bluuebunny/crossref_metadata_2025 huggingface dataset:
Yield Evaluation of a Glyphosate‐Tolerant Soybean Line after Treatment with Glyphosate
Authors: Delannay X. , Bauman T. T. , Beighley D. H. , Buettner M. J. , Coble H. D. , DeFelice M. S. , Derting C. W. , Diedrick T. J. , Griffin J. L. , Hagood E. S. , Hancock F. G. , Hart S. E. , LaVallee B. J. , Loux M. M. , Lueschen W. E. , Matson K. W. , Moots C. K. , Murdock E. , Nickell A. D. , Owen M. D. K. , Paschal E. H. , Prochaska L. M. , Raymond P. J. , Reynolds D. B. , Rhodes W. K. , Roeth F. W. , Sprankle P. L. , Tarochione L. J. , Tinius C. N. , Walker R. H. , Wax L. M. , Weigelt H. D. , Padgette S. R.
Published: July 2010

Transformation of soybean [Glycine max (L.) Merr.] with a gene encoding a glyphosate‐tolerance 5‐enolpyruvylshikimate‐3‐phosphate synthase enzyme from Agrobacterium sp. strain CP4 resulted in the development of glyphosate‐tolerant line 40‐3‐2. Glyphosate (N‐phosphonomethyl glycine) is the active ingredient of Roundup herbicide. Line 40‐3‐2 was yield tested at 17 locations in 1992,23 locations in 1993, and 18 locations in 1994. At those locations, broadcast applications of glyphosate at various rates were made over 40‐3‐2 or its derivatives from early vegetative growth to pod fill. No significant yield reduction was observed as a result of the glyphosate treatment at any of the locations. Development of glyphosate‐tolerant soybean promises to provide the farmer with access to a new weed control system that should result in lower production costs and reliable weed control under a wide range of conditions.
Combining Ability for Maize Weevil Preference of Maize Grain
Authors: Kang Manjit S. , Zhang Yudong , Magari Robert
Published: July 2010

Maize weevil (Sitophilus zeamais Motschulsky) can cause severe grain damage in maize (Zea mays L.). Knowledge of inheritance of weevils' preference would be helpful in designing breeding strategies to develop more tolerant/resistant cultivars. This study was conducted to estimate general (GCA) and specific combining ability (SCA) for weevil preference/nonpreference. We used a 10‐parent diallel cross in 1992 (Griffmg's Method 3, Model 1). In 1993, due to insufficient seeds for some crosses, two eight‐parent diallels (Griffing's Method 4, Model 1) were evaluated for GCA and SCA for maize weevil preference of maize grain. The two eight‐parent diailels were subsets of the original 10‐parent diallel. Second generation grain samples (100 g per plot) from F1 crosses grown in the field were evaluated for maize weevil preference during 96‐d (1992 experiment) and 108‐d (1993 experiments) periods in the laboratory. The GCA, SCA, and reciprocal mean squares from the 10‐parent diallel results from 1992 were significant. Both GCA and SCA were important in the analysis of the Subset 1 eight‐parent diallel combined across years, whereas only GCA was significant in the Subset 2 eight‐parent diallel combined across 1992 and 1993 data. Positive effects indicated non‐preference and negative effects, preference of grain. Common parent means and GCA effects showed that L108 transmitted the most nonpreference and Mo17, the least nonpreference to its hybrids. In the 1992 data, significant positive GCA effects were detected in L108, L605, and L654; and significant negative GCA effects in B73, Mo17, L329, L729, and L266. Mol7 had a significant positive maternal effect (11.6), whereas B73 had significant negative maternal effect (−11.93). The single cross Mo17♀ × B73♂ would possess more nonpreference than its reciprocal cross. Combined across years, analyses of two eight‐parent diallel subsets of the original 10‐parent diallel indicated GCA was more important than SCA in inheritance of preference/nonpreference.
Modifying Seedling Photomorphogenesis in Kleingrass by Recurrent Selection
Authors: Tischler C. R. , Voigt P. W.
Published: July 2010

In emerging Panicoid grass seedlings, elongation of the subcoleoptile internode (SCI) stops shortly after the coleoptile tip receives a red light stimulus. This results in final placement of the crown node (CN) near the soil surface. Because adventitious roots originate from the CN, excessive elongation of the SCI places the CN above the soil surface, adversely impacting seedling establishment. A recently described continuous low light system identifies species with excessive CN elevation. Our objectives were to use this system to determine if CN positioning could be modified by selection. Three cycles of recurrent selection were performed for elevated crown (EC) and low crown (LC) CN placement in kleingrass (Panicum coloratum L.) in a continuous low light (1.5 umol m−2 s−2) environment from 1991 to 1994 in central Texas. Selection in both directions was successful. In the EC populations, a relatively linear increase in CN elevation was observed across the three cycles, while in the LC populations, most of the progress was made in the first cycle. Effects of selection for CN placement on shoot growth were minor. A small increase was observed with selection for higher CN placement. The Cycle 3 EC and LC germplasm should be useful for further characterizing seedling photo‐morphological responses. In addition, the Cycle 3 LC germplasm should be less prone to excessive SCI elongation in field environments and may have superior establishment characteristics.
Variation in Water‐Use Efficiency and Its Components in Wheat: II. Pot and Field Experiments
Authors: Ehdaie B.
Published: July 2010

Two models have been suggested to facilitate the study of genetic variation for seasonal water‐use efficiency (WUE) and its components in spring bread wheat (Triticum aestivum L.). These models were used to estimate the contribution of each component trait to variation in WUE. Eight diverse bread wheat cultivars were grown in replicated pot and field experiments under well‐watered and droughted conditions. Significant genotypic variation was observed for WUE (ratio of grain yield to water used), evapotranspiration efficiency (ETE, ratio of total dry matter to water used), and harvest index (HI, ratio of grain yield to total dry matter). Modern short cultivars, on average, had higher WUE than old tall cultivars in well‐watered (1.225 vs. 0.984 g kg−1) and droughted (1.198 vs. 0.860 g kg−1) pot conditions, due mainly to higher HI. Two old tall cultivars exhibited highest values for ETE. Harvest index and ETE accounted for 85 and 15% and for 81 and 19% of variation in WUE in well‐watered and droughted conditions, respectively. Harvest index had a higher direct effect and was more highly associated with WUE than ETE. The negative correlation between HI and ETE was not significant. Carbon isotope discrimination (Δ) showed negative correlation with ETE in well‐watered ( − 0.82) and droughted ( − 0.68) treatments. Grain yield and HI of modern short cultivars, on average, were higher than those of old tall cultivars under field conditions. Mean Δ was lower in droughted (17.9%o) than in well‐watered (18.9%o) field conditions. Plant growth rates estimated at boot stage and at anthesis were negatively associated with a drought susceptibility index based on grain yield. Drought susceptibility index was not correlated with Δ. Water‐use efficiency in wheat could be improved by improving either transpiration efficiency or ETE.
Effects of Foliar Methanol Applications on Crop Yield
Authors: Albrecht S. L. , Douglas C. L. , Klepper E. L. , Rasmussen P. E. , Rickman R. W. , Smiley R. W. , Wilkins D. E. , Wysocki D. J.
Published: July 2010

Recent reports indicate that vegetative growth and yield of C3 crops are enhanced by foliar methanol application and that overall crop water use was reduced by methanol sprays. It has been suggested that methanol may act as a C source for the plant and a photorespiration inhibitor. Field experiments were conducted near Pendleton, OR, during 1993 and 1994 to determine if foliar methanol applications would increase crop growth and yield in the dryland agroecosystems common to the Pacific Northwest. Methanol solutions (200 or 400 mL L−1 with a surfactant) were applied to winter wheat (Triticum aestivum L.), spring wheat, spring barley (Hordeum vulgare L.) and pea (Pisum sativum L.) at several plant growth stages. Phytotoxic symptoms were observed only with the highest concentration of methanol. No significant response, either beneficial or detrimental, to methanol application was found in any crop. No differences were found in stomatal conductance or leaf specific weight between any methanol treatment and the controls. Methanol applications did not significantly increase crop growth or yield. We concluded that methanol applications will not benefit grain and pea production in the northwestern USA.
Respiration and Mitochondrial Characteristics of Imbibing Maize Embryos Damaged by High Temperatures during Desiccation
Authors: Madden R. F. , Burris J. S.
Published: July 2010

Hybrid maize (Zea mays L.) seed artificially dried to 120 g H2O kg−1 moisture in air temperatures of either 35 (LT) or 45°C (HT) was used to study the effect of desiccation temperature on mitochondrial function during early imbibition. In embryo culture experiments, embryo growth was delayed for embryos excised from HT treated seed compared with LT samples. After 1 h of imbibition, the rate of O2 uptake by LT axis tissue was greater than for HT dried samples. Uptake rates continued to increase for LT samples through the first 6 h of imbibition while rates for HT axes remained constant. Mitochondria isolated from LT axis tissue that had undergone imbibition for 4 h exhibited respiratory control with oxidative phosphorylation efficiency values of 0.79 and 0.77 for NADH and succinate assays, respectively. Mitochondria from imbibing HT axis tissue exhibited no respiratory control. Electron micrographs of cells from the radicle meristem region of both treatments showed that mitochondrial development during the initial 24 h of imbibition was impaired in HT samples. These results suggest that mitochondrial function and development, during the initial stages of embryonic tissue hydration, is impaired when maize seed are artificially dried with high air temperatures. We conclude that the development of mitochondrial function during this period is a key element in determining the rate of germination and subsequent seedling growth.
Evaluation of a Core Collection to Identify Resistance to Late Leafspot in Peanut
Authors: Holbrook C. Corley , Anderson William F.
Published: July 2010

Core collections have many potential uses and could greatly increase the utilization of germplasm resources. A core collection was recently selected for the U.S. germplasm collection of peanut (Arachis hypogaea L.) by clustering accessions based on phenotypic similarities and then randomly sampling 10% from each cluster. During the period 1986 to 1991, field studies were conducted to screen the entire collection for resistance to late leafspot [Phaeoisariopsis personata (Berk. & M.A. Curtis) Arx syn. Cercosporidium personatum (Berk. & M.A. Curtis)]. The purpose of this study was to use information on leafspot resistance for the entire collection to test the core collection concept in peanut. Disease ratings for the core collection accession(s) within each cluster were defined as the indicator value for that cluster. Data were examined to determine how many leafspot‐resistant accessions would have been identified by examining the core collection and all accessions from clusters having a resistant indicator value. The use of this two‐stage screening approach with the peanut core collection would have resulted in the identification of 61 leafspot resistant accessions. This approach would have required screening 27% of the entire collection and would have identified 54% of the resistant accessions in the entire collection. This approach would have resulted in the identification of the best four and eight of the best 10 sources of resistance in the entire collection. These results demonstrate that this core collection can be used to improve the efficiency of peanut germplasm evaluations.
Responses of Red Clover Cultivars to Stemphylium Leaf Spot
Authors: Berg C. C. , Leath K. T.
Published: July 2010

Stemphylium leaf spot, caused by Stemphylium sarciniforme (Cav.) Wiltsh., occurs on red clover (Trifolium pratense L.) at high severity levels in the northeastern USA and Canada during most seasons. Information on genetic variability for resistance to the disease and the effect of the disease on forage yield of red clover is lacking. The objectives of this research were to assess the levels of Stemphylium leaf spot on cultivars of red clover and to determine the impact of the disease on forage yield. Red clover was grown in the greenhouse and inoculated with S. sarciniforme to determine the levels of resistance within and among cultivars and to ascertain the degree of dry matter yield losses caused by this disease. Significant differences in leaf spot size severity scores occurred among 15 cultivars, but even the most resistant cultivars were scored as susceptible. Within each cultivar, 1 to 10% of the plants were scored as resistant phenotypes. When ≈ 30% of leaf area was affected by Stemphylium leaf spot, forage yield was reduced up to 30%. Uninoculated regrowth from previously inoculated plants was also reduced up to 30%. Selection for resistance to this disease in red clover should result in the development of resistant germplasm and should improve forage yield of the species.
Recombination‐Facilitated RAPD Marker‐Assisted Selection for Disease Resistance in Common Bean
Authors: Miklas Philip N. , Afanador Lucia , Kelly James D.
Published: July 2010

The use of RAPDs (random amplified polymorphic DNA) for indirect selection of disease resistance in common bean (Phaseolus vulgaris L.) is often limited by the amplification in susceptible germ plasm of DNA fragments equal in size to the resistance‐linked markers. We investigated whether a recombinant individual, with recessive resistance (bc‐3bc‐3) to bean common mosaic virus, but lacking the RAPD OAD19690 originally linked in repulsion, would enable indirect selection when crossed to a susceptible cv. C‐20 with an amplified fragment equal in size to OAD19690. Similar use of a recombinant for the marker OS13660, originally linked in coupling but now in repulsion with bc‐3, was investigated. Each marker segregated in reverse orientation with bc‐3 in a single population as the resistant parent was recombinant for both RAPDs. In the resulting F2 population of 81 individuals, OAD19690, originally in repulsion, now cosegregated in coupling with the bc‐3 allele, and could be used to obtain resistant progeny by selecting against it. Conversely, OS13660, originally in coupling, now cosegregated in repulsion. The strategy of recombination‐facilitated marker‐assisted selection has the potential to: (i) overcome limited use of dominant RAPD markers by broadening their range of application across all susceptible genotypes, (ii) change linkage orientation of a dominant RAPD marker to that with the greatest selection efficiency for a particular breeding program, and (iii) indicate whether a RAPD marker and same‐sized fragment assort independently or are amplified from the same or nearby genomic region.
Interpreting Yield Instability in Pea Using Genotypic and Environmental Covariates
Authors: Biarnès‐Dumoulin Véronique , Denis Jean‐Baptiste , Lejeune‐Héanut Isabelle , Etévé Gérard
Published: July 2010

The improvement of yield stability in many grain legume species and especially in dry pea (Pisum sativum L.) is a major breeding objective. It is therefore essential that breeders understand the basis of the yield instability phenomenon in order to develop stable and high yielding cultivars. The study of 10 genotypes, sown at two dates (early/late), during 2 yr (1991–1992), in France, at three I.N.R.A. experimental stations (Mons, Versailles, Dijon), confirmed the existence of high variability for yield. The environmental effect was preponderant and essentially due to differences of soil water availability during the flowering period. Genotype × environment (g × e) interaction also played an important part in yield variability. A factorial regression analysis was conducted with genotypic and environmental covariates to determine the genotypic morphological traits and the environmental factors involved in the g × e interaction. Three covariates played an important role: node number of the first flower (N1F) and the mean number of reproductive nodes (NR) of the main stem, as genotypic covariates, and the meteorological water balance during the flowering period (MWBF), as an environmental covariate. These variables explained 64% of the total g × e interaction. N1F and NR define, respectively, the beginning and the duration of the seed set period on the main stem of the plant. These results suggest that an important part of the g × e interaction in pea is determined by the differential response of genotypes, according to their earliness to flower (estimated by N1F) and the duration of the seed set period (determined by NR), when grown in environments with drought stress during the sensitive flowering period.
Physiology, Morphology, and Growth of Individual Plants of Selected and Unselected Bahiagrass Populations
Authors: Pedreira C. G. S. , Brown R. H.
Published: July 2010

Selection in ‘Pensacola’ bahiagrass (Paspalum notatum Flugge var. ‘saurae’ Parodi) has resulted in populations with higher forage yields. This research was conducted to study physiological and morphological traits that might be related to the yield increases. Plants of populations representing selection Cycles 0 (Pensacola), 9 (‘Tifton 9’) and 14 (T14) were grown in the greenhouse and leaf photosynthesis and plant growth were measured. Height and diameter were measured and rhizomes were counted on spaced plants of the same populations in the field. One field experiment was established with seedlings, and another with seedlings and plants taken from plots mowed to 3.5 cm every 2 wk for 2 yr. Leaf photosynthesis was higher for Pensacola than for Tifton 9 and T14. Dry weights of greenhouse‐grown plants were similar at 84 d of age, but for older plants of Tifton 9 and T14 weights were 31 and 58% greater, respectively, than for Pensacola. Tifton 9 and T14 were 26 and 60% taller, respectively, than Pensacola at 84 d of age, and height/diameter ratios of field‐grown plants were greater for Tifton 9 and T14, Pensacola had more rhizomes than Tifton 9 and T14. Plants of T14 from mowed plots were more prostrate and had 2.8 times more rhizomes than those from seedlings, but for Tifton 9 and Pensacola the source of plants had no effect. Winter survival at this location was greater than 90% for Pensacola, but it was 51 and 64% for T14 in two experiments. It appears that selection for increased yield in bahiagrass resulted in taller plants with fewer rhizomes, a greater tendency for winter injury, and a greater susceptibility to population shifts under close, frequent mowing.
Crown Freezing Tolerance and Field Winter Survival of Winter Cereals in Eastern Canada
Authors: Bridger G. M. , Falk D. E. , McKersie B. D. , Smith D. L.
Published: July 2010

Winter cereal production in many areas of eastern Canada is limited by a lack of consistent winter survival. A cold acclimated crown freezing test has been adopted to circumvent high variability associated with field tests. Relationships between field survival and crown freezing tolerance (LT50, lethal temperature for 50% of seedlings) of artificially acclimated wheat (Triticura aestivum L.) and barley (Hordeum vulgare L.) were investigated. Field survival was evaluated in 1989 and 1990 at several sites in southern Ontario with a field survival index (FSI). In separate experiments, the effect of rooting medium (calcined clay or soil), cold acclimation regime (constant at 2°C and 12‐h photoperiod or decreasing temperature and photoperiod), and developmental stage (two‐leaf or five‐leaf) on crown freezing tolerance were assessed with six genotypes of wheat and barley. The ability of the crown freezing test to differentiate 11 genotypes each of wheat and barley with from two to 20 replicates was investigated. The correlation between FSI and LT50 was strong, ranging from −0.66 to −0.96 and was not affected by rooting media, developmental stage, or cold acclimation regime. Increasing the number of replicates did not affect the relationship between FSI and LT50, but did increase precision. Eight replications were required to detect differences of 1°C among genotypes. A I°C difference corresponded to a field survival difference of 7.1% for barley and 4.6% for wheat. The range in field survival was narrow at 19.2% for barley and 22.6% for wheat. This implies that, under eastern Canadianc onditions, eight replicates of a crown freezing test could broadly categorize genotypes according to winterhardiness, but would not be sufficient to detect small differences. However, where freezing tests are used to assist in the identification of genotypes with higher levels of winterhardiness, a wide range of protocols can be used.
Immunoflourescent Localization of RuBPCase in Degraded C4 Grass Tissue
Authors: Miller M. S. , Moser L. E. , Waller S. S. , Kirch B. H. , Klopfenstein T. J.
Published: July 2010

Digestion‐resistant tissues found in C4 grasses may allow soluble protein to escape rumen degradation. The objective of this study was to use immunofluorescent localization to follow loss of ribulose 1,5‐bisphosphate carboxylase/oxygenase (RuBPCase) from switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman) parenchyma bundle sheath cells (BSC) during rumen degradation. Fluorescent signal was observed from switchgrass and big bluestem BSC through 24 and 16 h in situ digestion, respectively, and from BSC associated with both intact tissue fragments, and isolated vascular bundles in omasal digesta and fecal material from steers (Bos tarus L.) grazing switchgrass. Immunofluorescent localization demonstrated that in certain C4 grasses (i) parenchyma BSC can protect RuBPCase from degradation through 24‐h in situ incubation, (ii) BSC containing RuBPCase can exit the rumen prior to degradation, and (iii) protein protected by BSC can escape degradation in the whole gastrointestinal tract and be excreted.
Genetic Diversity in Elite Cotton Germplasm Determined by Morphological Characteristics and RAPDs
Authors: Tatineni V. , Cantrell R. G. , Davis D. D.
Published: July 2010

Limited interspecific introgression has been achieved in the breeding of the two primary cultivated species of cotton (Gossypium hirsutum L. and G. barbadense L.). Genetic diversity of 16 near‐homozygous elite cotton genotypes derived from interspecific hybridization was investigated at the DNA level with the random amplified polymorphic DNA (RAPD) procedure and at the phenotypic level with stable and highly heritable morphological characters. Eighty random decamer primers were used to amplify DNA via the polymerase chain reaction (PCR) and 135 RAPDs were generated. Nineteen morphological traits were measured on the genotypes in field experiments in 1992 and 1993. Morphological characters were chosen that easily distinguish typical G. hirsutum (upland cotton) from G. barbadense (Pima cotton). Dendrograms were generated for genetic distance from the RAPDs and average taxonomic distance from the morphological data. Both procedures produced two clusters with one resembling G. hirsutum and one G. barbadense. Classification of all genotypes based on the two methods gave similar results with a correlation of 0.63 between the genetic distance and taxonomic distance. Several genotypes were identified that were genetically and phenotypically distant from typical G. hirsutum and G. barbadense. The level of polymorphism exhibited by these genotypes could be exploited in genetic mapping populations to tag economically important traits, such as fiber quality. These genotypes also could serve as a germplasm source of unique alleles in G. hirsutum that are derived from G. barbadense. This experiment demonstrates for the first time that RAPD analysis can reliably determine genetic relationships within a diverse array of Gossypium germplasm.
Recovery Resistance To Downy Mildew In Pearl Millet Parental Lines ICMA 1 AND ICMB 1
Authors: Singh S. D. , Talukdar B. S.
Published: July 2010

Downy mildew [Sclerospora graminicola (S acc.) Schroet.] has been a major biotic factor affecting grain yield of pearl millet [Pennisetum glaucum (L.) R.Br.] in India for the last 25 yr. Many downy mildew resistant cultivars have been produce and several have been cultivated widely, but the vulnerability of their resistances to the disease has been a major cause of concern. Recovery resistance, in which the pathogen complete its life cycle without affecting the normal development of the plant, has potential for providing durable resistance to the disease. A high level of recovery resistanc(≥95%) was developed in ICMA 1 (81A, a leading male‐sterile line in India)and its maintainer line ICMB 1 (81B), through pedigree selection for five generations. The recovery trait in the selected line, designated as RECRES 81A, was stable against the major pathotypes present in India. RECRES 81A is agronomically and phenotypically similar to 81A, produces equally high yielding hybrids, and is being used to produce commercial hybrids.
Quantitative Trait Loci for Germination and Malting Quality Characters in a Spring Barley Cross
Authors: Thomas W. T. B. , Powell W. , Swanston J. S. , Ellis R. P. , Chalmers K. J. , Barua U. M. , Jack P. , Lea V. , Forster B. P. , Waugh R. , Smith D. B.
Published: July 2010

Absence of dormancy and good malting quality are significant targets of many barley (Hordeum vulgare L.) breeding programs. Expression of dormancy is strongly affected by the environment, and malting quality assays are expensive. Both groups of characters would therefore be suitable for marker‐assisted selection. The objective of this study was to identify quantitative trait loci (QTL) controlling germination and malting quality characters in a cross between the spring barley genotypes ‘Blenheim’ and E224/3 as an initial step in the development of a marker‐assisted selection scheme. The characters were measured on a random sample of doubled haploid lines from the cross grown in replicated trials each year from 1989 to 1992. The QTL were revealed by regression analysis of the data with marker scores from 120 mapped polymorphic loci. The QTL controlling hot water extract were located on barley Chromosomes 2, 3, and 7. Milling energy was largely controlled by a factor on Chromosome 7, a region also associated with extract viscosity. The denso dwarfing gene on Chromosome 3 was associated with a reduction in grain N but this was found to be a dilution effect as the locus had previously been found to be associated with an increase in grain yield. The germination characters showed little relationship with each other, possibly reflecting different mechanisms of control.
Patterns of Cross‐Tolerance to Herbicides Inhibiting Acetohydroxyacid Synthase in Commercial Corn Hybrids Designed for Tolerance to Imidazolinones
Authors: Siehl D. L. , Bengtson A. S. , Brockman J. P. , Butler J. H. , Kraatz G. W. , Lamoreaux R. J. , Subramanian M. V.
Published: July 2010

Two commercial corn (Zea mays L.) hybrids, ICI 8532 IT and Pioneer 3180 IR, designed for tolerance to imidazolinones, were evaluated for tolerance to various acetohydroxyacid synthase‐inhibiting herbicides at the whole plant and enzyme levels. The purpose was to establish and compare the underlying enzymatic basis for tolerance in these plants, which were produced by contrasting methods and contain different genetic complements of the altered target enzyme. ICI IT plants exhibited significant tolerance (40‐fold higher rates for 50% inhibition of growth than the control hybrid) to imazethapyr, and somewhat less to imazaquin and pyrimidyloxybenzoate. ICI IT plants were no more tolerant to chlorsulfuron or flumetsulam than the control hybrid. Pioneer IR plants were highly tolerant to all of the AHAS inhibitors tested, requiring rates 200‐ to 2000‐fold higher than those of the control hybrid for 50% inhibition of growth. The basis for tolerance was evaluated on acetohydroxyacid synthase (AHAS, EC 4.1.3.18) in vitro. Relative to unmodified AHAS isolated from the control hybrid, AHAS isolated from ICI IT corn was seven‐fold less sensitive to imazethapyr, five‐fold less sensitive to pyrimidyloxybenzoate and two‐fold less sensitive to imazaquin, but was as sensitive to chlorsulfuron and flumetsulam. AHAS from Pioneer IR corn was highly insensitive to all of the AHAS inhibitors tested. Sensitivity to the feedback inhibitor leucine was not detectably altered in the modified enzymes. Substrate saturation kinetics of AHAS isolated from ICI IT corn were identical with those of unmodified AHAS, while AHAS from Pioneer IR required a two‐fold higher concentration of pyruvate for half‐maximal saturation. The results support the theory that because the catalytic and herbicide binding sites of AHAS are distinct from each other, crops can be designed for tolerance to AHAS‐inhibiting herbicides with little effect on performance.
Temperature and Soil Water Effects on Maize Growth, Development Yield, and Forage Quality
Authors: Crasta O. R. , Cox W. J.
Published: July 2010

Topographical features in the northeastern USA result in different growing conditions between locations within close proximity. Dairy producers demand information on how these differences influence forage maize (Zea mays L.). Three hybrids were planted at two dates and two locations in 1990 and 1991 to evaluate the effect of growing conditions on growth, development, yield, and forage quality of maize. Dry matter (DM) yields, which averaged 16.4 Mg ha−1 at Aurora vs. 14.7 at Mt. Pleasant, NY, in 1990 and 12.7 vs 12.0 in 1991, correlated with DM accumulation at silking (r = 0.86), but not at the eighth‐leaf (V8) stage (r = 0.19). Maize at Aurora, NY, which had higher average temperatures (22.4°C) during the V8 to silking interval than Mt. Pleasant (20.4°C), accumulated more DM at silking in 1990 (822 vs. 678 g m−2) and 1991 (620 vs. 545) because of higher crop growth rates (28 vs. 23 g m−2 d−1 in 1990 and 22 vs. 20 in 1991) during the same length of growth interval. Location did not affect neutral detergent fiber (NDF) or in vitro dry matter digestibility (IVDMD) in 1990, but the cool compared with warm location had higher IVDMD (765 vs. 747 g kg−1) and lower NDF (376 vs. 397 g kg−1) in 1991. The dry 1991 growing season compared with 1990 had lower NDF (386 vs. 431 kg−1) and higher 1VDMD (756 vs. 717 g kg−1). Apparently, soil water differences between locations in the northeastern USA affect maize forage quality more than temperature differences do.
Pesticide Dissipation under Golf Course Fairway Conditions
Authors: Horst G. L. , Shea P. J. , Christians N. , Miller D. R. , Stuefer‐Powell C. , Starrett S. K.
Published: July 2010

The degradation and vertical movement of pendimethalin, chlorpyrifos, isazofos, and metalaxyl were monitored in Kentucky bluegrass (Poapratensis L.) turf managed as a golf course fairway. Intact turf‐soil cores from Mead, NE, on a Sharpsburg soil (fine montmorillonitic, mesic Typic Argiudoll) and Gilbert, IA, on a Nicollet loam (fine‐loamy, mixed, mesic Aqnic Hapludoll) planted to Kentucky bluegrass were periodically removed to 60‐cm depth through 113 d after pesticide application. Cores were sectioned into verdure, thatch, and multiple soil depths. While verdure contained high pesticide concentrations after application, precipitation, and clipping, and degradation reduced the amount in plant tissue with time. Thatch was highly retentive of the pesticides, generally containing the most residue throughout the monitoring period. Pesticide residues tended to be lower in soil at the Iowa site where more thatch was present. Little chlorpyrifos or pendimethalin moved through the thatch to the underlying soil. Isazofos was more mobile and metalaxyl moved through the entire soil column. Soil contained an average of 58% less pesticide than thatch over all sampling times, and concentrations in soil were highest at the 0‐ to 5‐ and 5‐ to 10‐cm depths. Average time for 50% dissipation in the turf‐soil profile (DT50) was 16, 12, 10, and 7 d for metalaxyl, pendimethalin, chlorpyrifos, and isazofos, respectively. The pesticides appeared to degrade more rapidly in the turfgrass environment than typically reported for other agronomic cropping systems. Variability in pesticide residue concentrations for each soil depth among the turf‐soil cores indicated non‐uniform dissipation in the field.
Drought Avoidance Characteristics of Diverse Tall Fescue Cultivars
Authors: Carrow R. N.
Published: July 2010

In recent years, turf type tall fescues (Festuca arundinacea Schreb.) are being used for northern to mid‐South climates in the USA. Limited information is available on the diversity among cultivars of drought resistance and avoidance characteristics, which are important for persistence under drought and high‐temperature stresses. Four cultivars (‘Rebel H’, ‘Rebel Jr.’, ‘Kentucky 31’, ‘Bonsai’) and ‘GA‐5’ endophyte‐free (EF) and endophyte‐infected (El) with Acretnonium coenophialura Morgan‐Jones and Gams were evaluated in a field study at Griffin, GA, (using a clayey, kaolinitic, thermic Typic Haphidult soil) for intraspecific differences in overall drought resistance and for drought avoidance characteristics. These grasses provided a range in morphological traits. Overall drought resistance ranking based on decline in turf quality, leaf firing (LF), and/or wilt expression during dry‐down was Rebel II (best) > Rebel Jr., Kentucky 31, GA‐5‐EF, GA‐5‐EI > Bonsai. The magnitude of differences in drought avoidance characteristics among cultivars (least cuitivar = 100% base) for each year, respectively, were 213 (1991) to 200% (1992) for late summer root length density (RLD) at 20‐ to 60‐cm depth; 182 (1991) to 173% (1992) for total root length (TRL) lat e summer; and127%for evapotranspiration (ET) averaged over all water use periods (i.e., 1991 and 1992). Field measured ET rates revealed much lower ET rates (33–73% less) for the combination of humid climate and mild drought stress than reported in the literature for semi‐arid/arid and well‐irrigated tall fescue. Additionally, multiple regression analysis demonstrated that high RLD (20‐ to 60‐cm depth) was associated with less LF and wilt; maintenance of ET at 4 to 8 d after irrigation was related to less LF; and high RLD (3‐ to 10‐cm depth) related to greater LF and wilt. This suggests that high RLD in the deeper root zone and the ability to maintain ET as the soil dries are important for drought resistance of tall fescues.
Transformation and Regeneration of Creeping Bentgrass (Agrostis palustris Huds.) Protoplasts
Authors: Lee Lisa , Laramore Cynthia L. , Day Peter R. , Tumer Nilugan E.
Published: July 2010

An efficient plant regeneration system from protoplasts of creeping bentgrass (Agrostis palustris Huds.) cultures is essential for gene transfer to these grasses through direct DNA uptake into protoplasts. A simple and efficient plant regeneration system for protoplasts isolated from embryogenic suspension cultures of seven creeping bentgrass cultivars was established. Suspension cultures were derived from embryogenic callus cultures established from surface‐sterilized mature seeds. Four creeping bentgrass cultivars were tested to determine their effect as feeders on plating efficiencies, callus development, and regeneration of protoplasts. Embryogenic suspension cultures from all four cultivars worked as feeders with plating efficiencies ranging from 0.05 to 0.32%. Protoplast derived calli formed within 3 wk after isolation and were regenerated with, or without, the addition of cytokinin to the regeneration medium. Some cultivars required the use of a particular feeder to regenerate plants. Plants were regenerated from all the cultivars tested. The bar gene, which confers resistance to the herbicide bialaphos [2‐amino‐4‐(hydroxymethylphosphinyl)butanoic acid], was transformed into protoplasts by means of either PEG or electroporation. Bialaphos‐resistant colonies were obtained from five creeping bentgrass cultivars. Resistant colonies of the cultivar Cobra were regenerated into plants. One hundred fifty‐three Cobra transformants analyzed were resistant to five times the field rate of commercial formulation of the herbicide. Molecular characterization of the transformants revealed the stable integration of the bar gene into the genome and expression of transcripts corresponding to the bar gene.
Proposed Ecological Descriptors and Their Utility for Plant Germplasm Collections
Authors: Steiner J. J. , Greene S. L.
Published: July 2010

Plant germplasm collections are important repositories of genes that ensure potentially useful sources of genetic variation are preserved for future uses. Detailed information about genetic differences among individuals or groups of accessions can be helpful for management and utilization of germplasm collections. Presently, a description of the collection site is required when collecting accessions, but the kinds and amount of information recorded that describe the natural environmental features of the collection site may vary greatly depending on the collector. This paper discusses the need for providing standardized and detailed ecological descriptors for collected accessions that can be entered into the U.S. National Plant Germplasm System (NPGS) Germplasm Resources Information Network (GRIN) database and provides a set of necessary tools to accomplish this. Proposed in this paper are (i) a flexible set of ecological descriptors that capture the most important ecological features of the collection site and its environment so that a standardized description can be given of the natural conditions where accessions are found, (ii) revised ac cession data collection form that can be used to describe the natural features of the collection site, and (iii) a method to retroclassify poorly documented accessions that do not have detailed descriptions of the collection site. The widely adapted perennial forage legume birdsfoot trefoil (Lotus corniculatus L.) is used to demonstrate the principles presented in this paper.
Selection of Stable Cultivars Using Phenotypic Variances
Authors: Xie C. , Mosjidis J. A.
Published: July 2010

Genotype‐environment interactions reduce the correlation between phenotype and genotype and decrease selection progress. Type 1 stability measures (simple variance across environments S2i and related coefficient of variability CVi) are biased because they do not distinguish the effects of locations and years. We propose the unbiased estimate of phenotypic variance (Vp) and phenotypic coefficient of variability (PCVi) as an alternative to S2i. The Vp, unlike S2i and Type 4 stability measure MS Y/L (years‐within‐location mean square), includes location, year within location, and error variance components from analysis of variance based on a linear model. The F‐test can be used to classify cultivars into location unstable, year unstable, or both location and year unstable, or vice versa. The actual model used in data analyses was based on the mean across replications in each environment (Pij.) because the plot (replication) data were not available. Hence, the corresponding Vp and PCVi were denoted as V′P and PCV′i. The V′P underestimates Vp. Monte Carlo simulation was used to evaluate the performance of V′P and S2i. A wheat (Triticum aestivum L.) data set was used to demonstrate the calculation of the above parameters. The results from rank correlation showed that V′P was correlated to MS Y/L, the regression coefficient (bi), PCV′i, and S2i (P < 0.05). The V′P was not correlated to the residual mean square of deviation from the regression (δ2i). The V′P and S2i had similar sampling errors. When less than 18 locations and 6 years are used, Ve is particularly useful since S2i is biased.
Rice Seed Vigor and Seedling Establishment in Anaerobic Soil
Authors: Yamauchi M. , Winn Tun
Published: July 2010

The rice (Oryza sativa L.) crop is established under hypoxia when sown into flooded or water‐saturated soft. This study was conducted to clarify the interrelationship between seed vigor and seedling growth in anaerobic soil and to identify seedling characteristics that predict establishment in the field. Different levels of seed vigor were obtained with different cultivars, times of harvest, and accelerated aging treatments. Seeds of cultivars tolerant of anaerobic soil (ASDI, JC178, Taothabi, and Kuhei 2) and of intolerant cultivars (IR36 and IR50) were produced by harvesting 25, 30, 35, and 40 d after heading. Another set of seeds was aged at 43°C and 100% relative humidity for 0, 3, 6, and 9 d. The characteristics measured were germination and germination rate in petri dishes, coleoptile and mesocotyl lengths in N2 gas in llasks, and seedling establishment, vigor index (which indicates the speed of emergence), height, leaf development, mesocotyl length, and shoot weight in flooded soil in trays and in water‐saturated soil in the field. The harvest time did not affect seedling establishment in the field. Aging reduced seedling establishment significantly in the cultivars tested except ASD1, which was tolerant to aging. Seedling establishment in the field was closely correlated with the vigor index in the field (simple linear correlation coefficient r = 0.8 to 1.0), establishment and vigor index in the tray (r = 0.5 to 0.9), and coleoptile length in N2 gas (r = 0.4 to 0.9), suggesting that these characteristics would be useful in the prediction of seedling establishment in anaerobic soil.
A Cold‐Regulated Protein from Bermudagrass Crowns Is a Chitinase
Authors: Gatschet M. J. , Taliaferro C. M. , Porter D. R. , Anderson M. P. , Anderson J. A. , Jackson K. W.
Published: July 2010

Sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis (PAGE) and fluorography of in vivo radiolabeled proteins has revealed that protein synthesis in crowns of ‘Midiron’ and ‘Tifgreen’ bermudagrasses (Cynodon dactylon L. Pers. × C. transvaalensis Burtt‐Davy) is altered in association with cold acclimation (CA). Increased synthesis of some proteins in association with CA in Midiron crowns correlates with the greater freezing tolerance of Midiron compared with Tifgreen. This study was undertaken to (i) characterize further alterations in protein synthesis in Midiron and Tifgreen crowns utilizing analytical isoelectric focusing (IEF)/SDS‐PAGE [two‐dimensional (2D‐) PAGE], and (ii) identify cold‐regulated (COR) proteins, proteins encoded by genes persistently upregulated during CA, through sequence analysis of peptides recovered after micropreparative 2D‐PAGE and protease digestion. Plants were grown for 26 d in controlled‐environment chambers under acclimating [8/2°C (day/night) cycles with 10 h photoperiods] or nonacclimating [28/24°C] conditions. Proteins synthesized by isolated crowns were radiolabeled in vivo for 16 h with 35S‐methionine and 35S‐cysteine. Among several groups of COR proteins synthesized in Midiron and Tifgreen crowns, low molecular weight (about 20–28 kilodalton) basic (LB) COR proteins were synthesized in greater amounts and numbers in Midiron than Tifgreen crowns. Among the LB COR proteins, a 27‐kD basic COR protein was synthesized prominently in crowns of both Midiron and Tifgreen plants. This protein from Midiron crowns was designated COR27 and identified as a chitinase (E.C. 3.2.1.14) through protein sequencing.
Genotype × Planting Date Interaction and Selection of Early Maturing Soybean Genotypes
Authors: Akhter M. , Sneller C. H.
Published: July 2010

Maturity group (MG) IV soybean [Glycine max (L.) Merr.] cultivars can produce acceptable yields in April through late‐June plantings in the mid‐south. Seed quality from early plantings is often poor, thereby requiring use of late‐June‐planted seed quality nurseries for seed producers and breeders. This range of planting dates may produce genotype × planting date interactions (GDI). Our objective was characterize the extent and potential impact of GDI on MG IV cultivar development. Twenty‐seven indeterminate and nine determinate MG IV genotypes were planted in mid‐April, May, or late‐June in 1992, 1993, and 1994 in Arkansas. Data were collected on yield, height, number of main stem nodes, and days from planting to maturity. The GDI was significant only for height, number of nodes, and days to maturity for comparison of indeterminate lines in April vs. June plantings. There were no significant and repeatable genotype rank changes between planting dates for any trait: no planting date specific adaptation was noted for any genotype or growth habit. Heritability of seed yield, plant height, and number of nodes of indeterminate genotypes was generally greater from April or May plantings than from June plantings. The genetic correlation of plant height or number of nodes with overall yield was generally also greater from early plantings than from late plantings. Yield gain from indirect selection for increased height or node number was greater when the selection was conducted from early plantings vs. late plantings. Our results indicated a selection advantage from early plantings of MG IV indeterminate genotypes.
Response to Selection for Reduced Grass Tetany Potential in Crested Wheatgrass
Authors: Asay K. H. , Mayland H. F. , Clark D. H.
Published: July 2010

Grass tetany (hypomagnesemia) has caused substantial economic losses in ruminant animals grazing crested wheatgrass (Agropyron spp.) and other cool‐season (C3) grasses. This malady is most prevalent in early lactating animals grazing forage that is deficient in Mg, Ca, and carbohydrates and with high levels of K. The K/(Ca + Mg) ratio expressed as moles of charge is often used to estimate the grass tetany potential of forage samples. Previous studies have shown that heritable variation exists in crested wheatgrass populations for traits associated with grass tetany, and research was conducted to determine the genetic response to selection for these traits. Selections were made during 1985 from two crested wheatgrass breeding populations in Utah (‘I‐28’ and ‘Hycrest’) based on a reduced grass tetany potential (RTP) index, which incorporates the K/(Ca + Mg) ratio along with concentrations of Ca, Mg, and K. Mean values for the K/(Ca + Mg) were reduced by 5% in 1‐28 and 11% in Hycrest after one cycle of selection. Narrow‐sense heritability values based on actual genetic advance and parent‐progeny regression ranged from 0.62 to 0.82 in analyses of data combined across two sampling dates and two years (1988 and 1989). Genetic response to selection on the basis of RTP index was closely associated with the K/(Ca + Mg) ratio and concentrations of Ca and Mg but not with levels of K. Correlations between the K/(Ca + Mg) ratio and crude protein content and digestibility suggested that selection for RTP would likely be accompanied by improved forage quality in the Hycrest breeding population.
Effect of 1BL.1RS on Agronomic Performance of Soft Red Winter Wheat
Authors: McKendry A. L. , Tague D. N. , Miskin K. E.
Published: July 2010

The wheat (Triticura aestivura L.)‐rye (Secale cereale L.) translocation, IBL.IRS, has been reported to enhance yield potential in hard wheat germplasms. This study was designed to evaluate the impact of IBL.IRS on yield potential in soft red winter wheat. Agronomic traits associated with yield potential were measuredin 40 F9‐derived sister lines in two soft red winter wheat genetic backgrounds, SW85*294 and SW85*5626. The presence of IBL.IRS had no significant impact on grain yield, kernel weight, biological (total aboveground) yield, harvest index, fertile tillers, spikelets per head, or kernels per spikelet. This effect was independento f productione nvironment in which the translocation was assessed. The presence of the translocation caused a 3.3‐ and 4.0‐cm reduction in plant height in SW85*5626a nd SW85*294,r espectively. A significant reduction in lodging was associated with reduced height. Heading date was delayed ≈ 1 d in SW85*294 but was not affected in SW85*5626. The elfeet of genetic backgrounwd as large relative to the effect of the translocation for all traits measured. These data suggest that where grain yield is a primary objective of the breeding program, emphasis should be placed on selection for genes on other wheat chromosomersa ther than for the presence of the IBL.IRS translocation.