Coleoptile Emergence in Rice Seedlings in Different Oxygen Environments

Coleoptile emergence precedes primary root emergence in rice seeds germinated under stagnant or continuously-aerated water or in normal air. This pattern of rice seed germination in oxygen-poor as well as in normal oxygen environments differs from previous descriptions in the literature that the primary root emerges first when germination occurs on a well-drained substratum whereas the coleoptile emerges first during germination under water. Evidence is presented here that the rice coleoptile provides a primary morphological region for oxygen entry into germinating rice seeds.