| The diploid Watermelon and melon inbred line were used as experiment materials. Mutation effect of tetraploid were studied by using proherbicide ORYZALIN as mutagen in different methods. Comparing the mutagenic effect of different treatments methods (field dropping seedling,smearing,seed soaking,germinated seeds were immersed into ORYZALIN solution) and different ways of stem training. Study watermelon shoot tip on effect of ORYZALIN treatments of regeneration system. Mutation effect of tetraploid were preliminary studied by treatments of dropping seeding and smear in diploid melon materials. The conclusion as follows:1 Mutation effect in Field:The results showed that the mutation effect of watermelon tetraploid were best with 40mg/L ORYZALIN for 6d in dropping seeding and with 125mg/L in smearing growing point, the variation frequency was up to 47.06% and 37.29%. The concentration and time were the key factors for dropping seedling tetraploid inducement, the concentration was important factor for smearing treatment. The mutation effect of tetraploid were increased with the increasing of concentrations and the prolongation of treatment time in dropping seeding. And it were 3.33% only by treatment of the germinated seeds were immersed into ORYZALIN solution. It has not evident variation were found by way of seed soaking. The mutation effect of tetraploid by different way of stem training after dropping seeding treatment on watermelon materials, mutation rate of tetraploid were higher by pinching one time than non pinching to main stem.The mutation effect of two melons(M452,BM52) were compared by dropping seedling and smearing the results showed that it all were best with 40mg/L ORYZALIN for 4d in dropping seedling, the variation frequency was up to 30%.And the highest variation frequency up to 31.58% with 275mg/L ORYZALIN by smearing way to melon BM52.And the mutation rate were increased with the increasing of concentration.2 Establishment of the diploid watermelon regeneration system: using watermelon cotyledons,cotyledon callus and shoot tips as explants, and MS containing 6-BA,IAA and IBA as basical media. The induction rate of adventitious bud in different concentration of hormones on watermelon regeneration system were studied. The results showed that the optimum medium was MS+6-BA1.0mg/L+IBA0.1Mg/L for inducting adventitious bud of cotyledons and cotyledon callus, the induction rate was 43.33% and 76.67%. the optimum medium was MS+BA2.0m g/L for inducting adventitious bud of shoot tips. the induction rate was up to 96.67%. The induction rate of adventitious bud for explants of shoot tips were highest and the induction speed were fastest, the shoot tips was considered as best explants. The induction rate of adventitious bud has little difference with same explants and culture conditions to different experimental materials.3 The effects on growth of watermelon shoot tips by ORYZALIN treatments: using watermelon shoot tips as explants, and MS+6-BA2.0mg/L as induction medium of adventitious bud. The shoot tips were implant separately in MS solid and liquid media added different concentrations ORYZALIN for 1-5d and immersed 9,24h, the grows point of shoot tips were embedded by using agar contained different concentrations of ORYZALIN. The survival rate and growth status of shoot tips were compared by different treatments after 4w. The results showed that: the solid media contained ORYZALIN 4mg/L,inoculation treatment for 3d, and the liquid media contained 40mg/L ORYZALIN, immersed treatment for 9h was more suitable, the survival rate of shoot tips was separately up to 60% and 80%; comparing with the control, malformation plants were found at above two treatments. The survival rate of shoot tips was very low, it were only 3.33% by treatment of the agar embedded. The indication of survival rate was a decreased tendency as the concentration of ORYZALIN and treated time were increasing .
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