Influence of Light on Phosphate Metabolism in Lettuce Seed: Spectral Response Red, Far-Red Interaction

Abstract

The spectral response of phosphate uptake and esterification in hydrated lettuce seed was determined. Compared to nonirradiated seed, enhancement in,the red (550 - 650 m[mu]) and inhibition in the far-red (700-750 m[mu]) and blue (450 m[mu]) regions of the visible spectrum was observed. Activities approached the levels of nonirradiated seed after exposure to the near-ultraviolet region. Under continuous irradiation, red light accelerated and far-red depressed phosphate metabolism. Partial repetitive reversibility of the phosphate response was obtained on alternating extended exposures of the seed to red and far-red light. The repetitive reversibility was complete, and independent of the initial band used, when short exposures were employed. These effects of light on phosphate metabolism correlate exactly with the germination response, and provide a sensitive biochemical parameter of the effects of monochromatic light on lettuce seed germination.