Selection of Tetraploid of a Yellow Flesh Mini-Watermelon Using Oryzalin

In order to provide parent material for small-type triploid watermelon, this study has been carried out to induce high-quality tetraploid watermelon. We induced tetraploid plants of watermelon by treating the growing points of seedlings of a small-type yellow flesh diploid watermelon with 40, 60 and 100ml/L Oryzalin for different treating time. The autotetraploid plants were selected and identified basing on morphology, determination of the number of chloroplasts in stomatal guard cells, flow cytometry analysis and hybridization. Then we observed a stable autotetraploid material. The results showed that tetraploid watermelons could be obtained under different treatments. The most effective way was extirpating the interior leaves at the 8th day after sowing, then treating the growing points of seedlings with 100mg/L Oryzalin for 6d. The treated seedlings could all survive and the induction frequency of the tetraploid watermelon was 33.33%.