Significance of Physiological Differentiation of Root Activities Among Rice Plants (Oryza Sativa L.)

Abstract

The comparison of plant growth behaviour between the japonica and indica rices proves that the former is more adapted to the detrimental reduced paddy. The root-oxidizing ability of twenty rice cultivars were examined. The japonica rice showed higher oxidizing ability than the indica one. The respiration rate and cytochrome oxidase activity were higher in japonica rice. The assay of peroxidase, catalase and glycolate oxidase were higher in the root of japonica rice also. The root tips of rice plants were excised and cultured aseptically in improved nitrate-containing R 1 and R 2 and nitrogen modified media. The excised roots of indica rice grew better than those of japonica rice in R 1 and R 2 media. However, japonica rice roots grew well in a media of urea as the nitrogen source. The activities of nitrate reductase (NR) and glutamate dehydrogenase (GDH) in the root were detected. The activities of NR and GDH were higher in the indica rice root. The results clearly showed that some physiological differentiation exists between japonica and indica type rices. The significance of these differences was discussed from the view point of cultivation and breeding of rice plants.