| Phyllostachys rivalis H. R. Zhao belongs to Poaceae Shibataeeae Phyllostachys Sieb. et Zucc. Sect. Heterocladae Z. P. Wang. It mainly distributes in Guangdong, Fujian and Zhejiang provinces et al. It grows in the direction of edge, valley generally and could survive under the long-term waterlogged environment. Now studies on resistance to water and wet environment of bamboo are very weak. Carrying out the study of the fluid resistance bamboo breeding and mechanism in Ph. rivalis had important practical significance. It could realize vegetation restoration of wetlands and areas with fluctuating water tables. It could also reduce collapse, landslides and other geological disasters. This study aimed to reveal the physiological and ecological response, adaptation mechanism of Ph. rivalis to long-term water-logging environment, and provide a theoretical basis for its application in vegetation restoration of wetlands and areas with fluctuating water tables.Thus, in the paper we studied the effect of long-term water-logging on morphological and physiological plasticity of rhizome and root system in Ph. rivalis. The main research results were as follows:1 The effect of long-term water-logging on morphological structure of rhizome and root system in Ph. rivalisThere was no obvious impact of long-term water-logging on the length and diameter of rhizome, diameter of roots in Ph. rivalis. The morphological characteristics of rhizome had been less affected generally under water-logging for 3 months. And less rhizome were submerged, while the growth of roots was inhibited to some extents. Furthermore, with water-logging time extended, submerged roots and rhizome grew abundantly, and the roots and rhizome in soil were promoted. Hence all results indicated that Ph. rivalis could adapt to waterlogged conditions gradually through growth regulatio.2 The effect of long-term water-logging on biomass allocation of rhizome and root system in Ph. rivalisUnder long-term waterlogged conditions,for ratios of rhizome biomass in soil and water, there were no obvious variations; for root biomass in soil to total biomass, too. And the ratio of root biomass in water to total biomass, and the ratio of root biomass in water to root biomass in soil both increased significantly. Hence all results indicated that Ph. rivalis could carry out adaptive adjustment through reasonable biomass distribution under long-term waterlogged conditions3 The effect of long-term water-logging on antioxidant system of rhizome and root in Ph. rivalisIn general,root activity, antioxidant enzyme activity, MDA content, relative electron conduction and soluble protein content of primary roots is significantly higher than the secondary roots.In long-term flooded conditions,root activity, antioxidant enzyme activity of primary and secondary roots were significantly lower than CK.Relative electron conductivity and MDA content increased significantly. Root activity and CAT activity of bamboo rhizome roots growing in water is significantly higher than those growing in soil,on the contrary is SOD and POD activity.And Ph. rivalis can adapt to stress of long-term flooded conditions by maintaining the overall higher levels of root activity, antioxidant enzyme activity, soluble protein content,especially primary roots and bamboo rhizome roots growing in water.The results indicated that rhizome roots of Ph. rivalis could adapt to long-term flooded conditions and survived through the balance adjustment of antioxidant system. Response of primary roots to water-logging is much stronger than the secondary roots,and the bamboo rhizome roots growing in water plays an important role in adapting the flooded conditions.4 The effect of long-term water-logging on nutrient stoichiometric characteristics of rhizome and root in Ph. rivalisThe contents of N, P, and K in Ph. rhizome–roots decreased significantly under water-logging in the third month. However, no obvious impact was noted on the contents of C, Ca, Fe, and Mg and C/P, N/P, and N/K. The nutrient contents, stoichiometric ratio, and nutrient accumulation altered markedly with prolonged water-logging. Meanwhile, the contents of C, N, P, and Ca and C/K, N/K, and P/K decreased, and the contents of K, Fe, and Mg and C/N, C/P, and N/P increased with prolonged water-logging. The accumulation of nutrients was significantly inhibited before water-logging in the sixth month. However, the accumulation of nutrients showed a significant increase under water-logging in the twelfth month; this was mainly because of significant increase in the root biomass. Thus, we showed that maintaining strong nutrition stability is a strategy of Ph. rivalis in response to environmental stress. The rhizome–roots of Ph. rivalis can sustain high nutrient absorption and accumulation through producing large numbers of roots, both in soil and water, and show adaptive regulation of the nutrient stoichiometric ratio in response to environmental stress. Since Ph. rivalis can survive in long-term waterlogged environments, it could be used for vegetation restoration of wetlands and areas with fluctuating water tables. In addition, it may play an important role as one of the bamboo species that can be used for purifying eutrophic water bodies.5 Physiological and ecological response of Ph. rivalis after long-term water-loggingWater-logging for 3 months could produced membrane lipid peroxidation, weaken antioxidant enzyme activity,enlarge the permeability of cell, reduce osmotic adjustment capacity. when water supply resumed normal for 3 months, the content of main nutrient and stoichiometric ratio in leaves adjusted adaptively. The antioxidant system of Ph. rivalis could get effective recovery, especially the activity of SOD, relative conductivity, the content of MDA and soluble protein could get back to normal level. The harm of chloroplast cells could also be repaired to some extent, the content of main nutrient and stoichiometric ratio in leaves could get back to normal level completely. Hence all results indicated that Ph. Rivalis had extreme ability to restore growth and could try to be used for vegetation restoration of wetlands and areas with fluctuating water tables. |
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