Study of physiological and biochemical responses of some hazelnut cultivars under ‎drought stress and re-watering conditions

Due to decreasing in precipitation and under-ground water resources and increasing the chance of drought stress, it is necessary to select drought resistant or tolerant cultivars and genotypes. Hazelnut is one of the most important nut trees. In order to study responses of six hazelnut cultivars (‘Fertile’, ‘Ronde’, ‘Longue’, ‘Segorbe’, ‘Gerd’ and ‘Merville’) to drought stress, a RCBD based factorial experiment was carried out on three-year-old outdoor potted saplings. Irrigation treatments included control (regular watering), and drought stress (withdraw watering). Rewatering after drought stress period was performed and recovery of plants after one day and after one week were studied. Results of variance analysis showed significant differences between irrigation treatments as well as the cultivars. Photosynthetic pigments and the quantum efficiency decreased under drought stress, whereas, MDA and proline contents increased. The highest quantum efficiency of photosystem II was observed in control treatment (0.731) and the lowest was in stress treatment before rewatering, but one week after rewatering it returned to the control level. Gerd cultivar with highest amount of photosynthetic pigments had also the highest amounts of antioxidant compounds (phenolic compounds and flavonoids). Proline content had negative correlations with most of the studied characters except MDA. Under drought stress, ‘Longue’ and ‘Ronde’ expressed the lowest and the highest leaf injury (necrosis %), respectively. ‘Longue’, ‘Fertile’ and ‘Gerd’ cultivars were more tolerant to drought than other cultivars.