SEED ACTIVATION AND SEED GERMINATION UNDER MOISTURE STRESS

Abstract

SUMMARY Seeds of calabrese and carrot were held at 10°C or 20°C for periods of up to 21 days in water or polyethylene glycol ‘6000’ solutions of from −5 to −20 bars. Seeds were subsequently placed to germinate in a favourable environment or were first dehydrated before transfer to this environment. The seeds’ ability to germinate was virtually unaffected by any of the temperature, water potential or duration treatments. Increasing water stress progressively reduced the levels of water content and oxygen uptake rates after initial imbibition, and delayed the onset of germination with the accompanying increase in these factors. At −15 and −20 bars, water content remained approximately constant throughout the experiment but oxygen uptake rates fell after day 6. The results have a direct bearing both on the seed ‘priming’ treatment used to accelerate seed germination and on the tolerance to drought of seeds in the field.