The effect of forage utilization on the grain yield of wheat

Abstract

Wheat (Triticum aestiuum L. em. Thell.) is used as both a grain and a forage crop throughout Texas. It is the general practice to graze wheat during the winter, remove the cattle in the spring and allow the wheat to produce a grain crop. Data are needed on the effect of forage utilization on wheat grain production to enable farmers to make management decisions about the alternative uses of their crop. There is also a need to develop information on factors that might be altered by management practices or incorporated into breeding programs that would improve the yield of wheat used as a dual propose crop. Field and greenhouse experiments were conducted to determine the effect of forage removal at different stages of plant development on wheat grain yield. Two cultivars were harvested for forage throughout the vegetative stage of growth, and the final forage harvest was timed to correspond to the early joint, mid joint, or late joint stage of development. Care was taken not to remove any growing points in any of the treatments. All treatments, including a check that was not harvested for forage, were harvested for grain at maturity. Additional treatments were added in the greenhouse experiments to test the effect of lowering the level of carbohydrate reserves prior to harvest by placing the plants in the dark for 48 hours, and of reducing the residual leaf area after harvest by removing all exposed leaf laminae. Delaying the final forage harvest resulted in a significant progressive reduction in grain yield for both cultivars in each of three consecutive years in the field experiments and in each of two greenhouse tests. Delaying the final forage harvest in the field experiments generally resulted in reduced tiller survival and fewer seeds per head but had little effect on the average weight per seed. Till number at maturity was not affected by the timing of the forage harvest in the greenhouse experiments. The number of seeds per head was decreased in both greenhouse experiments as the forage harvest was delayed, but differences were not statistically significant in the second test. The effect of the treatments on the average weight per seed was variable...