Study the effects of water deficit on chlorophyll fluorescence indices and the amount of proline in six barley genotypes and its relation with canopy temperature and yield

Controlling drought stress and its related problems had confronted mankind in thousands years. In other to investigate the effects of water deficit on chlorophyll fluorescence indices and the amount of proline in six barley genotypes, an experiment split plot based on randomized complete block design with three replications was conducted in Farm Seed and Plant Improvement Institute Karaj in 2002. In this study, the main plots were irrigated in five levels (0, 20, 50, 75 and 100 % of plant water requirement), and sub-plots were barely genotypes in six levels (Torkaman, Karon×kavir, Rihany, C-74-9, Ghorghan-4, Kavir×Badia). The results showed that water deficit caused chlorophyll fluorescence indices or photochemical efficiency of photosystem II declined significantly due to increasing of initial fluorescence (Fo) and decreasing of maximum fluorescence (Fm). With increasing stress, proline accumulated under water deficit increased although there were significant differences among genotypes under water deficit. Water deficit caused relative chlorophyll content decreased. However, between 100 and 75% plant irrigation no significant differences were seen. Water deficit caused grain yield decreased but canopy temperature increased significantly and genotypes with cooler canopy under control treatment were tolerant to drought and showed higher yield than other genotypes under drought condition. Means comparison of interaction of water limitation×barley genotypes showed that the highest grain yield was obtained in the plots which Karon×kavir and Kavir×Badia genotypes were applied without of water limitation and the least of it was obtained in the plots which Ghorghan-4 genotype under drought condition or with full water limitation was applied.