Relationship between IAA, sugar content and fruit-set in snake fruit (Zalacca salacca)

The main problem of snake fruit production in Indonesia is high fluctuation of fruit production between different harvesting seasons, due to fruit-set failure in some parts of the year. The objective of this research was to find out the relationship between IAA and sugar content of leaves and flowers in relations to the failure of fruit-set in three flowering seasons of snake fruit (April, July, and October). The study was conducted at the production center of snake fruit in Bali (Karangasem Regency) by using Completely Randomized Design. The results showed that fruit-set in April, July and October was 54.16, 47.00 and 70.10%, respectively. Low fruit-set was found associated with low IAA content both in leaves and flowers. The lowest percentage of fruit-set found in July (47.00%) was related to the lowest IAA content in the leaves (10.06 ng g-1) and flowers (20.60 ng g-1). However, the highest percentage of fruit-set in October (70.10%) was correlated to the highest IAA content in the leaves (29.67 ng g-1) and flowers (52.56 ng g-1). Low fruit-set was also closely related to the low content of sugar in the leaves. The lowest percentage of fruit-set in July was caused by the lowest total sugar (24.54%) and reducing sugar (6.56%) content in the leaves, whereas the highest percentage of fruit-set on October related to high total sugar (30.58%) and reducing sugar (12.22%) content in the leaves. It can be concluded that failure of fruit-set in snake fruit was associated with low IAA and sugar content in leaves and flowers.