bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Nomenclature in Clovers and Special‐Purpose Legumes: II. Crimson and Subterranean Clover
Authors: Pederson G. A.
Published: July 2010

Crimson clover, Trifolium incarnatum L., and subterranean clover, T. subterraneum L., are important annual legumes used for winter grazing in the U.S. Southeast. There is no single report of the inheritance of qualitative characters in these two species. The objective of this paper was to compile the reported gene names and symbols for crimson and subterranean clover characters and to propose symbols for characters of each species in accordance with the Trifolium genetic nomenclature system. A new system for naming alleles of the leaf mark locus M in subterranean clover is also proposed. The inheritance and gene symbols are given for 16 characters in crimson clover and 34 characters in subterranean clover. These characters consist mostly of flower color and leaf variants in crimson clover and anthocyanin pigmentation, isoflavone, leaf marking, and seed color variants in subterranean clover. The inheritance is reported for three characters in crimson clover and four characters in subterranean clover that have not been assigned gene symbols.
Inheritance of Resistance of PI 372129 Wheat to the Russian Wheat Aphid
Authors: Nkongolo K. K. , Quick J. S. , Peairs F. B. , Meyer W. L.
Published: July 2010

Knowledge of the inheritance of resistance to pests in wheat (Triticum aestivum L.) is important to plant breeders. A study was conducted to determine the inheritance of resistance to the Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), in a wheat line, PI 372129, that was previously identified as a good source of RWA resistance. The susceptible wheat cultivars Carson, Lamar, and TAM 107 were crossed with PI 372129. The parents and progenies from these three crosses were artificially infested with RWA in the greenhouse. There was close association between leaf chlorosis and leaf rolling, two components of the RWA damage rating system. Seedling reactions of the F1, F2, and backcross generations indicated that a single dominant gene governs RWA resistance in PI 372129. Data describing the mechanism of RWA resistance of PI 372129 indicate that this gene is probably different from Dnl and Dn2 (identified in PI 137739 and PI 262660, respectively). Reciprocal crosses revealed no evidence of cytoplasmic effects.
Genetic and Genotype ✕ Environment Effects for Rough Rice and Head Rice Yields
Authors: Gravois K. A. , Moldenhauer K. A. K. , Rohman P. C.
Published: July 2010

High rough rice and head rice yields are important to U.S. rice (Oryza sativa L.) producers for maintaining successful farming and milling operations. Unconfounded estimates of genetic and genotype ✕ environment (GE) variances for rough rice and head rice are lacking for U.S. rice breeding programs and would be useful aids to breeders in developing efficient programs. Our objectives were to estimate genetic and GE variance components for a rice population representative of a final testing stage in the Arkansas rice breeding program, to determine the relative importance of years, locations, and replicates in rice cultivar trials, and to demonstrate the usefulness of regression in genotypic stability analyses. Data were gathered on 19 genotypes at four locations in 1986, 1987, and 1988. Genotype ✕ year (GY) variance was the most important source of variation for head rice yield, whereas the genotype ✕ year ✕ location (GYL) variance was the most important source of variation for rough rice yield. The genotype ✕ location (GL) variance was the least important source of variation for both traits. An optimum experimental design in the Arkansas rice trials conducted on silt loam soils would include two locations replicated twice and repeated for a minimum of 3 yr. Regression techniques for estimating genotypic stability were most useful when regression was based on a year index, especially for head rice. The % Best statistic was significantly correlated with the mean and provided information on genotypes that consistently ranked in the top yield category [LSD (0.05)] across environments.
Combining Ability for Yield Characteristics and Earliness of Pink Bollworm‐Resistant Cotton
Authors: Wilson F. Douglas
Published: July 2010

Some germplasm lines of cotton, Gossypium hinutum L., that show resistance to pink bollworm (PBW), Pectinophora gossypiella (Saunders), also carry agronomic properties that could enhance derived germplasm. The objectives of this study were to determine (i) the agronomic performance of four germplasm lines having resistance to PBW, one having susceptibility, and the check cultivar, Stoneville 825 (ST 825); (ii) combining ability for lint yield, yield components, and earliness; (iii) F1 hybrid performance; (iv) the relative contributions of yield components to yield. Half‐diallel analysis of the six parents and their 15 F1 hybrids, grown at Maricopa, AZ, for 2 yr, revealed significant year, general combining ability (GCA), and specific combining ability (SCA) effects for lint yield and bolls per plant, seeds per boll, lint weight per seed, and earliness (cumulative lint yield, as a percentage of total yield at the third of five harvests). Year ✕ GCA and year ✕ SCA were significant only for lint weight per seed. Only T39C‐1‐L‐RES (a PBW‐resistant germplasm line) equalled ST 825 in lint yield per plant, but it was later in maturity; both showed GCA effects for high yield and number of bolls. Stoneville 825 achieved its high yield by producing many relativeiy small bolls, while T39C‐1‐L‐RES produced fewer but larger bolls. The T39C‐1‐L‐RES ✕ ST 825 F1 showed SCA effects for high yield, seeds per boll, and earliness. This F, yielded 11% more total lint than ST 825 by countering 13% fewer bolls per plant with 25% more seeds per boll. It was also earlier than ST 825: it yielded 18% more lint by third harvest.
Recurrent Selection for Resistance to Exserohilum turcicum in Eight Subtropical Maize Populations
Authors: Ceballos H. , Deutsch J. A. , Gutiérrez H.
Published: July 2010

There are few reports on the progress achieved through recurrent selection for quantitative resistance to diseases in tropical or subtropical maize (Zea mays L.) populations. The objective of this study was to evaluate the progress achieved after four cycles of full‐sib S1 recurrent selection in eight subtropical populations from the International Maize and Wheat Improvement Center (CIMMYT). Selection was primarily for improving polygenic resistance to the northern corn leaf blight (NCLB) induced by Exserohilum turcicum (Pass.) Leonard & Suggs, and the common rust (Puccinia sorghi Schw.). Evaluations were made under three environments (high, medium, and no disease pressure) represented by two locations each. A very rapid increase in resistance was obtained for both diseases (19 and 6% cycle−1 for NCLB and rust, respectively) without changing the maturity of the populations or reducing grain yield potential as measured by planting under relatively disease‐free conditions. Under disease pressure, yield was found to be associated with resistance to NCLB (r = 0.52**; significant at P = 0.01), reduced stalk lodging (r = −0.51**), and greater number of ears per plant (r = 0.60**). Results suggest high heritability values for polygenic resistance to NCLB. It was also demonstrated that the full‐sib S1 recurrent selection methodology employed was highly effective in achieving the initial breeding objectives in all the populations involved.
High Molecular Weight Glutenin Genes: Effects on Quality in Wheat
Authors: Dong H. , Cox T. S. , Sears R. G. , Lookhart G. L.
Published: July 2010

To utilize electrophoretic variants of wheat (Triticum aestivum L.) storage proteins as rapid screening criteria in selection of parents or progeny for end‐use quality, breeders should know the relative effects of the alternate alleles at the storage‐protein loci on which selection will act. The objective of this study was to determine the direct effects of high molecular weight (HMW) glutenin genes on quality in wheat, without the confounding effects of linkage disequilibrium. Genetic analyses of the direct effects of loci coding for glutenin subunits on mixing time, mixing tolerance, absorption, and protein concentration were conducted with 135 random wheat selections from a randomly mated population. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS‐PAGE) was used to screen for HMW glutenin subunits. Significant differences were observed among alleles within loci for some of the quality traits measured. Some of the epistatic interactions also were significant, indicating that the effects of some subunits depend partly on which of the snbunits coded by other genomes are present. The Subunit 5 + 10 combination at the Glu‐Dl locus had the largest positive effects on dough mixing traits, and the 6 + 8 combination at Glu‐Bl had large negative effects on most traits. Alleles at Glu‐Al had no significant effects on any traits. Glutenin‐based selection for increased mixing time and tolerance gave lower predicted gains than phenotypic selection.
Stability of Morphological Traits Conferring Bird Resistance to Sunflower across Different Environments
Authors: Gross P. L. , Hanzel J. J.
Published: July 2010

Bird depredation is a major concern of sunflower (Helianthus annuus L.) producers wherever the crop is grown in the world. Development of bird‐resistant varieties would provide an economical, environmentally safe method of contending with the problem. Morphological traits that confer resistance to depredation by birds have been identified. These traits include long involucral bracts, horizontally oriented heads, concave heads, and long head‐to‐stem distances. The objective of this study was to determine the stability of the traits when cultured in different environments. Breeding lines BRS1, ND208, ND492, ND495, ND162, and ND223‐16, which possess resistance traits, and seven susceptible counterparts, ND221, ND224, ND505, HA89, ND581, ND223‐1, and ND223‐3, were grown at three locations in North Dakota in 1988 and 1989. Measurements of the traits were made at the R7 stage of development. Genotype, environment, and genotype ✕ environment effects were all significant (P < 0.05). The genotype ✕ environment interaction effects, however, were not the result of changes in rank between resistant and susceptible genotypes, but represented differences in magnitude of response in the genotypes when grown in diverse environments. Results of this study indicate that performance of hybrids possessing these traits can be expected to be stable across a wide geographical area.
Soil Temperature and Moisture Effects on Downy Brome vs. Winter Canola, Wheat and Rye Emergence
Authors: Blackshaw Robert E.
Published: July 2010

Downy brome (Bromus tectorum L.) causes serious yield reductions in winter cereals in the western USA and Canada. Current control practices often are ineffective. A study was conducted under controlled‐environment and field conditions to determine the effect of soil temperature (5‐30 ¼C) and moisture (−0.03 to ‐1.53 MPa) on the rate and total emergence of downy brome relative to that of winter cultivars of canola (Brassica napus L.), wheat (Triticum aestivum L.), and rye (Secale cereale L.) with the aim of developing improved cultural control measures. A strong temperature‐moisture interaction was found for all species. Downy brome emergence was affected more by varying soil temperature and moisture conditions than rye or wheat but less than winter canola. Wheat and rye emergence was >88 and 82%, respectively, across the entire range of soil temperature and moisture conditions. Canola emergence decreased to <60% in cool, dry soils. Downy brome emergence remained <70% for all soil temperature and moisture conditions, a sufficiently high percentage to pose a serious weed problem. Downy brome usually emerged more slowly than the crop species, but the additional time required to reach 50% emergence compared with that of the crop species was no more than 8 d. Results indicated that differences between downy brome and canola, wheat, and rye in their soil temperature and moisture requirements for optimal emergence are likely insufficient to allow development of cultural control practices to reduce the establishment of competitive stands of downy brome in these winter crops.
Chemical Composition of Parenchyma and Sclerenchyma Cell Walls Isolated from Orchardgrass and Switchgrass
Authors: Grabber J. H. , Jung G. A. , Hill R. R.
Published: July 2010

The isolation and analysis of cell‐wall types (CWT) such as parenchyma and sclerenchyma provide a means of understanding the complex chemistry of forage fiber. Our objective was to compare the composition of purenchyma and sclerenchyma cell walls of field grown orchard grass (Dactylis glomerata L.) and switch grass (Panicum virgatum L.) harvested at four stages of plant maturity. Leaf blades, leaf sheaths, and stems were analyzed for fiber constituents. Parenchyma and sclerenchyma cell walls were mechanically isolated from plant parts and analyzed for neutral sugars, alkali‐labile phenolic acids, and lignin. Neutral‐detergent fiber (NDF), hemicellulose, cellulose, and lignin concentrations differed (P < 0.05) between plant parts. Parenchyma cell walls differed widely in composition, with urabinose ranging from 25 to 81 g kg−1; xylose, 92 to 282 g kg−1; glucose, 410 to 634 g kg−1; p‐coumaric acid, 1 to 19 g kg−1; ferulic acid, 2 to 10 g kg−1; and lignin, 38 to 104 g kg−1. Sclerenchyma cell walls were more uniform in composition, with arabinose ranging from 10 to 30 g kg−1; xylose, 204 to 330 g kg−1; glucose, 411 to 533 g kg−l; p‐conmaric acid, 5 to 16 g kg−1; ferulic acid, 3 to 9 g kg−1; and lignin, 51 to 99 g kg−1. In most cases, the ratios of xylose to urabinose and p‐coumaric acid to ferulic acid were lower (P < 0.05) in purenchyma compared with sclerenchyma, and in leaf blade or leaf sheath CWT compared with those of the stem. These results suggest that the chemistry of CWT is complex and that studies of heterogenous preparations such as NDF are confounded by the chemical diversity of CWT contained in forages.
Selection Procedure Based on Cross and Line Performance
Authors: Rasmusson Donald C.
Published: July 2010

Plant breeders have suggested that breeding progress could be enhanced by first selecting crosses, and then selecting individual lines within these crosses. Evaluation of F1 progenies and early generation bulk populations have been recommended as methods of identifying superior crosses, but have not been widely adopted. The purpose of this note is to propose a method of selection, referred to as cross‐line selection, that relies on both cross and line performance when selecting individual lines. The procedure is intended for use at the time of replicated yield testing when each cross is represented by several lines and there are several yield trials. It entails allocation of individual lines of each cross to different trials, so each cross is represented in more than one trial by subsets of lines. Selection of individual lines is done within crosses that have high subset means compared with other crosses. While experiments have not been done to evaluate the procedure, I encourage its use because of its value in identifying high‐yielding lines in our breeding program.
Sample Number Effect on Precision of Measurements of Rice Canopy Photosynthesis and Leaf Area
Authors: Ellis J. E. , Counce Paul A. , Cox A. D.
Published: July 2010

To effectively utilize resources in the measurement of canopy photosynthesis, acceptable statistical precision is necessary. Our objective was to determine the effect of sample number per plot on effective precision of canopy apparent photosynthesis (CAP) and leaf area index (LAI) measurements. A rice (Oryza sativa L.) field experiment with four N fertilizer treatments (0,67,134,201 kg ha−1) was sampled in 2 yr when rice was at the panicle differentiation stage of growth. Samples were taken at four locations in each plot for CAP and LAI. The CAP and LAI error mean squares were reduced by 32 to 81%, and 20 to 53%, respectively, by increasing numbers of samples from one to four. Given similar experimental conditions, between two and four samples per plot would be necessary to detect differences among the treatments for CAP. A single sample per plot would suffice to detect differences in LAI. To detect differences in canopy photosynthesis of flooded rice experiments when repeated samples of the same plots cannot be made, additional sampling of plots is likely to be necessary to detect treatment differences for CAP, but not for LAI.
Recurrent Selection for Seed Size in Soybean: I. Response to Selection in Replicate Populations
Authors: Tinius C. N. , Burton J. W. , Carter T. E.
Published: July 2010

Seed size is an important component of soybean [Glycine max (L.) Merr.) yield. The objectives of this experiment were to investigate the response to recurrent mass selection for increased seed size on male‐sterile (MS) plants, examine the indirect response on seed size and seed yield of derived male‐fertile (MF) plants, and evaluate the repeatability of selection response across replicate populations. Plant germplasm was developed from the intermating population N79‐1500, which segregates for male sterility. The base population was divided into three replicate subpopulations and MS plants were selected for large seed size in each separately. After four cycles of selection in two of the subpopulations and three cycles in the third, composites of the parents of each cycle were tested at four locations in North Carolina for 2 yr. There was a significant (P ≤ 0.01) increase in both MS and MF seed size for all subpopulations; the rate of increase in MS seed size was approximately twice that of MF seeds. The increase in mean MF seed size was associated with an increase in the frequency of seeds in the larger size classes and a decrease among the smaller classes. Seed yield increased linearly (P ≤ 0.01) for two of the subpopulations at rates of 46 ± 18 and 78 ± 27 kg ha−1 cycle−1. The third showed a nonsignificant increase (17 ± 19 kg ha−1 cycle−1). Recurrent mass selection for increased seed size facilitated by genetic male sterility may be an effective adjunct in a conventional breeding program to increase the yield potential of populations yet require only slightly more resources.
Retrospective Index Weights Used in Multiple Trait Selection in a Maize Breeding Program
Authors: Bernardo Rex
Published: July 2010

Most selection indices require specification of relative trait weights. Breeders often have difficulty in assigning weights to traits, although they can subjectively select genotypes based on performance for multiple traits. Retrospective selection indices describe selection already practiced in a population and quantify the relative trait weights used intuitively by a breeder. In this study, a team of breeders subjectively selected lines in 7 (Set A) and 10 (Set B) maize (Zea mays L.) populations evaluated at two sets of locations. Retrospective index weights were calculated as b = C−1s, where b is a vector of retrospective trait weights, C is the phenotypic variance‐covariance matrix among traits, and s is a vector of selection differentials for the different traits. In Set A, the average retrospective index was IA = yield − 0.028(moisture) − 0.059(stalk lodging) − 0.036(root lodging). Based on standardized (unitless) relative weights, yield was the most important trait, followed by stalk lodging, moisture, and root lodging. In Set B, the average retrospective index was IB = yield − 0.009(moisture) − 0.017(stalk lodging) − 0.002(root lodging) − 0.016(smut infection) − 0.097(barrenness). The order of trait importance was yield, moisture, barrenness, stalk lodging, root lodging, and smut infection. When applied to independent data sets, 78% of the lines selected by the breeders also had the highest index values. Thus, retrospective selection indices may be useful to a breeder in multiple‐trait selection. Most of the poorer genotypes in a population may be eliminated based on index values, giving the breeder more time to examine the more promising genotypes.
Stem Infusion of Maize Plants
Authors: Boyle Mark G. , Boyer John S. , Morgan Page W.
Published: July 2010

A delivery method was developed for rapid exogenous supply of dilute or concentrated doses of water‐soluble materials to maize (Zea mays L.) plants. The point of access was through a small cavity, prepared in the stem, which acted as an infusion port. A rubber serum bottle stopper with a septum served as an adapter both to seal the opening and to provide a means of liquid access. Conventional hypodermic needles were used to transport the liquid from an external reservoir across the septum of the stopper. Liquids were gravity‐fed under pressure heads ranging from 0 to 100 cm of water. During daylight hours, well‐watered plants could be infused with concentrated solutions such as liquid tissue culture media at 2 to 3 mL h−1 per infusion site. Water or dilute solutions could be infused at 5 to 10 mL h‐−1 per infusion site. Multiple infusion sites were possible, thereby increasing the total rate of fluid infusion per plant. Infusions by this technique were used to provide physiologically significant quantities of nutritional or regulatory substances to maize plants. For example, a daily increment of ≈5 g dry weight of culture medium per plant, a quantity equivalent to the dry matter produced daily by photosynthesis, could be externally provided by the infusion ≈30 mL d−1 plant−1. This allowed all the nutritional requirements of the plants to be supplied externally in a modest volume of solution. Infusion of 10−4 M (±)‐abscisic acid also could be used to induce stomatal closure and temporarily reduce photosynthesis. Various applications of this technique to maize and other species may be possible.
Peanut Genotype Response to Interference from Common Cocklebur
Authors: Fiebig W. W. , Shilling D. G. , Knauft D. A.
Published: July 2010

Weeds can cause serious yield reductions in peanut (Arachis hypogaea L.). Genetic differences have been found in several crop species for tolerance to weed competition, but no such findings have been reported for peanut. Field experiments were conducted in 1987 and 1989 near Gainesville, FL, to determine the effects of interference by common cocklebur (Xanthium strumarium L.) on pod yields of four peanut genotypes (‘NC 7’, BL‐8, BL‐10, and F8143B). Effects on leaf and stem dry weight, leaf area, and node number also were measured. The genotypes were grown with and without common cocklebur interference. The entire section of peanut row on either side of the cocklebur plants was harvested at 45, 90, and 135 days after planting (DAP). Two increments were harvested separately, one 0 to 25 cm and the other 25 to 50 cm from the cocklebur plant. At 45 DAP, few differences were noted in response to cocklebur competition. At 90 DAP, weed competition reduced shoot dry weight, stem dry weight, leaf area, and node number for all genotypes except F8143B. By 135 DAP, measured vegetative traits were reduced for all genotypes in both years. Competition reduced vegetation of NC 7 more than the other genotypes, while F8143B was less affected. At distances of 0 to 25 cm from cocklebur, pod yields were reduced by 50% for NC 7, 30% for BL‐10, 26% for BL‐8, and 13% for F8143B. Cocklebur plants 25 to 50 cm from peanut had less effect on pod yields; F8143B was least affected and NC 7 most affected at this distance. This indicates there is potential for developing peanut cultivars with improved competitive ability against weeds. Such cultivars would be beneficial in situations where pesticide usage needs to be reduced.
Creeping Bentgrass Cultivar Water Use and Rooting Responses
Authors: Salaiz T. A. , Shearman R. C. , Riordan T. P. , Kinbacher E. J.
Published: July 2010

Low evapotranspiration (ET) rates and deep extensive root systems are desirable drought avoidance characteristics. In this study, 10 creeping bentgrass (Agrostis palustris Hudson) cultivars were evaluated for ET and rooting responses. Evapotranspiration measurements were made in the field during 1987 and 1988 using minilysimeters filled with fritted clay. Crop coefficients (Kc) were determined for each cultivar using a Nebraska modified Penman equation for potential ET. Root distribution experiments were conducted in a controlled environment using a specially designed hydroponic system. Cultivar ET rate differences were repeatable over the 2‐yr field study. ‘Seaside’ and ‘SR‐1020’ ranked high in ET and had Kc values consistently >1, while ‘Pennlinks’ and ‘National’ ranked low, with Kc values consistently <1. Cultivars differed for total root production and root distribution. ‘Cobra’, ‘Penncross’, Pennlinks, ‘Providence’, and SR‐1020 produced roots to depths of 600 to 750 ram. ‘Emerald’, ‘Prominent’, and ‘Penneagle’ did not produce roots beyond 450 ram. Evapotranspiration rate and root distribution variability among creeping bentgrass cultivars could serve as selection criteria in a turfgrass breeding program interested in improving drought resistance.
Ash in Forage, Esophageal, and Fecal Samples Analyzed Using Near‐Infrared Reflectance Spectroscopy
Authors: Windham W. R. , Hill N. S. , Stuedemann J. A.
Published: July 2010

In study of the plant‐animal interface, knowledge of the organic fraction of pasture, esophageal, and fecal samples can help predict energy intake and digestion. Ashing of the large sample volumes necessary to conduct interface studies, however, is cumbersome and impractical. This study was initiated to examine the use of near‐infrared reflectance spectroscopy (NIRS) as a means of predicting ash concentration in pasture, esophageal, and fecal samples. Pasture mixtures of alfalfa (Medicago sativa L.) and tall fescue (Festuca arundinacea Schreb.) were defoliated by grazing animals. Pasture, esophageal, and fecal samples were collected and scanned by NIRS. A calibration subset was selected, samples were ashed, and the data used for equation development. The optimum equation was developed using log 1/reflectance (R) spectral data and produced standard errors of calibration (SEC) and validation (SEP) of 14.4 and 14.2 g kg−1, respectively, regardless of whether ash or organic matter data were used. Equations selected during calibration contained three wavelength pairs within 40 nm of one another. New calibration equations were generated by forcing in one wavelength in the neighboring pair ± 20 nm from the selected band. Validation error of calibration equations with forced wavelengths was not different from that of the original calibration equation. It was concluded that wavelength pairs were necessary to calculate slope differences of spectra from samples varying in ash concentration. Recalibration of the instrument with a subset of pasture and esophageal samples unproved SEC and SEP to 9.5 and 9.8 g kg−1, respectively; recalibration with a subset of fecal samples improved SEC and SEP to 10.6 and 12.7 g kg−1, respectively.
Field Apparatus for Testing Allelopathy of Annual Bluegrass on Creeping Bentgrass
Authors: Brede A. D.
Published: July 2010

Golf‐course superintendents have long observed the competitive nature of annual bluegrass (Poa annua L.) as a weed on creeping bentgrass [Agrostis stolonifera L. var. palustris (Huds.) Farw.] putting greens. Allelopathy has been suggested as a contributing factor in this competitiveness. This study tested the allelopathy hypothesis under putting‐green conditions using a modified field approach of the conventional stair‐step experimental procedure. Annual bluegrass and creeping bentgrass sand putting greens, each 297 m2, were established, and leachate from these greens was used to irrigate replicated sand‐based creeping bentgrass test greens. Moisture sensing and irrigation of the test plots were under continuous electronic control. The leachate sampling and delivery system functioned flawlessly throughout the 2‐yr period, in spite of weather extremes (>40 °C). After two growing seasons of monthly monitoring, no consistent effects on turf color, foliar ground cover, shoot density, or disease incidence were found in the test green to indicate allelopathy.
Screening Rose Clover and Subterranean Clover Germplasm for Isoflavones
Authors: Gildersleeve Rhonda R. , Smith G. R. , Pemberton Indre J. , Gilbert C. L.
Published: July 2010

Subterranean clovers (Trifolium brachycalycinum Katzn. and Morley, T. subterraneum L., and T. yanninicum Katzn. & Morley) contain phytoestrogenic isoflavones. High levels of these compounds are responsible for sheep (Ovis aries) reproductive disorders. Our objective was to screen the available subterranean and rose clover (T. hirtum All.) germplasm from the USDA Plant Introduction collection for isoflavone content. Clover plants were grown in the greenhouse and sampled when the seedlings were 42‐d old. Leaves were extracted with methanol (7 d at 5 °C) and analyzed using highperformance liquid chromatography techniques. Isoflavones were very low (<0.2 g kg−1) or not detectable in rose clover. Total isoflavone levels in subterranean clover ranged from 0.1 to 18.5 g kg−1. The information generated in this study will aid in identification of subterranean clover lines with low isoflavone traits.
Tolerance to Phytophthora Rot in Soybean: I. Studies of the Cross ‘Ripley’ ✕ ‘Harper’
Authors: McBlain B. A. , Zimmerly M. M. , Schmitthenner A. F. , Hacker J. K.
Published: July 2010

The pathogen Phytophthora megasperma Drechs. f. sp. glycinea T. Kuan & D.C. Erwin (Pmg) was shown to be the causative agent of a seed rot, damping off, and root and stem rot of susceptible cultivars of soybean [Glycine max (L.) Merr.]. Genetic control Ping has been partitioned into two classes: hypocotyl resistance and tolerance. The hypocotyl‐susceptible ‘Ripley’ was observed to have a very tolerant reaction to Pmg in the field and in Race 4 slantboard tests in 1984. This study examined inheritance of tolerance in the cross Ripley ✕ ‘Harper’ (a caltivar with a low level of tolerance), evaluated Ripley as a donor parent of Pmg tolerance, and determined the value of the slant‐beard test on single plants. Tolerance to Pmg (using the slant board with Race 4) was inherited quantitatively (h2= 54%). The slant‐board test had single‐plant escapes that reduced ability to select superior F2 plants. It was a sensitive test if 20 or more plants were tested per line. Slant‐beard and field tolerance data did not correlate as well as expected (r = 0.34, P < 0.01). Eighteen percent of the F2 lines from this cross were no inter than Ripley and at least as tolerant as Harper based on field tolerance scores. Less than 1% of the F2 lines were as early or earlier than Harper and as tolerant as Ripley. Ripley is not a good donor parent for Midwestadapted caltivars tolerant to all prevalent races. One line was identiffed which has earliness, indeterminate stem termination, and Riple's tolerance for Races 1,3, and 4.
Nuclear and Cytoplasmic Control of Another Culture Response in Wheat: I. Analyses of Alloplasmic Lines
Authors: Ekiz Hasan , Konzak C. F.
Published: July 2010

These studies were initiated to obtain definitive evidence for the role of cytoplasm genetic variation in anther culture and to test for nuclear ✕ cytoplasmic gene interaction on the anther culture responses in wheat (Triticum aestivum L.). Both cytoplasmic and nuclear genetic variations are potentially exploitable for practical purposes through recombination, breeding and selection. The roles of cytoplasmic and nuclear genetic factors in the control of anther culture responses were investigated by comparing the culture responses of alloplasmic lines in three spring wheat cultivars (Selkirk, Siete Cerros 66, and Penjamo 62) and their nucleus donors. Significant increases or decreases caused by alien cytoplasms were observed for callus induction, plant regeneration (albino and green plants), or green plant regeneration. In addition, significant nucleus ✕ cytoplasm genetic interactions were found for all three components of anther culture responses in two subsets of alloplasmic lines having common cytoplasms but different nuclear genotypes. Each of the components of anther culturability in wheat may be controlled independently by cytoplasmic and nuclear genes as well as by nucleus ✕ cytoplasm gene interactions.
Combining Ability for Test Weight and Agronomic Traits of Oat
Authors: Pixley K. V. , Frey K. J.
Published: July 2010

The relative importance of additive and nonadditive variation for agronomic traits provides guidelines for setting breeding strategies for cultivar development. To estimate the relative importance of general and specific combining ability (GCA and SCA) for five traits of oat (Avena sativa L.), 24 oat genotypes were mated according to a Design II scheme. The 24 parents were a sample from elite germplasm available for cultivar development at Iowa State University and in various regions of the USA. Test weight, grain yield, harvest index, date of heading, and plant height were measured for 10 random F2‐derived F3 lines from each of 95 crosses. The oat lines were evaluated in 1988 in four replicates at each of three locations in Iowa. Both GCA and SCA were significant (P ≤ 0.01) for all traits; GCA, however, accounted for 75% of the variability among crosses for test weight, 85% for grain yield, 82% for harvest index, 72% for date of heading, and 85% for plant height. We speculate that additive ✕ additive epistasis was primarily responsible for the observed significant SCA because the estimate of SCA represents 1/4 σ2D + 1/2 σ2AA, and in our experiment σ2D seemed small (based on contrasts of parent vs. offspring means). We suggest that breeders use mild selection intensities in early generations of inbreeding to avoid discarding lines before favorable epistatic combinations form. In regard to parent selection, our results indicate that most parents could be used as male or female in a cross without affecting segregation for these five traits; however, midparent values alone do not adequately predict which crosses produce the most outstanding lines.
Inheritance of Growth Habit in Pigeonpea
Authors: Kapoor R. K. , Gupta S. C.
Published: July 2010

Determinate (DT) pigeonpea [Cajanus cajan (L.) Millsp.] has a production advantage but the genetics of this trait and indeterminate (IDT)and semideterminate (SDT) growth habits are not well defined. Inheritance of DT, SDT, and IDT growth habits in short duration pigeonpea was studied in F1, F2, and BC1F1 generations of 15 crosses involving six parents (two of each growth habit) grown in the field in 1986. The segregation pattern in the crosses involving IDT and DT parents indicates that IDT growth habit is governed by a single dominant allele. Smilarly, crosses between SDT and DT parents showed that the SDT trait also is controlled by a single dominant allele. the F2 population of the crosses between IDT and SDT parents segregated in the ratio of 12 IDT to 3 SDT to 1 DT, suggesting that the expression of the SDT allele (Dt2a) was masked by the presence of the IDT allele (Dt1) and that the homozygous recessive genotype for both genes (dt1dt1dt2dt2) has the DT phenotype. The results obtained in BC1F1 with both parents also supported the F2 data. The desirable determinate phenotype can be obtained from crosses of different phenotypes, including IDT ✕ SDT, provided the IDT parent has the Dt1___dt2dt2a genotype.
Gametophytic Heterosis for In Vitro Pollen Traits in Alfalfa
Authors: Groose R. W. , Bingham E. T.
Published: July 2010

Heterosis may occur in gametophytes of polyploid sporophytes. for genes expressed in the diploid pollen (n = 2x) of autotetraploid plants (2n = 4x), favorable dominance, overdominance, and increased epistatic interactions are possible and could result in heterosis for microgametophytic traits. Pollen competition could function to maintain high levels of heterozygosity in autotetraploid populations if highly heterozygous pollen is more competitive for ovules. The objectives of this study were to evaluate heterosis for microgametophytic traits and to compare performance of microgametophytic and important sporophytic traits in autotetraploid (2n = 4x = 32) alfalfa (Medicago sativa L.) using populations bred to be isogenic (same alleles and allele frequencies) but to differ in levels of heterozygosity. In vitro, more higly heterozygous pollen was more germinable and produced longer pollen tubes, indicating gametophytic heterosis. Numerouos positive correlations between microgametophytic and sporophytic traits were observed in these populations.
Thermal Properties of Hydrated Soybean Hulls
Authors: Muzilla M. , Helsel Z. , Unklesbay K. , Unklesbay N.
Published: July 2010

To successfully incorporate soybean [Glycine max (L.) Merr.] hulls (seed coats) into human foodstuff, thermal characterization of the hulls is needed. Our objective was to determine the density, heat capacity, thermal conductivity, and thermal diffusivity of finely (0.84 mm) and coarsely (2.36 mm) ground unprocessed and processed (lignin‐reduced) soybean hulls. The density of the soybean hulls ranged from 1.02 to 1.05 g cm‐3. Heat capacity values ranged from 4725 to 5247 J kg‐1 K‐1. The heat capacity values of the fine of processed soybean hulls were significantly (P < 0.05) greater than the values of the unprocessed ones. The coarsely ground, processed soybean hulls exhibited a 35% greater thermal conductivity value than with other treatments. Thermal diffusivity values ranged from 1.24 to 1.71 ✕ 10‐7 m2 s‐1. Although food scientists and engineers can use these data to help creat efficient food processes and equipment, awareness by crop scientists of these parameters may assist in the future genetic development of desired soybean hull characteristics.
Morphological Trait and Maturity Group Relations with Digestibility of Orchardgrass
Authors: Lentz E. M. , Buxton D. R.
Published: July 2010

Time and labor could be saved in initial screenings if plant breeders had better information on the relationship of morphological traits and of maturity groups to forage quality. This study was conducted to investigate these relations in orchardgrass (>Dactylis glomerata L.). Fifty clones from two maturity groups (anthesis differed by 8 d) were selected divergently for leaf‐blade width, leaf‐blade length, tiller number, growth habit, and seed weight. Space‐planted clones were harvested on a common date in spring (near anthesis of the late group) and summer (after 5 wk of regrowth), and were separated into plant parts before determining in vitro digestible dry matter (IVDDM). Anatomical characteristics were examined for narrow‐ and wide‐blade clones from the two maturity groups. Samples were stained with safranin to identify lignified cell walls, and cross‐sectional areas were quantified by image analysis. Leaf‐blade width was most consistently associated with IVDDM. Wide‐blade clones of the late group were more digestible than narrow‐blade clones during spring growth, but little difference existed during summer regrowth. Differences in digestibility were greatest in stems of reproductive tillers (≈8%). Wide‐blade clones had the same or morelignin in stems than did narrow‐blade clones, but wide‐blade clones had less lignin as a percentage of cross‐sectional area than did narrow‐blade clones. Differences in IVDDM between maturity groups were also most evident during spring growth, when stems of reproductive tillers in the late group were 16% more digestible than those in the early group. Thus, selecting for wide blades and late maturity can be an effective method for initial screening for high digestibility in orchardgrass germplasm.
In Vitro Dry Matter Disappearance and Cell‐Wall Concentrations of Flaccidgrass Masticates Predicted by Near Infrared Reflectance Spectroscopy
Authors: Villalobos J. L. , Burns J. C. , Fisher D. S. , Pond K. R.
Published: July 2010

The degree of ingestive mastication of the diet selected from the pasture canopy by grazing ruminants and the quality of the resulting particles are related to animal performance. This study was conducted to determine if near infrared reflectance spectroscopy (NIP.S) could be used to predict quality of freeze‐dried esophageal extrusa (including saliva) and extrusa particles separated by size. Masticates of flaccidgrass (Pennisetum flaccidum Griseb.) were obtained from a rotational grazing experiment in 1987 and 1988 at the start (initial) of grazing and after 3 d (final) of grazing. Masticates were freeze‐dried and dry‐sieved to give seven particle classes. Best NIPS prediction equations were obtained for the whole masticates (not sieved) and sieved classes when the total data set (whole masticate plus sieved classes) were separated into year and initial vs. final day of grazing. Standard errors of calibration (SEC) for predicting vitro dry matter disappearance (IVDMD), in vitro organic matter disappearance (IVOMD), and neutral‐detergent fiber (NDF) ranged from 14.3 to 26.9 g kg‐1 for masticates at initial grazing and from 17.9 to 28.2 g kg‐1 on the final day of grazing. Standard errors of validation (SEV) slightly exceeded SEC ranging from 13.5 to 28.7 g kg‐1 for masticates at initial grazing and from 19.4 to 28.1 g kg‐1 for masticates on the final day of grazing. Whole masticate samples only, from both the initial and the final day of grazing, gave similar SEC (ranging from 17.6 to 21.0 g kg‐1) and SEV (ranging from 16.9 to 19.9 g kg‐1) as those obtained from the total data set. These SEV are acceptable for analytical purposes and show that NIPS can be used to predict IVDMD, IVOMD, and NDF of esophageal extrusa from flaccidgrass pastures.
Leakage of Intracellular Substances from Alfalfa Roots at Various Subfreezing Temperatures
Authors: Sulc R. Mark , Albrecht Kenneth A. , Palta Jiwan P. , Duke Stanley H.
Published: July 2010

Alfalfa (Medicago sativa L.) freezing tolerance is often determined by measuring leakage of electrolytes from root tissue subjected to only one subfreezing temperature, ‐8 °C. This study was conducted to evaluate the effects of a wide range of subfreezing temperatures on the leakage of intracellular substances from very cold‐hardy (Heinrichs and Vernal) and less cold‐hardy (5432 and Nitro) alfalfa cultivars. Roots of all cultivars were harvested in late antumn of the seeding year and subjected to seven subfreezing temperatures, from ‐4 to ‐16 °C. Injury was determined by measuring the leakage of electrolytes, substances absorbing light at 265 nm (A265), and malate dehydrogenase (MDH) activity from roots after thawing. All measurements of leakage of intracellular substances increased with decreasing subfreezing temperatures, except that those of the less coldhardy caltivars tended to plateau from ‐6 to ‐10 °C. All three leakage measurements followed a similar general trend across subfreezing temperatures, indicating that leakage of electrolytes and A~5 generally reflected substantial membrane damage (leakage of MDH). However, the leakage of electrolytes from roots of very coldhardy cultivars was much more apparent than the leakage of MDH activity at relatively warmer (e.g., ‐4 to ‐6 °C) subfreezing temperatures. This was not true for cultivars with low freezing tolerance, indicating that they suffered substantial membrane damage at all subfreezing temperatures used in this study. The ‐8 °C freezing treatment did not maximize differences among the cuitivars used. Differences in cultivars with high and lower levels of cold‐hardiness were most apparent at temperatures above ‐8 °C and below ‐8 °C, respectively.
Cotton Cultivar Responses to Suboptinal Postemergent Temperatures
Authors: Bradow Judith M.
Published: July 2010

Planting cotton (Gossypium hirsutumd L.) according to an empirically determined earliest planting date increases the probability that fully‐emerged seedlings will be exposed to suboptimal temperatares which significantly affect subsequent development and yield. Most cotton chilling‐stress studies have dealt with the effects of temperatures <10 °C on germinating seeds and emerging seedlings. In this study, the responses of 10‐d‐old seedling roots and shoots of three cultivars of cotton to 10, 15, 20, 25, 30, and 35 °C were determined, using an adaptation of a seed‐vigor testing procedure that employs paper‐towel scrolls and environmental chambers. Inhibition of root and shoot growth (i.e., root and shoot elongation and fresh weight accumulation) at cool temperatures was less in ‘Coker 315’ than in ‘Deltapine 61’ or ‘Paymaster 145’. The capacities of Coker 315 and Deltapine 61 for recovery from a 5‐d exposure to suboptimal temperatures during a subsequent 48 h at 30 °C were greater than that of Paymaster 145. Chilling (10‐25 °C) increased root, but not shoot, relative water content in each cuitivar. The levels of growth inhibition caused by nonoptimal temperatures, and the capacities for regaining pretreatment water relations and resuming growth after chilling stress, differed according to treatment temperature and cultivar. Both decreasing chilling response and increasing poststress recovery capacity offer possibilities for crop improvement in cotton.
Soil Water Potential: Effects on Soybean Looper Feedin on Soybean Leaves
Authors: Lambert Lavone , Heatherly Larry G.
Published: July 2010

Defoliation by soybean looper, Pseudoplusia includens (Walker), often is uniformly high over portions of soybean [Glycine max (L.) Merr.l fields but is uniformly low, or progresses more slowly, over other portions of the same fields. Through the use of insect bioassays the effect of soil water potential (SWP) and two soil types were investigated to determine if they are factors associated with observed soybean looper defoliation patterns. Tests were conducted using excised leaves from greenhouse‐grown plants and laboratory‐reared insects. In Test I, a significant (P ≤ 0.01) reduction in 10‐d larval weights and an increase in larval development periods was caused by plants grown at reduced SWP for 15 d before bioassay initiation. No differences in 10‐d larval weights or development periods associated with Dubbs silt loam (fine‐Silty, mixed, thermic Typic Hapludalf) or Sharkey clay (very‐fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) soils occurred in Test I. In Test II, a large, significant reduction occurred in 10‐d larval weights and an increase occurred in development periods that was associated with plants grown at reduced SWP for 27 d before bioassay initiation. A small, significant decrease in 10‐d larval weights and an increase in larval development periods under reduced SWP was associated with Sharkey clay in Test II. In Test III, a small, significant reduction in 10‐d larval weights and an increase in development periods was associated with plants grown for 24 d at moderately reduced SWP. The effects observed in these tests are great enough to be taken into consideration when conducting host‐plant resistance research and when making insect control decisions.