bluuebunny/crossref_metadata_2025 huggingface dataset:
Chromosomal Location of Genes Influencing Grain Protein Concentration and Mixogram Properties in ‘Plainsman V’ Winter Wheat
Authors: Stein Ira. S. , Sears Rollin G. , Hoseney R. C. , Cox Thomas S. , Gill Bikram S.
Published: July 2010

A disomic F2 substitution study was conducted to elucidate the chromosomal location of genes influencing the high grain‐protein concentration (GPC) in ‘Plainsman V’ (PV) wheat (Triticum aestivum L.) and to give preliminary information on genes influencing its dough mixogram peak time and tolerance. Plainsman V has been used extensively in the Kansas State University wheat breeding program and is included in the pedigree of many lines because of its high GPC and strong gluten. Data were collected over 2 yr on PV F2 substitution lines derived from crossing PV with the monosomic set of ‘Wichita’. In the first year, F3:4 lines from substitution lines were grown at two locations. The F3:4 lines IA, 1B, 4B, 5B, and 7A were identified as critical chromosomes. In a second study of the progeny, 1A, IB, and 7A had PV's higher GPC, suggesting chromosomal location of positive factors. Other chromosomes may be involved. Preliminary results suggest that Group 2 chromosomes have positive effects on mixogram peak time. The data do not give conclusive evidence for location of factors influencing mixogram tolerance; however, there is some evidence that there is a positive factor on 6A and a negative factor on 2D. In this study, no association was observed between location of factors influencing grain‐protein concentration and location of factors influencing the mixogram traits in Plainsman V.
Induced Mutations of a Genetic Suppressor of Resistance to Wheat Stem Rust
Authors: Williams Norman D. , Miller James D. , Klindworth Daryl L.
Published: July 2010

A genetic suppressor of resistance to stem rust, Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn., of wheat (Triticum aestivum L.) is on the long arm of chromosome 7D. Mutation or inactivation of the suppressor gene would allow expression of the suppressed resistance genes already present in hexaploid wheat or of resistance genes transferred to wheat from diploid or tetraploid relatives. Our objective was to induce a mutation of the suppressor gene and describe its inheritance. Seed treatment of the hexaploid wheat cultivar Canthatch (CTH) with ethyl methanesulfonate produced 15 stem rust‐resistant mutants. The mutant lines were tested for reaction to 13 races of stem rust, and crossed with CTH and 7D aneuploids of CTH and ‘Chinese Spring’ (CS). Parental, F1, F2, and F3 seedlings were tested for reaction to race CRL‐QSH of stem rust. Similarity among the 15 mutants in reactions to 13 races of stem rust indicated that each of the mutants had a similar genetic alteration resulting in an inactivated or deleted suppressor gene. The suppressor gene mutations showed incomplete dominance and monogenic inheritance in crosses with CTH. One mutant was ditelosomic 7DS and lacked the suppressor gene. Allelism tests indicated that the mutated gene(s) in the other 14 mutants were at or near the same locus on 7DL. Crosses between the mutants and CS monosomic 7D or CS ditelosomic 7DS indicated that CTH may have three recessive genes for resistance that were inhibited by the suppressor. The mutant lines may permit the use of the suppressed genes for stem rust resistance in hexaploid wheat and related species to breed hexaploid wheat cultivars with improved resistance.
Chromosomal Location of Wheat Quantitative Trait Loci Affecting Agronomic Performance of Seven Traits, Using Reciprocal Chromosome Substitutions
Authors: Berke Terry G. , Baenziger P. Stephen , Morris Rosalind
Published: July 2010

A major limitation to the genetic improvement of wheat (Triticum aestivum L.) is the lack of information about quantitative trait loci (QTLs). The objective of this study was to determine the chromosomal locations of QTLs controlling grain yield and yield components, grain test weight, plant height, and anthesis date. Reciprocal sets of chromosome substitution lines in duplicate between two hard red winter wheat cultivars, Cheyenne (CNN) and Wichita (WI), were used to identify the chromosomes bearing QTLs. Field trials were conducted in Nebraska at Lincoln in 1987, at Lincoln, Mead, and Alliance in 1988, and at Lincoln, Mead, Alliance, and North Platte in 1989. Wichita had major QTLs on chromosomes 3A and 6A that increased grain yield in Cheyenne and major QTLs on chromosome 36 that decreased grain yield in Cheyenne, while Cheyenne had major QTLs on chromosomes 3A and 6A that decreased grain yield in Wichita. The increase in grain yield by WI 3A and WI 6A was due to a significant increase in seed weight. The decrease in grain yield by CNN 3A and CNN 6A was due to a significant decrease in culms per square meter. The decrease in grain yield by WI 3B was due to a significant decrease in winterhardiness, resulting in decreased seed weight and culms per square meter. We identified one Wichita and seven Cheyenne chromosomes with QTLs affecting seeds per culm, seven Wichita and five Cheyenne chromosomes with QTLs affecting seed weight, one Wichita and three Cheyenne chromosomes with QTLs affecting culms per square meter, and one or more chromosomes with QTLs affecting each of the other agronomic traits.
Chromosomal Location of Wheat Quantitative Trait Loci Affecting Stability of Six Traits, Using Reciprocal Chromosome Substitutions
Authors: Berke Terry G. , Baenziger P. Stephen , Morris Rosalind
Published: July 2010

A major limitation to the genetic improvement of wheat (Triticum aestivum L.) is lack of information about the effects of quantitative trait loci (QTLs) on stability of agronomic traits across environments. Our objective was to determine the chromosomal locations of QTLs controlling stability of grain yield and yield components, grain test weight, and plant height. Reciprocal sets of chromosome substitution lines in duplicate between two hard red winter wheat cultivars, Cheyenne and Wichita, were used to identify chromosomes that carried QTLs affecting stability. Data from the two parental cultivars, 40 Wichita chromosome substitutions in Cheyenne, and 34 Cheyenne chromosome substitutions in Wichita, grown in six environments in Nebraska, were used to compute the regression coefficient on the environmental index (b1), the mean square of the deviation from regression (S2d), and the coefficient of variation (CV). Little variation existed among the substitution lines for S2d and CV, so bl was the primary stability parameter used to describe the lines. Wichita had one or more major QTLs on chromosomes 3A, 6A, 2B, and 3D that increased b1 of grain yield in Cheyenne. Cheyenne had one or more major QTLs on chromosome 1D that decreased b1 of grain yield in Wichita. We identified one Wichita and two Cheyenne chromosomes with QTLs affecting stability of seeds per culm, one Wichita and three Cheyemme chromosomes with QTLs affecting stability of seed weight, nine Wichita and eight Cheyenne chromosomes with QTLs affecting stability of culm per square meter, and seven Wichita and four Cheyenne chromosomes with QTLs affecting stability of grain test weight.
Vernalization Requirement of Winter and Spring Oat Genotypes
Authors: King Stephen R. , Bacon Robert K.
Published: July 2010

Unfavorable weather conditions often make it desirable to plant oat (Avena sativa L.) in the spring in areas where winter oat cultivars are usually planted. Information regarding vernalization requirements is needed to determine whether winter or spring oat cultivars should be planted. Twenty‐five winter and five spring oat genotypes were evaluated for responsiveness to vernalization. Germinated seeds were vernalized at 5 °C and a 12‐h photoperiod for 0,12,24, or 48 d. Seedlings were transplanted to a greenhouse with an 18‐h photoperiod and temperature of 21 °C day/18 °C night. All winter oat genotypes responded to cold treatment with a decrease in days to heading, whereas none of the spring oat cultivars responded to vernalization for days to heading. Although there was variability among three plantings of the experiment, 24 d of vernalization was sufficient to fully vernalize all winter genotypes. The length of time required for panicle emergence for the winter oat genotypes was reduced by the 24‐d cold treatment an average of 19 d compared with the nonvernalized controls. The cultivars Dubois and Madison were the most responsive to vernalization, showing an average decrease of 52 and 45 d to heading, respectively, after 24 d of cold treatment in three experiments. Vernalization reduced plant height in many of the winter oat genotypes. Dubois and Madison were the only genotypes that consistently increased in plant height in response to vernalization. There were no differences in any of the measured variables between the 48‐ and 24‐d treatments. Results indicate that either spring or winter oat can be planted in the spring in the winter oat area if the winter oat has a short, facultative vernalization requirement.
Identification and Inheritance of Metribuzin Tolerance in Wild Soybean
Authors: Kilen Thomas C. , He Guohao
Published: July 2010

An economically important agronomic trait that has not been evaluated extensively in the wild soybean (Glycine soja Sieb. & Zucc.) is tolerance to herbicides. Identification and genetic characterization of tolerance to a widely used herbicide, metribuzin [4‐amino‐6‐(l,l‐dimethylethyl)‐3‐(methylthio)‐l,2,4‐triazin‐5(4H)‐one], in G. soja may help provide greater diversity in the gene pool for this trait. This study was conducted to identify tolerance to metribuzin in the wild soybean and to determine the genetic control of the trait. Crosses were made between metribuzin‐tolerant G. soja selections and metribuzin‐sensitive selections of G. max (L.) Merr. The F1, F2, and F3 populations from these crosses were grown hydroponically, and evaluated for reaction to a concentration of 125 µg L−1 metribuzin. The F1 plants were tolerant, the F2 population segregated in a 3 tolerant : 1 sensitive ratio, and the F3 population segregated in 1 tolerant : 2 segregating : 1 sensitive ratio, suggesting a single dominant gene controlling tolerance. The F2 populations from crosses between metribuzin‐tolerant G. soja accessions and the metribuzin‐tolerant cultivar Tracy‐M were all tolerant. This indicates that tolerance to metribuzin in these two wild soybeam accessions is controlled by alleles at the same locus as the Hm gene in Tracy‐M. Therefore, the metribuzin tolerance in the wild soybean is probably the same as that found in most of the cultivated soybean accessions and in most commercial cultivars. The significance of identifying tolerance to a currently used herbicide in the wild soybean is the suggestion that other useful traits needed in modern agriculture may be found in this primitive gene pool.
Evaluation of Methods for Quantification of Drought Tolerance in Wheat
Authors: Clarke John M. , DePauw Ronald M. , Townley‐Smith T. Fred
Published: July 2010

Quantification of the drought tolerance of wheat (Triticum spp.) genotypes is of interest to physiologists investigating traits associated with adaptation to dry conditions and to breeders developing cultivars for dry areas. The objective of this research was to assess drought tolerance in terms of minimal depression of yield in dry compared with favorable environments (drought susceptibility index, S) with a superiority measure (P) based on the sum across environments of the mean‐squared differences between genotype yield and the maximum yield in each environment. Twenty‐five hexaploid (T. aestivum L.) and 16 tetraploid (T. turgidum L. var. durum) wheat genotypes were grown in separate experiments under dry and irrigated conditions on a Swinton loam (Aridic Haploboroll) soil. There was year‐to‐year variation in S within genotypes and changes in genotype ranking within years. No single cause for this variability was identified. The S index did not differentiate between potentially drought‐tolerant genotypes and those that had low yield potential from other causes. P was correlated with mean yield in both the hexaploid (−0.96**) and tetraploid (−0.94**) groups (both significant at P = 0.01). However, P was strongly influenced by high yield environments; this was alleviated by standardization of the yield data. Although P appears to be a possible method to quantify average superiority of genotypes across locations, its suitability requires further assessment. There seems to be no simple technique to quantify drought tolerance that would assist physiologists in choosing genotypes in which to evaluate putative drought tolerance mechanisms.
Response of Soybean Growth to Root and Canopy Competition
Authors: Marvel James N. , Beyrouty Craig A. , Gbur Edward E.
Published: July 2010

Interplant competition in soybean [Glycine max (L.) Merr.] influences plant growth. Because of the difficulty of evaluating root competition, studies to date have concentrated on competition within the canopy. We used a below‐ground porous membrane to isolate and evaluate the effects of root and canopy competition on soybean growth. Field studies were conducted in 1985 and 1986 on a Captina silt loam (fine‐silty, siliceous, mesic Typic Fragiudult) with four competition treatments imposed on ‘Forrest‘ soybean: (i) no competition, (ii) root competition only, (iii) canopy competition only, and (iv) root and canopy (combined) competition. At growth stage R4, leaf area was reduced 29% by root competition and 48% by canopy competition. Root competition reduced net assimilation rate by 48% in 1985 and 10% in 1986, while canopy competition resulted in a 28% reduction both years. Combined competition reduced total plant dry weight an average of 78%, with intermediate dry weights for root or canopy competition. At R4 and R8, shoot dry weight was reduced 31 and 43% with root competition, and 57 and 62% with canopy competition, respectively. Canopy competition reduced root dry weight at R4 by 43% in 1985 and 70% in 1986. Root competition reduced root dry weights in both years by 24 and 42% at R4 and R8, respectively. Canopy and combined competition resulted in taller plants with smaller stem circumferences while root competition did not alter shoot structure. Results suggest that canopy competition may have a greater influence on plant development than root competition.
Divergent Selection for Anthesis Date in Annual Ryegrass
Authors: McLean Scott D. , Watson Clarence E.
Published: July 2010

Anthesis date is the major factor controlling distribution of forage yield and quality of annual ryegrass (Lolium multiflorum Lam.) in the spring. This study was initiated to evaluate variation and selection response for anthesis date and to measure correlated responses in annual ryegrass. Four annual ryegrass cultivars were evaluated for heading date, anthesis date, spikelets per spike, and florets per spikelet over 3 yr in the field at Mississippi State, MS. Only spikelets per spike and florets per spikelet, showed significant cultivar × year interactions. Differences among cultivars were observed for all four characteristics. Two cycles of phenotypic recurrent selection for earlier and later antbesis date were performed on each cultivar. Response after two cycles of selection for late anthesis in the early cultivar, Florida 80, was greater (11.1 d) than selection for early anthesis (6.0 d); however, response to selection for early anthesis in the late cultivar, Marshall, was greater (4.8 d) than selection for late anthesis (2.7 d). The tetraploid, ‘Multimo’, exhibited similar responses to selection for both early and late anthesis date. Late selections within each cultivar showed increased numbers of spikelets per spike compared with the respective unselected parent population. Number of florets per spikelet decreased in most selected populations compared with the respective unselected parent populations. There appeared to be sufficient genetic variation after two cycles of selection to allow for additional gain from selection for anthesis date in most populations.
Genotype ✕ Environment Interaction Effects on Winter Rapeseed Yield and Oil Content
Authors: Shafii Bahman , Mahler Karen A. , Price William J. , Auld Dick L.
Published: July 2010

Since rapeseed (Brassica napus L. subsp, oleifera (Metzg.) Sinsk. biennis) is a relatively new crop in the USA, little is known about cultivar performance across diverse environments. During the 1986– 1987, 1987–1988 and 1988–1989 growing seasons, six cultivars of winter rapeseed were grown at 12, 16, and 17 locations across the USA, respectively. These genetically diverse cultivars were grown as controis in the U.S. Winter Rapeseed Variety Trial. Average seed yields across locations in these trials ranged from 0.727 to 6.287 Mg ha−1 while oil contents in these trials ranged from 33.6 to 45.4%. Testing of winter rapeseed cultivars in different environments is important in evaluating yield and oil content stability to define performance and a range of adaptation. Our objective was to diagnose the genotype × environment (GE) interaction patterns for seed yield and oil content using the Additive Main effects and Multiplicative Interaction (AMMI) statistical model. Results indicated a significant GE interaction influenced the relative ranking of genotypes (cultivars) across environments. ‘Glacier’ had small interaction effects for both seed yield and oil content. ‘Bienvenu’ produced the highest average yield across 27 environments (2.487 Mg ha−1). ‘Bridger’ had the highest percent oil content (40.9%), while Glacier and Bienvenu seemed more stable across 25 environments. Examination of the GE interaction structure revealed specific areas of the USA that could consistently produce competitive yields of high quality canola and industrial rapeseed if adapted cultivars were grown.
Performance and Stability of Pearl Millet Topcross Hybrids and Their Variety Pollinators
Authors: Mahalakshmi Viswanathan , Bidinger Francis R. , Rao Kattekola P. , Raju Dendukuri S.
Published: July 2010

A majority of farmers in the arid and semiarid regions of Africa and South Asia continue to cultivate their local landraces of pearl millet [Pennlsetum glaucum (L.) IL Br.], rather than improved varieties. The reasons for this preference for local landraces may include their better yield stability and adaptation to environmental stress, although their grain yield potential is often lower than that of the new varieties. This study was conducted to test the hypothesis that the yield potential of such landcrases could be improved without seriously affecting their stability and adaptability, by using them as pollinators in topcross hybrids. Three pollinator groups (five accessions per group) reflecting three levels of breeding effort were crossed on two malesterile lines selected to specifically advance time to flowering and to increase individual grain mass. Top crosses and their pollinators were evaluated in India, during the rainy season at three locations (ICRISAT Center, 17.50° N, 78.47° E; Anantapur, 14.68° N, 77.62° E; Fatehpur, 27.17° N, 75.13° E) in 1988 and 1989 and at Hisar (29.15° N, 75.73 ° E) in 1989, and during the dry season in irrigated and stress conditions at ICRISAT also in 1988 and 1989. Mean grain yields ranged from 66 to 477 g m−2. The adaptability, stability, and responsiveness of the top crosses and their pollinators were compared using joint regression analysis. Analyses of adaptability, based on the predicted grain yield of top crosses and their pollinators in two low yielding environments, indicated that the top crosses were either equal or superior to their pollinators. Analysis of stability based on the deviations from regression indicated that the top crosses were either as stable, or more so than their pollinators. Analyses of responsiveness, as measured by the regression coelticient, indicated that the top crosses were more responsive to improved environmental conditions than their pollinators. The results suggest that rapid improvement in adapted inndraces is possible through their use as topcross hybrids in pearl millet.
Pairwise Rank Superiority of Winter Wheat Genotype for Spring Stand
Authors: Souza Edward , Sunderman Donald W.
Published: July 2010

Rank statistics can be used as a simple method of summarizing multienvironment data when the assumptions of uniform variances and main effects across environments are violates. A pairwise rank superiority measure is described for analysis of genotypes across environments when usual statistical measures are invalid or too complex for clear data presentation. Eight years of spring stand data for five winter wheat (Triticum aestivum L. emend. Thell.) genotypes were summarized from two locations with intermittent infection by snow mold [Typhula spp. and Microdochium nivale (Ces. ex Beri. & Vogl.) Samuels & Hailer Fusarium nivale Fr Cesati] using ranking of pairs of cultivars to measure relative superiority across environments. For each cultivar pair, a snow mold tolerant cultivar was compared with a susceptible check or another tolerant cultivar. The percent of trials in which a tolerant genotype was superior to the comparison genotype was compared with the null hypothesis of equal performance for each genotype. The snow mold tolerant hard red winter wheat ‘Survivor’ was found to be superior to ‘Manning’, a locally adapted hard red winter wheat, in 78.8% of the trials in which significant stand reduction had occurred. Survivor was significantly superior to Manning for the ability to establish a spring stand based on a t‐test comparison to the null hypothesis of 50% (P < 0.01). Survivor was also superior to the hard red winter wheat cultivars Blizzard and Weston when significant stand reductions occurred, but Survivor was not superior to the soft white winter wheat cultivar Spragne. Measuring the frequency of superior performance within a set of environments with similar stress allows relatively simple cultivar recommendations to be made to growers despite the presence of genotype × environment interactions.
Soil Phosphorus Availability and Pearl Millet Water‐Use Efficiency
Authors: Payne William A. , Drew Malcolm C. , Hossner Lloyd R. , Lascano Robert J. , Onken Arthur B. , Wendt Charles W.
Published: July 2010

Pearl millet [Pennisetum glaucum (L.) R. Br.] production in the West African Sahel is constrained by low, erratic rainfall and low soil nutrient (particularly P) availability. Outdoor pot and growth chamber experiments tested the hypothesis that increasing soil P supply increases transpirational water‐use efficiency (WUET), under waterstressed and non‐water‐stressed conditions. Pearl millet was grown outdoors under semiarid conditions in covered pots containing 85 kg of acid, P‐deficient Betis sand (sandy, siliceous, thermic Psammentic Paleustalf). Plants were treated with four P levels and two water treatments, and harvested at 14‐d intervals. Significant main and interactive effects on WUET due to P level, water treatment, and time of harvest were found. The slope of the curve relating DM to cumulative transpiration (Tcum) increased with P level and water stress when data from all harvests were pooled. In the growth chamber, WUET of nonwater‐stressed plants ranged with increasing P level from 3.22 to 9.12 g kg−1 at 29 days after sowing (DAS) in pots containing 6 kg soil, and from 0.84 to 9.24 g kg−1 at 49 DAS in pots containing 18 kg soil. The ratio of leaf net photosynthetic rate to transpiration 0,WUEGMS,) at 500 μmol m−2 s−1 photosynthetic photon flux density (PPFD) ranged from 1.88μg mg−1 for plants receiving no P to 10.25μg mg−1 for those receiving 0.310 g P 6 kg−1 soil. Between PPFD levels orS00 and 2000 μmol m−2 s−1, plants receiving no P increased WUEGAS to only 3.60 μg mg−1, whereas those receiving higher levels of P increased WUEGAS to as much as 18.2μg mg−1. Our finding that increasing soil P avail° ability increases WUET under water‐stressed and non‐water‐stressed conditions reinforces previous conclusions that water supply in the Sahel and similar semiarid environments cannot be effectively managed for improved crop production without addressing soil fertility constraints.
Rapid and Nondestructive Method for Detecting Composition Changes in Wheat Germplasm Accessions
Authors: Tao Kar‐ling J. , Perrino Pietro , Spagnoletti Zeuli Pierluigi L.
Published: July 2010

Gene banks around the world have had difficulty detecting changes in the genetic composition of germplasm accessions after seed storage and regeneration. The large number of accessions requires a rapid and easy test. This study was conducted to develop such a test for wheat (Triticum spp.) accessions. A phenol test modified by soaking seeds in 40 °C water for 30 rain and then exposing them to 130 mM phenol solution vapor on a wire screen can differentiate among genetic types by staining in up to five colors: dark brown, brown, light brown, fawn, and ivory. The test is nondestructive. Phenol test results from gene‐bank accessions indicate that there was no significant change in the population composition after regeneration in homogeneous accessions such as bread wheat (T. aestivum L.) cultivars Sprint Aquileja, and Adria, and durum cultivars (T. turgidum L., durum group) Appulo, Capeiti, and Creso. Several heterogeneous durum wheat accessions showed significant changes, however. In the Italian durum wheat accession MG 8001, the dark brown phenol‐stained seeds increased from 11% to 95% after eight regeneration cycles. Gliadin polyacrylamide gel electrophoresis and root tip chromosome counting, conducted on the same seed, indicated that the dark‐brown phenol‐stained seeds were bread wheat instead of durum wheat. Thus, the modified phenol test could be a useful test for gene banks to detect changes in the composition of heterogeneous germplasm accessions after regeneration and storag.
Genetic and Maternal Variances and Covariances of Kernel Growth Traits in Winter Wheat
Authors: Rasyad Aslim , Van Sanford David A.
Published: July 2010

Early maturity is an essential characteristic of soft red winter (SRW) wheat (Triticum aestivum L. emend. Thell.) cultivars that are grown in a double‐crop system. Historically, breeders have used heading or flowering date as an indicator of maturity. We were interested in assaying variation for postanthesis traits that may affect maturity in a defined reference population of SRW wheat. Forty‐four F5 lines from a single‐cross population, and the 22 reciprocal F1, F2, and F3 kernel generations, were evaluated in several field experiments from 1987 to 1989. Anthesis date, kernel weight at 20 days after anthesis (DAA), kernel growth rate (KGR), final kernel weight, and effective filling period (EFP) were measured. Direct additive and maternal additive components of variance and heritability were estimated. We observed significant variation among the F5 lines for kernel weight at 20 DAA and for KGR, but not for EFP. Significant (P ≤ 0.05) maternal effects for kernel weight at 20 DAA and for KGR were observed in the F1 and F2 generations but were absent in the F3. Heritabilities ranged from 0.16 for EFP to 0.80 for anthesis date in the parental lines. We observed a significant genetic correlation (rG = 0.99, P < 0.01) between kernel weight at 20 DAA and KGR, which leads us to conclude that kernel weight at 20 DAA may be used as an indirect selection criterion for kernel growth rate in developing early‐maturing genotypes.
Partitioning of Genotype × Environment Interactions of Winter Wheat Forage Yield
Authors: Krenzer Eugene G. , Thompson J. David , Carver Brett F.
Published: July 2010

Wheat (Triticum aestivum L. emend. Thell) is used as a dual‐purpose crop in the southern Great Plains, with 35 to 55% of the acreage grazed in the fall and winter, followed by grain harvest in late spring. Cultivar selection is primarily based on grain yield. This study was conducted to characterize genotype × environment (GE) interactions for fall and winter forage production in hard red winter wheat and to identify cultivars with favorable levels of stable forage production. Eighteen cultivars were grown in six environments. Forage was clipped until the early joint stage (Feeke's 5–6), when canopy height reached ≈20 cm. Fall forage produced prior to winter dormancy, and winter regrowth before early joint, were both influenced by GE interactions. The mean correlation of each cultivar with all other cultivars ranged from 0.91 to 0.97 for fall forage and 0.84 to 0.93 for winter forage. Based on Shukla's stability variance (σ21), three cultivars were unstable (σ21 > 0) for fall forage, whereas 10 cultivars were unstable for winter forage. Cultivars with low mean correlations were also classified as unstable. Rank stability differences for fall forage resulted primarily from three genotypes (Agripro ‘Wrangler’, AGSECO ‘7846’, and ‘TAM W‐101’) showing exceptionally high stability rather than lack of stability. Changes in rank order would not be expected to hinder selection of hard red winter wheat genotypes stable for fall forage production. Fall forage yield differences were sufficiently large to be important to wheat‐stocker cattle producers.
Photoperiod, Temperature, and the Interval from Sowing to Tassel Initiation in Diverse Cultivars of Maize
Authors: Ellis R. H. , Summerfield R. J. , Edmeades G. O. , Roberts E. H.
Published: July 2010

Photoperiod and temperature influence the time from sowing to tassel initiation (TI) in maize (Zea mays L.), with appreciable genetic differences in relative sensitivity to these factors. Three experiments were run to examine these photothermal responses and genetic differences within 12 diverse cultivars chosen to represent germplasm adapted to temperate, tropical highland, tropical lowland, and subtropical environments. Photoperiod influenced the rate of progress toward TI in all cultivars (P < 0.05), with a threefold differences in sensitivity among them. In three of the more photoperiod‐sensitive cultivars (all adapted to the tropics or sub tropics), the value of the critical photoperiod, above which progress to TI is delayed by increase in photoperiod, was close to 13 h d−1. Temperature also influenced rate of progress toward TI. For many cultivars the optimum temperature (To) for rate of progress towards TI was appreciably cooler than the range from 30 to 34 °C that is generally assumed to apply throughout development from sowing to anthesis in maize; estimated values of To in a 12‐h photoperiod (Exp. 3) varied from 19 to 22 °C in the tropical highland cultivar H‐32 to 31 °C in the tropical lowland cultivar Tuxpeño Crema I Cycle 18. In the five cultivars examined, inherent earliness (i.e., time taken to TI in optimum environments) was almost identical, despite considerable differences in To, while relations between rate of progress to TI and suboptimal temperatures were curvilinear, with similar base values (mean 9.4 °C). Curvilinear relations were also detected at supraoptimal temperatures in three of the five cultivars. Curvilinearity in each of these relations (in contrast with the linear relations reported in many other crops) may be compatible with symptoms of damage to maize plants exposed continuously to extreme temperatures (e.g., 12 and 37 °C).
Ethylene Biosynthesis and Ethephon Metabolism and Transport in Barley
Authors: Foster Kenneth R. , Reid David M. , Pharis Richard P.
Published: July 2010

When applied to barley (Hordeum vulgare L.) for lodging control, ethephon (2‐chloroethylphosphonic acid) also promotes tillering. These tillers do not mature prior to harvest, and may compete for assimilates and reduce yield. This combined field and greenhouse study was conducted to investigate the possibility that promotion of tillering by ethephon includes (i) an effect of ethephon on ethylene biosynthesis, (ii) ethephon transport and metabolism, and (iii) a direct effect of ethephon in the plant base near the tiller buds. Ethylene release from flag leaves, spikes, and stems was determined by photoionization gas—liquid‐chromatography, 1‐Aminocyclopropane‐1‐earboxylic acid (ACC) and conjugated ACC were quantified by combined gas chromatography—selected ion monitoring—mass spectroscopy. Ethephon transport was monitored with [14C]ethephon, and by measuring ethylene release from untreated plant parts. Ethephon treatment resulted in a substantial increase in ethylene release from both flag leaves and spikes, peaking 1 to 2 d after treatment and remaining above controls for at least 15 d after treatment. No effect of treatment was observed on ACC and conjugated ACC levels; thus, ethephon application did not alter endogenous ethylene biosynthesis. Decreasing amounts of [14C]ethephon were observed (TLC analysis) in the flag leaves and spikes over a 27 d period after flag leaf treatment with [14C]ethephon. Increasing amounts of [14C]ethephon metabolites (putative conjugates) were found in these organs over the same period. Breakdown of these conjugates, followed by ethylene release, probably accounts for elevated long‐term ethylene emanation from flag leaves and spikes. while ethephon was transported from the flag leaf to the spike, little transport was observed from the flag leaf to the base of the plant. Injections of ethephon into the base promoted tillering, and reduced elongation of the upper stem. Foliar ethephon treatments which reduced plant height also increased post‐treatment tillering. It is concluded that the tillering response following ethephon treatment does not include a modification of ethylene biosynthesis, and the amount of ethephon imported into the base is insufficient to be a direct signal for the tillering response. Induction of tiller growth may be a result of ethephon inhibition of upper stem elongation, rather than a direct response of the buds to ethephon.
Development of Sulfonylurea‐Resistant Rapeseed Using Chemical Mutagenesis
Authors: Tonnemaker Kole A. , Auld Dick L. , Thill Donald C. , Mallory‐Smith Carol A. , Erickson Donna A.
Published: July 2010

Residual levels of sulfonylurea (SU) herbicides in the soil have limited rapeseed (Brassica napus L. var. napus) production in the Pacific Northwest. In a greenhouse screening procedure, the test herbicide suppressed the growth of susceptible rapeseed plants but allowed normal growth of resistant plants. Mutant (M2) populations of ‘Cascade’, ‘Bridger’, and ‘Cathy’ winter rapeseed, ‘R‐500’ spring rapeseed (B. rapa L. subsp. rapa), and ‘Tilney’ spring mustard (Sinapis alba L.; syn F. hirta Moench.) were screened with DPX‐G8311, a 5:1 mixture of the SU herbicides chlorsulfuron (2‐chloro‐N‐[[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)amino]carbonyl]benzenesulfonamide) and metsulfuron {(methyl l‐[[[[(4‐methoxy‐6‐methyl‐l,3,5‐triazin‐2‐yl)‐amino]carbonyl]amino]sulfonyl]benzoate)}, applied preemergence at 7.5 g a.i. ha−1. Approximately 243 000 M2 seedlings were screened and 178 were selected for additional tests. In progeny tests, several M3 and M4 families were identified that survived 6.5 g a.i. ha−1 DPX‐G8311 applied preemergence but failed to survive the same rate of DPX‐G8311 applied postemergence. DPX‐G8311 was applied preemergence at 0 to 64 g a.i. ha−1, to one M3 and six M4 families to determine a dose × family response relationship. Calculated 50% growth reduction (GR50) values for both number of nodes produced and dry weight accumulation were up to 25 times greater for the selected M3 and M4 families than for the susceptible cultivar Cascade. Rapeseed lines resistant to soil residual levels of SU herbicides but susceptible to SU herbicide foliar applied would allow rapeseed to be planted after a small‐grain cereal to which a SU herbicide had been applied.
Environments for Selecting Widely Adapted Spring Wheat
Authors: Braun Hans‐Joachim , Pfeiffer Wolfgang H. , Pollmer Wolfgang G.
Published: July 2010

Breeding widely adapted wheat (Triticum aestivum L.) genotypes with stable and high yields across environments is particularly important for developing countries since yield stabilizing inputs are often limited or not available. To evaluate the screening ability of locations for identification of such genotypes, data collected for 19 yr by the International Spring Wheat Yield Nursery (ISWYN) were analyzed; 1221 trials at 268 locations in 69 countries were involved. To compare single‐experiment parameters, i.e., genotypic variance (σ̂2g)k, error variance (σ̂2e)k, heritability (h2)k, and coefficient of variation (CV)k, trials without major biotic stresses were divided into three groups according to mean grain yield. Genotypic variance, error variance, and heritability increased and (CV)k decreased with yield. Group means for the four parameters were significantly (P = 0.01) different. A fourth group containing trials with major biotic stresses had the highest, but not significantly higher, average estimates for (σ̂2g)k, (h2)k, and (CV)k. The screening ability for each location was calculated as the correlation, rk, between mean grain yield of genotypes at each location and mean yield across locations. The screening ability was highest for locations with no major abiotic and biotic stress factors apart from leaf rust (Puccinia recondita Roberge ex Desmaz. f. sp. tritici) and stem rust (P. graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn.). CIMMYT's principal test site, Ciudad Obrégon, Sonora, Mexico, was most suitable for screening, with an average rk of 0.77. Sensitivity to photoperiod, cold tolerance, need for late maturity, tolerance to problem soils, and resistance to diseases other than rusts were the main adaptation‐limiting and location‐specific factors.
Phenological Variability: Effect on Determination of Leaf Water Loss in Wheat
Authors: Clarke John M.
Published: July 2010

Low rate of water loss (RWL) from excised leaves has been suggested for screening wheat (Triticum spp.) genotypes for adaptation to dry growing conditions. Large‐scale RWL screening of phenologically diverse genotypes could be difficult, because RWL is known to vary within genotypes with leaf age and insertion level. To evaluate the effect of phenological diversity on measurement of RWL, 10 durum wheat (T. turgidum L. var. durum) genotypes were grown for 3 yr (1988‐1990), each with three planting dates, on an Aridic Haploboroll at Swift Current, SK, Canada. Heading dates of the genotypes varied by an average of 7 d; across seeding dates, the heading date range was 19 to 32 d. Leaves were sampled from the three seeding dates for RWL determination at various growth stages. Genotype seeding date interactions were significant (P < 0.01) in many cases, but significant (P = 0.05) changes in genotype rank order occurred for only one sampling date in 1989, and for three dates in 1990. Similarly, there were significant (P < 0.01) genotype × sampling day interactions within seeding dates and some significant (P = 0.05) changes in genotype rank order. In most cases the rank changes were comparisons in which some genotypes had passed the heading stage and others had not. It appears that RWL screening of phenologically diverse genotypes is possible with low risk of genotype growth stage interactions, provided that sampling is completed before any genotypes reach the heading stage of growth.
Cotton Seedling and First‐Bloom Plant Characteristics: Relationships with Drought‐Influenced Boll Abscission and Lint Yield
Authors: Cook Charles G. , El‐Zik Kamal M.
Published: July 2010

Root growth and distribution are important plant adaptations to conditions where limited soil water availability is a major constraint to crop growth and yield. Field studies were conducted to evaluate root characteristics at seedling stage and first bloom of six cotton (Gossypium hirsutum L.) genotypes, and to determine the relationship between root growth parameters and drought‐influenced boll abscission and lint yield. Genotypes included in the studies were: Tamcot SP37H (SP37H), Tamcot CD3H (CD3H), TX‐CABUCS‐2‐1‐83 (CABUCS), TX.MACAOS‐3‐84 (MACAOS), Paymaster 303 (PAY303), and Deltapine 41 (DPL41). Significant differences occurred between genotypes for seedling and first‐bloom plant measurements, with CD3H and CABUCS having higher levels of seedling vigor, more rapid root system establishment and lower root‐to‐shoot ratios. Regression analyses indicated a positive association (R2 = 0.47, P < 0.01) between drought‐induced boll abscission and root‐to‐shoot ratio at first bloom, while a negative relationship (R2 = 0.30, P < 0.01) was observed between dryland lint yield and first‐bloom root‐to‐shoot ratio. Results suggest that selection for and incorporation of increased seedling vigor, rapid root‐system establishment and lower root‐to‐shoot ratios into future cotton germplasm could improve drought tolerance and lint yields in regions subjected to limited or poorly distributed rainfall conditions.
Nulls for the Major Soybean Bowman‐Birk Protease Inhibitor in the Genus Glycine
Authors: Domagalski Juliann M. , Kollipara Krishna P. , Bates Anne H. , Brandon David L. , Friedman Mendel , Hymowitz Theodore
Published: July 2010

The Bowman‐Bilk protease inhibitor (BBI) is a major antinutritional factor in soybean [Glycine max (L.) Merr.]. This study was conducted to determine nulls for the major soybean BBI in the genus Glycine. A monoclonal antibody‐based competitive enzyme‐linked immunosorbent assay (ELISA) was used to rapidly detect the relative levels of the major soybean BBI in unpurified seed extracts. A total of 12 690 accessions from 13 species were tested. All of the G. max and G. soja Siebold & Zucc. accessions from the USDA Soybean Germplasm Collection contained BBI. The BBI nulls were found hi several of the wild perennial species: G. curvata Tind., G. cyrtoloba Tind., G. latifolia (Benth.) Newell & Hymowitz, G. microphylla (Benth.) Tind, G. tabacina (Labill.) Benth., and G. tomentella Hayata. The absence of BBI was confirmed by additional immunochemical methods and by enzymatic determination of trypsin and chymotrypsin inhibition. The BBI nulls identified in this study could potentially be utilized in the production of a soybean cultivar lacking the major soybean BBI.
Inheritance of Alectra Resistance in Cowpea Genotype B 301
Authors: Singh B. B. , Emechebe A. M. , Atokple I. D. K.
Published: July 2010

Two parasitic weeds, Striga gesnerioides (Willd.) Vatke and Alectra vogelii Benth., cause heavy yield losses in cowpea (Vigna unguiculata (L.) Walp.) throughout the semiarid regions of sub‐Saharan Africa. Several sources of resistance have been identified, including B 301, a landrace from Botswana that has shown complete resistance to both striga and alectra. Striga resistance in B 301 is conditioned by a single dominant gene. Our objective was to determine the inheritance of alectra resistance. B 301 was crossed to three susceptible cultivars (IT84S‐2246‐4, SUVITA‐2, and IT82D‐849) and F1, F2, and backcross seeds were obtained. The reaction of parental, F1, F2, and backcross plants to alectra infestation was evaluated. Test populations were planted in plastic pots of 13 cm diani. filled with a mixture of sand and soil and ≈800 alectra seeds. The roots of each plant were examined for alectra attachment 10 wk after planting, and the number of resistant and susceptible plants in each population were recorded. All plants of B 301 and backcrosses to B 301 were completely free from alectra. All plants of IT84S‐2246‐4, SUVITA‐2, and IT82D‐849 were susceptible. All F2 populations segregated 15 resistant : 1 susceptible, and backcrosses to the susceptible parents segregated 3 resistant : 1 susceptible indicating duplicate dominant gene inheritance. We propose the gene symbols Rav1 and Rav2 (resistance to Alectra vogelii) for this trait.
Responses to Reciprocal Recurrent Selection in BSSS and BSCB1 Maize Populations
Authors: Keeratinijakal Vichien , Lamkey Kendall R.
Published: July 2010

Improvement of germplasm as a parental source for developing inbreds has been an important part of most maize (Zea mays L.) breeding programs. Reciprocal recurrent selection is a cyclical breeding procedure designed to improve the interpopulation cross of two base populations. The objective of this study was to evaluate the direct and indirect responses of 11 cycles of reciprocal recurrent selection in the BSSS(R) (Iowa Stiff Stalk Synthetic) and BSCB1(R) (Iowa Corn Borer Synthethic no. 1) maize populations. The populations per se, populations per se selfed, interpopulation crosses, and interpopulation crosses selfed corresponding to C0, C4, C7, C8, C9, C10, and C11 of the populations were evaluated. Testcrosses of the original and advanced cycles of the populations per se with inbreds B73 and Mo17 and with BSSS(R)C0 and BSCB1(R)C0 also were evaluated in the study. Response in grain yield of the BSSS(R) × BSCB1(R) interpopulation cross was 6.95% (or 0.28 Mg ha‐1) cycle‐1. Grain yield of BSCB1(R) increased 1.94% (or 0.06 Mg ha‐1) cycle‐1, but grain yield of BSSS(R) did not change significantly. Midparent heterosis of the interpopulation cross increased from 25.44 to 76.04% from C0 to C11. Inbreeding depression in the population crosses increased from 1.01 to 2.32 Mg ha‐1 after 11 cycles of selection. The frequency of heterozygotes for grain yield in the population crosses seems to have increased with cycles of selection. Testcrosses to the C0 populations and the inbreds showed linear increases in grain yield, indicating that selection Improved general and specific combining ability of the populations. Selection was effective in reducing root and stalk lodging. No changes in grain moisture were observed. changes in other agronomic traits were in the desired direction.
Coefficient of Parentage and Cluster Analysis of North American Dry Bean Cultivars
Authors: McClean Phillip E. , Myers James R. , Hammond James J.
Published: July 2010

Archaeological, morphological, and biochemical data suggest that common bean (Phaseolus vulgaris L.) was domesticated separately in South America and Central America. Variation in seed size, shape, and color is common in both centers of domestication and has been maintained as market classes. Despite extensive global transport, market classes have remained distinct. Although variation has been measured in genotypes from the two centers of domestication, the inter‐ and intra‐market class genetic diversity among North American dry bean cultivars is generally unknown. Estimating genetic diversity improves the assessment of potential vulnerability to disease epidemics and the design of experiments requiring diverse genotypes. One method of assessing genetic diversity, based on pedigrees, is the coefficient of parentage (r). Coefficient of parentage data can be used in cluster analysis to identify groups of related cultivars. This study used the coefficient of parentage ta determine the degree of relationship among 143 dry bean plant introductions, landraces, breeding lines, and cultivars, represent. ing the major market classes grown in North America. Using r‐values, 16 clusters were found, with 13 cultivars unassigned to any cluster. Three major clusters, which corresponded to small (navy and black), medium (pinto, pink, great northern, and red Mexican), and large (kidney) seed size, were observed. Crossing among these major groups was rare, although more recombination had occurred between the large and medium‐seed size groups than between any other combination of groups. In general, the medium‐seed size group exhibited more recombination and greater variability than the small‐seed group. Mean within cluster r‐values suggest that intra‐market class genetic diversity is narrow, but the genetic diversity among market classes is greater. Therefore, exploiting the diversity among market classes would broaden the genetic base of dry bean breeding populations.