La perception géotropique dans la coiffe des racines de Lentille

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Abstract
In its initial phase, the geotropic response of Lens culinaris roots cannot be explained by a simple action by sliding, pressure or contact of amyloplasts on a sensitive surface located along the longitudinal wall. The following parameters were considered as functions of the root inclination: the distance (.hivin.d) which the amyloplasts move; their number of contacts (.hivin.c) with parietal cytoplasm and the variable (sin .alpha.) of the transversal component of the statolith weight (.hivin.M .times. g sin .alpha.). The initial rate of curvature (.hivin.V), at the various angles, was related to the sedimentation of the amyloplasts by the equation .hivin.V = a log b .hivin.d .hivin.c sin .alpha. (where a and b are constants). The geotropic stimulation was dependent upon the sine of the angle (.alpha.) of the root inclination and explain the sine rule deviation. The role of statoliths is discussed in the light of recent literature on growth inhibitors which are involved in the geotropic reaction.