Performance of wheat and triticale varieties in a variable soil water environment. IV. Yield components and their association with grain yield

Abstract

Yield components (Y_c) and their association with grain yield (GY) were studied in seventeen varieties of Triticum aestivum, T. durum and triticale grown for five years in irrigated and unirrigated environments. The varieties were categorized into four contrasting groups based on their drought susceptibility indices (S) and yield potentials (Y_p). The slope (b) and intercept (a) of the linear regression between Y_c and the environmental index, and S values of Y_c were estimated. Their relationships with b, a and S of GY were also studied irrespective of the parameter used. Total dry matter (DM) and the number of grains per m² (GNO) were always positively correlated with GY. GWT (1000-grain weight) was not correlated with GY. There was considerable variation among the groups in their Y_c at different water-availability levels. The group of varieties having low S and moderate Y_p produced more spikes per m² (SPIKES) relative to other groups irrespective of the water availability. Simultaneously, their increased number of grains per spike (GNOSP) in drought environments relative to irrigated environments partially offset the accompanying reduction in SPIKES. The group of varieties characterized by high Y_p and low S had highest yield in irrigated and moderate drought environments because they had both more SPIKES and more GNOSP. By comparison, the varietal group having high Y_p and high S had higher GNOSP but lower SPIKES. Varieties which had low Y_p and were susceptible to drought had the lowest SPIKES, GNOSP and DM. It was concluded that maintenance of SPIKES would provide an advantage in environments varying in soil water availability. Performance in irrigated environments would depend on the maintenance of high GNOSP also. Higher DM production would be advantageous in all environments.