MANAGEMENT PRACTICES AND LEASE ARRANGEMENTS USED BY OKLAHOMA WHEAT, WHEAT PASTURE, AND WHEAT PASTURE LIVESTOCK PRODUCERS

Winter wheat is grown for three purposes in the Southern Plains, grain-only, forage-only, and as a dual-purpose forage plus grain crop. The USDA's wheat cropping practices survey does not differentiate among the three uses. Little information on actual production practices across use is available. Results of a survey are presented.Crop Production/Industries,

Performance of wheat varieties in Oklahoma - 1988

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

DERIVATION AND OPTIMIZATION OF A STOCHASTIC LIVESTOCK WEIGHT GAIN RESPONSE TO STOCKING DENSITY MODEL

Dual-purpose winter wheat production is an important economic enterprise in the southern Great Plains of the United States. Because of the complex interactions involved in producing wheat grain and beef gain from a single crop, stocking density is an important decision. The objective of the research is to determine the stocking density that maximizes expected net returns from dual-purpose winter wheat production. Statistical tests rejected a conventional linear-response plateau function in favor of a linear-response stochastic plateau function. The optimal stocking density of 1.48 steers per hectare (0.60 steers per acre) is 19% greater with a stochastic plateau than with a nonstochastic one.Livestock Production/Industries,

Spring wheat and spring oats

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

Characteristics of phonon transmission across epitaxial interfaces: a lattice dynamic study

Phonon transmission across epitaxial interfaces is studied within the lattice dynamic approach. The transmission shows weak dependence on frequency for the lattice wave with a fixed angle of incidence. The dependence on azimuth angle is found to be related to the symmetry of the boundary interface. The transmission varies smoothly with the change of the incident angle. A critical angle of incidence exists when the phonon is incident from the side with large group velocities to the side with low ones. No significant mode conversion is observed among different acoustic wave branches at the interface, except when the incident angle is near the critical value. Our theoretical result of the Kapitza conductance $G_{K}$ across the Si-Ge (100) interface at temperature $T=200$K is 4.6\times10^{8} {\rm WK}^{-1}{\rmm}^{-2}. A scaling law $G_K \propto T^{2.87}$ at low temperature is also reported. Based on the features of transmission obtained within lattice dynamic approach, we propose a simplified formula for thermal conductanceacross the epitaxial interface. A reasonable consistency is found between the calculated values and the experimentally measured ones.Comment: 8 figure

Performance of wheat varieties in Oklahoma - 1987

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

Winter wheat fall±winter forage yield and grain yield response to planting date in a dual-purpose system

Abstract Previous published research suggests that if fall±winter grazing of winter wheat is properly managed, it will not reduce grain yield. However, highly aggregated state average data suggest that fall±winter grazing is associated with lower grain yields. This study was undertaken to determine the trade-o, or substitution in production, between winter wheat fall±winter forage yield and grain yield across planting dates. Data from experiment station trials were used to estimate response functions and to determine optimal planting dates. The estimated response functions suggest relatively large dierences in expected fall±winter forage yield and expected grain yield across planting date. Optimal planting date is sensitive to the value of fall±winter forage relative to the value of wheat grain. Producers will optimally plant wheat intended for dual-purpose use earlier than wheat intended for grain-only. The expected yield from the earlier planted dual-purpose wheat is lower than the expected yield of the later planted grain-only wheat as a result of the earlier planting date.

Contributions of leaf rust resistance and awns to agronomic and grain quality performance in winter wheat

Wheat (Triticum aestivum L.) cultivars grown in the Great Plains usually bear awned spikes for their putative value to grain yield and quality. Awnletted cultivars are generally limited to forage-only systems. We hypothesized that an awnletted type would be more acceptable to grain producers if flag leaf senescence is delayed by protection against leaf rust (caused by Puccinia triticina Erikss.), the principal foliar disease affecting wheat production in the southern Great Plains. In field experiments under moderate levels of leaf rust infection, our objective was to estimate the effects of awns and leaf rust resistance according to the action and interaction of genes controlling these traits. Our analysis focused on agronomic and quality attributes previously shown to be influenced by these genes. Experimental lines were developed from crosses between leaf rust-susceptible (awnletted or awned) near-isolines of 'Century' and two leaf rust-resistant, awned backcrossed-derived lines with Lr41 or Lr42 from Triticum tauschii (Coss.) Schmal. For most attributes, genes controlling awns and rust resistance acted additively but with unequal effects. For the average effects of Lr41 and Lr42, grain yield increased by 63 and 26%, test weight increased by 5 and 3%, and kernel weight increased by 14 and 9%. Averaged across resistant and susceptible types for each gene, awns increased yield by 6.2 and 0%, increased test weight by 1.7% (either Lr gene source), and increased kernel weight by 6 and 4%. Rust resistance was more effective in compensating for the absence of awns than awns were in compensating for the lack of rust resistance. Leaf rust resistance improved milling quality by increasing flour yield and kernel diameter, independent of the presence or absence of awns. The development of awnletted cultivars with acceptable grain yield potential and quality appears achievable, but their utility in a grain-only production system will be limited without leaf rust resistance.Peer reviewedPlant and Soil SciencesEntomology and Plant Patholog

Covariation for microsatellite marker alleles associated with Rht8 and coleoptile length in winter wheat

Wheat (Triticum aestivum L.) cultivars with greater coleoptile elongation are preferred in low-precipitation dryland regions and in early-planted management systems of the Great Plains, but the presence of GA3 (gibberellin)-insensitive dwarfing genes tends to restrict coleoptile elongation. The agronomic value of Rht8 and the discovery of its diagnostic microsatellite marker, Xgwm 261, have accelerated breeders' interest in Rht8 as an alternative dwarfing gene. Our objectives were to determine allelic distributions at the marker locus in contemporary samples of hard winter and soft red winter wheat relative to samples of Chinese accessions from a Rht8-rich geographic region, and to compare coleoptile elongation in the presence or absence of Rht8 determined by the Xgwm 261 marker. The 165-bp (primarily hard winter wheats) and the 174-bp (primarily soft red winter wheats) alleles of Xgwm 261 were most frequent. About 8% of all U.S. accessions carried the 192-bp allele diagnostic for Rht8, compared with 64% of the Chinese accessions. Coleoptile length varied among accessions from 4.4 to 11.4 cm. Frequency distributions for 192- and non-192-bp genotypes showed no advantage of the 192-bp allele to coleoptile elongation. None of the 192-bp genotypes from the Great Plains showed greater coleoptile length than 'TAM 107', a hard red winter cultivar without Rht8 often chosen over contemporary cultivars for its greater emergence capacity with deeper seed placement. Since coleoptile elongation may be controlled by several quantitative trait loci, identifying only the presence of 192-bp allele of Xgwm 261 may be misleading if the primary motivation for its deployment is to increase coleoptile length in a semidwarf plant type.Peer reviewedPlant and Soil Science

Genetic trends in winter wheat yield and test weight under dual-purpose and grain-only management systems

Wheat (Triticum aestivum L.) cultivars of the southern Great Plains are traditionally bred in environments managed for grain production only but are commonly grown for the dual-purpose of producing winter forage and grain from the same crop. To what extent grain yield and test weight are consistently expressed in those environments requires investigation relative to long-term attempts to improve them genetically. A historical set of hard red winter (HRW) wheat cultivars was evaluated under grain-only and dual-purpose management systems to compare their agronomic performance and derived estimates of genetic progress. Separate experiments were established for each system featuring whole-plot treatments of a foliar fungicide and split-plot treatments of 12 cultivars. The study was conducted for 3 yr at the Wheat Pasture Res. Ctr. near Marshall, OK. Dual-purpose experiments were generally grazed from November through February. Yield in the grain-only system improved 18.8 kg ha^-1 yr^-1, equivalent to 1.3% of the mean yield for Turkey. The rate of progress in the dual-purpose system was significantly lower at 11.3 kg ha^-1 yr^-1, equivalent to 0.9% of the mean for Turkey. Management for grazing had a more profound influence on estimates of yield improvement than did management for disease protection. Linear trends in test weight were not evident under either system, nor were cultivar differences influenced by management system consistently across years. Breeding practices should emphasize selection for grain yield in both environments if future progress is to be maximized in both.Peer reviewedPlant and Soil SciencesAnimal Scienc