Response of perennial and Italian ryegrass cultivars to temperature and soil water potential

Abstract

The rate of leaf extension (LER) in swards of perennial and Italian ryegrass was examined in relation to daily mean air temperature. Cultivars studied were an Italian, an Italian-perennial hybrid, a tetraploid perennial and diploid perennial cultivars in three maturity groups. A range of response to temperature was apparent. The Italian, the hybrid and the tetraploid perennial cultivar showed higher LER values than those of the diploid perennials. Amongst perennial cultivars the tetraploid cv. Reveille was shown to have a lower rate of photorespiration than the diploid cv. Gremie. These data are discussed in relation to the use of daily temperature observations in predicting leaf growth.