Appraisal of some physiological traits in two wheat cultivars subjected to terminal drought stress during grain filling

Abstract

In a greenhouse experiment, two winter wheat (Triticum aestivum L.) varieties differing in post anthesis drought resistance, tolerant (cv. Zagros) and sensitive (cv. Marvdasht), were subjected to either well-watered (WW) or water-stressed (WS) from anthesis to maturity. All physiological parameters were affected by drought stress. Results show that water deficits enhanced the senescence by accelerating loss of leaf chlorophyll and soluble proteins and the loss was more in Marvdasht than Zagros. The net CO2 assimilation rate (P_N) in flag leaves during water deficit displayed a strict correlation with the drought sensitivity of the genotypes and showed an early reduction in Marvdasht. The effect of drought on grain yield was primarily due to the significant reduction in grain weight, particularly in drought-sensitive Marvdasht. The results indicate that the main physiological factor associated with yield stability of Zagros under drought stress may be attributed to the capacity for chloroplast activity in the flag leaf, which apparently allows sustained P_N of flag leaf during grain filling under drought stress.

Keywords: Assimilate, chlorophyll, flag leaves, grain yield, wheat (Triticum aestivum L.)