In this experiment, the leaf electrolyte leakage rate was used as an early screening index for heat tolerance in papaya breeding. The leaf electrolyte leakage rate of 8 lines was observed at the seedling stage. The two lines B23 and B5 were greater than Tainong No. 2.The electrolyte leakage rate of adult plants B21 and B5 is lower than that of Tainong No. 2, and the performance of the seedling stage and the adult plant are inconsistent. It is speculated that the cause may be surrounded by the late field in addition to high temperature, there is still a large amount of rainfall and disease effects, resulting in the two periods of measurement results are not exactly consistent.

Only at the beginning of the high temperature, pollen is released and set set normal fruits, and only after the continuous rain and the temperature drops, will there be a short period of pollen release and normal pistils. Then, only when the temperature dropped after continuous rain and pollen would be released for a short period of time and normal pistils appeared,indicating that the tested strains were Insufficient heat resistance This test is the first year of implementation. The test method is established. Later, more lines will be tested and field comparisons will be used to select heat-resistant varieties.

▲Fig.1. Leaf electrolyte leakage rate is low, and plants can still bear fruit normally during high temperature period (Left: Line B5, Right: Line B23)