Influence of Water Deficit on Photosynthetic Activity, Dry Matter Partitioning and Grain Yield of Different Durum and Bread Wheat Genotypes

We aimed to study the influence of soil water deficit on gas exchange parameters, dry matter partitioning in leaves, stem and spike and grain yield of durum (Triticum durum Desf.) and bread (Triticum aestivum L.) wheat genotypes in the 2013-2014 and 2014-2015 growing seasons. Water stress caused reduction of stomatal conductance, photosynthesis rate, transpiration rate, an increase of intercellular CO2 concentration. Photosynthesis rate positively correlated with growth rate of genotypes. Drought stress caused adaptive changes in dry matter partitioning between leaves, stem and spike of wheat genotypes. Stem dry mass increased until kernel ripening. Drought stress accelerated dry mass reduction in leaves and stem. High growth rate of spike dry mass was revealed in genotypes with late heading time. Spike dry mass positively correlated with photosynthesis rate and grain yield. Generally, bread wheat is more productive and tolerant to drought stress than durum wheat.