Effects Of Bacillus Subtilis On Water Movement And Winter-wheat Growth Characteristics On Saline Alkali Soil

Based on laboratory experimental study,theoretical analysis and mathematical models as approaches,this paper mainly studied the effects of Bacillus subtilis on salt stress in winter-wheat,definited the effects of Bacillus subtilis on soil physical properties,dynamic parameters of water salt movement in alkaline soil,and proved the effects of Bacillus subtilis on growth index and yield of winter-wheat in saline-alkali soil.The obtained results as follows:(1)Bacillus subtilis could effectively increase soil water retention capacity,decrease soil salt content and improve soil aggregate structure.When Bacillus subtilis was 3 g/kg,the cumulative.infiltration and evaporation were minimum,its profile water content was largest compared with the control group,and there was significant difference among different treatments(P<0.05).After the action of Bacillus subtilis in soil,the soil profile salt content decreased,different profile water stable aggregate content increased,and different treatments,difference were significance(P<0.05).(2)Bacillus subtilis could effectively promote winter-wheat plant height,improve leaf area development and increase winter-wheat biomass.When the amount of Bacillus subtilis in soil was 3 g/kg,the yield-increasing effect on winter-wheat was the most remarkable.Logistic model could reasonably describe the change process of plant height,leaf area index and biomass.(3)According to the analysis of soil water distribution,water consumption,water use efficiency(WUE),in the same salt treatment,the soil water content change rate on the treatrment of 1 g/kg,3 g/kg,5 g/kg,7 g/kg were all low in each growth stage compared with 0 g/kg.Besides,with the soil salt content increasing,the increase rate of soil water content in the same profile also showed the decreasing trend.As for WUE,in the salt treatment of 4 g/kg,treatment B3 increased by 29.13%compared with B0;in the salt treatment of 6 g/kg,treatment B3 increased by 27.85%;in the salt.treatment of 8 g/kg,treatment B3 increased by 25.67%.The binomial equation was used to fit the relationship between Bacillus subtilis content and soil WUE,both of which showed a good fitting relationship.(4)According to the analysis of soil salt distribution,nutrient distribution,in the three salt treatment,the soil profile salt content presented same trend in vertical direction.As for the average salt content,in the salt treatment of 4 g/kg,treatment B3 decreased by 26.99%compared with BO;in the salt treatment of 6 g/kg,treatment B3 decreased by 24.39%;in the salt treatment of 8 g/kg,treatment B3 decreased by 20.33%.At the same time,soil nitrate nitrogen and available phosphorus showed the increasing trend.Especially in B3 treatment,soil nutrnent uptake capacity was significant so that increased the nutrient utilization in every growth stage.(5)According to the analysis of root length,root weight and root length density on winter wheat,in the same salt treatment,the root length and root weight in every growth showed first increasing and then decreasing,its size order was B3>B5>B1>B7>B0.In each growth stage,with the increase of Bacillus subtilis content,the root length density increased first and then decreased.Especially in B3 treatment,root length,root weight and root length density reached the Maximum value.It could be known that suitable Bacillus subtilis could promote root growth on winter wheat.