EFFECTS OF PERIODS OF WARM WEATHER UPON THE WINTER HARDENED CONDITION OF A PLANT

Open Access
Publisher Website
Google Scholar
Abstract
The severed roots of alfalfa, and entire plants of alfalfa and winter wheat were exposed to alternate periods of low and high temps., suitable for "hardening" and growth, respectively. Several harden-ings and dehardenings to cold, of severed alfalfa roots are possible. When such alternations of temp. occur in the field in late winter, rehardening may occur, but is lessened by growth of new shoots. With winter wheat, successive rehardening is possible in unvernalized plants, or in the field if not much growth occurs during the interval of warm weather. A long day, with warm weather, is particularly likely to induce growth in vernalized winter wheat, with resultant loss of ability to reharden to cold. Retention of the ability to reharden following intervals of warm weather in late winter is not particularly characteristic of vars. of wheat that can endure low temps.