Intraspike yield distribution of diverse-tillering spring wheats: Effects of competition

Abstract

Three spring wheat (Triticum aestivum L.) genotypes (Neepawa, Siete Cerros and M1417) were subjected to four levels of tiller removal (MS remaining, MS + T1 remaining, MS + T1 + T2 remaining, control) at three plant densities (two, four and eight plants per 15-cm-diameter pot) in a controlled environment to assess the effects of interplant and intraplant competition on the intraspike yield distribution of genotypes with diverse tillering habits. Intraspike yield distribution traits varied significantly (P = 0.01) among genotypes and levels of plant competition. Genotypes did not respond uniformly to interplant or intraplant competition. When interplant competition was increased, the oligoculm genotype, M1417, exhibited a greater reduction in maximum kernels per spikelet (13%) and spikelet yield (36%) than either Siete Cerros (9, 17%) or Neepawa (6, 15%). Similarly, with increasing intraplant competition, M1417 responded by reducing maximum kernels per spikelet (6%) and spikelet yield (9%) whereas Siete Cerros and Neepawa exhibited increases for both traits (3 – 15%). The low-tillering genotypes tended to exhibit a greater sensitivity to competition for maximum spikelet yield or kernel number while Neepawa was more responsive for the rachis node at which yield or kernel number was maximized. Strong developmental dominance of the oligoculm habit appears to reduce plasticity and the ability to respond to competition-induced stress. Key words: Spring wheat, intraspike yield, tiller removal, plant competition