bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Relationships and Fingerprinting of Rapeseed Cultivars by AFLP: Consequences for Varietal Registration
Authors: Lombard V. , Baril C. P. , Dubreuil P. , Blouet F. , Zhang D.
Published: July 2010

At present, registration and protection of rapeseed (Brassica napus L.) cultivars relies on a small number of morphological traits. As the number of cultivars increases, the ability to distinguish them on the basis of these traits becomes more difficult. New descriptors like molecular markers are required to maintain the efficiency of registration testing. The objectives of this study were to (i) evaluate the discrimination power of 17 amplified fragment length polymorphism (AFLP) primer combinations tested on a collection of 83 spring and winter rapeseed cultivars, (ii) assess the structure of the genetic diversity revealed by AFLPs, and (iii) compare three genetic distance estimators (Jaccard, Sokal, and Michener and Sokal and Michener weighted by the PIC). A total of 324 polymorphic markers were scored, with an average of 19.1 markers per primer combination. The use of only two primer combinations was sufficient to identify uniquely all the cultivars. The analysis of the genetic structure of the diversity by cluster and principal component analyses and AMOVAs (analyses of molecular variance) clearly delineated three significant factors: the cultivar type (winter or spring), the country of origin (France or Germany), and the breeding company. The three measures of genetic distance were highly correlated (P < 0.001, r = 0.96–0.98) and led to similar groupings. AFLPs were shown to be a powerful method for identifying cultivars and analyzing the genetic structure of the diversity in rapeseed.
Molecular Marker Mapping of RSV4, a Gene Conferring Resistance to all Known Strains of Soybean Mosaic Virus
Authors: Hayes Alec J. , Ma Guorong , Buss Glenn R. , Maroof M. A. Saghai
Published: July 2010

Soybean mosaic virus (SMV) is a prevalent viral pathogen of soybean [Glycine max (L.) Merr.] wherever it is grown. Several genes that confer resistance in soybean to soybean mosaic virus have been identified. One of these resistance loci, Rsv4, confers resistance to all the known strain groups of SMV. This study was conducted to determine the map position of the Rsv4 locus in the soybean genome. A population of 255 F2 individuals from the cross of the SMV resistant line LR2 (Rsv4) by the susceptible line Lee68 (rsv4) was evaluated in a mapping study. DNA from 12 to 15 F2 individuals being either homozygous resistant or susceptible were pooled to produce bulk resistant and bulk susceptible DNA samples. Parents and bulks were screened with 101 AFLP primer pairs and two linked polymorphisms were identified. A putative linked marker, amplified by the primers Mse‐AAA and Eco‐AAG, was converted to a restriction fragment length polymorphism (RFLP) clone and a single polymorphic band was mapped 4.8 cM away from Rsv4. The same band was mapped in a second population containing 400 mapped loci and it was determined that this marker was located on the soybean D1b linkage group. Subsequent mapping in the original Rsv4 mapping population showed that the Rsv4 locus is flanked by the microsatellite markers, Satt542 at 4.7 cM and Satt558 at 7.8 cM.
Simple Sequence Repeat–Based Assessment of Genetic Diversity in Cotton Race Stock Accessions
Authors: Liu S. , Cantrell R. G. , McCarty J. C. , Stewart J. McD.
Published: July 2010

Effective use of converted day‐neutral Gossypium hirsutum L. race stocks in cotton genetic improvement programs depends on the extent of genetic variation for desirable alleles and the accurate characterization of the variability within and among germplasm accessions in the collection. This study was conducted to survey the molecular variation in the converted race stock collection by using simple sequence repeat (SSR) DNA markers and to determine the genetic distance of each race stock from a typical G. hirsutum cultigen. The molecular marker data will also provide a measure of the degree to which the recurrent photoperiodic parent has been recovered during backcross conversion to day‐neutral stocks. Fifty‐six flourescently labeled SSR primer pairs arranged in multiplex bins were used to genotype 97 day‐neutral BC4F4 race stock accessions. The majority of the accessions had genetic distances <0.25 from the G. hirsutum standard TM1. There was strong evidence that the accessions were heterozygous or heterogeneous, so 10 plants were genotyped within the most diverse nine accessions, those with genetic distance from TM1 >0.25. In some families, the primitive photoperiodic parent was recovered, and in others there was extensive linkage drag from the day‐neutral donor parent. The recovery of the primitive recurrent parent could be improved by marker‐assisted backcrossing with SSR markers reported in this experiment. Careful genotyping with SSR markers prior to introgression into breeding programs is suggested to ensure maximum genetic diversity and integrity of the exotic race‐stock donor germplasm.
Genetic Gain in Early Stages of a Soybean Breeding Program
Authors: St. Martin S. K. , Futi Xie
Published: July 2010

Multistage testing of genotypes is an essential feature in plant breeding programs. Little research is available to help breeders test efficiently. Our objective was to determine the genetic gain obtained in selected stages of a soybean [Glycine max(L.) Merr.] breeding program and to determine ways to increase the overall gain, if possible. The mean selection differential and genetic gain and their regression coefficient were determined for tests at the F3, F4, and F6generations of the Ohio State University‐Ohio Agricultural Research and Development Center breeding program during 1985 to 1997. Genetic gain for yield averaged −1.4% in the F3stage, 3.7% in the F4, and 9.1% in the F6stage, where percentages are based on the mean of the common check genotypes. Overall changes in maturity were small at each stage. Improvements in lodging resistance occurred in the F4and F6Negative yield gains in the F3were attributed to use of unreplicated plots and to the necessary selection pressure for early maturity. Examination of the selection differentials for individual lines indicated that selection could be intensified in the F4and F6generations with little risk of discarding potentially superior cultivars. The conclusion that near equality of the selection intensity across stages would be beneficial for this breeding program confirms the theoretical recommendations reported in earlier research.
Increase in the Yield of Cytoplasmic Male Sterile Maize Revisited
Authors: Stamp P. , Chowchong S. , Menzi M. , Weingartner U. , Kaeser O.
Published: July 2010

For decades, little attention has been paid to a potential increase in the yield of maize (Zea mays L.) as a result of cytoplasmic male sterility (CMS); however, interest is growing because CMS seed is relatively inexpensive to produce. The present investigations were carried out with two hybrids, `Corso' and `Silex', in Switzerland (in 1994 and 1995) and with an open‐pollinated cultivar, Suwan 2, in Thailand (1996). These cultivars were tested with non restored T‐cytoplasm or with fertile cytoplasm. They were grown with and without nitrogen fertilization at the recommended or at higher plant density; they were grown in Thailand with and without severe preanthesis drought. CMS increased the grain number per ear of all cultivars; in Corso and Suwan 2 a stable kernel weight resulted in an increase in grain yield as well. Plant density, nitrogen application, and drought did not significantly affect changes in the grain yield as caused by CMS. Choosing hybrids with a positive yield response to CMS is suggested; mixtures with a high percentage of CMS hybrids can then be made with their fertile counterparts.
Mineral Nutrition of Tomato under Diurnal Temperature Variation of Root and Shoot
Authors: Gent Martin P. N. , Ma Yong-Zhan
Published: July 2010

Should root and shoot temperature vary in synchrony to optimize nutrient uptake, particularly when there is a large difference in temperature from day to night (DIF) of air and soil? To answer this question, tomato (Lycopersicon esculentumMill.) seedlings were grown in greenhouses with the air heated to give either a +14°C DIF or a +5°C DIF in air temperature with a 16°C mean. The root medium was either unheated except by the air, or heated to 21°C constantly, only in the day, or only in the night. Experiments were repeated in early March and April in two years. Overall, growth was faster and there were higher concentrations of elements in leaves under +5°C compared with +14°C air DIF. Root‐zone heating significantly increased growth and nutrition, compared with no heating. There was a trend in growth and nutrient concentration with timing of root heating: constant > day > night. These differences in growth and nutrition were similar under a +5°C or +14°C air DIF, and they were slight compared with no root‐zone heating. For most nutrients, coordination of root and shoot activity related to uptake and metabolism did not require synchronous variation of air and soil temperature. Uptake and transport of nitrate was an exception. Heating roots in the day resulted in the highest nitrate concentration in leaves under a +14°C air DIF, whereas heating constantly was optimal under a +5°C DIF. Our results indicate nitrate metabolism did benefit from synchronous variation in air and root temperature.
Modification of Seed Germination Performance through Cold Plasma Chemistry Technology
Authors: Volin John C. , Denes Ferencz S. , Young Raymond A. , Park Scott M. T.
Published: July 2010

This study was conducted to determine if an alternate seed treatment approach based on plasma chemistry would offer a more viable alternative over traditional seed coating technologies. Seed germination characteristics were modified in five agricultural species by coating the surface of the seeds with macromolecules from a cold plasma process using a rotating plasma reactor. The source gas entering the plasma chamber during the reaction process determined the type of coating, and coatings were typically much less than 5.0 μm in thickness. To delay germination we utilized two different hydrophobic source gases, carbon tetrafluoride (CF4) or octadecafluorodecalin (ODFD). Seeds of radish (Raphanus sativus) and two pea cultivars (Pisum sativum cv. Little Marvel, P. sativum cv. Alaska) treated with CF4, resulted in a significant delay in germination compared with untreated controls. Similarly, plasma treatment with ODFD significantly delayed germination in soybean [Glycine max (L.) Merr.], corn (Zea mays L.), and bean (Phaseolus vulgaris L.) seeds. The degree of delay was dependent on the amount of coating applied, with an increased thickness of coating resulting in a greater delay in germination. To enhance germination we treated seeds with cyclohexane, or with a gas such as aniline or hydrazine. Seeds treated with cyclohexane resulted in a significant acceleration in germination percentage for soybean but not corn seeds, while hydrazine‐treated corn seed showed a small acceleration over control seed. However, both aniline‐treated soybean and corn seed had a significant acceleration in germination percentage. Tests of water uptake determined that the major mode of action of the plasma coatings was largely on the rate of imbibition. These results demonstrate a potentially important technique to modify seed germination characteristics in agricultural plant species.
Seedset on Synthetic Haploids of Durum Wheat: Cytological and Molecular Investigations
Authors: Jauhar P.P. , Dogramaci-Altuntepe M. , Peterson T. S. , Almouslem A. B.
Published: July 2010

Because of their great importance as cytogenetic and breeding tools, haploids have been produced in several crop plants, including wheat (Triticum aestivumL.). Reports of seedset on haploid plants are very rare. Earlier, we produced 142 haploids (; AB genomes) of seven commercial durum wheat (Triticum turgidumL.) cultivars (Cappelli, Durox, Langdon, Lloyd, Medora, Monroe, and Renville) by crossing them with maize (Zea maysL.). Of these, we studied 101 haploids. Some haploids from each of the cultivars set seed without colchicine treatment or cross pollination. The cytological basis of this interesting phenomenon was studied. Because all cultivars have the homoeologous pairing suppresserPh1, their haploids formed mostly univalents and had irregular meiosis. Yet, viable seed was formed on some haploids. The seedset varied with the genotype. Langdon, with a mean of 2.75 seeds per haploid, was the highest yielder. These seeds gave rise to normal disomic (; AABB) plants. The seeds had viable embryos formed by fusion of unreduced male and female gametes with 14 chromosomes each. The unreduced gametes were formed by two closely related first division restitution mechanisms resulting in meiotic non‐reduction: (i) complete failure of movement of univalents at anaphase I, followed by normal second (equational) division, and (ii) anaphase I movement of all univalents to one pole. Thus, formation of these gametes bypassed the reductional division but occurred by normal equational division. It is hypothesized that lack of pairing may be a prerequisite for the occurrence of meiotic restitution and hence chromosome doubling. Fluorescent GISH (genomic in situ hybridization) analyses of somatic and meiotic chromosomes of the haploid‐derived plants showed the complete duplication of both the A‐ and B‐genome chromosomes. Fertility of the derived disomics and the presence of two doses of the marker chromosome involving the 4A·7B translocation, an evolutionary landmark of durum wheat, further corroborated the precise duplication of all chromosomes. We found that the distal segment translocated from chromosome 7B constitutes approximately 24% of the long arm of 4A.
Tracing the Phylogeny of the Hexaploid Oat Avena sativa with Satellite DNAs
Authors: Li Cheng-Dao , Rossnagel Brian G. , Scoles Graham J.
Published: July 2010

The genus Avena contains 30 different species from diploid through tetraploid to hexaploid with different genome compositions. Research regarding the origin of the different genomes in the polyploid species has been inconclusive. The objectives of this research were to investigate the phylogenetic relationships of the Avena species by means of polymorphisms in satellite, minisatellite, and microsatellite DNA. A satellite DNA sequence, ASS49, was isolated from a microsatellite‐enriched library of the hexaploid oat Avena sativa L. Southern hybridization showed that ASS49 was a species‐specific rather than a genome‐specific satellite. ASS49 was able to distinguish species that may be the diploid and tetraploid progenitors of hexaploid oat. The phylogenetic relationship of Avena species was further investigated using 40 microsatellite and four minisatellite primers. These results appeared to support the findings with ASS49. It appears that the Ac‐genome diploid species (A. canariensis Baum Raj. et Samp.) is the progenitor and A‐genome donor of the hexaploid oat rather than the generally believed As‐genome species (A. strigosa Schreber). Instead, A. strigosa appears to be a member of a separate lineage of diploid and tetraploid species including the tetraploid species A. abyssinica Hochst.
Inheritance of Sugarcane Borer Resistance in Sugarcane Derived from Two Measures of Insect Damage
Authors: White W. H. , Miller J. D. , Milligan S. B. , Burner D. M. , Legendre B. L.
Published: July 2010

The sugarcane borer [Diatraea saccharalis (Fabricius)] is an important insect pest of sugarcane grown in the Americas. Environmental and economic concerns are driving these sugarcane industries to consider alternatives to insecticides for controlling damaging infestations of the borer. Breeding for resistance is a viable option; however, little is known of the inheritance of sugarcane borer resistance. The inheritance of sugarcane borer resistance in sugarcane (Saccharum spp. L.) was investigated in a field study conducted in 1990, 1992, and 1993. We measured resistance by both plant damage response ratings and mean percent internodes damaged. Seedling progeny (F1 plants generated from seed) from 21 to 27 crosses were evaluated each year. These progeny originated from a mating design with females nested within males. Parental genotypes were randomly selected for borer resistance, but were elite cultivars adapted to Louisiana. Data were collected from progeny infested with artificially introduced sugarcane borers. Narrow‐sense heritability on a single‐plot basis (36 plants measured per plot) for damage ratings and for percent damaged internodes were high and of comparable magnitude. For both traits, we detected neither dominance nor additive × year interaction; however, dominance × year interaction variance existed. The potential for genetic advance (GA) from direct selection against percent damaged internodes (GA = 33.9% of mean bored internode) was higher than that from direct selection for lower damage rating (13.5% of mean rating). The much greater resources needed to effect selection for percent bored internodes (approx. 24 times that for rating) suggested direct selection for damage rating may be more efficient. Because the traits were highly correlated and their heritabilities high, correlated gains in percent damaged internodes by direct selection for damage rating were nearly as high as direct selection for percent damaged internodes (31% indirect vs. 33.9% direct).
Wheat Polyphenol Oxidase
Authors: Demeke Tigst , Morris Craig F. , Campbell Kimberly G. , King Garrison E. , Anderson James A. , Chang Hak‐Gil
Published: July 2010

The enzyme polyphenol oxidase (PPO) has been implicated in discoloration of Asian noodles. The recombinant inbred line (RIL) populations, M6/‘Opata 85’, NY18/CC, and ND2603/‘Butte 86’ were used to investigate the distribution, chromosome location, and number of loci involved in wheat (Triticum aestivum L.) PPO. PPO activity was measured by means of the substrates L‐DOPA (L‐3,4‐dihydroxyphenyl‐alanine) and L‐tyrosine. The M6/Opata 85 RIL population had a normal distribution, while the ND2603/Butte 86 RIL population had a bimodal distribution for PPO activity (L‐DOPA assay). Transgressive segregants were observed for all three populations. Correlations between L‐DOPA and L‐tyrosine assays for PPO activity were low to medium and could be attributed to substrate specificity and environment. For the combined analysis of M6/Opata 85 RIL populations, the QTL marker Xfba314 (located on chromosome 2D) showed significant association with PPO activity for the L‐DOPA assay. For the combined analysis of NY18/CC, three QTL markers for L‐DOPA, and two different QTL markers for L‐tyrosine, revealed an association with PPO activity at LOD scores of >2.4. The QTL markers for the NY18/CC RIL population were located on chromosomes 2A, 2B, 3D, and 6B. The ND2603/Butte 86 population had relatively few other loci for linkage analysis and only the marker Xbcd907.RV.I located on chromosome 3BS showed a weak association with PPO activity on the basis of the L‐DOPA assay. The identified QTL markers will be useful for marker‐assisted selection as they build upon the evolving maps for these populations, and for resolving in greater detail the genetic basis of PPO activity in wheat.
Quantitative Assessment of Some Factors Limiting Seed Set in Buckwheat
Authors: Taylor Douglas P. , Obendorf Ralph L.
Published: July 2010

A healthy buckwheat (Fagopyrum esculentum Moench) plant produces numerous flowers but few seeds. The objective of this study was to investigate mechanisms responsible for the low frequency of seed set. Newly open and receptive flowers were pollinated at weekly intervals from 4 to 12 wk after seeding (WAS) on selected racemes of greenhouse‐grown plants. Flower number, seed set, abortion, and anatomical observations of egg sacs and proembryos were analyzed. Although flowers formed continuously for 7 wk, the period of maximum seed set under controlled conditions was brief (1–2 wk). Competition within the same nutritional unit (raceme) did not account for low average seed set per raceme. Neither the number of flowers nor frequency of seed set was decreased when developing seeds were on the same raceme. Abortion (≈10%) was not a major factor limiting seed set. Eighty percent of the flowers failed to initiate seeds even under controlled growing conditions when hand pollinated. Approximately 20% of megagametophytes appeared to be defective at anthesis. The proportion of ovules containing a proembryo at 24 h after pollination (HAP) paralleled the proportion initiating seeds, indicating that fertilization is a limiting process. Pollen tube remnants were observed near the micropyle in 65% of the unfertilized ovules at 24 HAP. Lack of fertilization accounts for most of the reduction in seed set, appears to be caused by failure of the pollen tube to grow into the micropyle, and increases with plant age at pollination. Flowers that form late in the plant cycle contribute little to seed set and may be ignored in yield management decisions.
Maize Kernel Weight Response to Postflowering Source–Sink Ratio
Authors: Borrás Lucas , Otegui María E.
Published: July 2010

In maize (Zea mays L.), the negative effects of increased stand densities on final kernel weight (KW) are attributed to reductions in the effective grain‐filling period, and not in kernel growth rate. This suggests that competition for assimilates among kernels only occurs at the last stages of grain filling. To test this hypothesis, two commercial hybrids of different KW were grown at two stand densities (3 and 9 plants m−2) during 1998 to 1999 and 1999 to 2000. Pollination treatments were performed in order to modify kernel number per plant (KNP) and to obtain a range of source–sink ratios. Pollination treatments altered KNP, and negative relationships were established between KW and KNP, with no differences between years. On the basis of regression analysis of the response of KW to changes in KNP, KW increased between 0.09 to 0.28 mg kernel−1 per unit decrease in KNP, depending on stand density and genotype. The theoretical potential KW was independent of preanthesis plant population effects, which affected ear growth significantly (P <0.01). Kernel weight was closely related to variations in kernel growth rate during the effective grain‐filling period (r2 = 0.84; P <0.001), and not to modifications in the duration of this stage. Within each hybrid, the plant source–sink ratio established during the postflowering period explained KW response to modifications in KNP, independently of stand density. Hybrids differed in the capacity to transform biomass produced at the postflowering period into KW. This was in agreement with differences between hybrids in the capacity to sustain KW when the source–sink ratio was reduced. It is concluded that assimilate limitations to kernel growth occur during the whole grain‐filling period.
Low R:FR Light Quality Delays Flowering of E7E7 Soybean Lines
Authors: Cober Elroy R. , Voldeng Harvey D.
Published: July 2010

A new locus (E7) controlling flowering and maturity time, and photoperiod response in soybean [Glycine max (L.) Merr.] was identified by means of 20‐h days of low (0.7) red:far‐red (R:FR) light quality. The objective of this study was to characterize light quality and photoperiod responses of E7E7 and e7e7 soybean near‐isogenic lines. E7E7 and e7e7 lines, in two genetic backgrounds, were grown in 20‐h photoperiods with four R:FR light qualities (0.7, 1.2, 2.3, 2.7) and in 12‐h photoperiods with 0.7 and 2.7 R:FR light quality. Under high R:FR, all isolines flowered early and similarly in both 12‐ and 20‐h photoperiods. In 20‐h photoperiods, as R:FR light quality approached that of natural day light (1.2), E7E7 lines flowered 6 to 7 d later than e7e7 lines, while under low R:FR (0.7), E7E7 lines flowered about 15 d later than e7e7 lines. Under low R:FR, all isolines flowered later under 20‐h compared with 12‐h photoperiods. Six ‘Harosoy’ isolines (e7e7 and 5 E7E7 lines) were grown in 1998 and 1999 in the field under natural daylength and daylength extended to 20 h with incandescent lamps (ILD). The e7e7 line matured 6 d earlier than the E7E7 line under natural and ILD photoperiod. An ILD treatment was simulated in growth cabinets with 4+12+4 h of incandescent light and was compared with 12‐, 20‐, and 24‐h photoperiods. All lines flowered early and similarly under 12‐h photoperiod. The 4+12+4‐h treatment delayed flowering less than the 20‐h photoperiod. Flowering was not delayed further when the photoperiod was extended from 20 to 24 h. The E7E7 lines were sensitive to light quality. They did not perceive long days of high R:FR light quality, but under natural daylight and under low R:FR light quality, E7 delayed flowering.
Quantifying Turfgrass Cover Using Digital Image Analysis
Authors: Richardson M. D. , Karcher D. E. , Purcell L. C.
Published: July 2010

Accurate cover estimates in turfgrass research plots are often difficult to obtain because of the time involved with traditional sampling and evaluation techniques. Subjective ratings are commonly used to estimate turfgrass cover, but the data can be quite variable and difficult to reproduce. New technologies and software related to digital image analysis (DIA) may provide an alternative method to measure turfgrass parameters more accurately and efficiently than current techniques. A series of studies was conducted to determine the applicability of DIA for turfgrass cover estimates. In the first study, plots containing a range (1–16) of bermudagrass [Cynodon dactylon (L.) Pers.] plugs of specific diameter (15.0 cm) were established to represent values of turfgrass cover from 0.75 to 12%, by 0.75% increments. Digital images (1280 by 960 pixels) were taken with a digital camera and processed for percent green color to a software package. Estimates of green turfgrass cover by DIA were highly correlated (r2 > 0.99) to the calculated values of turfgrass cover. In a second study, DIA of turfgrass cover was compared by subjective analysis (SA) and line‐intersect analysis (LIA) methods for estimating cover in eight plots of zoysiagrass (Zoysia japonica Steudel). The mean variance of percent cover determined by DIA (0.65) was significantly lower than SA (99.12) or LIA (13.18). Digital image analysis proved to be an effective means of determining turfgrass cover, producing both accurate and reproducible data. In addition, the technique effectively removes the inherent error and evaluator bias commonly associated with subjective ratings.
Endophyte infection can contribute to aluminum tolerance in fine fescues
Authors: Zaurov D. E. , Bonos S. , Murphy J. A. , Richardson M. , Belanger F. C.
Published: July 2010

Thirteen clonal pairs of endophyte‐free and endophyte‐infected fine fescues were evaluated in a growth chamber study for growth in three sand‐soil formulations differing in available aluminum. This set of plants consisted of four Chewings fescue [Festuca rubra L. subsp. fallax (Thuill) Nyman] and two strong creeping red fescue (Festuca rubra L. subsp. rubra) genotypes inoculated with endophytes originating from Chewings fescue, strong creeping red fescue, and Poa ampla Merr. hosts. The results revealed a considerable endophyte‐host interaction on plant growth in the different soils. In most cases, the effect of endophyte infection on dry weight was either positive or neutral. In a few cases, endophyte infection had a negative effect on dry weight. In some endophyte‐host combinations, the endophyte‐infected clone had significantly better growth in the high aluminum soils relative to the endophyte‐free clone. These results indicate that endophyte infection alone is not enough to confer aluminum tolerance in fine fescues, but in certain plant‐fungus combinations, endophyte infection can contribute to enhanced aluminum tolerance.
Germination, Emergence, and Yield of 20 Plant–Color, Seed–Color Near‐Isogenic Lines of Grain Sorghum
Authors: Pedersen J.F. , Toy J.J.
Published: July 2010

Although there is growing demand for sorghum [Sorghum bicolor (L.) Moench] with white seed and tan plant color, there is limited information on the overall agronomic fitness of sorghum with these characters. A set of experiments was conducted to evaluate the combined effects of plant color and seed color on sorghum germination, emergence, and agronomic performance. Twenty near‐isogenic lines with red seed/tan plant (RT), red seed/purple plant (RP), white seed/tan plant (WT), white seed/purple plant (WP) phenotypes were tested under field and laboratory conditions. Plant color × seed color interactions were not significant. Purple plant color phenotypes had higher cold germination, higher germination after accelerated aging, and greater seedling elongation at 10 d than tan plant color phenotypes. Plant color did not influence standard warm germination. No differences in standard warm germination or seed vigor test results were attributable to seed color. Seedling emergence under field conditions was higher for the red seed than the white seed phenotype. Grain yield was higher for the white seed than the red seed phenotype, and higher for the purple plant color than the tan plant color phenotype. Grain test weights from purple plant color lines were higher than those from tan plant color lines. All four phenotypes included relatively high yielding lines. There was considerable overlap between WT, WP, RT, RP lines in yield and other indicators of agronomic performance leading to the conclusion that white seed and tan plant color lines with comparable performance to red seed and purple plant color lines can be selected from segregating breeding populations.
Tillering, Internode Development, and Dry Matter Partitioning in Creeping Bentgrass
Authors: Cattani D.J. , Struik P.C.
Published: July 2010

High tiller density and stolon development are critical to wear tolerance and persistence of creeping bentgrass (Agrostis palustrisHuds. synonymA. stoloniferaL.). A better understanding of creeping bentgrass growth and development would be helpful in screening germplasm for improved turf characteristics. The objectives of this study were to determine tiller appearance and main stem elongation and development, and to determine above ground dry matter partitioning, in high and low tillering populations of creeping bentgrass grown under low light (150 μmol m−2s−1). Individual, pregerminated seeds of cv. Emerald and germplasm UM67‐10 were transplanted into 10‐cm pots containing an 80:20 (v/v) sand:peat media. Two growth cabinet experiments were conducted under 16‐ and 8‐h photoperiod and 20/15°C day/night temperatures. Phenological development was monitored through 35 d after transplanting (DAT). Dry weight per tiller was correlated to tiller age for main stem and primary tillers (r= 0.98 andr= 0.99) and secondary tillers (r= 0.93 andr= 0.99) for UM67‐10 and Emerald, respectively, at 35 DAT. Dry weight per tiller was related to tiller elongation. Population differences for dry weight accumulationper day were significant (P= 0.05) for lower order tillers. The germplasm UM67‐10 initiated tillering earlier and main stem elongation later than Emerald. Tillers per plant were correlated to tiller appearance date. Elongating tiller weight within populations was related to main stem elongation date and its final length. Late season planting, when daylight is decreasing, will result in a bentgrass stand with fewer tillers per plant and with little elongated stem growth. Screening germplasm for tiller production in a growth cabinet may facilitate identifying grasses with high tiller density and improved wear tolerance.
Determining Genetic Similarities and Relationships among Cowpea Breeding Lines and Cultivars by Microsatellite Markers
Authors: Li Cheng‐Dao , Fatokun Christian A. , Ubi Benjamin , Singh Bir B. , Scoles Graham J.
Published: July 2010

Cowpea [Vigna unguiculata (L.) Walp] is an important grain legume crop grown for its protein rich grains. It is an inexpensive source of protein in the diets of people in sub‐Saharan Africa. The International Institute of Tropical Agriculture (IITA) has been working on the improvement of cowpea for more than 30 yr. Over 60 countries receive cowpea cultivars improved by IITA for testing and adoption where needed. Many of these cultivars have identical parentage but look very different morphologically when grown in the field. Forty‐six microsatellite DNA markers were used to evaluate genetic similarities among 90 cowpea breeding lines developed at IITA. Twenty‐seven primer pairs could amplify polymorphic single‐locus microsatellites from all of these materials. Two to seven alleles per primer were detected with a polymorphic information content varying from 0.02 to 0.73. By means of only five polymorphic microsatellite primers, 88 of the 90 cowpea lines could be distinguished. A dendrogram based on the microsatellite polymorphisms generally agreed with the pedigree of the cowpea lines.
Interpretation of Genotype × Environment Interaction for Winter Wheat Yield in Ontario
Authors: Yan Weikai , Hunt L.A.
Published: July 2010

An understanding of the causes of genotype × environment (GE) interaction can help identify traits that contribute to better cultivar performance and environments that facilitate cultivar evaluation. Through subjecting environment‐centered yield of a multi‐environment trial data to singular value decomposition, the portion of yield variation that is relevant to cultivar evaluation is partitioned into noncrossover and crossover GE interaction, quantified by the first two principal components (PC), respectively. Each PC is a set of genotypic scores multiplied by a set of environmental scores. By relating the PC scores to genotypic and environmental covariates, GE interaction represented by each PC can be interpreted in terms of trait × factor interactions. This strategy was employed in analysis of the 1992 to 1998 Ontario winter wheat (Triticum aestivum L.) performance trial data. Results indicated that plant height and maturity were the major genotypic causes of GE interaction, whereas cold temperature in the winter and hot temperature in the summer were the major environmental causes of GE interaction. Positive interactions were found between earlier maturity vs. warmer winters or hotter summers, and between shorter plant height vs. warmer winters or cooler summers. In addition, better resistance to septoria leaf blotch (caused by Septoria secalis Prill. & Delacr.) was frequently associated with overall performance. The results of this study should help in determining breeding objectives and for selecting test sites or environments for winter wheat breeding in Ontario.
Development of a Chickpea Core Subset Using Geographic Distribution and Quantitative Traits
Authors: Upadhyaya Hari D. , Bramel Paula J. , Singh Sube
Published: July 2010

Chickpea (Cicer arietinum L.) is a major food legume and an important source of protein in many countries in Asia and Africa. Crop productivity continues to be low (0.78 t ha−1). A very small number of the 16 991 accessions in the ICRISAT germplasm collection that contain a high level of genetic variability have been used in the chickpea improvement program. The objective of our research was to develop a core collection of chickpea that will enhance utilization of these resources in improvement programs and simplify their management. Germplasm accessions were stratified by country of origin and the data on 13 quantitative traits were used for clustering by Ward's method. From each cluster, ≈10% of the accessions were randomly selected to constitute a core subset of 1956 accessions. A comparison of mean data using Newman‐Keuls test, variance using Levene's test, distribution using the χ2 test, and Wilcoxon's rank‐sum non‐parametric test for different traits indicated that the genetic variation available for these traits in the entire collection had been preserved in the core subset. The important phenotypic correlations among different traits, which may be under the control of co‐adapted gene complexes were also preserved in the core subset. This core subset will be a point of entry to the proper exploitation of chickpea genetic resources for the improvement of the crop.
Genetic Factors Influencing High Oleic Acid Content in Spanish Market‐Type Peanut Cultivars
Authors: López Yolanda , Smith Olin D. , Senseman Scott A. , Rooney William L.
Published: July 2010

Increasing the ratio of oleic to linoleic acid (O/L) in peanut (Arachis hypogaea L.) significantly improves the nutritional and quality attributes of the crop. In currently grown cultivars, the O/L ratio ranges from 0.8 to 2.5. Variation in peanut for O/L ratio has been characterized, and the O/L ratio is digenically inherited at two loci designated as Ol1 and Ol2 Previous research has been conducted with Virginia‐ and runner‐type peanut; however, there have been no reports regarding the inheritance and allele frequency at these loci in Spanish‐type peanut. The objectives of this study were to determine if the inheritance of the high oleate trait in Spanish‐type peanut is similar to that previously reported and to determine the allelic composition of Spanish‐type peanut at Ol1 and Ol2 Six different Spanish‐type peanut cultivars (low oleate) were hybridized with F435‐2—2 (high oleate). F2 and BC1F1 progenies were evaluated for the O/L ratio. Segregation patterns indicated that high oleic acid content is digenically inherited in Spanish‐type peanut, but there seems to be more allelic variation both within and among these cultivars. In addition, variation within the high and low oleate ratio classes indicated that other factors may be involved in determining the precise O/L ratio.
Rising Atmospheric Carbon Dioxide and Seed Yield of Soybean Genotypes
Authors: Ziska Lewis H. , Bunce James A. , Caulfield Frances A.
Published: July 2010

If intraspecific variation to rising atmospheric CO2 exists in soybean [Glycine max (L.) Merr.], such variation could be used to select for optimal, high‐yielding cultivars. To quantify the range and determine the basis for variation in seed‐yield with increasing CO2, eight ancestral and one modern soybean cultivar differing in determinacy, maturity group, and morphology were grown to reproductive maturity at two CO2 partial pressures, 40 Pa (ambient) and 71 Pa (elevated). Experiments were replicated three times in temperature controlled glasshouses during 1998 and 1999. Although all cultivars showed a significant increase in seed yield with elevated CO2,(∼40%) Mandarin, an ancestral indeterminate cultivar, showed a greater relative response of seed yield to increased CO2 than did all other cultivars (∼80%). The observed variation in seed yield response to CO2 was not correlated with any vegetative parameter. At maturity, significant correlations in the relative response of seed yield to CO2 were observed for both pod weight per plant and seed weight from branches. The later observation suggests that the sensitivity of seed yield response to CO2 was associated with plasticity in the ability to form new seed in axillary branches in a high CO2 environment. Genotypic differences in the seed yield response among existing ancestral soybeans suggests that sufficient germplasm is available for breeders to begin selecting lines which maximize soybean yield in response to increasing atmospheric CO2
Supraoptimal Soil Temperatures Induced Oxidative Stress in Leaves of Creeping Bentgrass Cultivars Differing in Heat Tolerance
Authors: Huang Bingru , Liu Xiaozhong , Xu Qingzhang
Published: July 2010

High temperature is a major factor limiting growth of cool‐season grasses during summer months. The objective of this study was to determine whether oxidative stress is involved in leaf injury induced by high soil temperatures in two creeping bentgrass (Agrostis palustris Huds.) cultivars, heat‐tolerant L‐93 and heat‐sensitive Penncross. Shoots and roots were exposed to four differential temperature regimes in growth chambers and water baths: (i) 20/20°C (control); (ii) 20/35°C (high soil temperature); (iii) 35/20°C (high air temperature); and (iv) 35/35°C (high shoot/soil temperatures). Turf quality, leaf photochemical efficiency (Fv/Fm), electrolyte leakage (EL), content of a lipid peroxidation product (malondialdehyde, MDA), and activities of the antioxidants superoxide dismutase (SOD) and catalase (CAT) were determined. Turf quality and leaf Fv/Fm ratio decreased, whereas EL and MDA contents increased under high soil temperature alone or in combination with high air temperature regimes in both cultivars, but to a greater extent in Penncross than in L‐93. Decreases in turf quality and Fv/Fm ratio and increases in EL and MDA were more pronounced at 20/35°C than at 35/20°C. The activities of SOD and CAT decreased with prolonged periods of high temperatures and to a greater extent for Penncross than for L‐93. The reductions in SOD and CAT activities were more severe at 20/35 than at 35/20°C. These results suggest that high soil temperature caused more severe oxidative damage to leaves than high air temperature by limiting antioxidant activities and inducing lipid peroxidation. This oxidative stress was associated with accelerated leaf senescence under high temperature conditions. Maintenance of antioxidant activities and low levels of lipid peroxidation was related to the better tolerance of creeping bentgrass to high soil temperature stress imposed on roots or high air temperature on shoots.
Nutritive Values of Smooth Bromegrass, Meadow Bromegrass, and Meadow × Smooth Bromegrass Hybrids for Different Plant Parts and Growth Stages
Authors: Ferdinandez Yasas S.N. , Coulman Bruce E.
Published: July 2010

Three hybrid populations between meadow bromegrass (Bromus riparius Rehm.) and smooth bromegrass (Bromus inermis Leyss) have been developed through hybridization and recurrent selection. The objective of this study was to determine the concentration of acid detergent fiber (ADF), neutral detergent fiber (NDF), and crude protein (CP) of leaf blades, stems, and whole‐plant herbage of three hybrid bromegrass populations (S‐9197, S‐9073 and S‐9183) and the two parental species at vegetative, heading, and anthesis stages of development. Generally, the highest leaf blade NDF, ADF, and lowest CP concentrations were observed in meadow bromegrass, regardless of the growth stage. For the stem fraction, hybrid S‐9183 had the lowest ADF (240 g kg−1) and NDF (532 g kg−1) at the vegetative stage. At anthesis, in 1997, stem NDF concentrations of meadow bromegrass, S‐9197, and S‐9073 were similar, but lower than S‐9183 and smooth bromegrass. At later stages of development, meadow bromegrass had higher stem CP concentrations (94–114 g kg−1) than other entries (62–110 g kg−1). For whole‐plant samples, NDF (359–490 g kg−1) and ADF (178–214 g kg−1) concentrations of the three hybrid populations were consistently lower than the parental species at the vegetative stage of growth. The hybrid populations, particularly S‐9183, were lower in NDF and ADF at early stages of maturity, suggesting that they have potential as high quality forage species for grazing and hay prior to or at heading.
Adaptive Ecology of Lotus corniculatus L. Genotypes: II. Crossing Ability
Authors: de los Santos G.Garcia , Steiner J.J. , Beuselinck P.R.
Published: July 2010

Birdsfoot trefoil (Lotus corniculatus L.) is a widely distributed polymorphic Old‐World perennial forage legume found in wild and naturalized populations throughout temperate regions of Europe, Asia Minor, North Africa, and North and South America. Exotic birdsfoot trefoil germplasm has rarely been used for birdsfoot trefoil genetic enhancement, and information about its crossing ability with other exotics and commercial quality germplasm is not available. The objectives of this research were to (i) characterize the crossing ability of 27 exotic birdsfoot trefoil genotypes with two genetically diverse hybridization testers, and (ii) determine if crossing ability among genotypes was related to their genetic background measured by random amplified polymorphic DNA (RAPD) markers and their ecogeographic origins. Crossing ability was determined using reciprocal crosses with one commercial‐quality germplasm and one exotic genotype tester. All possible crossing combinations for an eight‐genotype subset were also determined. Crossing ability was measured as the percentage of pollinated flowers that set pods, F1 progeny pollen viability, pod length, and seeds per pod. Self‐genotype pod set and pollen viability were not correlated. Intermediate bridge crosses were identified that could potentially overcome specific cross incompatibilities and be used to obtain progeny for any combination of genotypes. Genotype‐crossing ability was associated with ecogeographic features of the collecting site, but not with morphologic characteristics. This differs from findings that other genotype morphologic characteristics are associated with ecogeographic origins and genetic similarities based on RAPD markers. Exotic birdsfoot trefoil genotypes can be utilized with commercial‐quality germplasm using conventional crossing methods.
Interpretation of Genotype × Environment Interactions for Early Maize Hybrids over 12 Years
Authors: Signor C.Epinat‐Le , Dousse S. , Lorgeou J. , Denis J.‐B. , Bonhomme R. , Carolo P. , Charcosset A.
Published: July 2010

Genotype × environment interaction was investigated for grain yield of early maize (Zea mays L.) hybrids. Data were obtained from the French Association Générale des Producteurs de Maïs trial network and included 132 hybrids and 229 environments over 12 yr, following an unbalanced design. Analysis of genotype × environment interaction was done for the 1‐yr data sets, for the two successive years data sets, and for the 12‐yr data set. The magnitude of genotype × environment interaction variance was equal to, or greater than the genotypic variance. Interaction effect was modeled by factorial regression analysis using additional genotypic and environmental information. Genotypic covariates considered were the sum of growing day degrees (GDD) necessary from sowing to flowering and the GDD necessary from flowering to maturity. Environmental covariates were the mean temperature from sowing to the 12 leaf stage, the mean temperature from the 12 leaf stage to the end of the linear grain‐filling stage, the water balance around flowering, and the sum of solar radiation around flowering. These six covariates explained about 40% of the interaction effect in all analyses, with equal contribution of genotypic variates (20%) and environmental variates (20%). Flowering earliness of hybrids, water balance around flowering, and mean temperature from the 12 leaf stage to the end of the grain filling phase were determinants of genotype × environment interaction for grain yield in the considered area. A biological interpretation of the interaction was attempted through examination of the regression parameters.