The Studies On Photosynthetic Physiological Characteristics In Rice (Oryza Sativa L.) Induced By High By High Hydrostatic Pressure

The effects of high hydrostatic pressure on rice (Oryza sativa L.) seed germination, seedling growth and physiological characteristics were studied in this paper. The differences of photosynthesis, agronomic traits and yield traits between mutated strains induced by high hydrostatic pressure and the control (untreated) were compared. The results suggested that mutation induced by high hydrostatic pressure was possible to be a new method for breeding. The main results are as follows:1. The germination and seedling rate of rice seeds treated by high hydrostatic pressure was decreased remarkably. Synthesis of chlorophyll was restrained. The growth of survival seedlings was inhibited during 25 days after sowing and their chlorophyll content, protein content and antioxidant ability were lower than the control but after sowing 35 days the seedling growth could excess that of the control and their chlorophyll content, protein content and antioxidant ability were higher than their control as well.2. The total biomass and grain yield were increased to different extent in rice treated by high hydrostatic pressure. Photosynthetic pigments, net photosynthetic rate (Pn) and apparent quantum yield (AQY) in flag leaves of treated rice plants were increased in comparison with the control. The content of photosynthetic pigments, PS II photochemical efficiency (Fv/Fm) and photosynthetic O2 evolution maintained higher value in flag leaves of treated plants than that of the control.3. The agronomic traits and photosynthetic characteristics of three mutated strains, Mutant 1, Mutant 2 and Yueya I , were compared with the control variety (Yuexiangzhan). The results indicated that some agronomic traits including plant height, effective panicles, harvest index, and empty and shrink grain rate changed obviously. As compared with the control, the theoretical grain yield of the mutated strains was increased. The higher grain yield in mutated strains was mainly due to increasing the net photosynthetic rate and apparent quantum yield considerably at the stage from booting to filling.4. Photoinhibition at noon was decreased and could be recovered rapidly at evening in rice plant treated by high hydrostatic pressure. In addition, high hydrostatic pressure might improve the resistance to heat under heat stress and the resistance to low temperature (0 -5 ) in Winter.5. The effect of high hydrostatic pressure treatment was studied for several years and we have found this method is simple and easy to be operated, so it will be a possible new method serving breeding in the future.