Supranee Wunsri, Thawat Chittrakarn, Tripob Bhongsuwan, and Somsak Kongsaeng

pp. 839 - 848

Abstract

To determine the appropriate harvesting time of Tenera oil palm bunches, the spectral reflectance of
ripening bunches was investigated from images taken by a digital Canon PowerShot A20 camera. Every
second day images were taken from selected bunches at an oil-palm estate during the growth of the bunches
from immaturity to the over-ripe phase, to trace the changes in color which correlate with the process of
ripening. The images were analyzed measuring the changes in the three basic colors red, green and blue,
using a specially developed Color Analysis computer program for Oil-palm 'fruit' (CAOP), and determining
the correlation with the measured palm-oil content of the nuts. Of the three color-bands, the red light reflectance showed the best correlation with ripeness, as the
red color increased regularly and practically linearly up to the stage of the maximal oil yield. Some seven
days after the thus determined optimal harvesting date for the ripe bunches, some of the ripe nuts will detach
from the bunch and fall, but then it is too late to use the fallen nuts as indicators for harvesting. From our
investigations in the field and in the laboratory we recommend that harvesting should follow immediately
after the red reflectance starts declining, after having reached its peak value for the Tenera oil-palm some
5±3 days before nuts begin to detach from the bunch.