effect of cycocel on growth and photosynthetic pigments of tow olive cultivars under different irrigation intervals

the water deficiency is one of the serious problems in the arid zones. in order to investigate the effect of cycocel on different growth aspects of two olive cultivars (mary and mission), a greenhouse experiment was conducted using three factors of: cycocel at three levels (0, 500 and 1000 mg l-1), irrigation of three levels (irrigated at 5, 10 and 15 days intervals) and tow olive cultivars (mary and mission) in a factorial experiment based on randomized complete block design of three replicates for the lasted four months. the results showed that both cycocel treatments decreased plant height, increased root length and number of lateral shoots; but no significant difference in stem diameter, leaf numbers, total lengths of lateral shoots, fresh weight of stem and root, chlorophyll b and carotenoid content was observed compared with control. high cycocel level (1000mgl-1) increased fresh weight of leaf and chlorophyll a content than the control. also, results showed that increased periods of drought have reduced the plant height, stem diameter, leaf numbers, number of lateral shoots and total lengths of lateral shoots, root length, fresh weight of leaf, stem and root, increased chlorophyll a+b and carotenoid content in both cultivars. in above-mentioned parameters mission cultivar showed higher resistance to drought stress than the mary cultivar. results suggested that cycocel treatment can alleviate some negative effects of drought stress in mary and mission cultivars of olive.