Effect of seed hydration-dehydration pre-treatment on germination of soybean lines at sub-optimal temperatures

Abstract

The effect of temperature on germination and the effect of hydration-dehydration pre-treatments on germination at suboptimal temperatures were evaluated for several soybean (Glycine max) lines. Optimal temperatures for germination and hypocotyl-radicle elongation were ca. 31¦C and 27-31¦C respectively. Prior hydration at 31¦C hastened rate of germination and/or synchronized germination within seedlots at 10¦C, and in less vigorous seedlots, increased germinability. These effects were progressively dissipated by subsequent dehydration-storage treatments, a response more pronounced with dehydration at higher temperature, dehydration to original water content, and longer storage after dehydration. With less vigorous seedlots, germinability and/or rate of germination at 10¦C after dehydration and storage were actually reduced relative to untreated seed. The effect of pre-treatment appeared due to both an increase in the rate of initial water uptake at suboptimal temperature, and to the more rapid activation of metabolic activity during germination. Although the effect of pre-sowing hydration per se on germination at suboptimal temperature was encouraging, the magnitude and unpredictability of the effect following dehydration suggest that the approach may have limited practical application in mechanized soybean production.