Study On The Regulatory Mechanisms Of Rhizosphere Of Halophytes In The Yellow River Delta

The physical and chemical properties of rhizosphere soil and non-rhizosphere soil of halophytes in Yellow River Delta that include N, P, organic matter, salinity and so on were analyzed by water-salt regulation tests in laboratory and field scale. Rhizosphere effects were compared. The antioxidant enzymes, chlorophyll, proline and compatible solutes of halophytes were also investigated. Based on this study, changes of nutrient in the rhizosphere and regulation mechanism were explored, and suitable halophytes and conditions of water-salt regulation were screened. Technical regulation of water-salt regulation of halophytes was also established. This research gave basic data on the establishment of a typical coastal wetland restoration in the new model.1,Nitrogen accumulated more strongly in Tamarix chinensis Lour. and its rhizosphere than other two halophytes, while phosphorus accumulated more strongly in Suaeda salsa Pall. and its rhizosphere. These results provided fundamental basis for the phytoremediation of coastal wetlands, where the nitrogen and phosphorus could be intercepted by plants. Additionally, the reasons for rhizosphere effect of these three plants were not the same. The value of pH in rhizosphere was the main factor affecting the cumulative effect of available nitrogen in rhizosphere of Tamarix chinensis Lour., while the activity of rhizospheric microorganism and the salinity were the main factors for the cumulative effect of available phosphorus in rhizosphere of Suaeda salsa Pall.2,Salt tolerance of halophytes were analyzed by water-salt regulation tests in lab, and the results showed that Suaeda salsa Pall. was the best, followed by Limonium sinense Kuntze., Tamarix chinensis Lour. and Sesbania cannabina Poir.. The good root morphology and high microbial activity in the rhizosphere were the main reasons for the growth of halophytes. pH was significantly decreased in the rhizosphere soil of Limonium sinense Kuntze., and total microbial counts in the rhizosphere soil of Suaeda salsa Pall. significantly increased. The increase of chlorophyll in leaves of Tamarix chinensis Lour., Limonium sinense Kuntze. and Sesbania cannabina Poir. was abserved under salt treatments. Tamarix chinensis Lour. mainly relied on proline to adjust osmotic pressure, proline and soluble sugars were the main osmoregulation substances of Limonium sinense Kuntze., Sesbania cannabina Poir. and Suaeda salsa Pall. under 30‰salt treatment.3,The RGR of Suaeda salsa Pall. in the treatment without irrigation was significantly higher than other two treatments, the RGR of Limonium sinense Kuntze. in the treatment of saline irrigation was the best, while the RGR of Phragmites australis Trin. in the treatment of irrigation water was the best, followed by the treatment of saline irrigation and without irrigation with significant differences. Salt tolerance of halophytes were analyzed by water-salt regulation tests in field scale, and the results showed that Suaeda salsa Pall. was the best, followed by Limonium sinense Kuntze. and Phragmites australis Trin.. Available nitrogen, total microbial counts and activity in the rhizosphere soil of three halophytes were higher than non-rhizosphere, while salinity, chloride contents and pH were lower than non-rhizosphere, available phosphorus accumulated most strongly in the rhizosphere of Suaeda salsa Pall. after 40 days of water-salt regulation. Organic matter accumulated significantly in the rhizosphere of three halophytes in all treatments after 80 days of water-salt regulation.4,Oxidative damage of leaves and roots of three halophytes were caused by the salt treatment, MDA were accumulated, antioxidant enzymes did not change but the law. Proline and soluble sugar of leaves of three halophytes were all accumulated to adjust the osmotic stress.5,The rhizosphere effects of halophytes were more obvious in summer and autumn than spring and winter. Physical and chemical properties of soil have been improved after the five halophytes were planted. Compared with the non-rhizophere soil, salinity, chloride contents and pH all decreased in the rhizosphere soil, while total nitrogen, total phosphorus, available nitrogen, available phosphorus and t total microbial counts and activity all increased. Salinity and chloride contents decreased most obviously in the rhizosphere soil of Suaeda salsa Pall., but phosphorus accumulated most strongly., pH in the rhizosphere soil of Tamarix chinensis Lour. deseased obviously, but organic matter accumulated most strongly. Nitrogen accumulated strongly in the rhizosphere soil of Scorzonera mongolica Maxim. and Tamarix chinensis Lour.6,Suaeda salsa Pall. has the best of salt tolerance, and simple planting technique. The amounts of saveing water of Suaeda salsa Pall. is also the most, followed by Limonium sinense Kuntze., Tamarix chinensis Lour.. Tamarix Liu Duibin. is very important on establishing a stability sea ecosystem, The three native halophytes can be degraded as the preferred plant that were used in the reconstruction of ecology system of Yellow River Delta wetland. that gave important technical support on the establishment of a typical coastal wetland restoration in the new model.