RELATIONSHIPS AMONG WATER USE EFFICIENCY AND THE PHYSIO-AGRONOMIC TRAITS IN DURUM WHEAT (TRITICUM DURUM DESF.) CULTIVARS ASSESSED UNDER RAINFED CONDITIONS OF THE EASTERN HIGH PLATEAUS OF ALGERIA

Genetic advances in grain yield under rainfed conditions haves been low, slowed by genotype x environment interaction arising from unpredictable rainfall in drought prone areas. A good understanding of factors regulating yield provides the opportunity to identify and select for physiological and agronomic traits that increase both water use efficiency and grain yield under rainfed conditions. The results of this investigation exhibited large variation for physiological and agronomic traits among varieties and cropping seasons. Modern varieties had high harvest index, grain yield, and leaf chlorophyll content, low leaf relative water content, and were shorter than varieties derived from land races. Total dry matter and specific leaf area differences, among groups of varieties, were not significant. Water use efficiency for total dry matter showed no significant correlations with the measured physiological and agronomic traits, while water use efficiency for grain yield was significantly correlated with harvest index, plant height and to a lesser extent with leaf chlorophyll content. Path analysis, based on phenotypic correlations, showed the consistent direct and indirect effects of harvest index and to a lesser extent those of plant height. Selecting for plant height and harvest index could improve both water use efficiency and grain yield under drought prone environments.