Drought resistance in durum wheat

Durum wheat is widely grown as a rainfed crop in the semi-arid tropics. Its production is low and variable from season to season due to frequent drought-stress. Characterization of target environment and employing both analytical and empirical breeding approaches would speed up progress in the development of cultivars with improved adaptation to the prevailing weather conditions.Analysis of historical weather data and a crop growth model were used to predict the growing season and the optimum plant growth cycle in six different ecological regions of Ethiopia. The matching of crop development to the prevailing soil water availability patterns is considered as a major step towards sustainable durum wheat production.High yield and yield stability are equally important breeding objectives under drought conditions. The cause-effect relationships of the duration of vegetative period, the duration of grain-filling period, yield components (number of spikes/m 2, kernels/spike, kernel weight) and grain yield revealed a complex pattern of relationships. Longer grain-filling period, increased number of kernels per spike and limited tillering were found to be associated with drought- resistance.Increasing water use efficiency is the major focus of the dryland cropping system. The different definitions of water use efficiency are explained. Water use efficiency on the basis of grain yield proved the most valuable parameter. The ratios of water used before anthesis and after anthesis by drought-resistant and -susceptible cultivars were different.Relative growth rate (RGR) and its components (leaf area ratio, LAR, and net assimilation rate, NAR) changed with growth stage and moisture availability. Drought-resistant cultivars were characterized by a fast growth rate in the beginning and slow growth later. Deep rooting and a low shoot:root ratio are effective components of drought-resistance.Durum wheat straw is one of the major feed sources. The quality of straw varied among cultivars, but did not correlate with drought-resistance. Drought-stress considerably improved straw quality, due to reduced remobilization of assimilates.The research showed that there is considerable potential to improve the current low and variable durum wheat production in the semi-arid regions.