Eco-physiological Responses Of Oryza Rufipogon Griff.to Different PH And Water Treatment

Wild rice(Oryza rufipogon Griff.) had been listed as the national second-grade protected plant (gradually endangered species) in China, and it was investigated that the wild rice have been in imminent danger due to rapid loss of their natural community. The main cause is economic activities which led to the loss of habitat. At present, some measures have been taken to protect Oryza rufipogon, such as in-situ conservation and ex-situ conservation. This study based on plant physiological ecology theory, Yanshan wild rice was used as material in pot experiment. Included the two experimental settings:one was under five initial soil pH treatments (treatment F50:pH=4.5,treatment F30:pH=6.0, treatment F0:pH=6.8, treatment C10:pH=7.4and treatment C30:pH=8.0),the other was under three water treatments (YDH:Semi dry treatment, YDS:Alternate wetting and drying treatment, YDY:Shallow water treatment).Measured the photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) of the flag leaf of wild rice in heading stage, made a Photosynthesis-light response curve so that can calculate the light compensation point (LCP) and light saturation point (LSP). Measured the content of chlorophyll, soluble sugar content, proline content, MDA content, CAT activity and POD activity of the flag leaf of wild rice7days after heading stage. Integrated physiological index and photosynthetic indicators to determine the most appropriate environment for the Yanshan Wild rice growth in Karst areas. The results showed that:1.As the soil alkalinity increases, the plant height, stalk internode dry matter content and C/N of the flag leaf were increased first and then decreased. All indicators showed highest in pH6.8, pH4.5or pH8.0was the lowest, the difference was significant.2. Various physiological and biochemical metabolism were appropriate for wild rice at pH6.8treatment. It showed the highest chlorophyll content, soluble sugar content, while the proline content and MDA were the lowest at pH6.8treatment. At too acid or too alkaline treatment, these physiological indicators are significant changed, the chlorophyll content and soluble sugar content decreased, the proline content and MDA increased. The CAT and POD showed strongest activity at pH6.8treatment, at too acid or too alkaline treatment both were significantly reduced.3.The photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs) and light saturation point (LSP) were all showed maximum, while the light compensation point (LCP) showed lowest at FO treatment. Too acid or too alkaline treatment led a significant decline in the value of Pn, Tr, Gs and LSP, LCP raised. It can be speculated that the wild rice has a strong photosynthetic capacity at pH6.8and pH7.4.When the pH was greater or less than these two values, the photosynthetic capacity will be significantly affected.4.The growth status of wild rice for shallow water treatment was the best. The plant height, stalk internode dry matter content and C/N of the flag leaf were significantly higher than other two water treatments (P<0.05). The growth of wild rice for Alternate wetting and drying treatment was almost normal. The growth for Semi dry treatment was worst. View from the health status of growth, YDY>YDS>YDH.5. Various physiological and biochemical metabolism were appropriate for wild rice at YDY treatment. It showed the highest chlorophyll content, soluble sugar content, while the proline content and MDA were the lowest at YDY treatment. The wild rice could also grow normally at YDS treatment, and showed some adjustment adaptability. All the physiological parameters showed disorder at YDH treatment, the chlorophyll content and soluble sugar content decreased, the proline content and MDA increased. The CAT and POD activity at YDH treatment were significantly reduced.6.The wild rice’s photosynthesis reaction was very sensitive to different water treatments. With the reduction of water, Pn, Tr, Gs and LSP decreased gradually, and it showed significant difference for YDH treatment (P＜0.05). The differences of water use efficiency (WUE) between the three groups were not significant, and it showed YDH>YDS>YDY. The LSP value showed YDY>YDS>YDH, while the LCP showed YDH>YDS>YDY, it can be speculated that the wild rice has a strong photosynthetic capacity at YDY and YDS treatments.7.In summary analysts showed that Yanshan wild rice had adapt to growing in the Karst areas in which soil is slightly alkaline, and grow well in shallow water or water fluctuation alternating environment.