The Effects of Temperature upon Seed Development in Three Species of Forage Grasses

Abstract

The effects of three temperature regimes, 25°C day/20°C night, 20°C day/15°C night and 15°C day/10°C night upon seed development in S.22 Italian ryegrass, S.24 perennial ryegrass, S.215 meadow fescue and a Swiss ecotype of meadow fescue were investigated. The largest ovaries and largest seeds were obtained from the 15/10°C environment and floret fertility was greatest at 20/15°C. The largest seed weight per inflorescence was at 20/15°C, except for the Swiss ecotype of meadow fescue where it was greatest at 15/10°C. The percentage germination was highest from those seeds developed at 25/20°C and this was particularly marked at germination temperatures of 13–20°C. There was a low rate of germination of seeds from the 15/10°C treatment, but they produced seedlings with the largest dry weights. It is concluded that year to year temperature differences will affect the yield and quality of seed crops of forage grasses.