Biochemical responses of two wheat cultivars to late season drought stress and auxin and cytokinin application

In order to evaluate some biochemical responses of bread wheat (Shiraz cultivar) and durum wheat (Yavarous cultivar) to late season water stress and different auxin and cytokinin levels, a field experiment was carried out in research farm of the collage of Agriculture, Shiraz University during 2010-2011 growing season using a split split factorial as randomized complete block design with three replications. Irrigation regime (normal and cutting off water at anthesis), wheat cultivars (Shiraz and Yavarous) and factorial combination of auxin (0, 20 and 40 mg/L) and cytokinin (0, 50 and 70 Mm) levels were considered as main, sub and sub sub plats, respectively. The results showed that flag leaf proline and catalase content were increased linearly upon cutting off irrigation at anthesis; while, proline and catalase content did not show any significant changes after anthesis under normal irrigation conditions. Moreover, proline content in Yavarous cultivar was found to be significantly greater than Shiraz cultivar. Among cytokinin concentrations, the highest catalase activity was obtained from control treatment. As cytokinin concentrations were increased, catalase activity was decreased under well watered conditions. Peroxidase activity was increased under irrigation cut off conditions, and was enhanced with time lapse from anthesis. Chlorophyll a, b, carotenoid and total of foliage leaf were greater under cut off irrigation conditions. Deep understanding of biochemical responses of wheat cultivars to late season drought stress and its interaction with plant growth regulator needs further complimentary research.