Temperature and leaf growth in four grass species.
Leaf extension rates of perennial ryegrass, Italian ryegrass, tall fescue and timothy were measured in the field using artificial soil heating as a treatment. Leaf extension rates were generally greatest in Italian ryegrass and least in timothy. The interval between the appearance of successive leaves was generally longest in tall fescue and shortest in timothy. Leaf extension rates were closely related to the temperature in the region of the stem apex, though the relationship was different in the vegetative and reproductive phase. Leaves grew more slowly in the vegetative phase than in the reproductive phase at similar temperatures. The change occurred at the onset of floral initiation in each of the species. In the vegetative phase, temperature had the greatest effect on leaf extension in tall fescue and least effect in timothy. In the reproductive phase the difference between species was not significant.