Effects Of CPPU On Double-fertilization And Fruit-set In Melon(Cucumis Melom L)

The effects of CPPU on double fertilization, endogenous hormones, fruit characteristics in melon are studied. The results obtained are summarized as follows:1 The research of effect of CPPU on double fertilization of flower-bud pollination (BP) and flower pollination (FP) is carried out by means of paraffin method. Two hours after pollination, the third mitosis of megaspore completes in CK of BP; treated with CPPU, there is 17.65% mature embryo sac in ovary. At the same time, the percentage of embryo sac in which two polar nuclei close to each other is 80.00% in CK of FP, while the percentage of embryo sac in which two polar nuclei fused is25.00% when treated with CPPU. Ten hours after pollination, there are 17.39% mature embryo sacs in CK of BP, 35.71 % embryo sacs in which polar nuclei fused when treated with CPPU; the percentage of embryo sac in which polar nuclei fused reach 53.33%, 85.00% in CK and treatment respectively .24 hours after pollination, the percentage of embryo sacs in which polar nuclei fused reach 30.77%, 66.67% in CK and treatment respectively. The observation that the sperm nucleus comes into contact with egg nucleus appears in embryo sac with the percentage of 30.00%, 55.56% in CK and treatment respectively in FP.48 hours after pollination, the double fertilization of CK and treatment in BP or FP completes and the zygote is formed. Observations show that CPPU better the process of double fertilization in melon whatever in CP or FP.2 The contents of IAA, GA3 in melon are determined by means of HPLC. Five days after pollination, the level of IAA,GA3 are higher than that exactly before pollination, whatever in BP or FP .What's more, the change range of IAA is broader than that of GA3.In BP, the content of IAA in CK reaches 1.751 8mg.kg"1FW exactly before pollination,7.663 4mg.kg"'FW 5days after pollination in CK and 9.754 4mg.kg"'FW in treatment. The content of GA3 reaches 11.792 lmg.kg"'FW and 13.5523 mg.kg"'FW in treatment 5 days after pollination, which is 151% and 173%respectively compared to that exactly before pollination. In FP, the content of IAA in CK reaches 2.0387 mg.kg''FW before pollination, 8.2500mg.kg'1FW in CK and 10.4088 mg.kg"'FW in treatment 5 days after pollination. The content of GA3 reaches 14.2409 mg.kg"'FW in CK, 16.0143 mg.kg~'FW in treatment 5 days after pollination.3 Treated with 10 mg.kg"'CPPU, the fruit set rate increase 20.48% in BP,18.89% in FP respectively; single melon weight,23.65% in BP ,16.89% in FP; seed number of single melon 14.96% in BP , 11.02% in FP compared with CK.