Impact of Dual‐Purpose Management on Wheat Grain Yield

Abstract

Farmers in the southern Great Plains utilize wheat ( Triticum aestivum L.) as a forage and grain crop (dual purpose). The objective of this study was to evaluate the impact of dual‐purpose management on wheat grain yield using two multiyear data sets that included a diverse group of commercially released hard winter wheat cultivars and a limited number of advanced experimental breeding lines. Paired experiments were conducted from 1991 to 2010 at the Wheat Pasture Research Unit near Marshall, OK. Averaged across environments and years, grazing reduced wheat grain yield by 7% when both grazed and nongrazed plots were sown early to encourage lush forage growth. Regression analysis predicted an increase in wheat grain yield as a result of grazing in lower‐yielding (<1100 kg ha −1 ) environments but a decrease when nongrazed yield potential exceeded this value. When planting was manipulated to allow comparison of dual‐purpose and grain‐only systems, dual‐purpose management reduced grain yield by 14% as compared to grain‐only management. Grazing increased grain volume weight in both experiments by approximately 1%. Our results indicate that yield reductions in dual‐purpose wheat relative to grain‐only wheat arise due to the combination of grazing and earlier‐than‐optimal planting date.