Seed Aging: Chromosome Stability and Extended Viability of Seeds Stored Fully Imbided

Abstract

Increase in moisture content of seeds of Lactuca sativa L. and Fraxitnus americana L. in air-dry storage caused a rapid decline in longevity and an increase in the rate of accumulation of chromosome aberrations. Storage of seeds fully imbibed but unable to germinate allowed a high germination capacity to be maintained for long periods, together with a very low in- cidence of chromosome aberrations. Seedlings grown from dry-stored seeds showed an increase in morphological abnor- malities with length of storage, whereas seedlings from im- bibed-stored seeds appeared normal. It is suggested that in dry tissues, enzyme-controlled turnover and repair may be tem- porarily suspended, and that this may be an important factor in the loss of seed viability in storage. The effect of increasing seed longevity by lowering the moisture content of dry-stored seeds is discussed in relation to this hypothesis. The relevance of the proposal is also discussed in relation to ecological studies. air-dry. They ascribed this increased longevity to the state of dormancy of the imbibed seeds, in which a low metabolic rate could enable the seeds to survive even though the tissues were hydrated. However, as there is no reason to suppose that im- bibed seeds have a lower metabolic rate than air-dry seeds, even when dormant, this does not explain why imbibed seeds should survive for longer periods than air-dry seeds.