Impact of Concentration and Application Method of Paclobutrazol on Reducing Cucumber Transplanting Shock and Resistance to Water Stress

An experiment was conducted to test whether paclobutrazol application methods, time of application and concentrations would protect cucumber transplants against transplanting shock and water stress. A randomized complete block design experiment with four application methods (seed soaking, soil drench, spraying and root dipping) at three rates of paclobutrazol (0, 25 and 50 mg l-1) in factorial combinations was used. Half of potted plants grown under greenhouse conditions were subjected to drought by withholding irrigation and then were reirrigated. Results showed that except for root dipping treatment, other application treatments reduced height of plants. Non-paclobutrazol treatment significantly decreased leaf relative water content of deficit irrigated plants but in other treatments there were no significant differences between deficit irrigated and normal irrigated plants. It seems that paclobutrazol was most effective in improving resistance of plantlets to wilting after transplanting when applied at 25 mg l-1 using soil drench method and pretransplant paclobutrazol application to soil (drenching) at 50 mg l-1 can be useful on ameliorating water stress.