Seed Age and Salt Tolerance at Germination in Alfalfa¹

Abstract

There is widespread interest in evaluating the salt tolerance of crop germplasm, especially at the germination stage. Unfortunately, the effects of variation in seed quality on germination behavior under saline conditions are not well understood. In this study, we investigated the effects of natural and artificial aging on germination salt tolerance in alfalfa ( Medicago sativa L.) under laboratory conditions. The salt tolerance at germination of different aged seed lots from the same germplasm source was shown to differ significantly when expressed as a proportion of the nonsaline germination of each lot. Solute leakage from seeds during imbibition (a proposed measure of germination performance) increased as seed age increased. Increases in solute leakage of unstressed seed were correlated with declines in germination salt tolerance for aged but not fresh seed. Our research demonstrates the limitations inherent in comparing the germination salt tolerance of lots of alfalfa seed that differ in age and of using artificial aging and solute leakage tests to predict germination performance under stress.