Infructescence Development and Fruit Characterization of Nipa (Nypa fruticans Wurmb.) from the Semi-Wild Stands of Davao Region, Philippines

Abstract

The potential use of nipa (Nypa fruticans Wurmb.) as a source of bioethanol underscores the importance of understanding its infructescence (fruiting head) development beginning at female anthesis. Manual pollination
set-ups showed that stigmatic receptivity spanned 48 h with a peak at 36 h after onset of female anthesis. Weekly observations according to morphological changes at fruit set are categorized as follows: stage 1 is distinguished by the gradual hardening of exocarp and browning of fruits in the infructescence. The fruit color turned dark brown as development proceeded to stage 2 wherein some carpels fused forming bigger fruit. At stage 3, the infructescence began to bend owing to its weight with fruit color intensified to darker brown. At 21 weeks from female anthesis, the fruit head reaches its peak of rapid growth. The hanging of infructescence ensued at stage 4 that ultimately touched the ground at stage 5. This indicates full maturity at 25 weeks from the onset of female anthesis. In a separate study to characterize fruit development, fruit shape appears to be influenced by position in the infructescence rather than environmental conditions. Fruit samples categorized as developed had mostly spherical shape. They were likely located in strategic positions (polar end and equatorial region) of the infructescence which emerged first during female anthesis. A very dark brown hue indicated full fruit maturity.