The role of drought in change of some morphological and physiological charachteristics in citrus rootstocks

Water is a main factor in agriculture activities and almost 70 percent of world water resources are consumed in agriculture. The present research has been done to investige response of Citrus rootstocks to drought as factorial test based on randomized completely design with three replications. Factors included rootstocks in 10 levels [Poncirus (PT), Troyer citrange (TC),Citrumello (CR),Sour orange (SO),Cleopatra mandarin (CM), Rough Lemon (RF), Bakraii (B), Chang-sha (CH), Machrophylla (M) and Mexican Lime (ML)] and irrigation in two levels [optimum irrigation (fixed in field capacity) and withholding irrigation]. Results showed that drought induced increament of ion leackage percentage in all of the rootstocks and  the root to shoot dry weight ratio in PT, M and B and decrease of leaf water relative content in all of the rootstocks, leaf fresh weight in SO, stem fresh weight in CR, root fresh weight in TC, SO, CR and M, shoot fresh weight in SO and CR, total fresh weight in SO, CR and M, root to shoot fresh weight ratio in TC, CR, M and CM. Therefore, TC, CH and PT had good tolerance to drought because of lower ion leackage in TC, higher water storage in CH leaves and the higher root to shoot dry weight ratio in PT.