bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trichomes in Segregating Generations of Sorghum Matings. I. Inheritance of Presence and Density1
Authors: Gibson P. T. , Maiti R. K. 
Published: July 2010

The presence of trichomes on the leaves of sorghum [Sorghum bicolor (L.) Moench] is associated with reduced susceptibility to shootfly (Atherigona soccata Rond.) attack. Segregation ratios in successive generations of five single‐cross matings between trichomed and trichomeless parents indicated that the presence of leaf‐blade trichomes is recessive and controlled by a single locus. Inheritance of the trichome trait in three matings among four trichomed parents involved the same locus. The symbol tr is proposed for the gene controlling trichome presence.Trichome density on the abaxial leaf lamina varied among trichomed lines derived from single‐cross matings. Standard unit heritability for F4 on F3. estimated only in the cross IS 1054 x B CK60, was 0.75 on a plot basis.
Soybean Yield Potential—A Genetic and Physiological Perspective
Authors: Specht J. E. , Hume D. J. , Kumudini S. V. 
Published: July 2010

ABSTRACTSoybean [Glycine max (L.) Merr.] yields in the USA have risen 22.6 kg ha−1 yr−1 from 1924 to 1997, but in the last quarter century (1972–1997) have risen 40% faster, 31.4 kg ha−1 yr−1 This upward trend in on‐farm yield is fueled by rapid producer adoption of technologies emerging from agricultural research. Published estimates of the annual gain in yield attributable to genetic improvement averaged about 15 kg ha−1 yr−1 prior to the 1980s, but is now averaging about 30 kg ha−1 yr−1 in both the public and proprietary sectors. Periodic advances in agronomic technology, and a relentless rise in atmospheric CO2 (currently 1.5 μL L−1 yr−1), also contribute to the upward trend in on‐farm yield. In Nebraska, irrigated yield averages 800 kg ha−1 more than rainfed yield, and is improving at a 40% faster annual rate (35.1 vs. 24.9 kg ha−1). About 36% of the annual variation in the irrigated‐rainfed yield difference is attributable to annual variation in absolute rainfed yield. Inadequate water obviously limits absolute crop yield, but also seems to be an obstacle in terms of the rate of yield improvement. Several physiological traits changed during six decades of cultivar releases in Ontario that led to a genetic gain in yield of about 0.5% yr−1 Changes in some traits were obvious (improved lodging), but more subtle in others (greater N2‐fixation, greater stress tolerance). In terms of photosynthate supplied to sinks across a wide range of environments, recent cultivars seem to be superior to obsolete ones. To sustain and enhance soybean yield improvement in the future, technological innovation must be continually injected into the agricultural enterprise.
Yield Improvement in Temperate Maize is Attributable to Greater Stress Tolerance
Authors: Tollenaar M. , Wu J. 
Published: July 2010

ABSTRACTA retrospective analysis of the physiological basis of genetic yield improvement may provide an understanding of yield potential and may indicate avenues for future yield improvement. Rate of yield improvement of maize (Zea mays L.) hybrids in Ontario, Canada has been ≈1.5% yr−1 during the last five decades. Comparison of short‐season hybrids representing yield improvement from the late 1950s to the late 1980s showed that genetic yield improvement was 2.5% per year and that most of the genetic yield improvement could be attributed to increased stress tolerance. Differences in stress tolerance between older and more recent hybrids have been shown for high plant population density, weed interference, low night temperatures during the grain‐filling period, low soil moisture, low soil N, and a number of herbicides. Yield improvement is the result of more efficient capture and use of resources, and the improved efficiency in resource capture and use of newer hybrids is frequently only evident under stress. Improved resource capture has resulted from increased interception of seasonal incident radiation and greater uptake of nutrients and water. The improved resource capture is associated with increased leaf longevity, a more active root system, and a higher ratio of assimilate supply by the leaf canopy (source) and assimilate demand by the grain (sink) during the grain‐filling period. Improvements of resource use under optimum conditions have been small, as leaf photosynthesis, leaf‐angle distribution of the canopy, grain chemical composition, and the proportion of dry matter allocated to the grain at maturity (i.e., harvest index) have remained virtually constant. Genetic improvement of maize has been accompanied by a decrease in plant‐to‐plant variability. Results of our studies indicate that increased stress tolerance is associated with lower plant‐to‐plant variability and that increased plant‐to‐plant variability results in lower stress tolerance.
Nine Cycles of Recurrent Selection for Increased Groat‐Oil Content in Oat
Authors: Frey K. J. , Holland J. B. 
Published: July 2010

ABSTRACTIncreases in the groat (caryopsis)‐oil content of oat (Avena sativa L.) raise the energy value of oat grain. Nine cycles of recurrent phenotypic selection for high groat‐oil content were conducted in a genetically broad‐based oat population that included germplasm from the wild relative A. sterilis L. Our objectives in this experiment were to determine if selection for high groat‐oil content was effective and if selection reduced genetic variation for oil content; to identify agronomically acceptable lines with high groat‐oil content; and to document the indirect effects of selection on grain yield, groat fraction, and oil yield. We evaluated 100 random lines from the base (C0) population and each of the nine selection cycle populations in three environments. Mean groat‐oil content increased linearly during nine cycles of selection at a rate of 6.6 g kg−1 cycle−1 (equivalent to 6.7% of C0 population mean cycle−1) from a mean of 98.2 g kg−1 in C0 to 158.5 g kg−1 in C9. The rate of gain from selection did not decrease in later cycles. Oil yield increased at a rate equivalent to 1.9% of C0 population mean cycle−1, while mean groat fraction did not change and mean grain yield decreased at a rate equivalent to 3.2% of C0 population mean cycle−1 For all traits, genetic variation did not decrease during selection cycles. Selected S0‐derived lines from the population with groat‐oil contents >150 g kg−1 exhibited lower yield, greater lodging, and greater disease susceptibility compared with the best check cultivar.
Molecular Mapping of the Rcs3 Gene for Resistance to Frogeye Leaf Spot in Soybean
Authors: Mian M. A. Rouf , Wang Tianyuan , Phillips Daniel V. , Alvernaz Jennie , Boerma H. Roger 
Published: July 2010

ABSTRACTFrogeye leaf spot (FLS) (caused by Cercospora sojina Hara) is a foliar disease of soybean [Glycine max (L.) Merr.] that causes significant yield loss in southeastern USA. The Rcs 3 gene in soybean has been reported to condition resistance to all known races of C. sojina. Molecular mapping of the Rcs3 gene will be helpful in breeding soybean for resistance to FLS. The objective of this study was to map the Rcs3 gene with DNA markers. The parents, 123 F2 plants, and the F2:3 families from the cross of ‘Blackhawk’ (susceptible) × ‘Davis’ (resistant and original source of the Rcs3 gene) were scored for FLS reaction in the greenhouse after inoculation with race 5 of C. sojina. In addition, ‘Wright’ and the Wright6‐Rcs 3 (near isoline of Wright) were also scored for FLS by the same protocol. A resistant and a susceptible DNA bulk were created by pooling the DNA of 15 resistant and 15 susceptible F2 plants, respectively, from the Blackhawk × Davis population. The two bulks and resistant–susceptible near isolines (NILs) of Wright were screened with simple sequence repeat (SSR) markers from soybean linkage groups with known disease resistance gene clusters. The bulks and the NILs of Wright both showed a putative association between the Rcs 3 locus and a SSR marker Satt244 from linkage group (LG) J. A molecular map of the relevant segment of the LG J for the Blackhawk × Davis population was then created by screening the DNA of 95 F2 plants with the available polymorphic SSR and RFLP markers. We have mapped the Rcs3 gene for resistance to FLS in soybean near a previously known disease resistance gene cluster on LG J. The gene was closely linked to SSR markers Satt244 and Satt547. Close proximity of this gene with these SSR markers provides soybean breeders with an opportunity to use these markers for marker assisted selection (MAS) for FLS resistance in soybean.
Growth of White Clover Ecotypes, Cultivars, and Germplasms in the Southeastern USA
Authors: Brink G. E. , Pederson G. A. , Alison M. W. , Ball D. M. , Bouton J. H. , Rawls R. C. , Stuedemann J. A. , Venuto B. C. 
Published: July 2010

ABSTRACTNaturalized populations, or ecotypes, of white clover (Trifolium repens L.) are found in many southeastern U.S. pastures, often persisting despite adverse environmental and cultural conditions. Our objective was to compare the growth, morphology, and vegetative persistence of white clover ecotypes (small‐ to medium‐leaf) with selected cultivars (large‐leaf) and improved germplasm under grazing in four southeastern states. Seed or stolons of white clover ecotypes were collected primarily from grazed pastures in spring 1994 in Louisiana, Mississippi, Alabama, and Georgia, and increased by intercrossing. Plots of seven ecotype collections, ‘Osceola’, ‘Regal’, ‘Louisiana S‐1’, ‘Grasslands Huia’, ‘Grasslands Prestige’, Brown Loam Synthetic No. 2 germplasm, and Southern Regional Virus Resistant germplasm were established in October 1995 in each state. Plots were stocked continuously with cattle (Bos taurus) (5‐cm stubble) from January 1996 to January 1998. Stolon length and axillary bud viability, and number of stolon apices, rooted nodes, and seedlings were measured every 3 mo. Stolon length of the ecotypes usually exceeded that of the cultivars and germplasm at all locations, particularly in the winter and spring. By the end of the experiment, the ecotypes also exhibited greater stolon branching than the cultivars and germplasm (1580 vs. 320 branches m−2). Superior vegetative growth of the ecotypes was attributed to a greater proportion of the stolon nodes being both branched and rooted, particularly during the summer. White clover ecotypes represent a valuable source of germplasm to incorporate into breeding programs or to develop directly into more persistent cultivars.
A Comparison of Winter Cereal Species and Planting Dates as Residue Cover for Cotton Grown with Conservation Tillage
Authors: Bauer Philip J. , Reeves D. Wayne 
Published: July 2010

ABSTRACTWinter cereals are often used as cover crops before planting cotton (Gossypium hirsutum L.). Black oat (Avena strigosa Schreb.) is the predominate cereal cover crop for cash crops in southern Brazil and Paraguay, but limited information is available on the suitability of black oat as a cover crop in the southeastern USA. The objectives of this study were to compare black oat with adapted winter cereals for this region and to determine the effect of cereal residue species and amount on cotton growth, N status, and lint yield. In a greenhouse study in which black oat and rye (Secale cereale L.) residues were mixed with soil, tap root elongation of both cotton and radish (Raphanus sativa L.) was inhibited more by black oat residue than by rye residue. In a field experiment on a Goldsboro loamy sand (fine‐loamy, siliceous, thermic Aquic Kandiudult), cotton was grown in 1995 and 1996 following black oat, oat (Avena sativa L.), rye, and wheat (Triticum aestivum L.) that were planted at three different times (October, November, and December). All four winter cereals had similar biomass production at each planting date in 1995. In 1996, rye was the only species not visibly damaged by a low temperature of −12.2°C that occurred during the winter. Black oat biomass was comparable to wheat in all planting dates but averaged 60% less than rye over all three planting dates and was 37% less than oat in the October planting date in that year. Black oat tended to have a higher N concentration than the other cereal species. Cotton plant density was lowest following black oat and rye. Cotton growth, leaf blade N, and petiole NO3‐N were more dependent on residue amount than on residue species. Cotton lint yield following black oat was 120 kg ha−1 higher than lint yield of cotton following rye. Cotton following black oat, wheat, and oat had similar lint yield. Black oat may be a promising cover crop for the southeastern USA, but evaluations of other cultivars and/or improvement programs to improve cold hardiness are needed to improve the utility of this species.
Leaf Reflectance Spectra of Cereal Aphid‐Damaged Wheat
Authors: Riedell Walter E. , Blackmer Tracy M. 
Published: July 2010

ABSTRACTThe efficiency of field monitoring for insect pests would be improved with knowledge of reflected solar radiation from crop canopies during insect outbreaks. The objectives of this greenhouse study were to characterize leaf reflectance spectra of wheat (Triticum aestivum L.) damaged by Russian wheat aphids (Diuraphis noxia Mordvilko) and greenbugs (Schizaphis graminum Rondani) and to determine those leaf reflectance wavelengths that were most responsive to crop stress imposed by these aphid pests. When the ligule was visible on second oldest leaf, wheat plants were infested with four wingless adult Russian wheat aphids, four wingless adult greenbugs, or left uninfested (four replicate plants per treatment). Plants and aphid populations were allowed to grow under greenhouse conditions for 3 wk, after which leaf‐reflected radiation (from the adaxial surface across the 350–1075 nm range), dry weight, area, and chlorophyll concentrations were measured. When compared with the control, greenbug feeding damage caused general necrosis in oldest (first) leaves and dramatically lowered the dry weight, leaf area, and chlorophyll concentration of the second, third, and fourth leaves. Russian wheat aphid feeding resulted in a reduction in leaf dry weight and area in the third and fourth leaves, and a reduction in total chlorophyll concentration in all leaves. Leaf reflectance in the 625‐ to 635‐nm and the 680‐ to 695‐nm ranges, as well as the normalized total pigment to chlorophyll a ratio index (NPCI), were significantly correlated with total chlorophyll concentrations in both greenbug‐ and Russian wheat aphid–damaged plants. Thus, both of these wavelength ranges, as well as this reflectance index, were good indicators of chlorophyll loss and leaf senescence caused by the aphid feeding damage.
Nitrogen Fertilization and Supplementation Effects on Performance of Beef Heifers Grazing Limpograss
Authors: da C. Lima G. F. , Sollenberger L. E. , Kunkle W. E. , Moore J. E. , Hammond A. C. 
Published: July 2010

ABSTRACTSeasonally low N concentrations in ‘Floralta’ limpograss [Hemarthria altissima (Poir.) Stapf & C.E. Hubb.] limit intake and weight gain of growing animals. This research evaluated management alternatives for increasing summer weight gains of beef replacement heifers (Bos spp.) on limpograss pastures in Florida. Soils were sandy, siliceous, hyperthermic, aeric (Smyrna series) or ultic (Pomona series) Haplaquods. During 1992 and 1993, a factorial arrangement of two pasture N fertilization rates (50 and 150 kg ha−1) and three diet supplements (NONE, corn [Zea mays L.] plus urea [CU], and CU plus rumen undegradable protein [CUUP]) were studied in two replications of a completely randomized design. Supplementation with CU increased average daily gain (ADG) from 0.06 (NONE) to 0.41 kg on pastures fertilized with 50 kg N ha−1, but there was no ADG response to CU when N rate was 150 kg ha−1 When no supplement was fed, increasing pasture N fertilization from 50 to 150 kg ha−1 increased ADG from 0.06 to 0.36 kg. Grass crude protein (CP; 73 vs. 56 g kg−1) and in vitro organic matter digestion (IVOMD; 542 vs. 509 g kg−1) were greater at the higher N rate. Heifer plasma urea N (PUN) concentration was low (4.2 mg dL−1) when no supplement was fed and pastures received 50 kg N ha−1, suggesting that low CP was limiting ADG. These data indicate that N deficiencies of cattle grazing limpograss can be overcome by increasing rate of pasture N fertilization or by providing N supplements.
Factors Affecting Groat Percentage in Oat
Authors: Doehlert Douglas C. , McMullen Michael S. , Baumann Robert R. 
Published: July 2010

ABSTRACTThe groat percentage represents an important quality characteristic of oat (Avena sativa L.). Our objectives were to characterize mechanical factors of the oat dehulling process and the physical characteristics of the oat grain that affect groat percentage. Mechanical factors were determined with a compressed air dehuller. Physical characteristics of oat grain were evaluated from 10 genotypes grown at three locations with digital image analysis. Groat percentage as determined by hand dehulling was compared with mechanical dehulling. The strength and duration of mechanical stress required to separate the hull from the groat and the strength of the aspiration required to remove free hulls from the groats had significant effects on groat percentage results. Insufficient mechanical stress resulted in ineffective dehulling, but excessive stress resulted in groat breakage. Excessive aspiration removed groats as well as hulls, but insufficient aspiration left excessive hulls with groats. Groat percentage values obtained by hand dehulling or by mechanical means correlated well. Hand sorting of mechanically dehulled groats to remove hulls remaining after dehulling improved their correlation, indicating the importance of hand‐sorting mechanically dehulled oats. Test weight and oat size uniformity were highly correlated with groat percentage. Negative correlation between hulls remaining after dehulling with groat percentage suggested that heavier hulls, associated with lower groat percentage, were more difficult to remove by aspiration. Positive correlations between groat breakage during dehulling and groat percentage suggest that thin hulls provide less protection to the groat during dehulling, resulting in higher levels of breakage.
Selection and Evaluation of Smooth Bromegrass Clones with Divergent Lignin or Etherified Ferulic Acid Concentration
Authors: Casler Michael D. , Jung Hans‐Joachim G. 
Published: July 2010

ABSTRACTLignin and etherified ferulic acid (EthFA) are cell wall constituents believed to have important negative impacts on digestibility of forage cell walls. Our objective was to identify genotypes of smooth bromegrass (Bromus inermis Leyss) with unconfounded divergence in lignin and EthFA, such that their independent effects could be determined on in vitro fiber digestibility (IVFD). Eight clones were selected from each of four populations (‘Alpha’, WB19e, ‘Lincoln’, and WB88S). Selection was successful for EthFA in all populations except WB88S, creating repeatable divergence of 11.2 to 12.5%. Selection was unsuccessful for lignin concentration per se, most likely because of large genotype × environment interactions. Nevertheless, the resulting clones showed significant variation for both EthFA and lignin concentrations and these two variables were nearly independent among the selected clones. Both lignin and EthFA had significant negative effects on 96‐h IVFD, regardless of the statistical estimation method used. Across estimation methods, there was not a clear difference in the magnitude of the lignin and EthFA effects on IVFD. Both the total amount of lignin in the cell wall and the amount of ferulic acid cross‐linking lignin to polysaccharides via ether bonds appear to be under genetic control, and both components play a role in regulating the genetic potential for rumen degradation of cell walls in smooth bromegrass. These clones are a potential tool for conducting animal feeding trials using forages with relatively unconfounded differences in a single cell wall characteristic.
Genetic Diversity in Cotton Assessed by Variation in Ribosomal RNA Genes and AFLP Markers
Authors: Pillay M. , Myers G. O. 
Published: July 2010

ABSTRACTVariation in the ribosomal RNA genes (rDNA) and amplified fragment length polymorphism (AFLP) markers has been used to establish the extent of genetic diversity and relatedness in plants. The utility of these methods to detect inter‐ and intra‐specific variation in cotton (Gossypium spp.) has not been reported and could be useful in cultivar identification and in marker assisted selection. The objectives of this study were to: (i) determine the molecular organization of the rDNA genes by restriction enzyme mapping and (ii) assess the level of AFLPs in Old and New World species of cotton. A restriction site map of the rDNA gene structure of G. hirsutum L. cv. TM1 was constructed from DNA digested with 12 restriction enzymes and hybridized to heterologous probes. Four EcoRI‐MseI primer‐pair combinations were used for the AFLP analysis. The rDNA gene structure in cotton was found to be similar to that of most higher plants. The rDNA repeat size was 9.4 kbp in G. hirsutum and G. barbadense L., and 9.6 and 9.8 kbp in G. arboreum L. and G. herbaceum L., respectively. No intraspecific polymorphism was detected in the spacer. The presence of two SspI sites in G. arboreum and G. herbaceum and a single site in G. hirsutum and G. barbadense separated Old and New World cottons. The AFLP method produced a 10‐fold increase in the number of DNA bands per plant, compared with random amplified polymorphic DNA (RAPD) methods. The AFLP data assigned the species–genotypes into groups that corresponded with their origin and/or pedigree relationships.
Insect clip cages rapidly alter photosynthetic traits of leaves
Authors: Crafts‐Brandner Steven J. , Chu Chang‐chi 
Published: July 2010

AbstractIn plant‐insect interaction experiments, a clip cage is frequently used to isolate insects or other small pests on a leaf. Clip cage effects on the physiology of the leaf could possibly confound experimental results. Our objective was to quantitate the effects of an insect clip cage of the type typically used for small pests such as whiteflies (Bemisia sp.), aphids (Aphis sp.) and mites (Urticae sp.) on the photosynthetic traits of cotton (Gossypium hirsutum L. cv. Coker 100A‐glandless) and muskmelon (Cucumis melo L. cv. Imperial 45) leaves. Clip cages that enclosed 11.3 cm2 of both the abaxial and adaxial sides of a leaf were attached to young fully expanded leaves. For the leaf tissue within the clip cage, incident radiation was decreased and leaf temperature was increased. After 24 h, chlorophyll content of tissue within the clip cage was significantly increased compared with non‐caged‐control samples taken from the opposite half of the same leaf. Three days after clip cages were attached to leaves, compared with controls, the tissue within the cage had a lower light‐saturated, steady‐state CO2 exchange rate (CER) and leaf soluble protein content. The cage effect on CER and soluble protein could be explained, at least in part, by decreased light‐saturated initial Rubisco activity for leaf tissue within the clip cage. We conclude that the clip cages caused physiological and biochemical alterations of leaves that could alter insect nutrition. Thus, it is suggested that clip cage effects on leaf physiology and microenvironment must be considered when interpreting results of plant‐insect interaction experiments.