An Analysis of Growth of Oil Palm Seedlings in Full Daylight and in Shade

Abstract

Growth of seedling oil palms (Elaeis guineensis), in full daylight and under three levels of shade, was studied using growth analysis techniques. In full day-light, net assimilation rates (E_A) between o.15 and 0.32 g./dm.²/week were obtained associated with low leaf-area ratios (F) giving relative growth-rates (R_W) ranging fromI I.8 to 3.2 per cent, per day. There were no indications of seasonal differences within the small range of values found. The plants take about 90 days to adapt to shade conditions because the mean plastochron is 24 days, and shading effects are best studied on plants grown since germination under the shade treatments. Very different pictures of response to shade were obtained using plants grown initially in full light followed by 90 days' shade before sampling compared with plants grown under shade since germination. In the latter, except at the lowest light level used, I I.I per cent, of full day-light, there was very little effect of light on E_A or R_w, although the F values decreased as light increased. Extrapolation of the F values to the extinction point gave values similar to those obtained in another experiment on the effect of a number of shade levels on F. The physiological and ecological implications of these findings, particularly the low growth-rates and shade tolerance, are discussed.