Gibberellic Acid Influence on Aged and Unaged Barley Seed Germination and Vigor1

Abstract

AbstractGibberellic acid (GA) is presently used to break dormancy of cereal grains prior to germination testing. The increased use of vigor testing has led to an interest in the applicability of GA in breaking dormancy prior to vigor testing. The present study identifies the vigor criteria which are most suitable for the incorporation of GA in the testing procedure. The influence of GA (10 μM), artificial aging (41 C, 100% RH, 4 days), initial vigor level (high, medium, and low) and various interactions of these factors on the germination and vigor assessment of ‘Himalaya’ barley (Hordeum vulgare L., cv. Himalaya) seeds were determined. High vigor seeds exhibited higher germination, higher dry weight production and longer mean plumule than did medium and low vigor seeds. Artificial aging decreased germination of all vigor levels, with the greatest decrease exhibited by medium and low vigor seed lots. Artificial aging also decreased the mean plumule length and dry weight production. Exogenous GA slightly decreased the germination of aged and unaged seeds at Day 7, but not at Day 4. This decrease, however, did not affect germination test interpretations. Gibberellic acid also increased the mean plumule length but did not affect dry weight production or the number of abnormal seedlings. We conclude that physiological levels of GA did not adversely affect germination test results. Furthermore, GA did not affect the interpretation of vigor tests when measuring germination (7 and 4 day count) or dry weight production. However, GA did increase plumule length which suggests that this is a poor vigor criterion when using GA to break dormancy of barley seeds.