Developmental stage dependency of the effect of drought stress on photosynthesis in winter wheat (Triticum aestivum L.) varieties

Abstract

Drought stress frequently occurs in the reproductive stage of wheat, causing significant yield loss. To study the developmental stage dependency of the effect of drought stress on photosynthesis, plants of the drought-tolerant Plainsman V and sensitive Cappelle Desprez winter wheat varieties were grown in phytotron chambers and subjected to water withholding during three phenophases of reproductive development: meiosis, anthesis and early seed development (ESD).Stomatal conductance (gs) and net photosynthesis (Anet) showed similar characteristics. Meiotic-stage drought only decreased the values of Cappelle Desprez significantly. Stressed Plainsman V showed a significantly smaller reduction and better regeneration for these parameters at anthesis. The decreases in gs and Anet were similar in both varieties when drought was applied during ESD. Studies on the intercellular CO2 concentration (Ci) inflexion point implied that metabolic impairment was less typical of stressed Plainsman V than of Cappelle Desprez at meiosis and anthesis. The quantum efficiency of PSII (ΦPSII) did not decline in either genotype during meiotic-stage drought. Stressed Plainsman V showed significantly higher ΦPSII values compared to Cappelle Desprez at anthesis. During ESD, the values for stressed plants of both genotypes decreased to a similar extent.The results indicate that the effect of drought stress on photosynthesis shows developmental stage dependency during the reproductive life cycle of wheat.