Rates of Leaf and Tiller Production in Young Spaced Perennial Ryegrass Plants in Relation to Soil Temperature and Solar Radiation

Abstract

In an experiment designed to investigate the rate of leaf appearance and tiller production in young spaced plants of three clones of perennial ryegrass grown in the field, it was found that the rate of leaf appearance per tiller increased linearly with mean soil temperature up to approx. 14 °C. The rate of production of tillers in relation to the rate of leaf appearance (site filling) appeared to be virtually independent of weather conditions. In plants which were adequately established, but still relatively small, site filling was equal to or exceeded the theoretical steady state; all the tiller buds which were being formed were developing into visible tillers. Thus the relative rate of tiller production was controlled by the rate of leaf appearance. In larger plants site filling was less complete, and site redundancies were probably caused by within-plant competition for light at the tiller bases.