Association between water use efficiency components and stomatal conductance in some Iranian wheat cultivars

Wheat is a pivotal crop plant in Iran. However, it is mostly grown in drought prone areas of Iran. On the other hand, the trend of global warming is increasing. Therefore, in order to better use the limited water sources, it is needed to improve wheat yield by studying the mechanisms of enhancing water use efficiency (WUE). This study was conducted to determine the effect of stomatal conductance (gs) on water use efficiency and its components in wheat (Triticum aestivum L.). Seven bread wheat cultivars (Marvdasht, B.C.Roshan, Darab2, Vee/Nac, Shiraz, Chamran, Maroon) were grown in pots under well-watered conditions. The pattern of variation for WUE and its components was different for cultivars. Stomatal conductance showed a positive correlation with total water use, transpiration efficiency and grain yield. A path analysis revealed that transpiration efficiency had a higher direct effect on grain yield (0.91) than did harvest index (0.40). Although gs showed a direct effect of almost zero on grain yield, but imposed its effect indirectly via transpiration efficiency (0.47).