The influence of depth of sowing and temperature on pre-emergence weight changes in Subterranean clover (Trifolium subterraneum L.).

Abstract

The pre-emergence weight changes in subterranean clover (Trifolium subterraneum L. var. Bacchus Marsh) were measured at temperatures of 28, 21, 14, and 7°C. Plants were sown in washed sand at four depths, ½, 1, 1½ and 2 in., and daily determinations of plant weight and of the weight of cotyledon, hypocotyl, and root fractions were made until emergence from each depth took place. No differences could be detected in total plant weight or in the proportions of the constituent parts on any one day between plants sown at the various depths under a particular temperature treatment. The rate of transfer of material from the cotyledons to the rest of the plant increases with temperature, this increase being progressively reduced with each rise in temperature. The extent of cotyledonary reserves remaining on emergence was found to be significantly affected by both temperature and depth of sowing, being greatest at 1/2 in. and diminishing with depth. The optimal temperature for hypocotyl extension per unit of cotyledonary material translocated was 21°C. Cotyledon weight on emergence expressed as a percentage of total plant weight varied from 33 to 61, and appears to be markedly less than those reported for other species.