Effects of Drought Stress on Chlorophyll Fluorescence Parameters, Chlorophyll Content and Grain Yield of Wheat Cultivars

Abstract

Chlorophyll fluorescence quick variation c:m be used as a valuable index for evaluati~n of plants tolcrance to environmental stresses. In order to evaluate chlorophyll quick fluorescence fluctuations 'of different wheat cultivars under water-limited condition, a factorial experiment with a randomized complete block design was performed in Karaj, Iran. Treatments were seven different irrigation regimes and three bread wheat cultivars with four replications. The measurements of Chlorophyll fluorescence parameters were done on flag leaves about three weeks after flowering. Photo-system II photochemical capacity was calculated from the ratio of variable fluorescence to maximum chlorophyll fluorescence (FV/FM). In addition, Tin and FV were evaluated and relative water content and flag leaf chlorophyll were also measured. Results showed that different irrigation levels affected the FV, FV/FM and Tin significantly (p~O.05), but have not any significant effect on FO nnd I;M. There was a significant difference between different varieties and irrigation levels in respect to chlorophyll content, RWC and grain. The means of FV/FM, FV, TIn and FM were declined as soil water content was decrea!:ed, but FO was almost remained constant for all the treatments. High yielding varieties had higher Tin, FM, FV/FM, FV, chlorophyll content and RWC values. The FV and FV/FMhnd highest and FO had lowest correlation coefficients with grain yield. The existing synchronized pattern of variation in fluoresccnce parameters of all varieties indicates that high yielding varieties can avoid the negative effects of drought slTcss during grain filling period. The high correlation between fluorescence parameters and RWC confirm these