SOIL TEMPERATURE AND GROWTH OF MARQUIS WHEAT

Abstract

Plant height, root length and extent, and tiller number of greenhouse-grown Marquis wheat decreased as the soil temps. rose from 22[degree] to 42[degree]C. Dry weights of tops and roots and total dry weight, at time of harvest, were greatest in plants grown at a soil temp. of 22[degree], the lowest temp. maintained in these expts. The top/root ratio reached a maximum at 30[degree]-34[degree] C, falling again as the soil temp. was further increased. Leaves were largest at the lowest temp. and became lighter in color as the soil temp. rose above 32[degree]C. Increasing the soil temps. from 22[degree] to 34[degree] accelerated heading by as much as 11 days. Soil temps. above 34[degree]C retarded or prevented earing.