Root and shoot growth, water use and water use efficiency of spring durum wheat under early-season drought

Abstract

One of the common features of the Mediterranean climate of North Africa is the uncertainty of rainfall immediately after durum wheat (Triticum durum Desf.) emergence, leading to early-season drought. Impacts of drought during wheat reproductive development have been thoroughly investigated, while studies of early-season drought are lacking. The objectives of the research reported here were to examine genotypic differences for some morphological traits in response to early-season drought, and to determine the association of these traits with water use, water use efficiency in producing grain (WUE(g)) and dry matter (WUE(dm)). Experiments were conducted under field conditions on a Vertic Calicixerol. Four cultivars and two advanced lines of spring durum wheat were subjected to four water regimes, including a well-irrigated control and three water stress treatments. The three water stress treatments were imposed by withholding water during the period from emergence to either the onset, middle or the end of tillering. Subsequently, irrigation was used to provide adequate soil moisture for the remainder of the growing season. Total water use, WUE(g), and WUE(dm) were weakly associated with root length density under drought stress conditions WUE(g) and WUE(dm) were positively associated with relative growth rate under stress, relative growth rate upon recovery and shoot dry matter yields early in the season. To develop new cultivars with improved early vigor, vegetative biomass and WUE(g), as proved in this study, wheat breeders need to utilize parent materials with considerable improvements in these characteristics.