IMIS

Applicability of asymptotic (logistic) functions, commonly applied in growth analysis of plants is discussed and the emphasis put upon their formalistic, non-explanatory, character. A new growth model, which is a modification of the exponential function, is proposed. An attempt at explaining the essentially sigmoidal shape of the growth curve, and the possible deviations from it, is based on an equation containing paramters which may have certain biological or physical importance. It seems that efforts towards formulation of an explanatory model of plant dry matter accumulation could take advantage of the fact that all external or internal factors limiting growth act through modificatios of photosynthesis or related processes so the adequatae parameter (or variable) of the function can be an integrating measure of these effects.