The influence of red light on geotropism of decapitated Avena coleoptiles

The influence of red light on the geotropic curvature of decapitated Avena coleoptiles provided with agar blocks soaked in a solution of IAA is similar to the influence of red light on the geotropic curvature of intact coleoptiles. A small quantity of red light (0.6-2 J m~2) enhances the geotropic curvature, a larger quantity of red light (150-200 J m-2) causes a shift of the curvature to the apical part of the coleoptile stump.