Infructescence Development and Seed Characterization of Nipa Palm from Different Semi-Wild Stands of Davao Region, Southern Philippines

The versatility of nipa even under unstable environmental conditions and its potential use as source of bioethanol underscore the importance of understanding the fruit development of the palm. Female anthesis served as the reference point for determining the age of infructescence (fruit head). Weekly observations categorized according to morphological changes showed that Stage 1 is distinguished by a hard brown seed with dark brown tips. Stage 2 is characterized by seeds of even brown hue with some carpels fused forming bigger seed. At Stage 3, the infructescence began to bend owing to its weight with seeds having brown color with darker hue. At 21 weeks from female anthesis, the fruit head reaches its peak of rapid growth, which may also level off photosynthate demand. This suggests a halt to being a ‘sink’ in the succeeding stages. At Stage 4, the infructescence was already bending halfway the ground level. At Stage 5, the fruit head finally touched the ground. This indicates full maturity at 25 weeks from onset of female anthesis. In a separate study, environmental variability did not show statistical differences on seed morphometrics. However, position of seeds in the infructescence significantly affected viability. Seeds, if spherical, are considered viable and were located in the polar end opposite the peduncle and in the equatorial region. Dark brown seeds indicate full maturity. This study would be of value in the future as reference for seed maturity index, variability tests, and description of different stages for timing sap collection during tapping

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

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 pollinationset-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