Study On Drought Resistance Ability And Mechanism Of Wetland Plants

Wetland as the most rich biodiversity and one of the highest ecological function ecosystem in the world,not only could provide a variety of resources for human survival and development,and all play important role in the protection of biological diversity,flood storage against drought,rare species resources,water conservation and purification,etc.but climate change and the construction of large-scale water conservancy project had adverse effect on the wetland,resulting in wetland suffering periodic or long-term drought,Study of wetland plants response to drought stress,comparing the difference of drought tolerance ability of different wetland plants not only played an important role in recovery and reconstruction of wetland ecosystem,but also provided a reference for the research of Other facing drought region.this article implemented a potted experiment,Set up three different moisture gradient(CK?MD and SD),by measuring each wetland plant drought resistance under different drought stress to evaluate the drought resistance ability of five kinds of wetland plants(Phragmites australis.Scirpus validus.Typha orientalis.Zizania latifolia and Juncus effusus),and by measuring moisture of plant physiological characteristics?photosynthetic physiological and biochemical properties of wetland plants to explore the mechanism of drought resistance,In order to provide theoretical reference for wetland vegetation recovery in the future.now we obtained the following conclusions:1 In the aspect of drought resistance,by measuring T50 of five kinds of wetland plants under different drought stress,then sort the wetland plants according to T50,It was concluded that drought resistance of five kinds of wetland plants from strong to weak:Juncus effusus>Phragmites australis>Scirpus validus>Typha orientalis>Zizania l atifolia.2 In terms of tissue relative water content,at the initial stage of drought stress,tissue relative water content of all kinds of wetland plants had a different trend.In the late stage of drought stress,tissue relative water content of all kinds of wetland plants reduced significantly,Phragmites australis and Juncus effuses reduced slowly,showed stronger water storage?moisture adjustment ability and stronger drought resistance ability,Scirpus validus and Typha orientalis declined slightly faster,drought resistance ability took second place,but,Zizania latifolia.reduced fastest,The MD and SD group had significant difference compared with CK group.which showed Zizania latifolia had a bad water storage and moisture adjustment ability,Zizania latifolia had the worst drought resistance.3 In terms of tissue water retention,with the research of tissue water retention of five wetland plants,Found in vitro tissues within 24 hours,In almost all of the treatment group,Zizania latifolia.the rate of lose water was the fastest,water loss,water performance was the worst,because of the unique shape and structure,Scirpus validus and Juncus effuses showed the slow water loss in all of the treatment group,so water performance was good.4 In the aspect of photosynthetic pigment,the low amplitude of lower photosynthetic pigment,with a strong drought resistance.5 In the aspect of MDA content,from the change of MDA content,the drought resistance from strong to weak of the five wetland plants should be:Phragmites australis>Juncus effusus>Scirpus validus>Typha orientalis>Zizania latifoli a.this result was basically identical with the drought resistance of plant,indicating that the change of MDA content can be roughly as an index for drought evaluation.6 In the aspect of free proline content,through the accumulation of free proline content of these five kinds of wetland plants,we could conclude that the accumulation of free proline could not as indices of plant drought resistance screening,at the same time also could not determine plant accumulated proline was the result of the plant was hurt at the adverse circumstance,it also need further experiments.7 In terms of soluble protein content,with the aggravation of drought stress,the wetland plants were more or less affected by the drought stress.resulting in the increasing of soluble protein content.the continuing drought course,whether there was a new drought resistant protein and soluble protein in the corresponding enzymes,etc in the leaves of all kinds of wetlands,has yet to be further studied.8 In terms of photosynthesis parameters,with the aggravation of drought stress,transpiration rate and stomatal conductance of plants all had different degrees of decline,indicating that plants mainly by reducing transpiration water loss to resist the adverse effects brought by drought stress.9 In terms of chlorophyll fluorescence parameters,from the change trend of the ratio of the two groups,Fv/Fm and Fv/F0,the ability of drought resistance of these five wetland plants from strong to weak should be:Juncus effuses>Phragmite australis>Scirpus validus>Typha orientalis>Zizania latifolia.that were consistent with the measured results of drought resistance.10 By measuring drought resistance capacity of the five kinds of wetland plants,plant tissue water content under drought stress,the biochemical effect of drought stress on the wetland plant and photosynthetic physiological characteristics of wetland plants under drought stress change,speculated the possible mechanism of drought tolerance of wetland plant.in terms of water management,through the water storage and water retention to regulate tissue water content to maintain normal metabolism to resist drought stress.and the difference of morphological structure may also affect water storage and water retention;in biochemical level,wetland plants mainly through the accumulation of osmotic regulation substances regulated osmotic pressure to maintain normal moisture condition to resist drought stress;in photosynthetic physiological level,wetland plants on the one hand,by maintaining high transpiration rate made root absorb more moisture from the soil,on the other hand,through higher stomatal conductance increased gas exchange between the atmosphere and promoted the absorption of carbon dioxide to enhance the efficiency of photosynthesis to resist drought stress.