Relationships of Seed Weight, Seedling Vigor and Mitochondrial Metabolism in Barley¹

Abstract

Because of the effects of seed size on seedling vigor in small grains, it was of importance to distinguish seed size effects accurately within barley genotypes from heterotic seedling vigor of barley ( Hordeum vulgate L.) hybrids. Measurements of seedling vigor of germinating seedlings of several six,rowed, spring barley cultivars were made concomitantly with a study of seedling heterosis in barley hybrids. Seedling fresh weight, seedling mitochondrial protein and mitochondrial biochemical activity were positively correlated with seed weight. The increased quantity of mitochondrial protein of seedlings produced from heavy seeds is indicative of a higher respiratory rate and greater amount of energy (ATP) production. Thus, these seedlings have a greater growth potential than seedlings produced from lighter seeds of the same pure line. These experiments provided an accurate means of measuring the relative contributions of seed weight, genotype, and heterosis to seedling vigor in barley.