Blue light effects on the growth ofLolium multiflorumLam. leaves under natural radiation

Abstract

summaryPlants ofLolium multiflorumLam. were grown under natural radiation supplemented with blue light during the photoperiod. The blue light treatment reduced final length of the leaf sheath but did not modify lamina length compared with control non‐irradiated plants. Leaf sheath length was linearly and inversely related to the log‐fluence rate of supplementary blue light. The rate of leaf elongation was unaffected until the target leaf reached 35–70% of its final length. Red light had no effect at fluence rates that were inhibitory in the case of blue light and promoted leaf growth at high fluence rates. Plants grown under natural canopies also responded to supplementary blue light. Fully de‐etiolatedL. multiflorumplants respond to different fluence rates of blue light within a range found in natural canopies. The possible photoreceptor and ecological implications are discussed.