Prehydration and Priming Treatments that Advance Germination also Increase the Rate of Deterioration of Lettuce Seeds

Abstract

The influence of prehydration in water or priming in – 1.5 MPa polyethylene glycol 8000 solution for various periods, followed by redrying, on germination rate and longevity of lettuce (Lactuca sativa L.) seeds (achenes) was determined during controlled deterioration at 10% moisture content (fresh weight basis) and 40°C. Short prehydration treatments (up to 1 h) had little effect on either germination rate or longevity, but significantly improved root growth rates. Increasing durations of prehydration or priming reduced the mean time to germination by up to 61% relative to untreated seeds, but also reduced mean seed longevity by as much as 84% Prehydration and priming altered the relationships between germination rate and viability and between normal and abnormal seedlings during ageing. Prehydration in abscisic acid or at a temperature inhibitory to germination did not prevent the reduction in longevity under controlled deterioration conditions. While prehydration or priming treatments effectively accelerate subsequent germination rates of lettuce seeds, the redried seeds are nonetheless highly susceptible to deterioration in storage.