Evaluation of some physiological traits of winter cereals under low irrigation

Cereals, have particular and important role in consume pattern in any country in the world. Study of the physiological responses of different cereal species to drought stress can be help to identify the mechanisms involved in resistance to drought. Drought stress is considered to be the major environmental factor limiting crop growth and yield. This stress induces many biochemical, molecular, and physiological changes and responses that influence various cellular and whole plant processes that affect crop yield and quality. Some studies suggest that drought stress influences the thermal tolerance of photosynthesis. The purpose of this study was to investigate the effects of water stress on the growth, chlorophyll, Catalaz, accumulations of proline and carbohydrates of cold cereals. Therefore, an experiment was conducted to evaluate the effect of the low irrigation on chlorophyll a, b, total, proline, soluble sugar content, catalase enzyme and grain yield as a factorial experiment based on completely randomized design with three replications in the greenhouse of College of Agriculture and Natural Resources, Gonbad Kavoos University in growing season of 2015. The first factor was different cereal species including Kohdasht bread wheat, durum wheat Seimareh, six-row barley varieties of desert, two-row barley varieties Khorram, and Line 17 of hulless barley, triticale varieties Javanilu and the second factor was different levels of low irrigation including without drought stress (control) , moderate irrigation (5 days water disruption), severe low irrigation (10 days water disruption). In this study low irrigation was applied at flowering stage. Results showed that there was a significant differences between low irrigation levels for chlorophyll a, b and total, proline, soluble sugars and catalase (p < 0.01). The highest chlorophyll a content in moderate irrigation and sereve low irrigation were found in durum wheat and Kuhdasht by 0.33 and 0.21 mg/g, respectively. Maximum content of chlorophyll b and total in moderate irrigation and severe low irrigation conditions was obtained from Kuhdasht wheat. According to our results, maximum and minimum content of proline in under moderate irrigation were observed in Kuhdasht wheat by 98.34, 15.83 mg/g, respectively, while under severe low irrigation, the highest and the lowest content of proline were found in Line 17 of hulless barley by 103.90 and 16.50 mg/g. In this study, the highest soluble sugar content (190.87 mg/g) was recorded in the durum wheat under severe low irrigation conditions. According to the results of this study, different levels of drought stress caused a different response among cereal species, which can be attributed to genetic differences and their tolerance levels. As with the duration of irrigation, the amount of chlorophyll a, chlorophyll b and total chlorophyll in grain species decreased compared to the control. However, Kuhdasht cultivar was more resistant to drought stress than other species.