Benzyladenine treatment promotes floral feminization and fruiting in a promising oilseed crop Plukenetia volubilis

Plukenetia volubilis, whose seeds contain a high content of polyunsaturated fatty acids, produces approximately 60 male flowers but only 1-2 female flowers per inflorescence. Increasing the number of female flowers is critical for yield improvement of P. volubilis. In this study, we determined the effect of the plant growth regulator 6-benzyladenine (BA) on floral sex determination in P. volubilis. Exogenous application of BA converted male flowers on most of the inflorescences to female flowers, and approximately 8-20% of the induced female flowers further developed into fruits. Treatment with various concentrations of BA resulted in 3-41 female flowers per inflorescence, reaching the highest average of 23.9 at 160 mg/L BA treatment. There were 3-22 inflorescences with induced female flowers per branch on the trees treated with various concentrations of BA, and the highest average of 13.8 was observed at 20 mg/L of BA treatment. The average number of fruits per infructescence was 3.3 in the trees treated with the optimal concentration of BA (20 mg/L), compared with 1.3 for infructescences of the control trees. The results of this study show that BA is a plant growth regulator with the potential to induce floral feminization and promote fruiting of P. volubilis.