Frost resistance of the New Zealand narrow-leaved snow tussock grass, Chionochloa rigida

The frost resistance of tillers of Chionochloa rigida was measured at various dates and locations from late winter (August 2004) to early summer (December 2004). Frost resistance changed in accord with season, geographic location, and position on the tiller and was strongly related to estimated minimum temperatures at the date and site of collection. Foliar frost resistance was -21 degrees C in late winter and -10 degrees C in summer; leaf sheaths and bases were less frost resistance than laminas. The strong dependence on temperature suggests that the frost resistance of C. rigida would adjust to prevailing temperatures during a period of global warming, although it might render C. rigida more susceptible to episodic frosts. On a global scale, C. rigida is less frost resistant than many temperate pasture grasses and cereals and shows some affinity with tropical alpine vegetation.