Effects of Spermidine and Methyl Jasmonate on Vegetative and Reproductive Characteristics of Bell Pepper under High Temperature Stress

Bell pepper is on of the warm season crops. However¡ at temperatures above 30 ˚C in summer flower abscission are formed and reduce fruits yield. This experiment was carried out to investigate the effects of spermidine (0.1¡ 0.5 and 1 mgl-1 )¡ methyl jasmonate (0.001¡ 0.01 and 0.1 mM) and distilled water (control) to reduce the effect of high temperature on flower abscission of bell pepper plants. The experiment was done in a randomized complete block design in three replications. The plants were foliar sprayed at 5-6 leaf stage (before flowering) for two times with five day interval. Results showed that treatment with spermidine increased plant hight¡ number of lateral branches¡ relative chlorophyll¡ number of flowers¡ fruit set¡ fruit yield¡ ¡ antioxidant capacity¡ fruit vitamin C and reduced flower abscission significantly compared with control. Application of methyl jasmonate also led to significant increase of relative chlorophyll¡ fruit set¡ fruit yield¡ vitamin C and antioxidant capacity but reduced flower abscission and showed no significant effect on lateral branches¡ plant hight¡ the number of flowers compared with control. Application of spermidine on flower formation¡ increasing fruit yield and reducing flower abscission was more than methyl jasmonate. Finally¡ these plant growth regulators were able to reduce flower abscission increase flower formation¡ fruit set and yield.