The effect of temperature on the growth of S.170 tall fescue (Festuca arundinacea). 1. Constant temperature.
Various growth parameters of young seedlings of tall fescue cv. S170 grown at 10, 15, 20, 25 and 30 deg C were recorded. At 25 deg C individual leaves were twice as long and had twice the area of leaves at 10 deg C; they grew 4 times as rapidly, but for only half the time. At 10 deg C a new leaf appeared every 10.8 days, at 25 deg C every 5.2 days. Leaf width and the number of externally visible growing leaves were unaffected by temperature. For most aspects of leaf growth the optimum temperature was close to 25 deg C. LAR and its components, leaf weight ratio and specific leaf area increased with temperature; this largely accounted for a marked increase in RGR and the relative rate of leaf area increase between 10 and 25 deg C. Unit leaf rate [NAR] was less markedly affected by temperature and showed variation of only 20% from its maximum value between about 15-29 deg C. It was argued that between mid-May and late Oct., the unit leaf rate of a grass crop was likely to be more dependent on solar radiation than on ambient temperature.