The effect of temperature on cold hardening of Loliutn perenne seedlings

Abstract

SummaryThe variation in hardening responses under different temperature regimes for three cultivars of Lolium perenne L. is described. The relative cold hardiness of the cultivars was modified by different temperatures during hardening. A threshold temperature existed above which hardening did not occur, but this temperature varied between cultivars.Although continuous low temperatures (2 °C) favoured hardening, hardening also occurred under warm day and cool night conditions (15:2 °C) where cultivars showed contrasting hardiness responses in daylengths of 16, 12 and 8 h. Under some of these conditions both leaf growth and hardiness were possible.The significance of these results is discussed in terms of the development of screening techniques and breeding objectives.