Application of drip irrigation technology for producing fruit of Salak Gula Pasir (Salacca zalacca var. Gula Pasir) off season on dry land

Abstract: Naturally, Salak Gula Pasir (Salacca zalacca var. Gula Pasir) is flowering every three months or four times a year, but only one or two flowering seasons that the flowers can develop into fruit. The condition causes Salak Gula Pasir is available in the market in a short period (only 2-3 months) i.e. at the time of harvest (on-season) from December to February. This seasonal nature of Salak Gula Pasir occurs because Salak Gula Pasir is planted on dry land where irrigation depends only on rainfall, and drought occurs when water is shortage so that the plant internal water content is low that causes a high failure development rate of flower to become fruit (fruit-set failure). This study was aimed to overcome the fruitset failure by providing drip irrigation. Two treatments (with drip irrigation and without drip irrigation/control) with sixteen replicates were tested at Salak Gula Pasir production centre (at Sibetan village, Bebandem District, of Karangasem Regency, Bali) at two harvest seasons, i.e. Gadu (July) and Sela II (October). The results showed that the plant provided with drip irrigation significantly yielded fruit-set percentage higher that that without drip irrigation, both in Gadu and Sela II seasons. The percentages of fruit-set in Gadu and Sela II seasons provided with drip irrigation were 75.30% and 93.13%, respectively, while those without drip irrigation were only 59.94% and 61.67%, respectively. The increase of fruit-set observed for drip irrigation treatment associated with the increase of leaf chlorophyll content, relative water content (RWC) of leaves, and leaf N, P, and K contents. The increase of fruit-set led to higher number of fruits and fruit weight per plant under drip irrigation than that without drip irrigation. Based on the results of this study, drip irrigation can be applied to produce Salak Gula Pasir planted out of season on dry land. Keywords: drip irrigation, dry land, fruit-set, off-season, Salak Gula Pasir