a method for estimating the number of genes for resistance, (b) to determine the number of genes for resistance in five resistant inbreds, and (c) to ascertain if genes for resistance in different lines were in common.

The proposed method for estimating number of genes utilizes data from two classes of plants (diseased and healthy) in different segregating generations to determine the number of alleles for resistance that allowed symptom expression under the conditions of the test. With these data and with the expected frequency of plants with a given number of alleles for resistance in these segregating generations, estimates of the number of genes for resistance in the resistant parent can be made.

We found that inbreds GA209, Mp339, Mp412, T240, and Va35 had 2, 2, 2, 3, and 1 gene for resistance, respectively, to maize dwarf mosaic virus strain A. GA209 probably has one gene for resistance in common with Mp339. The gene for resistance in Va35 is different from both genes in Mp339.
Isoelectric Focusing of Esterases for Fine Fescue Identification1
Authors: Villamil C. B. , Duell R. W. , Fairbrothers D. E. , Sadowski J.
Published: July 2010

There is a growing need for a technique to validate identities of commercial lots of seed, particularly at the cultivar level. A technique that would aid in identification of species and subspecies of a genus such as Festuca would also be helpful. The purpose of the present work was to develop such methods.

Protein was extracted from ground and delipified seeds of cultivars or selections of known origin. Extracts were quantitatively added to polyacrylamide gel (with ampholite) in either rods or slabs and subjected to isoelectric focusing over a pH gradient of 4 to 9. After staining, up to 20 esterase bands. Isoelectric focusing on gel slabs provided a technique for simultaneous comparisons, both qualitative and quantitative, of band patterns of up to 18 entries side‐by‐side. Densitometric graphing aided in revealing consistent differences in relative density of specific bands, and made rapid identification of cultivars possible.

Environmental stability of esterase band patterns characterizing cultivars was demonstrated using samples from the same seed fields for 3 years and also from different fields each year. Neither year of production nor location of production significantly altered the isozyme banding pattern that characterized each cultivar. Species and subspecies among the fine fescues were shown to encompass cultivars having similarities in esterase patterns that differed from those of other subspecies. Those illustrated include Festuca rubra subsp. rubra, F. rubra subsp. commutata, F. rubra subsp. trichophytla, F. tenuifolia F. ovina subsp. duriuscula = F. longifolia, and F. ovina subsp. glauca.

We concluded that the esterase patterns developed were free from environmental influences and can be used satisfactorily for identification of fine fescue cultivars.
Response to Index Selection in Maize for Resistance to Ear Damage by the Corn Earworm1
Authors: Widstrom N. W. , Wiseman B. R. , McMillan W. W.
Published: July 2010

Three selection indexes, 1) derived by standard procedures (RS), 2) derived from direct and correlated responses of the index traits (RI), 3) from direct and correlated responses of the primary trait (RSI), were compared with selection for reduced corn earworm [Heliothis zea (Boddie)] injury per se (CEW) through four cycles of selection in the maize (Zea mays L.) population RFC. Responses for reduced corn earworm injury occurred for all methods of selection, but the significant rates of response of RSI and RI selection were larger than RS or CEW. CEW and RI selections resulted in tighter husks, shorter husk extension, and slightly less yield reduction than in RS and RSI selections. None of the index procedures were superior to conventional selection for resistance to corn earworm, but the RI index was judged to compare most favorably when considering all trait responses.

Phenotypic correlations obtained from S1 progeny data within each cycle indicated that the interrelationships among index traits, other than days to anthesis, had changed substantially during the course of four cycles of selection. The significant relationships of corn earworm injury with husk tightness and husk extension were greatly reduced and significant reversals of the relationship between husk tightness and extension occurred among the RS and RSI selections. The RI index will be revised for further comparison with conventional selection in this maize population for reduced injury by the corn earworm.
Inheritance of Lipoxygenase‐1 Activity in Soybean Seeds1
Authors: Hildebrand D. F. , Hymowitz T.
Published: July 2010

The objectives of this study were to determine the mode of inheritance of lipoxygenase‐1 (L‐I) activity in soybean [Glycine max (L.) Merr.] seeds and to investigate possible linkage of the L‐1 locus with the Le (seed lectin), Spl (β‐amylase), and W1 (flower color) loci. The inheritance of L‐1 in soybean seeds was determined by crossing the two genotypes that lack L‐l, Plant Introduction (P.I.) 133226 and P.I. 408251, with soybean cultivars (‘Williams,’ ‘Forrest,’ ‘Columbia,’ and ‘Altona’) having normal L‐1 activity. All F1 seeds had L‐1 activity. F2 seeds resulting from these crosses segregated 3:1 indicating that the presence of L‐1 is inherited as a simple dominant. F3 seeds from heterozygous F2 plants also segregated 3:1. Reciprocal crosses gave the same results indicating no maternal or cytoplasmic effects on the inheritance of L‐1 activity. The genesymbol Lx1 is assigned to the allele coding for the presence of L‐1 protein and lx1 for the lack a detectable L‐1 protein. Linkage studies indicate that the Lx1 locus is not linked to the loci coding for W, Le, or Sp1.
Association of N‐acetyl Loline and N‐formyl Loline with Epichloe typhina in Tall Fescue1
Authors: Bush L. P. , Cornelius P. L. , Buckner R. C. , Varney D. R. , Chapman R. A. , Burrus P. B. , Kennedy C. W. , Jones T. A. , Saunders M. J.
Published: July 2010

The alkaloid fraction of tall rescue (Festuca arundinacea Schreb.) has been implicated in poor forage quality but the alkaloid content of tall rescue varies greatly amongrazing seasons, pastures, and individual plants. The objective of this research was to identify the association between the presence of E. typhina (Fr.) Tul. in the plant and the N‐formyl and N‐acetyl loline alkaloids. Plants were grown in benomyl‐treated soil in the greenhouse to control the fungus and treated plants and seed from treated plants were established in the field to provide seed and plant tissue for analysis. The fungus was eliminated or its development severely inhibited by growing tillers for 6 weeks in soil treated with benomyl.

Accumulation of N‐acetyl loline and N‐formyl lollne in tall fescue was positively associated with the presence of the endophytic fungus, Epichloe typhina. Leaf tissue from treated plants contained very small amounts of N‐acetyl or N‐formyl loline. Plants from which E. typhina had been eliminated and that had been established in the field remained free of the fungus for at least 3 years.