Response of bread and durum wheat varieties to supplemental irrigation, nitrogen application and planting date

Abstract

Supplemental irrigation (SI) is defined as the application of a limited amount of water to crops normally grown under rainfed conditions to improve and stabilise production. It has become more important as yield increase due to crop improvement has substantially slowed since the green revolution. In Syria, large increases in crop yields were attained with the application of limited water in conjunction with rain. Now over 40% of rainfed wheat areas in Syria are under SI, contributing to over two thirds of domestic production. The need to optimise the management of SI is becoming more important, particularly in light of the increasing water scarcity in the rainfed areas of this region. The main tasks involved are to select the optimal amount of water to apply, the most responsive varieties, the most advantageous levels of nitrogen, and appropriate planting dates. Research into the response of four bread and four durum wheat varieties to various levels of SI, N and different planting dates was undertaken over three growing seasons from 1992/93-1994/95. The study took place at Tel Hadya, near Aleppo, Syria, on deep clays and well drained soils. Results showed that the response of bread wheat varieties (Mexipak, Cham 4, Cham 6, and Gomam) to SI is significantly different, with Cham 4 and Cham 6 producing the highest yield. Durum wheat varieties (Cham 1, Cham 3, Lahn and Om Rabi 5) also produced different responses to SI, but with lower level of significance. Response to N levels was water dependent and significantly different among both bread and durum wheat varieties. Delaying planting date adversely affected yield of both bread and durum wheats; however, neither were significantly different in response to this delay.