GROWTH-RESPONSE OF FESTUCA-ALTAICA, FESTUCA-HALLII, AND FESTUCA-CAMPESTRIS TO TEMPERATURE

In Alberta, the rough fescue complex consists of Festuca altaica Trin., Festuca hallii (Vasey) Piper, and Festuca campestris Rydb. The potential commercial value of these species for grazing, and their ecological significance, necessitates an increased understanding of their environmental adaptation. This study compared the growth response of the three species at five temperature regimes of 7:3, 12:8, 17:13, 22:18, and 27:23 degrees C (light:dark; 18-h photoperiod). Seedlings were established and grew for 10 weeks at 18 degrees C before being trimmed to a height of 3.5 cm and randomly assigned (36 pots of each species) to the growing environments. Growth was followed for 12 weeks. Temperature had a significant effect on most plant variables but the response differed among species. The optimal temperature for dry matter accumulation was 17:13 degrees C, and for tillering 12:8 to 17:13 degrees C. Festuca Hallii and F. campestris exhibited a faster tillering rate than F. altaica, which had the heaviest tillers and highest leaf extension rate. The root to shoot ratio declined at temperatures above 17:13 degrees C. The significance of these observations to the geographical distribution of the species is discussed.