The Influence of Light Intensity upon the Growth of an S. 37 Cocksfoot (Dactylis glomerata) Sward

Abstract

A sward of S. 37 cocksfoot (Dactylis glomerata) was grown in three different light intensities varied by means of muslin screens. Decreasing the light intensity to 60 and 40 per cent of full daylight decreased the growth-rate and the rate of tiller production, and so decreased competition between tillers and the death-rate of tillers. Light intensity affected the area of leaves but had no effect upon the number of leaves per tiller. The rate of increase in the total dry weight fluctuated because of loss through decay, and the rate of increase in the weight of green tissue was taken as a measure of the rate of assimilation by the swards. Since the growth-rate of the green tissue at each light intensity varied little over a wide range of leaf area index, it seems that grass swards may be able to increase the efficiency with which they use light by adaptation to a changing light environment as growth proceeds. The difficulties of performing a growth analysis in the presence of the high and variable rates of senescence and decay of plant parts found on an established sward are discussed.