Effect of terminal drought stress on accumulation and remobilization of soluble carbohydrates of internodes in two barley (Hordeum vulgare L.) cultivars

In arid and semiarid regions such as Iran with terminal drought, crops may depend more on stem soluble carbohydrates reserves for grain filling than the current photosynthesis. To investigate the effects of terminal drought on grain yield, carbohydrate accumulation and remobilization in tolerant (Yousef) and sensitive (Moroco) barley genotypes, the experiment was conducted in green house condition in randomized complete block design with three replications. Peduncle, penultimate and lower internode samples were collected from well-watered and drought-stressed plants at 7-days intervals after anthesis (in six stages). Based on the obtained results, the highest level of water soluble carbohydrate accumulation and remobilization was located in the penultimate. Maximum of total carbohydrate concentration and remobilization was less in Moroco compared to Yousef internodes under both drought and well-watered conditions. Water deficit significantly increased the total soluble carbohydrates remobilization from internodes of Yousef plants but these prominent differences were not found in the internodes of Moroco plants. Fructan and sucrose were the main sugars in the penultimate of the two cultivars. Evaluation of carbohydrate components in the penultimates showed that maximum concentration of fructan, sucrose, glucose and fructose in yousef was higher than morocco plants under both drought and well-watered conditions. Accumulation and remobilization of fructan increased in Yousef plants under terminal drought stress but not in Moroco. The results suggest that the higher induction of stem reserve production and remobilization in Yousef genotype during drought stress may play an important role in its yield production during grain filling period.