Water stress effect on durum wheat (Triticum durum Desf.) advanced lines at flowering stage under controlled conditions

Drought stress is a key factor affecting Morocco's agricultural productivity. In order to adapt to climate change, it is crucial to select new genotypes which may be slightly but not significantly less efficient. Durum wheat (Triticum durum Desf.) is one of the most important and cereal crops that are impacted by drought. The objective of this research was to assess the performance of 16 durum wheat genotypes to drought stress. From the beginning of flowering stage until the beginning of seed maturity, three levels of water treatment were applied, corresponding to 100%, 66% and 33% of field capacity. Three agro-morphological, five physiological and three biochemical traits were investigated in those genotypes grown under controlled greenhouse conditions over two years (2020 and 2021), by following completely randomized design (CRD) with three replications. The results showed that stomatal conductance, relative water content, leaf area, leaf temperature, SPAD values, proline, soluble sugars, glycine betaine and yield traits were significantly (p < 0.05) affected by the water treatment. In all the genotypes, three advanced lines had the highest seed yield, namely, DYT1TAZI (12.75 g) with a 16.2% decrease from the control, DYT11TAZI (12.74 g, down 17.5%) and DYT5TAZI (12.26 g, down 19.24%), were found to be the most drought-tolerant, stable and productive having exhibited their highest performance in the absence and presence of drought stress. They had the best seed yield per plant (>12 g; p < 0.001) associated with the highest relative water content RWC (>50%; p < 0.001), chlorophyll content (>50 SPAD; p < 0.001), proline content (400μg/100 mg MF; P < 0.001), soluble sugars content (500μg/100 mg MF; P < 0.001), and stomatal conductance (>0.6 mol m-2s-1; p < 0.001). Therefore, these lines could be selected as relevant and valuable germplasms to be used in durum wheat breeding programs aiming to develop drought-tolerant and high-yielding varieties. High relative water content and stomatal conductance along with low leaf temperature can be taken as selection indices in this breeding program.