The Soil Salinity Effects On The Growth Of Phragmites Australis In Yu Tian Oasis

The metabolism system of plants is in dynamic equilibrium when plat is in normal growth.When plant suffered from stress, it will launch its own defense system to protect to adapt to theadverse environmental impact, but this protective effect is limited. When the stress time is too longor the stress is too much, when it surpasses plants’ tolerate range, the defense system will becorrespondingly weakened and plants will be harmed. Plant Stress is one of today’s hottestresearched topics.In the semi-arid and arid dry climate areas, because of fewer rainfall and more evaporation,salt continue to accumulate on the surface; irrigation with saline water in coastal areas, seawaterintrusion and other factors resulting in higher levels of soil salinity; unreasonable application ofagricultural production and long-term fertilizer and sewage for irrigation will lead to soilsalinization. World’s saline land area is very large and it’s about400million hectares of about1/3irrigated farmland. China’s saline land is mainly distributed in the northwest, north, northeast andcoastal areas. With the development of irrigated agriculture, saline-alkali soil area will continue toexpand. Thereby increasing the salt tolerance of crops, enhance biological control and integrateddevelopment of the saline-alkali soil is a major issue in agriculture. The study area in Yutian Oasisselected in this paper is one of the more serious areas of typical soil salinization in Northwest.Through surveying Yutian Oasis soil salinity and reed’s growth conditions, we can come to thefollowing conclusions:1) Analysis of the Variation of Yutian typical zone soil salinity, the results indicate that serioussoil salinization and exhibit surface aggregation phenomenon; due to the interference of humanactivities, surface soil salinity ranged; soil salinity performance of the0-5cm soil layer a strongspatial correlation;5-30cm soil level of30to-70cm soil layer of soil salinity spatial correlation isvery weak;,0-30cm soil layer in the horizontal direction, soil salinity from east to west increase,then decreases and then increases, then decreases;30-70cm soil layer of soil salinity decreasesgradually from east to west;2) Comparative analysis between the three ecotypes of reeds and freshwater marsh reeds, mild salt meadow reed, heavy salinized meadow reed photosynthesis, the results show that thephotosynthetic rate and stomatal conductance size of the freshwater marsh reed>mild salt meadowreed> heavy salinized meadow reed. It shows that with the increase in the salinity of habitats reedphotosynthetic rate and stomatal conductance gradually reduce the high salt inhibit the growth ofreed.3)The salinity of the habitat the greater photosynthetic rate and photosynthetic active radiationhas a close positive correlation with the intercellular CO₂concentration has a close negativecorrelation seen from the correlation coefficient table of the three ecotypes of reeds heavy salinizedmeadow reedthe correlation among the indexes, means that each index the greater as the salinityincrease in the sensitivity for each other, a fragile ecological environment also increases. Pathanalysis further precise handsome elect a variety of factors affecting the photosynthetic rate andfound that the freshwater marsh reed is the most critical factor is the stomatal conductance, mildlysaline meadow reed Pn by the direct effects of PAR. Heavy salinized meadow reed Ta, PAR and Pnis a direct positive effect. Three ecotypes of reeds Ci the direct effect of Pn are the negative effectsof increased CO₂concentration in rooms Ci, will limit the photosynthetic rate of the conduct.4) In addition to the20cm layer and50cm layer of soil of Mg²⁺ion,50cm layer of soil of theCO₃^2-ion and HCO₃^-ions on the reed cover rate has a role in promoting the other layers of salt ionshave inhibited the reed cover rate. The role of salt ions on the reed plant height increases graduallywith increasing soil depth. Reed canopy layers of salt ions on the reed canopy role graduallydecreases with increasing soil depth.0cm soil of Na⁺+K⁺ion,50cm layer of soil of Mg²⁺ion20cmlayer of soil of Ca²⁺ions,20cm layer and50cm layer of soil the CO₃^2-ion and of HCO₃^-ions,50cmlayer of soil of SO42-ion reed density has inhibitory effects outside, the other the layer of salt ions onthe reed density has a catalytic role; its role gradually decreases with increasing soil depth.5) The growth indicators of reed and the relationship between soil moisture is a positivecorrelation that the layers’ soil moisture will promote reed growth; layers’ soil water content playa less obvious role in promoting reed cover, but more obvious in reed plant’s growth indicators,like height and density, crown length and crown width etc. The study shows that: With the increasing of salinity, the light utilization and photosynthesis ofreed will be decreased, and resulting in lower reed production. Ultimately it will result in losses onthe improvement of agricultural economy.