Effect of Cultivation Conditions on High Temperature Gender Alteration of Hermaphroditic Papaya (Carica papaya, L.)

Papaya, Carica papaya L., is one of the major fruits in the tropical and subtropical regions.Hermaphroditic variety is generally preferred for commerce as its more desirable fruit shape and quality can bring higher profitability.However, the plants gender expression can be affected by ambient temperature.At elevated temperatures, the plant tends to produce male flowers with intermittent fruiting, resulting in decreased yields.In order to search for remedy to overcome the problem, four treatments were tested on hermaphroditic papaya trees during the months of July and August in the years from 2007 to 2009. The treatments included (1) mulching under the tree with wet straw or fresh grass, (2) pruning inflorescence, (2) ring-girdling on trunk, and (4) combining the above three methods.The results showed that all treatments significantly repressed the gender alteration, decreased the numbers of male flowers and intermittent fruiting, and increased the number of fruits on the trees, as compared with the control.However, among the 4 treatments, the combination of 3 methods appeared to be the best, as it was most effective in completely suppressing the intermittent fruiting at high temperature.