Morphological and physiological attributes associated to drought tolerance of Ethiopian durum wheat genotypes under water deficit condition

The experiment was conducted to assess the differential morpho-physiological response to stimulated water deficit and to determine the relationship between some of these morphological and physiological traits and yield components of eighteen durum wheat genotypes grown in pots under lathhouse condition. Water deficit significantly affected gas exchange and chlorophyll fluorescence parameters. It reduced the net photosynthesis rate (Pn), transpiration rate (E) and stomatal conductance (gs) measured both at anthesis and grain-filling stages. Similarly, the value of initial fluorescence (Fo) was increased while variable fluorescence (Fv), maximum fluorescence (Fm) and optimum quantum yield fluorescence (Fv/Fm) were decreased under water deficit. RWC of the leaves was decreased by 36.7% while SLA increased by 12.6% due to moisture stress relative to the well-watered control. No significant correlations were found between chlorophyll fluorescence parameters and grain yield under water deficit condition. Similarly, no significant correlations were found between leaf gas exchange parameters and grain yield. On the other hand, peduncle length and excursion were positively correlated with grain yield while negatively correlated with drought susceptibility index under water deficit condition. Leaf posture and rolling had also a profound effect on grain yield and other attributes. Erect-leaved genotypes had more grain yield, HI, kernel numbers per spikelet and grain-filling rate but had lower kernel weight than droopy leaved. Similarly, genotypes exhibited strong leaf rolling under water deficit condition had more grain yield, kernel numbers per spike and water use efficiency. The genetic variability found for leaf posture, leaf rolling, peduncle length and excursion among the Ethiopian durum wheat genotypes suggests the opportunity for selection superior and adapted genotype in water-limited environments. These can be achieved by integrating these morphological traits as indirect selection in conjunction with other yield components.