Effects of environment and plant factors on foliar freezing resistance in tropical grasses. II.* Comparison of frost resistance between cultivars of Cenchrus ciliaris, Chloris gayana and Setaria anceps

The variability in foliar freezing resistance within and between five Cenchrus ciliaris, four Setaria anceps and six Chloris gayana ecotypes was examined in the laboratory over a sequence of freezing temperatures between –1.0° and –6.25°C. C. gayana and S. anceps ecotypes were generally more frost-resistant than C. ciliaris ecotypes. No significant differences in frost susceptibility were found in C. ciliaris, whilst S. anceps exhibited the greatest variability and C. gayana showed an intermediate degree of variability. The range of freezing temperatures which caused 50% foliage death (LT50) in C. ciliaris was –1.8° to –2.1°, in C. gayana –2.6° to –3.5° and in S. anceps –2.1° to –4.3°. ____________________ * Part I, Aust. J. Agric. Res., 29: 243 (1978).