Shoot Developmental Properties Associated with Grain Yield in Winter Wheat1

Abstract

A large proportion of winter wheat (Triticum aestivum L.) tillers fail to produce grain‐bearing spikes. Should tillers which fail to produce spikes be considered as lost photosynthate? Six selected winter wheat cultivars were grown under two nitrogen (N) fertilizer rates (0 and 70 kg N ha−1) in a 3‐ year (1980–1982) field study on a Rago silt loam soil type (fine, montmorillonitic, Mesic Pachic Argiustolls) to evaluate the relationships among grain yield, shoot emergence, shoot survival, and yield components. Live emerged shoot number per unit area was determined at selected dates throughout the growing season. Final spike number per unit area, grain yield, and yield components were measured at physiological maturity. Grain yield was positively correlated with shoot survival in all three years but was not correlated with maximum live shoot number in any year. Maximum live shoot number was not correlated with kernel number of the spike‐bearing shoots, and shoot survival was positively correlated with kernel number per spike in only 1 year of the study. Therefore, the production of spikeless shoots had little effect on the reproductive development of spike‐bearing shoots. Maximum live shoot number was negatively correlated with shoot survival in 2 of the 3 years of the study. Shoot survival was positively correlated with spike number in all 3 years, and spike number was positively correlated with kernel number per unit area and grain yield in 3 of the 3 years. Thus, shoot survival was more important than the number of shoots initiated in establishing the critical yield components of spike number and kernel number per unit area.