Fitting of photosynthetic response curves to photosynthetically active radiation in oil palm

Abstract

Light saturation curves represent the response of the net photosynthetic rate to the photosynthetically active radiation. These curves were obtained from individual leaves of oil palm genotypes (Elaeis guineensis, E. oleifera and the O.G interspecific hybrid) without any type of biotic or abiotic stress, fitting three nonlinear models: the rectangular hyperbolic model (Michaelis-Menten), the non-rectangular hyperbolic model (Prioul and Chartier) and the exponential model (Mitscherlich). The research was conducted at Barrancabermeja (Santander, Colombia) with the aim to compare the adaptations of these models and to identify the most suitable model for the crop. The rectangular hyperbolic model was qualitatively and quantitatively the most appropriate to describe the oil palm response under different conditions, in terms of the coefficient of determination (R2 a), the mean squared error (MSE) and the standard error (SE); therefore, using this model, the photosynthetic parameters showed higher and more realistic correlation (r) with the measured values. The non-rectangular hyperbolic model was the least appropriate model to estimate the maximum photosynthesis, dark respiration, saturation points, light compensation and photosynthetic efficiency. Thus, the rectangular hyperbolic model is the fastest, simplest and most appropriate option to access the light curve information in oil palms and can be incorporated into the gas exchange and growth models into the whole palm production system.