Do plants need darkness and light?
yes plants need both, the diurnal cycle influences the metabolic and physiological processes,also On a diurnal time scale water moves out of the cells and into the extracellular region in the morning and back into the cells in the late afternoon and evening. This leads to a diurnal cycle in the extracellular water content. The magnitude of the diurnal cycle gives a measure of the cross sectional area of the extracellular region that is filled with water during the daytime period. Over a multi-day period, the minimum value of the diurnal cycle will vary in proportion to the water content of the plant as a whole. As the plant dries out, both the magnitude of the diurnal cycle and the minimum value decrease.