Performance of Fall‐ and Spring‐Planted Durum Wheat in Western Colorado

Several years of fall planting of spring types (non‐vernalization requiring) of durum wheat ( Triticum turgidum L., durum group) in smallgrain cultivar performance tests in western Colorado have resulted in high grain yields with no observed plant stand losses. Comparison studies between fall and spring plantings of durum wheat have not been conducted. Field studies were conducted during 1988, 1989, and 1990 at the Colorado State University Fruita Research Center near Grand Junction to determine plant response of durum wheat cultivars to planting dates, and to study grain yield and yield component relationships of durum wheat cultivars when planted in the fall, early spring, and late spring. Fall‐ and early spring‐planted durum wheat generally had higher grain yields, test weights, kernel mass, and were taller than late springplanted wheat. Fall‐planted durum had fewer kernels per spikelet than wheat in spring plantings and a lower seed N concentration than durum in the late spring planting. Kernels per spikelet and kernel mass had the most consistent and highest direct correlations with grain yield. Our findings indicate that the potential exists to increase the productivity and widen the adaptation of durum wheat by identifying favorable temperate locations and using appropriate planting dates. Winter durum (vernalization‐requiring) cultivars developed for the USA would be useful in widening the adaptation and increasing the productivity of this class of wheat.