With rapid light curves is possible to determine three curve parameter: (i) The maximum rate of electron transport (ETRmax), reflecting the saturation capacity of a sample; (ii) & (alpha), Which is the initial slope of the light saturation curve, related to the maximum yield of PSII electron transport under conditions of limited light; and (iii) IK or light intensity at which alpha and electron transport rate max intersect, the point which is the initiation of saturation of photosynthetically active radiation (PAR).