Effect of drought stress on yield, chlorophyll contents and photosynthesis in tartary buckwheat (Fagopyrum tataricum)

Drought stress is one of the major abiotic stresses in agriculture worldwide. This study was carried out to investigate the effect of drought stress on chlorophyll content, photosynthesis and transpiration, stomatal conductance and yield characteristics in two varieties of tartary buckwheat (Fagopyrum tataricum). A pot experiment with three irrigation regimes was carried out in a split-plot block design with four replications. Treatments included control (no drought), drought stress imposed with 7 and 14 days during the beginning-flower stage. All physiological parameters were affected by drought stress. Drought stress significantly decreased chlorophyll a, chlorophyll b and total chlorophyll content, but the proline accumulation was increased, and the two varieties showed a similar trend. Photosynthesis, transpiration, stomatal conductance and yield were lower but intercellular CO2 concentration was higher under drought stress conditions than under control conditions. The drought stress significantly increased POD, SOD and CAT activity and H2O2 content, and endowed plants of tartary buckwheat with the resistance against oxidative stress and adapted to severe condition. Under drought conditions the variety JingQiao-2 gave the highest yield whereas ChuanQiao-1 gave the lowest yield. Drought stress for 14 days reduced seed yield more severe than that for 7 days. The results showed that the variety JingQiao-2 displayed a higher drought resistance than ChuanQiao-1 cultivar.