Light-dependent modifications in the metabolic responses of squash seedlings.

Light-induced modifications in lipoxidase metabolism and chlorophyll formation in the cotyledon of squash (Cucurbita moscata) seedlings were determined. The enzyme activity decreased as light intensity increased, but chlorophyll continued to accumulate long after lipoxidase activity had virtually disappeared. Considering the differences in the levels of irradiance required to manifest the optimal responses, and also from the results obtained with ultraviolet and red, far-red light treatments, any causal relationship between lipoxidase disappearance and chlorophyll synthesis was ruled out.