Effects of ethephon on activities of oxidase enzymes and sex differentiation of bitter gourd

ObjectiveEffects of ethephon on activities of peroxidase(POD),catalase(CAT)and superoxide dis-mutase(SOD)in bitter gourd and its sex differentiation was studied to provide reference for high yield of bitter gourd.MethodDifferent concentrations of ethephon were sprayed on foliage and stem tip of bitter gourd(Ruyu 33 and Ruyu 41),and distilled water was used as control(CK). After treatment,the samples of stem tip were taken on day 0,10,20 and 30 respectively to measure the activities of POD,CAT and SOD. Node of the first female flower and node of the first male flower were observed after transplant,and node rate in the first 35 nodes of female flower was calculated.ResultAt each measurement period,POD activity of 50.0 and 100.0 mg/L ethephon treated Ruyu 33 and Ruyu 41 were higher than those of other treatments in the same period. The highest values appeared on day 30 after treatment. SOD activity of Ruyu 33 in 50.0 mg/L treatment was lower than those in other treatments at the same period,the lowest value occurred on day 30 after treatment which was 32.7%of that in CK. SOD activity of Ruyu 41 in 100.0 mg/L treatment was lower than other treatments at the same period,and the lowest value occurred on day 30 after treatment which accounted for 45.1%of that in CK. The variation trends of CAT activity and SOD activity of Ruyu 33 and Ruyu 41 were the same after ethephon treat-ments. For Ruyu 33,after 50.0 mg/L ethephon treatment,positions of node of the first female flower(the 8.0th node) and node of the first male flower(the 5.2th node)were the lowest,and the node rate of female flower was the highest(0.465). All these indexes were significantly different from those in CK(P<0.05,the same below). For Ruyu 41,after 100.0 mg/L ethephon treatment,positions of node of the first female flower(the 9.8th node) and node of the first male flower(the 6.2th node)were the lowest,and the node rate of female flower was the highest(0.512). All these indexes were significantly different from those in CK.ConclusionSpraying ethephon increases POD activity of stem tip of bitter gourd,decreases activities of SOD and CAT,lowers the flower position of the first female and male node and increases the node rate of female flowers. The effects of spraying 50 mg/L ethephon on Ruyu 33 and 100 mg/L ethephon on Ruyu 41 are sound in early flowering and increasing the number of early female flowers.