The effects of temperature and fertilizer nitrogen on the spring growth of tall fescue and cocksfoot

A detailed study of the spring growth curves of two forage grasses, tall fescue and cocksfoot, over three successive years showed a large variability of growth over the vegetative phase. This variability was evident at levels of fertilizer N which were considered to be non‐limiting (60 kg N ha‐1 in autumn plus 120 kg N ha‐1 in February). At this level of N there was a relationship between yield in the vegetative phase and accumulated temperatures from the last cut in the autumn which was described by a regression common to the three years. The slope of this regression represents the potential growth of a variety. At a lower level of N a separate regression was needed in each year to relate growth to accumulated temperature. Variation in spring growth was not related to accumulated net radiation. Growth in the reproductive phase was related to accumulated temperature and accumulated net radiation from the 10‐cm ear stage.