STUDIES ON EMBRYO DEVELOPMENT AND CHANGES IN SENSITIVITY TO GAMMA RADIATION AND ALKYLATING AGENTS (MMS AND EMS) IN RICE SEEDS DURING SOAKING IN WATER

Rice seeds were soaked in water at various lengths of time. Embryo development and metabolic activity (RNA- and DNA-synthesis) were studied in relation to changes in sensitivity to gamma radiation and the chemical mutagens, ethylmethanesulfonate (EMS) and methylmethanesulfonate (MMS). During the initial stage when swelling and elongation of the embryo took place, the sensitivity to EMS and MMS was decreasing. In the second stage with higher metabolic activity the sensitivity to gamma radiation and the mutagen increased slowly. In the third stage the sensitivity increased proportionally with the rapid increase of DNA-synthesis in the embryos.