Evaluation of Drought Tolerance in Recombinant Inbred Lines of Wheat Derived from Cross Between Azar2 and 87Zhong291 Using Chlorophyll Fluorescence Parameters

Drought is one of the most important abiotic stresses affecting food production under dryland-rainfed conditions. In the present study, fluorescence parameters as non-destructive methods were used to assess drought tolerance in winter bread wheat. A population of 142 recombinant inbred lines in F8 generation, derived from a cross between Azar2 (Winter type) and 87Zhong291 (Facultative type), was used. Experiment was conducted using randomized complete block design with three replications under rainfed (drought stress) and supplementary irrigation during 2006-2007 seasons at Maragheh Experiment Station of the Dryland Agricultural Research Institute (DARI). The chlorophyll fluorescence characters including minimal fluorescence level from dark-adapted leaves (Fo), maximal fluorescence level from dark-adapted leaves (Fm), variable fluorescence level (Fv), maximum quantum efficiency of PSII photochemistry (Fv/Fm), non-photochemical quenching (NPQ), photochemical quenching (QUE), leaf water potential related to drought resistance (LWP), yield of photochemical energy conversion (YPEC), and performance index (PI) were measured. There were significant differences among genotypes with respect to chlorophyll fluorescence parameters under both conditions. Average grain yield under drought and irrigated conditions were 928 and 2547 Kg/ha, respectively. Under drought condition, grain yield ranged from 272 to 1935 Kg/ha. It varried from 3805.4 and 3804.9 Kg/ha under supplementary irrigation. Grouping of geneotypes based on grain yield revealed significant differences between high and low yielding groups with respect to chlorophyll fluorescence parameters only under drought condition. Based on regression analysis, significant and positive relationships were observed between grain yield and all chlorophyll fluorescence characters except QUE under droght condition. QUE had negative and significant association with grain yield. However, no significant linear relationships was found between grain yield and chlorophyll fluorescence parameters under irrigated condition. Correlation analysis indicated positive or negative significant correlation between chlorophyll fluorescence parameters. The results of present study indicated that chlorophyll fluorescence parameters along with morpho-physiological characters could be used as selection criteria in breeding wheat for drought tolerance.