Effect of Light Quality on Chloroplast Replication in Spinach

Abstract

Chloroplast growth and replication have been studied in spinach leaf discs cultured on sterile nutrient agar under lights of different spectral qualities. Over the intensity range 0-1-5 mW cm2 both red (632 nm) and blue (488 nm) laser light stimulate chloroplast division to the same extent as white light. By contrast low intensities (0-22-0-65 mWcm-2) of both white or green (525 run) light are ineffective for chloroplast replication but permit normal chlorophyll syn thesis and greater than normal chloroplast growth. The large plastids of discs grown in green light divide when exposed to high-intensity white light.