The growth responses to weather of simulated vegetative swards of a single genotype ofLolium perenne

Abstract

SUMMARYThe influence of ambient weather conditions on the regrowth and morphology of a perennial ryegrass sward, over the period May–October 1972, was assessed by following the performance in the field of a succession of vegetative, single genotype, simulated swards previously grown under standard conditions. Crop growth rates estimated from largely non-destructive measurements of growth components (leaf extension, leaf weight/length ratio, tillering rate and tiller density) agreed with, and were more precise than, rates determined from harvests; the components having the greatest influence on growth rate were leaf extension and leaf weight/length ratio. Leaf extension and appearance were closely dependent on temperature; leaf weight/length was only slightly affected by the weather. The growth rates of total above ground parts, especially of herbage above the cutting height, were largely determined by temperature and initial leaf-area index, and insensitive to insolation. At higher temperatures, a greater proportion of assimilates was partitioned into herbage growth.