The effect of light intensity on some morphological and physiological aspects of the crop perennial ryegrass (Lolium perenne L. var. 'Cropper') and its effect on seed production.

Abstract

Perennial ryegrass cv. Cropper was given high (188), intermediate (140) or low (84 cal/cm2 day between 400-700 nm) light intensity during the period 1 Apr.-30June using supplementary lighting, normal daylight and artificial shading, respectively. Other plots were given 174, 86 and 52 cal/cm2 day during 26 Aug.-1 Oct. and 106, 43 and 26 cal/m2 day until 29 Oct., without affecting the photoperiod. Increased light intensity in autumn or spring considerably increased tillering, while shading treatments gave a decrease. Differences in tiller numbers in autumn decreased during winter and early spring. Numbers of vegetative and reproductive tillers and weight/tiller increased with increasing light intensity in spring. Seed yield was closely correlated with number of reproductive tillers and less closely with number of seeds/head. Supplementary illumination in autumn had only a small effect on number of reproductive tillers but increased number of seeds/head. Maximum LAI of the top 3 leaves, internodes and inflorescences was 13.2, 11.6 and 7.7 in the 3 treatments respectively; these values were high compared with cereals. Amounts of water-soluble carbohydrates in reproductive tillers increased exponentially until ripening and then fell sharply. (Abstract retrieved from CAB Abstracts by CABI’s permission)