bluuebunny/crossref_metadata_2025 huggingface dataset:
Wheat Genotype and Environment Effects on Chinese Steamed Bread Quality
Authors: Hou Liming , Zemetra R. S. , Birzer Dianne
Published: July 2010

Chinese steamed bread (CSB) is a major end‐use product of wheat (Triticum aestivum L.) in the People's Republic of China. To gain and maintain the CSB market, wheat produced in the USA needs to have stable and superior quality. This study examines the changes in CSB quality due to wheat genotype and the environment in which it was grown. Sixteen wheat cultivars were grown in three locations for two growing seasons to provide a range of genotypes and environments. Chinese steamed bread quality was determined by volume (cm3), rheological value (g cm−2), exterior score, and interior score. Variability was determined by analysis of variance. Both genotype and environment were found to greatly influence CSB quality. One soft white winter wheat cultivar, Dusty, was found to have both superior and stable quality for all four quality indices. Other cultivars possessed either good quality or stability, but not characteristics for all indices. Based on these results, cultivars exist that produce wheat with a superior and stable quality for CSB. Such attributes would maintain or increase the export market for U.S. wheat.
Western Corn Rootworm Damage: Effect of Tillage on Plant Response and Grain Yield
Authors: Riedell Walter E. , Gustin Ralph D. , Beck Dwayne L. , Hanson Denise G.
Published: July 2010

Corn rootworms (Diabrotica spp.) are the most economically destructive insect pests of corn (Zea mays L.) in the U.S. Midwest. The objective of this 2‐yr field study was to measure plant response and yield under ridge tillage or spring disk tillage in fields artificially infested with western corn rootworm (D. virgifera virgifera LeConte). Corn rootworm infestations were applied at 0, 1650, 3300, or 6600 viable eggs m−1. We measured insect survival to adult, root damage ratings, nodal root volume (Nodes 4 and above) at maximum insect damage, and grain yield. In 1988, which was characterized by above‐normal temperature and below‐normal precipitation, root damage increased (6.7 rating at 1650 eggs m−1 to 7.9 at 6600 eggs m−1) and insect survival to adult decreased (4.9% at 1650 eggs m−1 to 1.2% at 6600 eggs m−1) with increasing infestation level under both tillage systems. During the 1988 season, plants grown under ridge tillage had larger nodal root systems (17.9 mL) than under spring disk tillage (9.9 mL). Ridge‐tilled plants also had greater yield (5.5 vs. 4.1 Mg ha−1 with no rootworm eggs; 4.3 vs. 3.1 with 1650 eggs m−1; and 4.1 vs. 2.2 Mg ha−1 with 3300 eggs m−1). In 1989, which had near normal temperature but below‐normal precipitation during the growing season, root damage increased (from a 1.1 to 5.9 rating as the infestation level increased from 0 to 6600 eggs m−1) and insect survival to adult decreased (from 1.3 to 0.7% as the infestation level increased from 1650 to 6600 eggs m−1) under both tillage systems. Tillage practice had no effect on plant response to rootworm feeding or yield. However, the number of nodal root axes per plant (22.4) and grain yield (8.8 Mg ha−1) were increased significantly under both tillage systems infested with 6600 eggs m−1 of row (29.0 axes per plant and 10.2 Mg ha−1). These results suggest that during a hot, dry growing season, ridge tillage increased yield for uninfested and rootworm‐infested plants when compared with yields produced using spring disk tillage.
Mepiquat Chloride and Temperature Effects on Photosynthesis and Respiration of Fruiting Cotton
Authors: Hodges H. F. , Reddy V. R. , Reddy K. R.
Published: July 2010

The bioregulator, mepiquat chloride (1,1‐dimethylpiperidinum chloride), consistently suppresses rank growth of cotton (Gossypium hirsutum L.), but yield responses are erratic. The objective of this study was to determine cotton plant response to mepiquat chloride (MC) at different temperatures, so that appropriate functions can be provided to the cotton crop simulation model. Cotton plant foliage was sprayed with MC at initial bloom, and maintained at four different day/night temperatures for 49 d. Carbon dioxide fluxes were measured continuously, and used to calculate photosynthetic and respiration rates. Plant components and leaf area were measured at the end of the treatment period. Mainstem growth rates and node addition rates were reduced by MC application at all temperatures. Gross photosynthesis increased linearly when the ambient air temperature increased to 30°C and declined at 40°C. Mepiquat chloride increased the canopy gross photosynthesis (Pg) within 48 h, suggesting a direct effect on photosynthesis. The increased Pg established on Day 2 persisted throughout the season at various temperatures, but the differences decreased at the end of the season. Respiration rates increased linearly as air temperature increased and decreased with plant age when expressed on unit weight basis. Biomass yields of cotton plants harvested 49 d after treatment were closely related to net photosynthetic assimilation accumulated over the same period. We conclude that MC and temperature impact cotton growth, development, respiration, and photosynthetic rates. This information will be useful for predicting optimum timing and amounts of MC application for improved management of cotton canopies.
High‐Temperature Sodium Hypochlorite Effects on Viability of Tilletia Controversa Teliospores and Wheat Seed
Authors: Chastain T. G.
Published: July 2010

Contamination of wheat (Triticum aestivum L.) grain by Tilletia controversa Kühn teliospores is a constraint to expanding international markets for U.S. Pacific Northwest wheat. Developing a method to kill teliospores on wheat grain and seed could be very beneficial for the region's agricultural economy. This study was conducted to evaluate high‐temperature NaOCl as a disinfestant for T. controversa teliospores and to ascertain the effect of NaOCl treatment on wheat seed viability. Contaminated ‘Stephens’ and ‘Daws’ winter wheat seed lots were exposed for 15, 30, or 60 s to 0, 0.07, 0.13, 0.27, or 0.67 M NaOCl solutions heated to 50, 55, or 60 °C. Wheat seed quality and teliospore viability were determined by standard germination tests and by lipase assays, respectively. Maximum teliospore mortality was achieved when the NaOCl concentration was ≥0.13 M. Stephens germination was generally not reduced by NaOCl heated to 50 and 55 °C, regardless of exposure time, but was reduced at 60 °C when exposed for 60 s. Germination was proportionally reduced by increased NaOCl concentration and time of NaOCl exposure. Daws was more susceptible to high‐temperature NaOCl treatment than Stephens. Seedling coleoptile length of both cultivars was not reduced when seed was exposed for ≤30 s to 0.13 M NaOCl when treatment temperature was ≤55 °C. The safest NaOCl concentration for killing teliospores on seed of both cultivars was 0.13 M when treatment temperature was ≤55 °C. Germination was similar regardless of seed moisture content prior to NaOCl treatment. The high‐temperature NaOCl treatment may be an important tool for solving phytosanitary restrictions imposed due to the presence of teliospores of T. controversa on wheat grain and seed.
Filtering Manifold for Determining the Fibrous Composition of Feeds
Authors: Mertens D. R. , Hintz R. W. , Sims L. S. , Cardoza R. D.
Published: July 2010

Analysis of the fibrous composition of feeds by the Goering and Van Soest procedure requires that samples be filtered in the presence of mineral acids and organic solvents. In this process, it is desirable to use a manifold that not only is resistant to these reagents, but also is inexpensive and easy to construct. The new design fits Gooch crucibles tightly and eliminates vacuum leaks and the associated foaming that hampers filtration of difficult samples.
Procedure to Estimate Genetic Gain by Stages in Multistage Testing Programs
Authors: St. Martin S. K. , McBlain B. A.
Published: July 2010

Development of cultivars requires testing in multiple stages, an expensive and lengthy process. Little research has been conducted on testing strategies. Our objectives were to develop a procedure to estimate genetic gains for each stage of testing and to illustrate the procedure using regional soybean [Glycine max (L.) Merr.] data. the procedure, a test in which a set of strains is evaluated is paired with a test in the next stage, in which selections from the set are reevaluated. Realized gains are estimated by comparison with checks common to the two tests. Regression of genetic gain on selection differential gives an estimate of the proportion of phenotypic superiority that is realized as genetic gain. Application of the procedure to regional test data revealed that genetic gains were small for all traits except grain yield. Genetic gains and regression coefficients of gain on selection differential for yield were near zero for Maturity Group 00, indicating that selection based on regional means was ineffective for this maturity group. The procedure may be valuable in identifying inefficient stages and in comparing genotypes in different stages of testing.
Resistance to Puccinia recondita f. sp. tritici in 50 Mexican Bread Wheat Cultivars
Authors: Singh R. P. , Rajaran S.
Published: July 2010

Bread wheat (Triticum aestivum L.) cultivars derived from CIMMYT germplasm are currently grown on a large area worldwide. Since limited information is available on genes for resistance to leaf rust in these wheats, the two main objectives of the study were to postulate the known Lr genes conferring low seeding reactions to 18 pathotypes of Puccinia recondita Roberge ex Desmaz. f. sp. tritici in 50 Mexican cultivars released between 1960 and 1988; and to evaluate the presence of additional adult‐plant resistance. Thirteen known genes were postulated to be present either singly or in combination: Lrl (in 12 cultivars), Lr3 (1), Lr3bg (2), Lrl0 (12), Lr13 (25), Lrl4a (5), Lr16 (5), Lrl7 (8), Lrl9 (1), Lr23 (3), Lr26 (9), and Lr27 + Lr31 (7). Additional temperature‐sensitive seedling resistance occurred in 25 cultivars. Area under the disease progress curve for these 25 cultivars indicated variable levels of adult plant resistance. Thirteen other cultivars with seedling susceptibility to one or more of the predominant field pathotypes were also partially resistant in the field. High levels of adult plant resistance occurred in some cultivars, even in the absence of known genes with major effects. ‘Penjamo 62’ and ‘Siete Cerros 66’ possessed the gene Ne2 for hybrid necrosis but lacked Lrl3, indicating that recombination can occur between the two loci.
Evaluation of Heterotic Patterns among Caribbean and Tropical ✕ Temperate Maize Populations
Authors: Pollak L. M. , Torres‐Cardona S. , Sotomayor‐Rios A.
Published: July 2010

The integration of tropical maize (Zea mays L.) germplasm into template breeding programs has been difficult and slow. More information on performance of temperate ✕ tropical populations and their heterotic combinations is needed. This study was conducted to compare heterotic patterns among four populations. Two, a Caribbean flint and a Caribbean dent, are useful in the tropics and have potential for temperate areas; the other two are temperate ✕ tropical populations adapted to the tropics. The four populations, their diallel crosses and reciprocals, and a commercial hybrid check were grown in two locations in Puerto Rico during two winter‐season environments. The best heterotic combination among the four populations was between the Caribbean flint and dent. The best‐yielding population per se was the temperate ✕ tropical population of Reid (Group B) heterotic pattern. The Caribbean flint population had highly significant negative maternal effects for yield. Both reciprocal crosses of the temperate ✕ tropical populations were low yielding. The results indicated that, for temperature breeding programs, both Caribbean populations should be useful for improving Corn Belt maize.
Prediction of Alfalfa Chemical Composition from Maturity and Plant Morphology
Authors: Hintz Rodney W. , Albrecht K. A.
Published: July 2010

To make informed harvest management decisions, producers need information on the chemical composition of alfalfa (Medicago sativa L.) forage. Our objective was to develop a fast and simple method for predicting forage chemical composition (crude protein, neutraland acid‐detergent fiber, and acid‐detergent lignin) using morohological characters. Five alfalfa cultivars werevaluated across a range of environments, growth cycles, and harvest maturities. The 15 morphological characters examined for association with chemical composition included number of nodes per plant, plant height, mean stage count (MSC), mean stage weight (MSW), and alternative stage of development descriptions. Simple regression analyses based on node number and plant height provided better prediction equations than when based on MSC or MSW. Multiple regression equations based on two and three morphological characters provided higher R2 and lower root mean squarerror (RMSE) values than did linear and quadratic models based on a single morphological character. Multiple regression of the two most easily measured characters, height of the tallest stem (MAXHT) and maturity stage the most mature stem (MAX), provided equations with RMSE values only slightly greater than those of the best two‐factor multiple regression models based on characters that are more difficult to measure. Thus, multiple regression techniques should improve the accuracy of predicting forage chemical composition, and the use of easily determined characteristicsuch as MAXHT and MAX may provide the best compromise between prediction accuracy and ease of use.
Seed Lengths Corresponding to the Final Stage in Seed Abortion of Three Grain Legumes
Authors: Duthion C. , Pigeaire Alix
Published: July 2010

Previous studies demonstrated that there is a final stage and a maximum dry weight for seed abortion in several grain legumes. In this work, the corresponding seed lengths were determined in soybean [Glycine max (L.) Merr.], pea (Pisum sativum L.), and white lupine (Lupinus albus L.). Two genotypes with differing seed size were studied for each species, and the white lupine cultivar Lublanc was placed in two different growing conditions. A photographic technique based on the difference in light transmission between carpels and seeds was used to monitor in a nondestructive manner the lengthening of seeds in their pod. The fate of each seed (aborted vs. nonaborted) was recorded at maturity and time‐courses of seed length were determined from the photos for seeds of the two categories. The lengthening pattern followed by aborted and nonaborted seeds and the maximum lengths attained by each of these categories showed that there was a given length after which seed abortion did not occur. This length was close for the two cultivars of each species. For Lublanc, growing conditions influenced the average size of aborted seeds but did not change the length after which seed abortion did not occur. The respective maximum length of any aborted seed and the length not exceeded by 95% of aborted seeds were 12 and 10 mm for soybean, 8.5 and 6 mm for pea, and 13 and 11.5 mm for white lupine.
Carbon Isotope Discrimination and Transpiration Efficiency in Common Bean
Authors: Ehleringer James R. , Klasen Stephen , Clayton Creed , Sherrill Dorothy , Fuller‐Holbrook Mindy , Qing‐nong Fu , Cooper Tamsie A.
Published: July 2010

Carbon isotope discrimination (Δ) values were measured in diverse genetic lines of common bean (Phaseolus vulgaris L.) as indicators of water‐use efficiency. Using on‐line Δ measurements, there was a close agreement between observed Δ values and those predicted by C3‐photosynthesis Δ models. Additionally, Δ values were also significantly correlated with transpiration efficiency estimates (W) measured in potted plants grown outdoors on a long‐term basis. Based on ancestral race and domestication center, there were no significant differences in W or Δ. However, differences occurred when cultivars were analyzed on the basis of the geographic region for which they had been developed. On average, lines developed for Central and South America exhibited significantly higher W values (0.63 vs. 0.57 mmol mol‐1, respectively) and lower Δ values (21.07 vs. 21.51‰, respectively) than did lines developed for North America. There were also small, but significant differences in the slopes of the relations between Δ and W that were dependent on the geographic region for which lines had been developed. North American common bean lines exhibited a steeper relationship between these two parameters than did Central‐South American lines. The basis for these apparent differences in transpiration efficiency is unclear, but may have been associated with variation in leaf conductances or paraheliotropic leaf movements among the two groups.
Populations Dynamics of Soybean Insect Pests vs. Soil Nutrient Levels
Authors: Funderburk J. E. , Teare I. D. , Rhoads F. M.
Published: July 2010

The use of fertilizers can influence crop injury from arthropod pests through alterations in crop growth or nutritional levels of plants parts. The objective of this field study was to determine the effect of soil nutrient levels on population dynamics (population density and cycles) of larval velvetbean caterpillars (VBC), Anticarsia gemmatalis (Hübner), and nymphal and adult southern green stink bugs (SGSB), Nezara viridula (L.), in relation to physiological development (V4 to R6) and yield of soybean, Glycine max (L.) Merr. ‘Braxton’ soybean was grown on a Norfolk loamy sand (fine, loamy, siliceous, thermic Typic Kandindult) during 1986 and 1987. Soil nutrient variables were four levels of P and three levels of K and Mg. Insecticides were not applied at any time during the experiment. Orthogonal comparisons were used to separate the effects of P, K, and Mg levels. The higher soil levels of P and K increased seed yields of each year. Yield results were not affected by Mg levels. Population densities of larval VBC at the higher levels of P were greater than at the lower levels of P. Population densities of VBC were increased by K in 1987, but not in 1986. Magnesium levels did not affect VBC either year. Adult populations of SGSB invaded and began reproducing at R4, but data are not shown due to poor precision of sample estimates resulting from a typical clumped dispersion pattern. Population density estimates of nymphal SGSB were greater at the higher P levels in 1986 when populations were very great, but not in 1987 when populations remained low. Population density estimates of nymphal SGSB were not affected by K or Mg. These findings should aid in implementation of cultural control strategies for these major pests of soybean in the southeastern USA.
Enhancement of Bean Emergence by Seed Moisturization
Authors: Wilson Dale O. , Trawatha Susan E.
Published: July 2010

Small additions of moisture to bean (Phaseolus vulgaris L.) seed prior to planting have been used to decrease seed damage and improve field performance. The objectives of this research included determination of optimum seed moisture and study of the interaction of seed moisture content with testa color (whiteness is associated with poor emergence), planting date, and irrigation timing. Pairs of bean lines near‐isogenic for testa whiteness were planted 2 May and bean lines near‐isogenic for testa whiteness were planted 2 May and 14 June 1988 and 11 May 1989. Prior to planting, seed was slowly adjusted to 70 and 140 g kg‐1 H2O in 1988 or 80, 100, 120, 140 and 160 g kg‐1 H2O in 1989. Plots were eiher pre irrigated or watered immediately after planting. Increasing seed moisture from 70 to 140 g kg‐1 improved emergence by 15 to 30% when plots were watered after planting, but had no effect when the field was pre‐irrigated. Likewise, moisturization improved emergence 11% at the early planting, but only 4% at the late planting. Testa whiteness, irrigation timing, and seed moisture content interacted in 1989. Emergence under pre‐irrigation was 20% better than with post‐irrigation with dry (80 g kg‐1) seed, but in the case of colored seed only, post‐irrigation resulted in 10% better emergence for the seed with 140 and 160 g kg‐1 moisture. Except for this effect, seed moisture did not interact with whiteness, suggesting that inbibitional injury is not responsible for the poor performance of white‐seeded lines.
Genetic Analyses of Male Fertility Restoration in Wheat: V. Anomalous Results of a Monosomic Analysis
Authors: Maan S. S.
Published: July 2010

A fertile line (L222) of common wheat (Triticum aestivum L.), with cytoplasm of T. timopheevii Zhu., and rfl and rf4 alleles of the major Rf genes on chromosomes 1A and 6B, respectively, was developed and analyzed for male fertility‐restoring genes. L222 descended from 1 of the 11 partially fertile monosomics in the backcross progeny of cytoplasmic male‐sterile (cms) Chris monosomic 1A/L22 (RflRfIrf4rf4), F1 monosomic lA//euploid Chris. Additional fertile monosomics were obtained from a second backcross of partially fertile monosomics in the F2 and F3 of the same cross. In their selfed progenies, monosomics and disomics were increasingly fertile, even though they were expected to have neither of the major Rf genes. L222 was analyzed for chromosomal location of Rf gene(s). A monosomic set of euplasmic ‘Chris’ and two tester stocks, cms ‘Era’ and cms Chris, were used for monosomic analysis. Plants were grown in a greenhouse at Fargo, ND. Results indicate that a major Rf gene was retained on chromosome 1A. An abnormally high incidence of univalent shift or contamination may explain the presence of Rfl on chromosome 1A of L222, but this was unlikely to occur in such a high frequency as to produce several fertile monosomics in three different backcross progenies. Two of the fertile monosomics were correctly identified as mono‐lA by testcrossing them to Chris ditelosomic 1AS. Therefore, a hypothesis was proposed that a mutagenic (mtg) gene mutated rfl to Rfl in some of the plants that were monosomic for chromosome 1A. The original Rfl and the mutant Rfl are both located on the short arm of chromosome 1A, but allelism was not tested. The proposed genotypes of L222, Chris, and Era are RflRfl fifi, rflrfl FiFi; and RflRfl fifi, respectively.
Increasing the Efficiency of Crop Selection for Unpredictable Environments
Authors: Zavala‐García F. , Bramel‐Cox P. J. , Eastin J. D. , Witt M. D. , Andrews D. J.
Published: July 2010

A key decision in crop breeding programs designed to improve productivity under variable environments is choosing the environment to use for selection. Productivity of the plants in the selection environment and/or a high correlation between yield in the test and the target environments have been used to identify the most appropriate selection environments. Several alternatives have been suggested. The objective of this study was to compare the relative efficiencies among indirect selection criteria to improve yielding ability in sorghum genotypes in a wide range of environments. Four dryland locations were used to evaluate 200 S1 families from two random‐mated sorghum [Sorghum bicolor (L.) Moench] populations (TP24D, which is an early maturing TP24 derivative, and KP9B) during the summers of 1987 and 1988. The relative efficiencies of indirect selection using yield from any single environment or mean yield from all eight environments were low, but when the indirect selection criteria involved yield combinations from stress, intermediate, and nonstress environment— such as mean productivity, rank summation, and selection indices— the relative efficiencies were higher than those using yield form any single environment. Thus, yield information representing the range of environments in the target area should be involved in the definition of the selection criterion to achieve gain in the selection of genotypes for unpredictable environments.
Combining Ability for Seed Yield and Its Components in Common Bean of Andean Origin
Authors: Singh Shree P. , Terán Henry , Molina Albeiro , Gutiérrez J. Ariel
Published: July 2010

Knowledge of parental combining ability is essential for creating useful genetic variation through hybridization. Our objectives were to examine combining ability for yield and its components for large‐seeded common bean (Phaseolus vulgaris L.) of Andean origin and to test an earlier observation that germplasms from Middle American races Durango and Jalisco possess positive general combining ability (GCA) for seed yield. Sixty‐four parents from different races and gene pools were randomly assigned to groups of 16. Within a group, eight parents were randomly chosen as females, the rest as males, and crossed in a Design II mating scheme. The resulting 256 F2 populations were evaluated in a reps‐in‐sets design with two replications at Palmira and Popayán, Colombia, in 1989. The experimental unit was a four‐row plot, 5 m long. The GCA effects using line × tester analysis were measured for seed yield (kg ha−1), pods per square meter, seeds per square meter, 100‐seed weight (g), and days to maturity. Mean squares due to males and females (vs. those for males × females) were larger in magnitude and significant (P < 0.05) for all traits; the smaller mean squares for males × females were significant only for seed weight and days to maturity. Mean yields of populations between races Durango and Jalisco were the highest, while populations between races Chile and Nueva Granada were the lowest. Populations between races Chile and Durango had the next‐lowest yields. Positive GCA effects were found for yield (19 parents), seed weight (6 of the 19), seeds per square meter (20), pods per square meter (19), and days to maturity (29). Negative GCA was found for days to maturity (25 parents).
Selection for Seed Growth Characteristics: Effect on Leaf Senescence in Maize
Authors: Crafts‐Brandner S. J. , Poneleit C. G.
Published: July 2010

Increasing the time that a crop canopy maintains an active photosynthetic apparatus could potentially increase economic yield. The objective of this study was to determine the effect of phenotypic recurrent selection for seed dry matter accumulation rate (DMAR) and seed effective filling period (EFP) on leaf senescence in selections of a maize (Zea mays L.) synthetic population, KyWVS. Selection groups included factorial combinations of high, same (same as Cycle 0), and low DMAR; and long, same, and short EFP. Cycles 3 and 5 were evaluated in the field in 1985 and 1986, respectively. Due to minimal interaction between DMAR and EFP with regard to senescence traits, each DMAR group was averaged across EFP levels and vice versa. Both DMAR and EFP were altered by selection, but the date of pollination remained relatively constant. As indicated by changes in chlorophyll, carbon dioxide exchange rate (CER), and photosynthetic enzyme activities during the grain filling period, selection for DMAR did not affect leaf senescence for either cycle. For both cycles, selection for short EFP led to earlier leaf senescence. For Cycle 5, long EFP genotypes maintained higher CER and higher levels of photosynthetic components at later sampling dates compared with the same EFP genotypes. In all cases differences in senescence were due to the time of completion, and not the time of initiation, of senescence. The results indicated that large genetic changes in DMAR can occur without any influence on leaf senescence. For this maize population, however, changes in EFP were closely associated with changes in leaf senescence characteristics.
Apical Development of Spring Barley under Field Conditions in Northeastern North America
Authors: Ma B. L. , Smith Donald L.
Published: July 2010

Although the apical development of barley (Hordeum vulgare L.) has been extensively researched, a complete description of spring barley apical development stages has not been published for continental North American field conditions. This study determined the timing and duration of the apical development stages, and the pattern and dynamics of spikelet primordium initiation. Data were collected for two barley cultivars for three successive seasons in eastern Canada. From the seedling stage to anthesis, apical development and the total number of primordia on the mainstem were monitored, and both were related to days after seeding (DAS) and to accumulated growing degree‐days (AGDD). The mainstem apex reached the double ridge stage 22 to 24 DAS (320–340 AGDD), awn initiation 40 to 42 DAS (≈650 AGDD), and anthesis 50 to 56 DAS (860–940 AGDD), with some variations among cultivars and years. Nine mainstem leaf primordia were initiated by 16 DAS. Spikelet primordium initiation was completed by awn initiation when 30 to 35 primordia had been formed. The data provide a description of barley apical development stages and indicate that spikelet primoridum production (i) occurs at a variable rate, (ii) is largely a function of thermal time, although genotype and climatic factors have some effect, and (iii) is related to time or thermal time in a curvilinear, rather than a linear fashion.
Explanations for Greater Light Interception in Narrow‐ vs. Wide‐Row
Authors: Board J. E. , Harville B. G.
Published: July 2010

Increased light interception (LI) is considered the main factor responsible for greater seed yield in narrow‐ compared with wide‐row soybean [Glycine max (L.) Merr.] culture. The objectives of this study were to determine the roles of leaf area index (LAI) and light interception efficiency (LIE) in creating greater LI in narrow‐row culture. Light interception efficiency is defined as LI/LAI. Field studies were conducted during 1987 and 1988 at optimal (May) and late (July) planting dates, with cultivars Forrest (Maturity Group V) and Centennial (Maturity Group VI), and at 100‐cm (wide) rows/normal density, 50‐cm (narrow) rows/normal density, and 50‐cm rows/high density. Plots were sampled at the V7, Rl, R3, R5, R6.5, and R6.8 developmental stages. The experiment was conducted at Baton Rouge, LA, on a Mhoon silty clay (fine‐silty, mixed, nonacid, thermic Typic fluvaquent) soil. Greater LI in narrow rows was more pronounced at late compared with optimal plantings and in Forrest, the short‐season cultivar, compared with Centennial, the full‐season cultivar. Results indicated that LAI was the dominant factor responsible for greater LI in narrow rows. Light interception efficiency played an important role in narrow‐row increased LI only when LAI was low and little mutual shading occurred. Selection criteria for cultivar‐genotype performance in narrow‐row culture at late plantings should be based on rapid leaf expansion rates (LER) and high LAI accumulation during vegetative and early reproductive development. Attainment of LAI of 3.5 to 4.0 by R1 should optimize yield. Due to a significant planting date × cultivar × developmental stage interaction for LAI, selection should be done at late rather than optimal planting dates.
Iron, Silica, and Aluminum Stresses and Varietal Resistance in Rice: Effects on Whitebacked Planthopper
Authors: Salim M. , Saxena R. C.
Published: July 2010

Certain physicochemical stresses affect the susceptibility of plants to insects. The objective of this study was to determine the effects of different levels of Fe, Si, and Al on the establishment of Sogatella furcifera (Horváth) on resistant IR2035‐117‐3 (IR2035) and susceptible Taichung Native 1 (TN1) rice (Oryza saliva L.) cultivars under glasshouse conditions in natural daylight of 12 h, 29/21 °C (day/night), and minimum 70% relative humidity. Insect population increased on rice plants grown in culture solution containing low (0.02 mg L−1) or high (40 mg L−1) Fe than on plants grown in standard culture solution (Fe at 2 mg L−1). Increased Si (400 mg L−1) reduced intake and assimilation of food, growth, adult longevity, fecundity, and population increase by S. furcifera on susceptible TN1 plants. Addition of Al to culture solution at 90 mg L−1 adversely affected insect biology. Regardless of the mineral stress, the difference between the resistance of IR2035 and susceptibility of TN1 cultivars remained distinct. Plants affected with low or high Fe stress had apparently less allelochemicals than did control (unstressed) plants. Mortality of S. furcifera first instars was greater on TN1 plants painted with steam‐distillate extract of Fe‐stressed or control IR2035 plants than on TN1 plants painted with TN1 extract or acetone. Iron and Al stresses significantly decreased the growth and biomass of rice plants. Resistance of rice plants to S. furcifera can be improved by application of Fe at optimum (2 mg L−1) and Si at high (400 mg L−1) rates.
Seeding‐Year Cutting Affects Winter Survival and Its Association with Fall Growth Score in Alfalfa
Authors: Sheaffer C. C. , Barnes D. K. , Warnes D. D. , Lueschen W. E. , Ford H. J. , Swanson D. R.
Published: July 2010

Evaluation of alfalfa (Medicago sativa L.) cultivar persistence normally requires at least 3 yr of testing in stressful environments. Fall growth score sometimes has been used to predict winter survival in the absence of long‐term tests. Our objectives were to evaluate the effect of seeding‐year cutting stress on alfalfa cultivar winter injury and plant survival in several Minnesota environments (locations), and to associate winter injury with cultivar fall growth score. Seeding‐year cutting schedules consisted of harvesting at intervals of 24, 30, 35, and 45 d at each of five site‐years. The locations were Lamberton in southwest, Waseca in southeast, Morris in west central, and Rosemount (2 yr) in east central Minnesota. Average alfalfa stands across cutting schedules were 93, 72, 46, and 55% in the year following seeding at Lamberton, Waseca, Morris, and Rosemount, respectively. No differences in winter injury due to cutting schedules occurred at Lamberton because of sufficient winter snow cover. At the other locations, cultivar differences in winter injury were least for the 45‐d schedule. The 24‐, 30‐, or 35‐d cutting schedules produced severe winter injury that differentiated cultivars at Morris, Waseca, and Rosemount. The most fall‐dormant cuitivar, Rambler, generally had the least winter injury, whereas nondormant ‘Nitro’ had the most winter injury. Fall growth score was correlated with winter survival in stressful environments and explained ≈45% of the variation in winter injury, spring stands, or yields for the 24.d cutting schedule treatment. Winter survival of alfalfa for the 35‐ and 45‐d cutting schedules in the most stressful environment, Morris, explained 42% of the variation in long‐term cultivar winter survival, while fall growth score explained 51%. An index combining seeding‐year cutting stress results with fall growth score was a better predictor of long‐term cultivar winter survival than seeding‐year results alone. Alfalfa winter survival is a complex trait that is difficult to predict.
Predictors of Alfalfa Forage Quality: Validation with Field Data
Authors: Sanderson Matt A.
Published: July 2010

The mean stage system for describing alfalfa (Medicago sativa L.) morphological development and quality has potential as a management tool. Published equations for predicting alfalfa leaf, stem, and herbage quality have not been tested widely. Study objectives were to (i) test published equations for predicting quality from mean stage weight (MSW) or count (MSC) or growing degree days (GDD, base = 5°C) with forage quality data for alfalfa stems, leaves, and herbage, and (ii) test a published equation for converting MSC values to MSW. Two published data sets from Iowa (n = 83 and1 6) and two unpublished data sets from Texas (n = 830 and 164) were used. Predicted values of neutral‐ and acid‐detergent fiber (NDF and ADF), acid‐detergent lignin (ADL), in vitro true digestibility (IVTD), and crude protein (CP) for leaves, stems, and herbage were regressed on observed values. In most instances, intercepts and slopes were significantly different from zero and one, respectively, for values from any predictor regressed on actual values, indicating that the prediction equations were biased; however, the prediction error frequently was less than the calibration error. Values of NDF and ADF in alfalfa stems predicted from GDD equations for actual values better than did predicted values from MSC and MSW equations for the Iowa data sets. For the Texas data sets, GDD was inaccurate and imprecise in predicting NDF or IVTD of herbage. Values of MSW predicted from MSC fit observed values well. Biases in the prediction equations indicate that calibration for specific geographic or environmental regions and frequent recalibration are necessary.
Induction Temperature of Heat‐Shock Protein Synthesis in Wheat
Authors: Hendershot Kerry L. , Weng Jian , Nguyen Henry T.
Published: July 2010

The adverse effects of heat stress are a major limitation to realizing the genetic potential for productivity of wheat (Triticum aestivum L.). This study was undertaken to characterize the temperature‐dependent induction response of heat‐shock protein (HSP) synthesis in wheat seedlings, and to determine if HSPs could be detected in flag leaves of flowering wheat plants at nonlethal temperatures similar to those encountered during agricultural production. The HSP profile was characterized by isoelectric focusing and polyacrylamide gel electrophoresis of 35S‐methionine labeled products of an in vitro translation of poly (A)+ RNA obtained from seedling leaf blades exposed to temperatures of 22, 25, 28, 31, 34, and 37 °C for 2 h and in flag leaf blades exposed to 32 °C for 2 h. Synthesis of HSPs was detected in seedling leaf tissue during heat shock between 28 and 31 °C and in flag leaves at 32 °C. This observation in seedlings was confirmed by northern blot analysis utilizing HSP 16.9 and HSP 70 32P‐labeled probes. These results indicate that both low and high molecular weight HSPs are synthesized in wheat as a response to heat stress when leaf temperatures increase ≈ 10 °C above the optimal growth temperature of 18 to 23 °C. Detection of low and high molecular weight HSPs synthesized in seedlings and flag leaves of flowering plants suggests that HSPs are synthesized before leaf temperatures reach levels that are considered injurious to growth and development.
Inheritance of Seed Set in Crosses of Spring Barley and Hordeum bulbosum L
Authors: Devaux P. , Adamski T. , Surma M.
Published: July 2010

Seed set limits use of certain barley (Hordeum vulgare L.) genotypes in H. bulbosum L. doubled‐haploid production. This study was conducted to determine the genetic basis of low seed set in the spring barley cultivar Apex crossed with H. bulbosum. Two hundred F2 plants, all having Apex as one parent and either Havila, Krystal or Roland as the other parent, were crossed with one clone of H. bulbosum. Parameters of haploid production efficiency (seeds/100 florets, embryos/100 seeds, and plants/100 embryos), were measured. Segregation ratios in the three F2 populations suggest that reduced seed set in Apex is governed by a single codominant gene. Haploid production efficiencies were intermediate between the two parents and were acceptable for applied plant breeding.
Classification of Soybean Cultivars Based on Mitochondrial DNA Restriction Fragment Length Polymorphisms
Authors: Grabau Elizabeth A. , Davis William H. , Phelps Norris D. , Gengenbach Burle G.
Published: July 2010

Mitochondrial DNA restriction fragment length polymorphisms (RFLPs) are convenient markers for identifying cytoplasmic variation among plant cultivars. We have undertaken a systematic study to classify soybean [Glycine max (L.) Merr.] germplasm into cytoplasmic groups based on RFLPs for several mitochondrial genes. This analysis substantially increases the total number of cultivars that have been examined for cytoplasmic diversity and includes many of the maternal ancestors of currently grown cultivars. It also allows comparison with studies involving chloroplast diversity in soybean. The classification presented here is based on analyses by Southern hybridization using a cloned 2.3‐kilobase (kb) HindIII DNA probe earlier shown to differentiate those cultivars derived from ‘Lincoln’ as a maternal ancestor. We have extended these studies to include 138 cultivars and old domestic varieties and have revealed a total of four cytoplasmic groups. Probes from several other soybean genes, including genes for cytochrome oxidase and adenosine triphosphate (ATP) synthase subunits, as well as the small ribosomal RNA gene, have been used as markers to show that the diversity extends to other regions of the mitochondrial genome as well.
Use of Pathogen Filtrate to Differentiate Physiological Resistance of Dry Bean to White Mold Disease
Authors: Miklas P. N. , Grafton K. F. , Secor G. A. , McClean P. E.
Published: July 2010

White mold, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is major concern to the dry bean (Phaseolus vulgaris L.) industry because it reduces yield. Incorporating partial physiological resistance (PPR) into bean is one strategy to combat the disease, but this requires a reliable screening technique. The objective of this work was to develop a reliable screening method to identify bean germplasm that express PPR to S. sclerotiorum. An in vitro method that assayed weight of calli formed on a medium amended with crude culture filtrate of S. sclerotiorum was evaluated. Hypocotyl explants of eight bean genotypes (six cultivars, a breeding line, and one plant introduction), taken from 7‐d‐old seedlings, were incubated for 15 d on a solid Murashige and Skoog‐based medium, containing 5.0 μM/ kinetin and 2.5 μM picloram, and amended with 200 mL L−1 culture or control filtrate. Callus fresh weight, expressed as a percent of the control (CWPC), was analyzed over two runs. Lack of a genotype × run interaction, and a genotypeffect (P < 0.05) for CWPC indicated that this screening method gave repeatable results and was able to differentiate PPR among the eight genotypes. The field resistant ‘Sierra’ and ‘C‐20’ had the greatest PPR, as indicated by high C‐%VPC values, and the field susceptible ‘UI‐114’ and ‘Upland,’ the least PPR. These results to fungal metabolites parallel field resistance of the genotypes, implicating PPR as an important component of the field reaction of a given genotype. The callus‐weight assay may provide a way to differentiate dry bean germplasm for partial physiological resistance to S. sclerotiorum.
Divergent Selection for Nodule Aspartate Aminotransferase and Asparagine Synthetase Activities in Alfalfa
Authors: Degenhart N. R. , Barnes D. K. , Vance C. P.
Published: July 2010

Root nodule aspartate aminotransferase (AAT) and asparagine synthetase (AS) catalyze synthesis of the two primary nitrogenous compounds translocated from alfalfa (Medicago sativa L.) nodules. The objectives of this research were to (i) determine the heritability nodule AAT and AS activities, (ii) evaluate the effect of selection for AAT and AS activities on characteristics associated with N2 fixation, and (iii) assess relationships among nodule characteristics, N concentration, and plant dry weight. One nondormant and two moderately dormant alfalfa populations were divergently selected for nodule AAT and AS activities. Plants were grown in a greenhouse under N2‐dependent conditions and the first regrowth at early bloom was measured for nodule fresh weight, nodule soluble protein concentration, plant dry weight, N concentration, acetylene reduction activity (ARA), and nodule activities of AAT, AS, glutamate synthase (GOGAT), and phosphoenolpyruvate carboxylase (PEPC). Realized heritabilities for AAT and AS were 0.64 and 0.15, respectively, after one cycle of phenotypic selection. Nodule fresh weight responded negatively to divergent selection for AAT and AS activities in populations that had previously been selected for high nodule enzyme activity. Simple correlations among the activities of AAT, AS, GOGAT, and PEPC and nodule soluble protein concentration ranged between r = 0.60 and r = 0.87 (P = 0.01). Specific activities of nodule AAT and AS did not appear to be desirable selection criteria for improving N2 fixation because correlated responses of ARA, plant dry weight, and N concentration were variable or nonsignificant.
Acid Soil Stress Tolerance in Tissue Culture‐Derived Sorghum Lines
Authors: Miller D. R. , Waskom R. M. , Duncan R. R. , Chapman P. L. , Brick M. A. , Hanning G. E. , Timm D. A. , Nabors M. W.
Published: July 2010

Acid soil stress limits crop productivity on nearly one‐half of the nonirrigated arable land in the world. Improvement of acid soil tolerance in sorghum [Sorghum bicolor (L.) Moench] has been approached through conventional breeding programs and more recently through biotechnology. This study was initiated to determine if improved acid soil tolerant tissue culture regenerates could be developed from sensitive parental lines and whether tolerant regenerants with desirable agronomic traits could be selected under field stress conditions. Tissue culture regenerated lines of sorghum and their non regenerated checks were field tested for acid soil [Typic Kanhapludult] tolerance (50% Ai saturation at pH 4.2‐4.6) near Griffin, GA, from 1986 to 1990. Two R5 lines derived from ‘Hegari’ and two R5 lines from RTx430 demonstrated improved acid soil tolerance in 1989. Field test results indicated that these four lines had significantly higher ratings for vigor (2.6‐3.4 vs. 4.8‐4.9), plant survival (12–30 vs. panicles harvested (2–9 vs. 0), and seed yield (20‐85 g plot−1 vs. 0) than their nonregenerated checks. During 1990, selected R7 lines were advance tested on acid soils near Griffin with similar results. Three of these improved selections were then evaluated for early seedling development in a greenhouse soil study using the same acid soils from the field. These results showed that one Tx430 regenerated line had improved root development at low pH during the seedling stage. This research indicated that variation for acid soil stress tolerance was produced through tissue culture and that agronomically desirable genotypes were selected using appropriate field testing procedures and stress levels.
Combining Ability and Heterosis among Eight Complete Spring Hexaploid Triticale Lines
Authors: Barker T. C. , Varughese G.
Published: July 2010

A diallel study of spring hexaploid triticale (× Triticosecale Wittm.) lines was conducted to (i) determine the combining ability effects and heterotic patterns among eight complete spring hexaploid triticales, (ii) study the effect of stress on the stability of combining ability effects and heterotic patterns in two well‐defined moisture regimes, and (iii) determine the relative importance of additive vs. nonadditive genetic effects. Eight parents and 28 crosses were tested at two sites (full irrigation vs. under drought stress) in Mexico. Drought effects reduced yield from 8.3 to 5.7 Mg ha−1, test weight from 746 to 722 kg m−3, and height from 127.5 to 102.1 cm. Entry × site interaction was nonsignificant for yield, suggesting stability of combining ability and heterotic patterns. Entry × site interactions for test weight and height were due to one or a few parental lines. Tests for average heterosis (performance of parents vs. crosses) were highly significant for all traits in both environments. Yield showed mean percentage heterosis over high parent of 7.2% (19.7% maximum) under irrigation and 25.2% (68.2% maximum) under drought. Heterotic patterns for test weight and height were consistent across environments, but some combinations were positive and others negative relative to the high parent. Highly significant general combining ability (GCA) effects were found for all traits under both moisture regimes. Highly significant specific combining ability (SCA) effects were found only for yield, which was due to a single combination. The importance of GCA vs. SCA was clear for all traits in both environments, but GCA/ SCA sums of squares was lowest for yield, indicating more nonadditive effects for yield than for test or height among these Fl'S. This was further reflected by a large percentage high parent heterosis for yield. It seems that triticale has potential as a hybrid crop, particularly under droughtstressed growing conditions.