Abstract: 【Objective】To elucidate the impacts of tillage methods on the development of saline-alkali farmland and maize growth by examining the growth and development of maize roots under deep ploughing straw returning.【Methods】From 2021 to 2022,two tillage methods,shallow rotation no returning（CK）and deep ploughing straw returning（DPR）,were set up on mild,moderate and severe saline-alkali land. The local main maize varieties DK159 and JSH257 were used as experimental materials to analyze the effects of different treatments on soil physical and chemical properties,maize root growth status and yield.【Results】Compared with CK,the bulk density in DPR soil decreased,water content increased,alkaline hydrolytic nitrogen,total N,available P,available K and organic matter content increased significantly（P<0.05）. The soil total salt content and pH value decreased by 5.48%-48.98% and 1.25%-13.71%,respectively. The root length,root surface area,average root diameter and root volume of DPR maize significantly increased（P<0.05）. The root indexes improved most in the mild saline-alkali soil,with increases of 62.13%,62.99%,26.46% and 69.67%,respectively. In comparison with the CK,the yield of maize increased by 14.08%-33.61% with the highest increase in moderate saline-alkali soil.【Conclusion】Deep ploughing straw returning effectively improved soil physical and chemical properties,reduced soil total salt content and pH value. With the decrease of total salt content,maize root length and root volume increased significantly,increasing root surface area,improving the ability of maize plants to utilize soil nutrients,and ultimately increasing yield.

Key words: Saline-alkali soil, Deep ploughing straw returning, Maize, Root growth, Yield