Phenology of Flowering and Fruit Set in Snake Fruit (Salacca Sumatrana Becc.)

The Sidimpuan snake fruit (Salacca sumatrana Becc.) tree flowers throughout the year. However, the fruits are produced seasonally. The level of production is directly related to flowering and fruit set. A low level of fruit formation results in a low number of fruits that can be harvested. A deeper understanding of the phenology of flowering and fruit set in Sidimpuan snake fruit may help solve the problem of low off-season production, and is the focus of this study. The study was conducted in the village of Palopat Maria, a subdistrict of Padangsidimpuan Hutaimbaru, Indonesia. The methodology included surveys and descriptive analysis with direct counting of inflorescences and fruits on each sample plant twice a week over each of three sampling periods (May–August 2016, September–December 2016, and January–April 2017). The results showed that the Sidimpuan snake fruit is a monoecious plant with hermaphrodite flowers. The inflorescences set at the base of the midrib of the fronds every 1.0–1.5 months. The plants had five–six flowering stages, and two–three stages of fruit set were observed. The period between the appearance of new flowers and fruit harvest lasted 5–6 months. The highest average number of flower bunches was observed in the January–April flowering period (6.23/tree) and the lowest was in May–August (5.33/tree, i.e., 14% less). The number of fruit bunches was the highest in May–August (4.37/tree), and the lowest in September–December, and was more than 40% less. Analysis of variance indicated that the flowering period significantly affected the percentage of fruit set. The highest fruit set was 85.5% during May–August, and the lowest was 44.0% during September–December. The average leaf nitrogen content in the flowering period of May–August and September–December was significantly different and higher than that in January–April. The average levels of phosphorus and potassium did not vary significantly throughout the year. The difference in fruit set affected the level of production in each flowering season.