Temperature and leaf growth in Lolium perenne. 3. Factors affecting seasonal differences.
Shoot growth rates of perennial ryegrass cv. S24 were examined in spring and autumn in relation to seasonal changes in temperature in the region of the stem apex. Seasonal trends were present in all growth attributes but particularly the rate of leaf extension which at similar temperatures was significantly higher in spring than in autumn. Further studies in controlled environment showed that this effect was independent of other environmental factors and that some mechanism strongly linked with the change from the vegetative to the reproductive phase was involved.