Effects of 1-Naphthyl Acetic Acid ( NAA ) and Gibberellic Acid ( GA3) on Sex Expression and Growth of Papaya ( Carica papaya L. )

Abstract

A study was made on sex expression of papaya plants treated with NAA and GA₃ . The results showed that NAA treatment reduced the proportion of male plants compared with those treated with the control treatment, but this chemical did not change the relative proportion of female and hermaphroditic plants,The GA₃ treatment did not alter the proportion of male, female and hermaphroditic plants. However, the maleness character appeared before the other two sex categories. Other effects of the growth regulators were on the vegetative and reproductive growth. The NAA treatment resulted in the expression of epinasty in the sprayed plants, resulting in the plants being smaller that those in the control treatment. On the other hand, the GA₃ treated seedling grew more vigorously than the control plants. Over the 90 days growing period, maximum growth rate in all treatments was recorded at the 60^th – 70^th days after sowing. Flowers in the NAA treated plants were seen at about six days later than those in the control treatment. In the GA₃ treated plants, the flowers were seen at about 20 days earlier than those in the control treatment.