土壤微生物膜固沙对沙生植物幼苗光合和荧光特性的影响

In order to reveal the effects of soil microbial film sand fixation on photosynthetic and fluorescence characteristics of psammophyte seedlings,Ammopiptanthus mongolicus and Astragalus laxmannii seedlings were selected.Pot experiment with different application methods(spray,mix)and application amount(0,1,3,5,7 and 10 g kg-1).The characteristics of plant gas exchange and chlorophyll fluorescence after soil microbial biofilm formation were analyzed.The results show that:(1)The hardness and thickness of the consolidated layer were significantly higher than that of the control(P<0.05),when the application amount of bacterial was greater than 1 g·kg-1.When the application amount was greater than 5 g·kg-1,the activities of urease and sucrase in soil were significantly higher than that of the control(P<0.05).(2)There was no significant effect on net photosynthetic rate of Ammopiptanthus mongolicus(P>0.05).The net photosynthetic rate of Astragalus laxmannii in 3-7 g·kg-1 treatment was significantly higher than that of the control(P<0.05).And the transpiration rate,net photosynthetic rate and intercellular CO2 concentration were significantly higher than those of Ammopiptanthus mongolicus(P<0.05).(3)Compared with the control group,Fv/Fm in 1 g·kg-1 treatment group was significantly decreased(P<0.05).The Fv/Fm of Astragalus laxmannii treated with more than 5 g kg-1 was significantly higher than that of the control group(P<0.05).Except for 3 g kg-1 treatment,the Fv/Fm and QP of Ammopiptanthus mongolicus were higher than those of Astragalus laxmannii.(4)Soil properties,photosynthetic gas exchange and chlorophyll fluorescence were partially mediated models.The ratio of direct effect of soil characteristics on chlorophyll fluorescence properties was 66.67%,and the ratio of indirect effect on chlorophyll fluorescence properties was 34.23%by affecting photosynthetic gas exchange.Soil microbial film sand fixation technology improves the hardness,thickness of the consolidated layer and soil enzyme activity.Soil microbial membrane sand fixation technology can improve soil quality,stomatal conductance of leaves and mediate effect to enhance the photosynthetic efficiency and capacity of Ammopiptanthus mongolicus and Astragalus laxmannii,which has a greater effect on the photosynthetic rate of Astragalus laxmannii and electron transport of Ammopiptanthus mongolicus.The research results can provide theoretical basis and scientific support for improving soil microbial films sand fixation technology.