Abstract
Poor establishment of rice seedlings by the direct sowing method under submerged conditions in the field is a serious problem in Battambang province in Cambodia. In Toulsamron there was a low rate of establishment of rice seedling of 18 Indica varieties under submerged paddy soil conditions. Black and white gel matter developed in poorly established seedlings. Energy - Dispersive X - ray Fluorescence Spectrometer analysis suggested the black gel matter might be iron oxide. White gel matter was observed on established seedlings under submerged conditions without soil, and it was thought to be oozing matter from the seeds. However the white gel matter does not cause poor establishment of seedlings. Dissolved oxygen was lower than in pure water, when the water containing oozing matter was added to the Toulsamron paddy soil. Ethanol was found in the water containing oozing matter. The ethanol solution with Toulsamron soil decreased dissolved oxygen, also the oxidation-reduction potential decreased, the pH reached to near neutrality and the amount of Fe2+ increased. These phenomena suggested low dissolved oxygen conditions at seed germination.
