bluuebunny/crossref_metadata_2025 huggingface dataset:
Solar Energy Recovery by Elephantgrass, Energycane, and Elephantmillet Canopies
Authors: Woodard K. R. , Prine G. M. , Bachrein S.
Published: July 2010

Elephantgrass (Pennisetum purpureum Schum.) and energycane (Saccharum spp.) have been identified as biomass plants for renewable energy. A field study was conducted at Gainesville, FL, in 1989 and 1990 to identify plant attributes that allowed these C4 bunchgrasses to accumulate high annual dry matter (DM) yields and to compute the efficiency by which solar energy is collected and stored in plant biomass. Entries were PI 300086 (PI3) and N51 elephantgrasses, L79‐1002 (L79) energycane, and S41 elephantmillet [Pennisetum glaucum (L.) R. Br. × P. purpureum Schum.]. Plots were mowed to 10‐cm height on 28 March to begin the season. For PI3, light interception by the top green portion of the canopy was greater than 90% from 49 to 217 d after mowing. For L79, interception increased from 83% on 49 d after mowing to 90% on 91 d and remained above 90% to 245 d after mowing. Two‐year means for radiation‐use efficiency (RUE), computed for near‐linear DM accumulation phase, were 1.25 g DM MJ−1 of total solar radiation (TSR) for PI3, 1.26 for N51, 1.24 for L79, and 1.11 for S41. Mean energy concentrations of mature growth ranged from 17.1 to 18.2 kJ g−1 DM. Two‐year average percentages of TSR converted to chemical DM energy, were 2.3 for PI3, 2.3 for N51, 2.2 for L79, and 1.9 for S41. These bunchgrasses produced greater annual DM yields than other C4 plants because tillers grew vegetatively for 30 to 35 wk. During this period, a green canopy top was maintained and light interception and RUE continued at levels generally expected for actively growing C4 grasses.
Regional Diversity in Nondormant Alfalfas from India and the Middle East
Authors: Warburton M. L. , Smith S. E.
Published: July 2010

Alfalfa (Medicago sativa L.) is an important crop in many desert regions with long growing seasons. Very non‐winterdormant (nondormant) cultivars are derived primarily from germplasm obtained from low elevations in the Middle East and India. Improved understanding of diversity in alfalfas from these regions may enhance conservation and utilization of this germplasm resource. To better characterize patterns of diversity in very nondormant Indian and Middle Eastern alfalfas, we evaluated 34 accessions from low elevations in western, central, and northern India, and throughout the Middle East in a field trial in Tucson, AZ, during 1989 to 1992. Middle Eastern accessions included representatives of geographical groups formulated in previous research. Cluster analysis and plots of the first three principal components of 12 agronomic and six morphological traits were used to describe patterns of variation among accessions. Both analytical approaches showed that Indian accessions were phenotypically distinct from the Middle Eastern germplasm evaluated. Northern Indian germplasm was much more persistent and higher yielding than that from western India and was generally more similar to the majority of Middle Eastern accessions than to accessions from western India. Most accessions from the Gujarat state in western India were exceptional, exhibiting very poor persistence and adaptation to temperatures near 0 °C. Arabian accessions were generally distinctive, especially those from western and southern Arabia which exhibited very rapid regrowth following harvest. Results of this study and previous research suggest that at least six regional germplasm groups exist among nondormant North African, Arabian, and Indian alfalfa germplasm.
Dry Matter Concentration as an Index of in Vitro Dry Matter Disappearance in Bermudagrass
Authors: Degenhart N. R. , Burton G. W.
Published: July 2010

Simple and cost‐effective procedures for predicting forage quality are needed. The objective of this study was to determine if dry matter concentration (DMC) could be used as an index of in vitro dry matter disappearance (IVDMD)in bermudagrass (Cynodon spp.). Data were from two bermudagrass trials at Tifton, GA. The 1983 and 1985 trials contained 32 and 28 entries replicated five times. Plots were harvested four times a year for 3 yr, except in 1987 when only three harvests were taken. A negative correlation was observed between DMC and IVDMD. Coefficients of determination (r2) from the regression of entry mean IVDMD on DMC from individual harvests ranged from 0.01 to 0.82. Entry DMC means averaged across harvests within years provided consistent index of IVDMD(r2 = 0.20, 0.65, 0.49, 0.57, 0.60, and 0.59). Regression coefficients differed among groups of bermudagrass entries having different genetic backgrounds. When screening bermudagrass entries for forage IVDMD, ≈50% of the entries could be eliminated based on forage DMC if the entries are replicated over space and time.
Improved Method for Maintaining Soil Moisture Levels for Plant Seedling Research
Authors: Rossi F. S. , Neal J. C. , Whitlow T. H.
Published: July 2010

Semipermeable membrane systems are available, yet, plant seedling research requires adaptations that allow for consistent performance by utilizing materials that encourage adequate growth responses. Soil‐filled semipermeable membrane envelopes, enclosed in 1‐cm‐thick stainless steel wire frames, equilibrate with polyethylene glycol (PEG) 10000 solution with osmotic potential (ψπ) of −0.4 MPa within 36 h and equilibrate with −0.8 MPa solution within 60 h. Linear relationships existed between predawn plant water potential (ψ), soil matric potential (ψm), and PEG ψπ. Improvements compared with previously reported methods included reduced equilibration time and stainless steel frame construction which aided in avoiding Zn toxicity associated with galvanized metal.
Polyhaploid Production in the Triticeae: Wheat × Tripsacum Crosses
Authors: Riera‐Lizarazu Oscar , Mujeeb‐Kazi Abdul
Published: July 2010

Wheat, Triticum aestivum L., haploid production relies heavily on its crosses with bulbous barley, Hordeum bulbosum L., and on anther culture, procedures influenced by genotypic specificity. Wheat × maize, Zea mays L., crosses are devoid of this constraint. In this study eastern gamagrass [Tripsacum dactyloides (L.)L.) is utilized. Cross success is anticipated to extend (i) the range of species available for Triticeae haploid production, and (ii) the crossing cycle duration. Intel‐generic crosses of T. aestivum (2n ‐ 6x = 42; AABBDD), T. turgidum L. (2n = 4x = 28; AABB), and T. turgidum × Aegilops squarrosa L. (T. tauschii) synthetic hexaploids (2n = 6x = 42; AABBDD) with Tr. dactyloides (2n = 2x = 36) as the pollen donor resulted in progenies that were polyhaploids of the Triticeae parents, presumably due to elimination of the Tr. dactyloides chromosomes during early embryo development. Embryo recovery frequencies were 20.6% for T. aestivum cultivars, 26.8% for T. turgidum cultivars and 23.5% for the synthetic hexaploids. Plant regeneration ranged between 66.7 to 78.5% over the three maternal crossing groups. As with maize, polyhaploid production in the Triticeae with Tripsacum is dependent upon a postpollination treatment with 2,4‐D (2,4‐dichlorophenoxyacetic acid) to promote embryo development and shows no strong genotypic specificity. Limited meiotic analyses for the T. aestivum cultivars and synthetic hexaploids gave metaphase I associations characteristic of nonallosyndetic chromosomal pairing. Pollinations with Tripsacum, together with maize pollinations offer an extended crossing cycle and in addition extend the range of alien species for producing polyhaploids in the Triticeae.
Germination of Perennial Ryegrass and Annual Bluegrass Seeds Subjected to Hydration‐Dehydration Cycles
Authors: Allen P. S. , White D. B. , Markhart A. H.
Published: July 2010

Seeds that encounter widely fluctuating water conditions during germination could die, become dormant, lose hydration‐dependent steps toward radicle emergence through dehydration, or incrementally accumulate events required for radicle emergence. These alternatives were evaluated with seeds of perennial ryegrass (Lolium perenne L.) and annual bluegrass (Poa annua L. var. annua) exposed to repeated hydration‐dehydration episodes. Seeds were cycled between liquid (hydration phase, Ψ = 0 MPa)and vapor (dehydration phase, Ψ = − 4 or − 10 MPa) environments for up to 16.5 cycles or 328 h, with phase durations of 8, 16, or 24 h. Cycling generally resulted in delayed, but more uniform germination. Cycled seeds required fewer hours in contact with liquid water to germinate than did continuously hydrated seeds and were not killed by repeated dehydration for up to 24 h at −10 MPa. Coleorhiza tissue that emerged from perennial ryegrass seeds following accumulation of 24 hydration‐phase hours retracted during dehydration, but this did not negatively affect radicle emergence upon subsequent rehydration. Annual bluegrass seeds were prevented from germinating by 8‐h hydration phases coupled with 16‐ or 24‐h dehydration phases at − 10 MPa. Upon transfer to continuous hydration, however, seeds germinated within 36 h. These data support the hypothesis that seeds of perennial ryegrass and annual bluegrass can progress toward germination with intermittent hydration.
Simulating Grass Seed Passage through the Digestive System of Cattle: A Laboratory Technique
Authors: Ocumpaugh W. R. , Swakon D. H. D.
Published: July 2010

Seed of numerous grass species are known to be ingested by cattle (Bos spp.) and remain germinable, while seed of other grass species do not. The seed and animal factors that control the fate of grass seed have eluded researchers. Earlier research showed that seed germination declines linearly with increased residence time in the gastrointestinal tract of cattle. The objectives of this research were to develop modifications to the two‐stage in vitro dry matter digestion procedure (used for evaluating forage digestibility) so the procedure will produce the linear decline in seed germination observed in vivo. A series of in vitro trials was conducted with seed of ‘Alamo’ and ‘Sunburst’ switchgrass (Panicum virgatum L.), TEM‐LD1 kleingrass (P. coloratum L.), ‘Pensacola’ bahiagrass (Paspalum notatum Flugge), and sideoats grama [Bouteloua curtipendula (Michx.) Torr.], with all but the latter having known good seed survival in vivo. The main modification to the two‐stage in vitro dry matter digestion procedure was to shorten the acid‐pepsin phase to about 7 h. We used 24, 48, and 72 h total digestion times to develop the procedure, but screening of species could be done at a single digestion time. Results confirmed that forage similar to diets consumed with seed must be included in in vitro tubes with seed, the acid‐pepsin digestion phase needs to be 7 to 10 h long to provide linear germination responses, and the in vitro procedure will rank species similar to in vivo for relative seed germination. A standardized procedure is described in the text.
Performance of Near‐Isogenic High and Low Oleic Acid Hybrids of Sunflower
Authors: Fernández‐MartÍnez J. , Muñoz J. , Gómez‐Arnau J.
Published: July 2010

The development of hybrids with high levels of monounsaturated oleic acid is an important goal among sunflower (Helianthus annuus L.) breeders. The objective of this study was to determine the association of high oleic alleles with agronomic and chemical characters of sunflower. Two cytoplasmic male sterile and two restorer parental lines averaging 890 g kg−1 oleic acid and their isogenic counterparts with 230 g kg−1 oleic acid were crossed to obtain four high‐oleic and four Iow‐oleic acid near‐isogenic hybrids. The pairs of isogenic hybrids were evaluated for agronomic performance in a replicated test at several locations differing widely in temperature and water availability during seed formation. High oleic acid hybrids produced significantly greater seed yield, oil content, and above‐ground biomass than low oleic acid hybrids. For the other evaluated characters, high oleic acid hybrids were earlier and less self‐compatible than their isogenic counterparts with low oleic acid forms, although there were differences between environments and genetic backgrounds. The high oleic acid hybrids averaged 626 g kg−1 higher oleic acid content than low oleic hybrids. This difference was lower for open‐pollinated seed although high oleic hybrids maintained oleic acid levels near 775 g kg‐1 under open pollination. The high oleic OL allele appears to have a positive influence on yield and oil content and a negative effect on self‐compatibility; but it depends somewhat on the genetic background into which they are introduced.
Linkage Between Endopeptidase Ep‐D1d and a Gene Conferring Leaf Rust Resistance (Lr19) in Wheat
Authors: McMillin David E. , Johnson Jerry W. , Roberts John J.
Published: July 2010

Biochemical markers linked to pest resistance genes would be useful to plant breeders. This study was conducted to determine if biochemical markers could be found closely linked to genes conferring leaf rust resistance in wheat (Triticum aestivum L.). Near‐isogenic lines have been developed in ‘Thatcher’ for a number of genes, Lrl to Lr31, conferring resistance to leaf rust, caused by Puccinia recondita Rob. ex Desm. Fifteen of these Thatcher near‐isogenic lines were evaluated for the isozymendopeptidaseo Two of the near‐isogenic lines (Lrl and Lrl9) had endopeptidase phenotypes that differed from the Thatcher backcross parent. The endopeptidase phenotype observed in the near isogenic line possessing Lrl9 was completely different from any other phenotype normally observed in wheat. The leaf rust resistant Thatcher near‐isogenic line possessing Lrl9 was crossed with the leaf rust susceptible cultivar ‘GA 100’ (PI538257). The 59 F2 progeny were grown in the greenhouse and evaluated for leaf rust resistance and endopeptidase phenotype. All F2 progeny exhibiting the Lrl9 endopeptidase phenotype were resistant to leaf rust. Maximum likelihood estimation, using the F2 phenotypic data, indicated a very tight linkage with a recombination value of 0.01 ± 0.009 map units for the Lrl9 and Ep‐D1d loci. In addition, no recombinant F2 genotypes were found among the 30 F2 plants for which F3 progeny were obtained. Thus, the gene Lrl9, which confers resistance to leaf rust, and the gene Ep‐Dld which encodes endopeptidase phenotype EP‐Dld, are linked. This linkage will enable rapid detection of seedlings possessing Lrl9 in wheat improvement programs.
Isozyme Variation in Cultivated Oat and Its Progenitor Species Avena sterilis L
Authors: Murphy J. P. , Phillips T. D.
Published: July 2010

Effective identification of wild accessions with potential to enhance variation for complex, Iow‐heritability traits is a prerequisite to broader utilization of conserved genetic resources. In two previous studies, 23 enzyme systems were assayed in 405 oat cultivars (Avena sativa L. and A. byzantina C. Koch) and in 1005 accessions of the progenitor species. A. sterilis L. The objectives of the present report were to (i) compare isozymic variation in cultivated oat with a broad geographical sample of accessions of the progenitor species and (ii) propose strategy to assist in the efficient sampling of progenitor germplasm by North American oat breeders. Avena sterilis displayed a greater level of isozymic diversity compared to cultivated germplasm based upon number and frequencies of variants. Three sampling strategies are discussed whereby a representative core of A. sterilis accessions could be selected from the progenitor germplasm pool. A combined strategy is outlined that incorporates elements of all three, with selection of accessions from (i) the center of isozymic diversity (Turkey), (ii) six clusters of A. sterilis accessions identified by multivariate analysis of genetic distances between accessions without regard to provenance data, and (iii) those accessions with variants present at intermediate to high frequencies in A. sterilis from individual countries or clusters yet absent in cultivated germplasm. Selected A. sterilis accessions could be used in combining ability analyses with cultivated germplasm. Subsequent, more extensive, exploitation of the germplasm collection might be based on results from these exploratory evaluations of breeding potential.
Crystalline Cellulose and Cotton Fiber Strength
Authors: Benedict C. R. , Kohel R. J. , Jividen G. M.
Published: July 2010

The variation in the bundle fiber strength measurements of cotton (Gossypium hirsutum L.) fibers due to differences in cellulose crystallinity and chain length have not been examined. This study was conducted to determine the length of the cellulose chains (expressed as the weight‐average molecular weight, M̄w) in the crystalline microfibrillar fragments isolated from different cotton fiber and to relate these values to bundle fiber strength. Crystalline microfibrillar fragments were isolated by treating cotton fibers with acetic acid/nitric acid reagent. The crystalline cellulose was dissolved in a lithium chloride solution of N,N‐dimethylacetamide. The 13C‐nuclear magnetic resonance spectrum of the cellulose solution showed chemical shifts at 103.1, 73.2, 74.2, 75.8, 78.5, and 59.9 ppm for the glucose carbons. The chemical shifts were similar to the chemical shifts in the 13C‐nuclear magnetic resonance spectra of other cellulose solutions. The sharpness of the chemical shifts indicated a true solution of crystalline cellulose. Gel permeation chromatography of the crystalline cellulose solution on three linear columns of 1 × 106 Å to 500 Å of ultrastyragel in a Waters 150C GPC separated the dissolved crystalline cellulose into a population of different sized molecular weight chains. The weight average molecular weight of the population of cellulose chains in the crystalline cellulose from TM‐1 cotton fibers was 1.83 × 105 daltons. The average length of the cellulose chains in the crystalline cellulose (measured as the weight average molecular weight of the crystalline cellulose) from different cotton fibers was correlated (r = 0.94) to the bundle fiber strength of the cotton fibers. The data support the conclusion that the average length of cellulose chains in the crystalline cellulose areas of the microfibrils is a component of bundle fiber strength measurements of cotton fibers.
Red Clover Seed Production: II. Plant Water Status on Yield and Yield Components
Authors: Oliva R. N. , Steiner J. J. , Young W. C.
Published: July 2010

Limited information on crop water stress response is available for red clover (Trifolium pratense L.) seed production. The purpose of this study was to quantify the effects of plant water status on red clover flower production, seed yield, and seed yield components. Five supplemental irrigation treatments were applied in 1990 and 1991 to first and second year red clover grown on a Woodburn silt loam (fine‐silty, mixed, mesic Aquultic Argixeroll) near Corvallis, OR. A nonirrigated control was also maintained. Increased plant water stress reduced the duration of season‐long bud and flower production, stem length, potential seed yield, and seed yield. Application of water soon after haying increased total above‐ground phytomass but increased seed yield less than watering at peak flowering. Root deterioration from a root and crown rot disease complex reduced second‐year seed yield. Root rot index increased with increased levels of plant water stress, indicating that supplemental water applications reduced root rot severity. The reduction in seed yield resulting from increased plant water stress was primarily caused by a decrease in floral fertility, and less conclusively, by reductions in flower number per unit area. One irrigation filling the active soil profile during peak flowering provided adequate water to maintain seed production and achieve high water‐use efficiency. Contrary to popular belief, it was shown that red clover was not adversely affected by high levels of available soil water in a well drained soil. Also, yield losses to root disease in the second year of seed production can be greatly reduced by supplemental irrigation compared to non‐irrigated clover.
Imazapyr for Common Bermudagrass Control in Sod Fields
Authors: Griffin Keith A. , Dickens Ray , West Mark S.
Published: July 2010

Common bermudagrass [Cynodon dactylon (L.) Pers.) is a serious weed in sod production fields of the southeastern USA. Although several herbicides control this species in row crops, control in sod fields generally has not been acceptable. Field studies were conducted to determine the efficacy of imazapyr [(±)‐2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl]‐3‐pyridine carboxylic acid] for eradicating common bermudagrass and for subsequent herbicide effects on growth of ‘Tifway’ bermudagrass [Cynodon dactylon × C. transvaalensis (L.) Pers.], ‘Emerald’ zoysiagrass (Zoysia japonica Stued. × Z. tenuifolia Willd. ex Trin.), common centipedegrass [Eremochloa ophiuroides (Munro.) Hack.], and ‘Raleigh’ St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntzel] planted in treated areas the year following applications. Single and one or two repeat applications of imazapyr at 0.8, 1.1, and 1.7 kg a.e. ha−1 per application were made 1 June, 15 July, or 1 September and were compared with glyphosate [N‐(phosphonomethyl) glycine] applied at 2.2 kg a.i. ha−1 on the same dates. All herbicide treatments provided >90% control of the common bermudagrass. A single July application of imazapyr at 1.1 kg a.e. ha−1 eradicated (100% control) common bermudagrass. Single applications of imazapyr were less injurious to the introduced turf species than multiple applications at the same total rate. Less injury to desirable species occurred in 1989 than in 1988, a year of limited rainfall. Bermudagrass and centipedegrass were injured less when planting was delayed until mid‐summer the year following treatment, while spring plantings of St. Augustinegrass and zoysiagrass exhibited little or no effects from imazapyr applied the preceding year. Results indicate that common bermudagrass can be eradicated by a single application of 1.1 kg a.e. ha−1 of imazapyr, and desirable, warm‐season turfgrasses can be successfully established the following growing season.
Amino Acid Profile of High Seed Protein Soybean
Authors: Serretti C. , Schapaugh W. T. , Leffel R. C.
Published: July 2010

Soybean [Glycine max (L.) Merr.] is used extensively to meet the protein needs of animals and humans. Although a good source of protein, soybean's nutritional value is limited by low concentrations of sulfur‐containing amino acids (i.e., methionine and cysteine). Thus, it is often necessary to supplement diets with synthetic amino acids, a practice that can be expensive and adds complexity to the diet formulation process. The objective of this study was to determine if amino acid concentrations in recent high protein germplasm releases differ from those in normal protein cultivars. The high protein (HP) lines BARC‐6, BARC‐7, BARC‐8, and BARC‐9 and a normal protein check, either Essex or Manokin were grown in eight different environments from 1989 to 1991. Seed was analyzed for amino acid concentrations, protein, oil, crude fiber, ash, carbohydrate, and moisture. Protein concentration of HP lines ranged from 495 to 530 g kg−1. The HP lines were lower in oil, crude fiber, and carbohydrate compared to the checks. Concentrations of 14 of the 17 amino acids differed among entries. Concentration of cysteine of BARC‐8, 13.7 g kg−1, was higher than any other entry. Methionine concentration of BARC‐7 (10.8 g kg−1) and lysine concentration of BARC‐9 (55.0 g kg−1) were significantly lower than the checks. Feeding trials are necessary to determine the practical significance of these amino acid differences.
Staging Soybean Seedling Growth from Germination to Emergence
Authors: Muthiah S. , Longer David E. , Harris W.M.
Published: July 2010

Scientists engaged in seed research are often forced to refer to sequential developments of seedling growth in terms of days or hours after planting. Such terms are imprecise, because seedlings develop at different rates depending on seed condition, treatment, and environment. Fehr and coworkers in 1971 published an accurate and consistent description of soybean [Glycine max (L.) Merr.] development from emergence to harvest maturity. Our objective was to devise a system of staging soybean seedling development up to emergence. Laboratory germination was conducted on four soybean cultivars, representing three maturity groups, in a specially designed germination apparatus. Rate of growth and seedling development were recorded at 6‐h intervals between onset of imbibition and full seedling development. Six developmental stages were identified, based on distinct and consistent morphological changes. Adoption of this developmental staging system will allow more precise scientific communication regarding soybean development from the initiation of germination to emergence.
Inheritance of Glaucousness and Epicuticular Wax in Durum Wheat
Authors: Clarke John M. , McCaig Thomas N. , DePauw Ronald M.
Published: July 2010

Glaucousness, the waxy bloom on the surface of leaves and other plant parts, is associated with amount of grain yield in wheat (Triticum spp.), and quantity of epicuticular waxes is associated with water loss through the cuticle, wettability by pesticide sprays, and disease susceptibility. The inheritance of glaucousness and epicuticular wax quantity is not well understood in durum wheat (T. turgidum L. var. durum). Crosses were made among diverse glaucous (gl) and nonglaucous (ng) genotypes, and in some cases, the F1 was backcrossed to each parent. Segregation for visible glaucousness was observed in the field in the parental, F1, F2, and BC1F1 generations. Epicuticular wax quantity was determined gravimetrically in the parental, F1, F2 and BC1F1 generations of the cross ‘Hugenot G’/‘Hugenot W’ and the parental and F1 generations of six other crosses. With the exception of crosses involving the ng parent Hugenot G, gl by ng crosses indicated that nonglaucousness is controlled by a single, completely dominant gene, as has previously been reported. Crosses with Hugenot G showed codominance of glaucousness and nonglancousness, and the heterozygote was of intermediate glaucousness. Epicuticular wax quantity of the cross Hugenot G/Hugenot W seemed to be controlled by the same codominant alleles, and the mean wax quantities of the parents, F1, F2, and BC1F1 agreed with expectation. Similarly, wax quantity of the other gl by ng crosses indicated that wax quantity was controlled by either the same gene as visible glaucousness or a tightly linked gene
Comparative Stability of 40 Indeterminate and Semideterminate Soybean Lines
Authors: Ablett G. R. , Buzzell R. I. , Beversdorf W. D. , Allen O. B.
Published: July 2010

Indeterminate, semideterminate, and determinate soybean [Glycine max CL.) Merr.] cultivars differ primarily in the timing of cessation of main stem growth. This timing affects mature plant height, lodging resistance, and the length of the flowering and reproductive periods. In the northern soybean production areas of North America, indeterminate (Dt1 Dt1 dt2 dt2) cultivars predominate, although several studies have shown that agronomic performance of soybean lines with a semideterminate (Dt1 Dt1 Dt2 Dt2) stem type is similar. A previous comparison of a few indeterminate and semideterminate lines tested across eight Illinois environments provided evidence that the semideterminate might have less yield stability than the indeterminate plant type. The general scarcity of commercially available semideterminate cultivars may be the result of this potential yield instability. This study utilized a large number of genotypes to further evaluate the relative stability of the semideterminate in comparison with the indeterminate stem type. From two crosses, 20 pairs of F3‐derived sister lines (Maturity Group I‐II) differing for stem termination were evaluated across nine environments for yield and plant height. Genotype × environment variance components were significant and of similar magnitude for semideterminate and indeterminate lines, indicating that progress from selection should be similar for each. Stability analysis identified eight indeterminate and nine semideterminate lines as stable for yield. Ten semideterminate, but only six indeterminate lines, had significant deviations from regression for plant height. Overall, the results indicate that stability should not be a barrier to breeding progress for the semideter‐minate plant type in areas where Maturity Groups I and II soybean are grown.
Three Strategies for Population Development in Breeding High‐Yielding Soybean Cultivars with Improved Iron Efficiency
Authors: de Cianzio S. R. , Voss B. K.
Published: July 2010

Improvement of yield and iron (Fe) efficiency in soybean [Glycine max (L.) Merr.] is important for cultivars grown on some calcareous soils. The objective of the study was to compare three‐way cross populations with single‐cross and backcross populations for selection of high‐yielding soybean cultivars with improved Fe‐efficiency. Three high‐yielding, Fe‐inefficient cultivars were crossed to a moderate‐yielding Fe‐efficient line to develop single‐cross populations. F2‐derived lines were evaluated for Fe efficiency in field tests on calcareous soil, and selected lines were crossed to their high‐yielding Fe‐inefficient recurrent parent to develop the backcross populations, and to the two other high‐yielding Fe‐inefficient parents to develop the three‐way cross populations. F4‐derived lines from the single‐cross and three‐way cross populations, BC1F3‐derived lines from the backcross populations, the parents and a check cultivar were evaluated for seed yield on noncalcareous soils in replicated tests in three environments, and for Fe efficiency on calcareous soil in replicated tests in four environments. The backcross populations had the highest average seed yield not significantly different from the seed yield of the three‐way cross populations, and the single‐cross populations had the lowest average seed yields. The single‐cross populations had the highest average Fe efficiency. Compared with a check cultivar that had high yield and adequate Fe efficiency, the average percentages of superior lines for both traits were 15% for the backcross, 9% for the three‐way, and 5% for the single‐cross populations. When an Fe‐efficient genotype with moderate seed yield is used as a parent, a backcross or three‐way cross are appropriate for development of cultivars with improved seed yield and adequate Fe efficiency. Single‐crosses could also be considered if a high level of Fe efficiency is necessary. Phenotypic correlations for the mean of the populations and the mean performance of the parents of each population were significant for seed yield (r = 0.84), and for chlorosis ratings (r = 0.91), indicating that parent performance for these traits may be important in deciding the population type to use.
Natural Cross‐Pollination of Twelve Soybean Cultivars in Arkansas
Authors: Ahrent D. K. , Caviness C. E.
Published: July 2010

Previous experiments have shown that some cross‐pollination (usually <1%) occurs in soybean [Glycine max (L.) Merr.] under field conditions. Information is needed on a broader spectrum of germplasm to determine if genotypes differ significantly for this trait and should be managed differently to produce genetically pure seed in small plots bordered by other genotypes, Twelve soybean cultivars differing in maturity were evaluated during two growing seasons to determine the extent of cross‐pollination under field conditions where both honey bees (Apis mellifera L.) and indigenous insect populations were present. Flower color, pubescence color, and quintafoliolate leaves were used as genetic markers to measure extent of cross‐pollination when plants were grown in adjacent rows 102 cm apart. In maturity group (MG) IV, cultivars did not differ significantly (P > 0.05) for percent cross‐pollination in 1990, but were different in 1991 and when the 2 yr were combined. ‘Competitor’ was significantly higher for percent cross‐pollination (1.22%) than the other cultivars within this MG. Cultivars within MG V and V1 differed significantly in 1990 but were not different in 1991. Based on a 2‐yr average, cross‐pollination varied from a low of 0.09% for ‘Walters’ to a high of 1.63% for ‘Brim’. Results show that cultivars differ significantly (P > 0.05) in the extent of cross‐pollination and as much as 2.5% outcrossing may occur in MG IV, V, and VI cultivars in some environments where adequate pollinators are present and other conditions are favorable. Based on these results, soybean breeders should use greater isolation of initial progeny rows and breeder seed of a new cultivar than has commonly been used in the past because of the increased potential for outcrossing of some cultivars.
Alien Cytoplasmic Effects on Agronomic Performance of Two High‐Yielding Semidwarf Spring Wheat Cultivars
Authors: Busch R. H. , Rauch T. L.
Published: July 2010

The nucleo‐cytoplasmic interactions of common wheat (Triticum aestivum L.) with two of its relatives [T. macha L. and Triticum dicoccoides (Koern. ex Asch. & Graebner) Aarons.] were studied to determine the effect of the foreign cytoplasm on agronomic traits. Two high‐yielding, semidwarf spring cultivars were crossed reciprocally with one cytoplasm source each of T. macha and T. dicoccoides to produce four populations with both alloplasmic random lines and euplasmic random lines. Previous reports on these cytoplasm sources were based on the performance of backcross lines in which the recurrent parents were low‐yielding, normal height cultivars released in the 1950s and 1960s. Between 30 and 60 random F4‐derived F6 lines from all populations were grown in five environments in Minnesota from 1986 through 1988. Grain yield, days to head emergence, and plant height were measured in each environment. No significant differences were detected between alloplasmic lines and euplasmic lines for the measured traits in any population. This was in contrast to an earlier report that T. macha cytoplasm increased grain yield in the backcross lines of an old normal height cultivar. Diversity for cytoplasm apparently caused little or no change in normal agronomic performance when using these sources of alien cytoplasm.
Pollen‐Parent Effects on Protein Quality and Endosperm Modification of Quality Protein Maize
Authors: Pixley Kevin V. , Bjarnason Magni S.
Published: July 2010

Quality protein maize (Zea mays L.) (QPM) has protein of high nutritional value conferred by the opaque‐2 (o2) gene and vitreous endosperm because of numerous modifier genes. Superior protein quality is only expressed when endosperm tissue is homozygous recessive (o2o2). During QPM research and development, it is common to evaluate trials in which QPM genotypes randomly interpollinate. We do not know if protein quality determinations for entries in such trials are valid measures of what would be expressed in a pure stand. In this study, we used nine QPM and three o2 (unmodified, soft endosperm) cultivars as females for six pollen treatments to measure the effect of pollen source on protein concentration of grain, tryptophan concentration in grain, tryptophan concentration in protein, and endosperm modification (translucency) in three environments. The pollen treatments were four QPM hybrids, one normal‐endosperm maize cultivar, and self‐pollination. Pollen of normal‐endosperm maize reduced tryptophan in grain by 37% and tryptophan in protein by 38% but improved endosperm modification of QPM females by 36% relative to pollen of QPM males. Pollen of normal‐endosperm maize and QPM did not differ in effect on protein concentration of grain. Protein quality traits did not differ for QPM cultivars pollinated by self or by other QPM males. Kernels were slightly more vitreous, however, for females pollinated by other QPM males than for those that were self‐pollinated. Effects of females were significant (P < 0.01) and the interaction of males × females not significant for QPM entries for all traits. We conclude that it is valid to evaluate QPM germplasm in trials where entries randomly interpollinate, provided that pollen of normal‐endosperm maize is excluded.
Changes in Protein Complexes of Durum Wheat in Developing Seed
Authors: Bénétrix Florence , Kaan François , Autran Jean‐Claude
Published: July 2010

End‐use quality of wheat derives from the functional properties of its storage proteins. Storage proteins are synthesized during grain development and undergo modifications mainly during grain dehydration, with increased level of aggregation. This study was conducted to determine whether changes in protein complexes of durum wheat [Triticum turgidum (Desf.)] during seed development relate to seed quality. Protein extracts of developing seeds of cultivars Capdur and Tomclair were reduced and examined by sodium dodecyl sulfate poly‐acrylamide gel electrophoresis (SDS‐PAGE). Results confirmed synthesis of both gliadins and glutenin subunits early during maturation with qualitative compositions remaining nearly constant. Size‐exclusion high‐performance liquid chromatography (SE‐HPLC) on unreduced protein extracts was used to follow quantitative changes in distribution of protein complexes. Among the five chromatographic fractions corresponding to different sizes of aggregates or monomers, F1 (excluded peak) and F2 (complexes of intermediate size) increased more rapidly in Capdur (good pasta quality) than in Tomclair (poor pasta quality). Characterization of the chromatographic fractions by electrophoresis showed that low‐molecular‐weight (LMW) subunits of glutenin are mainly involved in the largest complexes and are the ones most clearly showing differences between cultivars. The tendency of LMW subunits to aggregate during grain dehydration may help explain differences found in pasta quality among durum wheat cultivars.
Inheritance of Agrobacterium tumefaciens‐Induced Tumorigenesis of Soybean
Authors: Bailey M. A. , Boerma H. R. , Parrott W. A.
Published: July 2010

Soybean [Glycine max (L.) Merr.] genotypes differ widely in response to inoculation with wild‐type strains of Agrobacterium tumefaciens (Smith and Townsend) Conn. The objective of this work was to study the inheritance of tumorigenesis in soybean so as to gain a better understanding of the A. tumefaciens‐soybcan interaction. A rapid, nondestructive assay for tumorigenesis was developed, which consisted of inoculating hypocotyls of partially etiolated seedlings at multiple wound sites. Four soybean genotypes were screened for tumorigenesis and each had a quantitatively distinct phenotype. ‘Peking’, a highly tumorigenic genotype, was crossed with two relatively non‐tumorigenic genotypes, ‘Century’ and ‘Thomas’. The extent of tumor formation of F1 plants was intermediate to that of the parents, while the F2 frequency distributions were continuous and no distinct phenotypic classes were observed. Variance component heritability on a plot basis was 0.30 for Peking × Century and 0.44 for Peking × Thomas, and on an entry‐mean basis was 0.62 for Peking × Century and 0.76 for Peking × Thomas. The results indicate that tumorigenesis of soybean is a quantitative trait and heritability estimates were moderate to high. Thus, it should be possible to introgress tumor forming capacity into resistant genotypes. Such an approach may help alleviate genotype restrictions to genetic transformation.
Morphological Diversity and Relationships in the A‐Genome Cottons, Gossypium arboreum and G. herbaceum
Authors: Stanton Marsha A. , Stewart J. McD. , Percival A. Edward , Wendel Jonathan F.
Published: July 2010

The Asiatic or A‐genome cottons, Gossypium arboreum L. and G. herbaceum L., are potentially important genetic resources for cotton breeding programs. The National Plant Germplasm System (NPGS) contains approximately 400 accessions of these species, but little information is available on the diversity within the collection or on characteristics of individual accessions. This investigation was initiated to provide a morphological description of each accession. These data were used to evaluate the range of diversity represented within the collection and to address the questions of species and race distinctions. Multivariate techniques were used to assess similarities among accessions and to evaluate morphological parameters contributing to the variation in each species. Means for 41 of 53 characters were significantly different between species, although high infraspecific variability resulted in range overlap for all characters. Principal component analysis separated the two species. Accessions from southern Africa and racial designations of africanum and wightianum formed clusters within G. herbaceum based on the first two principal components; no clusters were noted within G. arboreum. Accordingly, the validity of infraspecific or racial classifications for most of the accessions of this latter species in the current NPGS collection is questionable. Additional germplasm acquisitions from under‐ or non‐represented areas could expand genetic diversity in the collection.
Synergistic Effect of Low Temperature and High Sucrose Concentration on Maize Pollen Viability in Aqueous Medium
Authors: Broglia Marinella , Brunori Alberto
Published: July 2010

Maize (Zea mays L.) pollen can be stored up to several hours in inert medium such as paraffin oil. However, biological activity and genetic manipulation are almost precluded. In aqueous media, maize pollen loses viability within a few minutes when in conditions different from those promoting germination. We have evidence that viability of maize pollen can be preserved in a hypertonic aqueous solution at 0°C. Detrimental if individually applied, low temperature and high sucrose concentrations, together, allow storage of maize pollen up to 10 to 12 hr in an aqueous medium. Such stored pollen can then germinate on agar medium. The lack of in vivo fertilization by liquid pollination, at first interpreted by an osmotic hypothesis, led us to the development of a new, rapid procedure for in vitro germination. Short‐term storage of maize pollen in aqueous medium is now possible and should support new techniques of genetic manipulation.
Probability of Net Gain of Favorable Alleles for Improving an Elite Single Cross
Authors: Metz Grant
Published: July 2010

Choice of donor to improve an elite single cross maize (Zea maize L.) hybrid is critical to the success of a breeding program. Theory has been developed to identify lines (Iw) possessing favorable dominant alleles not present in the elite single cross (I1 × I2). This paper evaluates the probability of Iw to improve I1 × I2. Assuming complete dominance, μG' estimates the relative number of loci with favorable alleles in Iw but not in I1 or I2. The estimates μD' and μF' are the relative number of loci with favorable alleles in I1 or I2, respectively, but not in Iw. Thus, the probability of a net gain of favorable alleles (PNGg) from Iw = max[μG'/(μG' + μ μG'/(μG' + μF')], which estimates the relative number of loci where favorable alleles can be gained as a proportion of the relative number of loci where favorable alleles ca be either gained or lost. The PNGg can be estimated from phenotypic values of I1 × Iw, I2 × Iw, I1 × I2, I1, and I2. Iw per se need not be evaluated. If partial dominance and/or complementary epistasis is prevalent, μE' and μC' estimate additional loci where favorable alleles could be gained from Iw to improve I1 and I2, respectively, while μD', μF', and μB' estimate additional loci where favoralbe alleles could be lost from I1, I2, or both I1 and I2, respectively. Thus, the probability of a net gain of favorable alleles (PNGccg) from Iw = max[(μE + μG)'/(μB + μD + μE + μG)',(μC + μG)'/(μB + μ + μF + μG)']. In this case, Iw needs to be evaluated. The statistics PNGg and PNGccg can be used to estimate the genetic probability to success of a donor (Iw) to improve an elite hybrid.
Leaf Gas Exchange Parameters Vary among Cotton Genotypes
Authors: Pettigrew W. T. , Meredith W. R.
Published: July 2010

In trying to increase the yield of upland cotton (Gossypium hirsutum L.), breeders have indirectly selected more for increases in harvest index than in photosynthesis. Future cotton yield advances may need increases in both harvest index and photosynthesis. The objectives of this study were to determine if differences in leaf CO2‐exchange rate (CER) existed among cotton genotypes, investigate physiological mechanisms for the gas exchange differences, and determine if gas exchange parameters were related to genotypic lint yield variability. Field studies were conducted from 1990 to 1992 on 18 cotton genotypes. Leaf CER, chlorophyli.(Chl) concentration, soluble protein concentration, specific leaf weight (SLW), lint yield, and yield components were determined each year. In addition, Chl fluorescence measurements were made in 1992. The CER of the 18 genotypes significantly varied about 10% from a low of 26.0 μmol m‐2 s‐1 to a high of 28.8 ltmol m‐2 s‐1. DES 119 and MD 51 ne had higher CER, whereas the CER of Dixie King and Stoneviile 508 were lower. The genotypes differed in leaf Chl and soluble protein concentration in both 1991 and 1992. The CER was positively correlated with leaf Chl concentration (r = 0.768*) and SLW (r = 0.568*) in 1991. No difference in the Fv/Fm parameter of Chi fluorescence was found among the genotypes in 1992. A significant positive association (r2 = 0.205**) was found between lint yield and CER during the boll filling period in 1990 and 1991. CER was positively associated with fiber micronaire (r = 0.772*) and fiber maturity (r 0.797*) in 1992. As some cotton breeders bred for higher yielding genotypes, they may have inadvertently selected for increased photosynthesis.
Antioxidant Response to NaCl Stress in Salt‐Tolerant and Salt‐Sensitive Cultivars of Cotton
Authors: Gossett Dalton R. , Millhollon Eddie P. , Lucas M. Cran
Published: July 2010

The mechanism(s) importing salt tolerance to plants remains unresolved. Although cotton (Gossypium hirsutum L.) is classified as salt‐tolerant plant, variation in salt tolerance has been observed among different cultivars. The purpose of this study was to determine if more salt‐tolerant cultivars contain higher constitutive or inducible levels of antioxidants than more salt‐sensitive cultivars. Greenhouse‐grown salt‐tolerant (cv. Acaia 1517‐88 and Acala 1517‐SR2) and salt‐sensitive (cv. Deltapine 50 and Stoneville 825) cotton plants treated with either 0 or 150 mM NaCl were analyzed for differences in growth and antioxidant capocities. The 150 mM NaCl treatment resulted in more than 40% reduction in growth of Deltapine 50 and Stoneville 825 and less than 30% reduction in the Acala cultivars. The more salt‐tolerant cultivars had higher constitutive levels of catalase (121‐215%) and u‐tocopherol (312‐420%). The salt treatment resulted in a 38 to 72% increase in peroxidase activity and a 55 to 101% increase in glutathione reductase activity in the Acala cultivars while the activities of these enzymes remained constant or decreased in the more sensitive cultivars. The Acala cultivars also exhibited a lower oxidized/reduced ascorbic acid ratio and a higher reduced/oxidized glutathione ratio than the more sensitive cultivars when grown at 150 mM NaCl. When subjected to a one‐time salt treatment, lipid peroxidation in Deltapine 50 increased 51% over Acala 1517‐88. These data indicate that protection from oxidative damage by higher levels of antioxidants and a more active ascorbate‐glutathione cycle may be involved in tbe development of salt tolerance in cotton.