Effects Of Water Retaining Agent On Soil Water Retention And Plant Growth And Photosynthetic Physiology In Desert

Water is the key factor affecting the success or failure of desert vegetation restoration and afforestation in arid area.Water retaining agent is a new kind of polymer material with super strong water retention,which is widely used in agriculture.Based on the Euphrates poplar seedlings,grey Euphrates poplar seedlings as the research object,through the different dosage of water retention agent and super absorbent polymers with nitrogen dosage of selection,design of field experiment,the different dosage of super absorbent polymers on soil physical and chemical properties,p.euphratica seedling growth and photosynthetic physiology and water retention agent and the influence of nitrogen with the grey optimal formula of p.euphratica seedling growth,photosynthetic physiological effects,It provides theoretical guidance for desert vegetation restoration,shelter forest construction and application and extension of water retaining agent in sandstorm area.The research results of this paper are as follows:（1）The application of water retaining agent can significantly increase the soil water content,which increases with the increase of the amount of water retaining agent,increases the soil porosity,improves the mass of aggregates>0.25mm in water-stable aggregates,and thus improves the soil aeration permeability and makes the soil structure reach a stable state.（2）The application of water retaining agent significantly increased the content of soil available nutrients,among which,the contents of soil available N,P,K and organic matter were the highest under the treatment of 0.4%water retaining agent,indicating that the treatment of 0.4%water retaining agent could improve the content of soil available nutrients compared with other treatments.（3）Photosynthetic growth of POPULus euphratica seedlings with different amount of water retaining agent was different.The results showed that the photosynthetic parameters of P.euphratica seedlings were significantly improved by each treatment.Net photosynthetic rate（Pn）,stomatal conductance（Gs）,transpiration rate（Tr）,instantaneous water use efficiency（WUEinst）,apparent quantum efficiency（AQY）,light saturation point（LSP）and maximum net photosynthetic rate（Pnmax）were all the highest in 10g/plant water retention agent treatment.Transpiration rate（Tr）and instantaneous water use efficiency（WUEinst）were not significantly different from CK（P>0.05）,and other light response characteristic parameters were significantly different from CK（P<0.05）.It indicated that the dosage of water retaining agent was not the more the better,and 10g/plant was the best dosage to promote the growth of P.euphratica seedlings.（4）A certain amount of water retaining agent combined with nitrogen fertilizer could increase the growth of POPULus euphratica seedlings.The plant height,ground diameter,biomass,root length,root surface area and root volume of P.euphratica seedlings under 0.4‰treatment were significantly different from those of CK（P<0.05）,indicating that 0.4‰treatment could promote the growth of P.euphratica seedlings.（5）The photosynthetic parameters of each water retaining agent combined with nitrogen fertilizer treatment were higher than CK.Net photosynthetic rate（Pn）,stomatal conductance（Gs）,transpiration rate（Tr）,instantaneous water use efficiency(WUE_inst),apparent quantum efficiency（AQY）,light saturation point（LSP）and maximum net photosynthetic rate（Pnmax）were all the highest in 0.4‰treatment.Higher than ck35.03%31.98%,18.15%,16.67%,138.43%,32.65%,44.09%,respectively,indicating that 0.4‰treatment significantly increased the photosynthesis of P.euphratica seedlings.（6）The malondialdehyde（MDA）content,superoxide dismutase（SOD）activity,peroxidase（POD）activity,proline（Pro）content and soluble protein（SP）content of all treatments were lower than those of CK.The content of MALondialdehyde（MDA）,antioxidant enzyme activity and soluble protein（SP）were significantly decreased in 0.4‰treatment compared with CK（P<0.05）,but the content of proline（Pro）was not significantly different from CK（P>0.05）,indicating that 0.4‰treatment could improve the drought resistance of P.eurex seedlings.In conclusion,the optimal application amount of water retention agent for POPULus euphratica growth was 10g/plant,the optimal concentration of water retention agent for improving soil physical and chemical properties was 0.4%,and the optimal application amount of water retention agent combined with nitrogen fertilizer for populus euphratica growth was 0.4‰.