Abstract

In arid and semi-arid climates characterized by low rainfall with a great annual and inter-annual irregularity, drought can occur at any time inducing large losses in crop yield. Leaf rolling is one of the adaptive morphological responses to the water deficit observed in a number of species including cereals. It reduces the leaf area exposed to sunlight and transpiration. The aim of the present work was to characterize the agronomical impact of water stress on a set of 16 Moroccan durum wheat varieties and to examine the possible correlations between leaf rolling and agronomic performances of these varieties. Experiments were conducted during three cropping seasons on a soil with a clay-loam texture at Tamellalet, in Marrakech region. The water stress was applied for one week to the studied varieties at tillering, and the degree of leaf rolling was determined at the end of the stress period. Strong differences between the varieties in the degree of leaf rolling upon water stress and in the ability to counteract drought were observed. Varieties displaying high leaf rolling showed less reduction in the yield components (number of ears per plant, number of grains per ear and weight of grains). The strong correlation observed between the degree of leaf rolling and maintaining of agronomic performance suggests that leaf rolling can be a criterion for water stress tolerance in durum wheat. This trait could thus be used as a morphological marker of tolerance to water stress.

Key words: Durum wheat, water stress, leaf rolling, agronomic traits, grain yield, drought tolerance, Morocco.