Effects of Water Stress and Cycocel as a Growth Retardant on Growth of Two Olive Cultivars

Many experiments have been carried out to decrease the negative effect of drought stress and obtain suitable growth under water deficit conditions. Application of plant growth regulators (especially growth retardants) is one of the proposed methods. This study was conducted to investigate the effect of Cycocel application on growth of two olive cultivars (Shengeh and Roghani) under water stress condition. The design of experiment was completely randomized with six replications (Factorial arrangement). Treatments included irrigation intervals (2, 4, 6, 8 weeks) and Cycocel concentrations (0, 500,1000,2000,4000 mg per litter). Some indices such as height, chlorophyll, leaf area, root, and shoot weight (fresh and dry) were measured. Results indicated that interaction of C.C.C treatment and irrigation intervals on height of olive cultivars was not significant, probably due to the response of these cultivars to concentrations of C.C.C. Although drought stress decreased the number of leaves in both cultivars, the application of CCC (500 mg per litter) thwarted the adverse effects of drought stress. Cycocel increased chlorophyll content significantly (500 mg per litter in Roghani and Shengeh and 6 weeks irrigation interval). Cycocel application decreased leaf area, but in Shengeh cultivar increased leaf area in 6 week irrigation interval. Overall, the results indicated that the application of Cycocel with concentration of 500 mg per litter in 6 week irrigation intervals in both cultivars (Roghani and Shengeh) was the best treatment for controlling the adverse effects of drought. Also, results indicated that such changes were dependent on Cycocel concentration and drought level.