Effects Of Deep Straw Return On Growth And Yield Of Maize In Saline-alkali Land

Saline-alkali land was an important land resource,and deep straw return could effectively improve soil properties and fertility.Under the background that the rigidity of cultivated land area decreases,but the demand for corn continues to increase,this experiment set up two tillage methods of shallow rotation（CK）and deep straw return（DPR）on mild（S1）,moderate（S2）and severe（S3）saline-alkali land from 2021 to 2022.The local main cultivars DK159 and JSH257 were used as experimental materials.The effects of deep straw return on maize growth index,physiological characteristics and yield in different saline-alkali soils were analyzed.To clarify the effect of tillage improvement on maize growth in cultivated land with different salinization degrees.It provided a theoretical basis for straw returning to improve saline-alkali soil,increased maize yield and saline-alkali land production efficiency.The main results were as follows:（1）Soil bulk density,compactness and p H value in saline-alkali land were significantly different between locations and tillage methods.After deep straw return,soil bulk density and soil porosity decreased significantly in S2,and soil water content changed greatly in S1.Soil available phosphorus and available potassium content increased the most in S1,and soil available nitrogen,total nitrogen and organic matter increased the most in S2.The total salt content and p H value of the soil were significantly lower than those of CK.The total salt content decreased the most in S3,and the p H value decreased the most in S2.（2）After deep straw return,the emergence rate,uniformity,plant height,ear height and leaf area index of maize were significantly increased.Dry matter accumulation were increased to varying degrees.Among them,the seedling emergence rate,ear height,leaf area index and dry matter accumulation increased the most in S2.The uniformity and plant height increased the most in S1.In mild saline-alkali soil,the root length,root surface area,root average diameter and root volume increased by 62.13%,62.99%,26.46%and 69.67%,respectively,compared with the shallow rotation,and the effect was the most significant in the 10～20 cm and 40～50 cm soil layers.With the decrease of soil total salt content,root length and root volume increased significantly,thereby increasing root surface area.（3）The photosynthetic characteristics of maize were significantly improved after deep straw return.Deep straw return significantly increased the SPAD value of maize.Fv/Fo,Fv/Fm,q P,ΦPSII increased,and q N decreased.Among them,Fv/Fo and q N have the largest amplitude in S1;Fv/Fm,q P andΦPSII increased the most in S2.The SPAD value increased the most in S3.Antioxidant enzyme activity and inorganic ion content also changed significantly.The activities of SOD,POD and CAT decreased the most in S1.K⁺and Na⁺had the largest amplitude in S2.Ca²⁺and Mg²⁺increased the most in S1 and S3,respectively.The soluble sugar content decreased the most in S2.（4）After deep straw return,the yield increased by 24.23%,among which the yield and1000-grain weight increased the most in S2,increasing by 33.61%and 15.31%respectively.The number of grains per spike increased the most in S1,which was 12.72%.The yield was the highest when the total salt content was 1.12 g/kg and the p H value was 8.80.The increase of SPAD value and K⁺content had the greatest influence on maize yield.