Influence of initial seed moisture and temperature conditions during germination and emergence on seedling survival and yields of soybean (Glycine max L. Merrill)

Abstract

Injury to soybean seedlings caused by low temperature (5°C) at the beginning of germination was greatly reduced when instead of chilling (10°C) a higher temperature (20°C) was applied at the end of germination and during emergence. A new interpretation of the physiological mechanism involved in this reversibility of chilling injury was proposed. Hydration in water vapour of soybean seeds with initial moisture content of from 5 to 10% to a level of 30%, dry weight basis, increased seedling survival under controlled conditions of germination and emergence at respectively 5°C and l0°C as well as under natural soil conditions in field experiments both after early and late planting dates. A modified method of seed hydration in water vapour (i.e. conditioning or hardening of seeds against cold) was developed for practical application. In field experiments conditioning of seeds increased seedling survival and thus also yields per unit area of plot but had no significant effect on yield per plant. Seed conditioning may have practical significance in soybean growing and for breeding purposes when equalizing the number of plants per plot is important for comparing new varieties and breeding forms.