Genotype difference in rice postgermination growth under hypoxia

Abstract

Rice ( Oryza sativa L.) genotypes that can establish seedlings in flooded anaerobic soil had longer coleoptile in postgermination growth than other genotypes (controls) in a gas flow of N 2 and air, or under various degrees of hypoxia created in closed flasks in the dark. The tolerant genotypes produced as much or more ethylene than the control genotypes, although both had the same activity of ethylene-forming enzyme. Ethylene stimulated coleoptile elongation of both genotypes to the same degree. The coleoptile elongation of the tolerant genotypes remained greater than that of the controlseven in the presence of Co 2+ and l-α-(2-aminoethixyvinyl)glycine. Thus, the longer coleoptile of the tolerant genotypes might be explained by a mechanism that is independent of ethylene and O 2. Mesocotyl and shoot elongation of the tolerant genotypes was more stimulated by ethylene than that of control genotypes. These developmental characteristics of tolerant genotypes may accelerate seedling establishment in flooded anaerobic soil.