Evaluation of some physiological, biochemical traits and yield of three rye cultivars under water deficit stress conditions

Water stress is one of the most important threatening factors for the production of crop plants in the arid and semi-arid regions of the world. Understanding plant responses to drought is of great importance and also a fundamental part of making crops stress tolerant. Water stress reduces plant growth and manifests several morphological, physiological and biochemical alterations leading to massive loss in yield of major crops including Rye. Drought susceptibility of a genotype is often measured as a function of the reduction in yield under drought stress, while the values are confounded with differential yield potential of genotypes. The aim of this study was to evaluate the effect of water deficit stress on some physiological, biochemical traits and yield of three Rye cultivars.

This experiment was carried out as split plot based on randomized complete block design with three replications in Dezful region during 2014-2015 growing season. Treatments included water deficit stress (irrigation after 75, 1000 and 150 mm evaporation from Class A evaporation pan) in main plots and three rye cultivars (Stratoskaya, Danko, Montanum) were in subplots. The evaluated traits included chlorophyll a, chlorophyll b, carotenoids, soluble proteins, quantum yield of photosystem II, soluble sugars, proline content and grain yield. Analysis of variance was performed using statistical analysis system (SAS version: 9.3). The means were analyzed using the Duncan's test at 5% probability level.

The results showed that water deficit stress reduced the content of chlorophyll a (27%), chlorophyll b (32%), carotenoids (19%), soluble proteins (71%), quantum yield of photosystem II (28%), grain yield (33%) and in contrast, it increased the amount of soluble sugars (83%) and proline content (145%) compared to the control treatment. The slicing intersections of water deficit stress and cultivar showed that in terms of grain yield, Danko cultivar under irrigation conditions after 75 mm evaporation and Stratoskaya cultivar under irrigation conditions after 150 mm evaporation from the evaporation pan of Class A evaporation had the highest and lowest grain yields with 2414 and 1147 kg per hectare, respectively.

In general, it can be said that under irrigation conditions after 150 mm evaporation Montanum cultivar because of more photosynthetic durability and better osmotic regulation than the other two cultivars had more tolerance to water deficit stress and it had higher grain yield.