The effect of temperature on the growth of S170 tall fescue (Festuca arundinacea). 3. Leaf growth and tiller production as affected by transfer between contrasting regimes.
Rates of leaf growth and tiller production were compared in plants of tall fescue cv. S170 grown continuously at (a) alternating 20/10 deg C, (b) alternating 10/5 deg C, or transferred (c) from (a) to (b), (d) from (b) to (a), when the 4th leaf was fully expanded. Under constant conditions, laminae on the main shoots were longer, wider, heavier and attached to longer sheaths in (a) than in (b), leaves appeared more frequently both on the main shoot and on subsidiary tillers, leaf primordia were produced more rapidly, and leaf elongation (and presumably also cell division) was more rapid. In high temperatures laminae were characteristically longer in relation to their width and in relation to the length of the sheath and had higher specific leaf areas but lower contents of water-soluble carbohydrate than those grown at lower temperatures. Tillering was more rapid at high temperature, to an extent matching the rate of leaf appearance. After transfer to different conditions, different plant attributes adjusted to the change at different rates. Content of water-soluble carbohydrates adjusted very rapidly, leaf width much more slowly, while specific leaf area over-adapted initially. Rate of leaf growth adjusted immediately, but the extent to which it did so depended on the direction of transfer; (c) adapted as early as leaf 5, while adaptation of (d) was incomplete even at leaf 7, probably because of inability to match the rate of assimilate production characteristic of plants in (a). [For Part 2 see HbA 44, 186]