Abstract:Abstract: 【Objective】By comparing and analyzing the 2 varieties winter wheat changes of stem morphological characteristics, basal node coarse cell wall composition and stem mechanical characteristics under different molybdenum-nitrogen ratio treatments, to explore the effect of molybdenum and nitrogen combined application on lodging resistance of winter wheat. 【Method】 By using 97003 and 97014 as materials, four nitrogen application levels (N 0 kg/hm2, N120 kg/hm2, N 210 kg/hm2, N 300 kg/hm2) and three Mo application levels ((NH4)2MoO4 0 kg/hm2, (NH4)2MoO4 0.75 kg/hm2 and (NH4)2MoO4 1.5 kg/hm2 were set up to compare the lodging rate of different, and the reasons of wheat lodging difference were analyzed from physiological, morphological and mechanical indexes. 【Result】 1) The distance from the break to the top and the bending moment of the wheat molybdenum low-efficiency cultivar 97014 at the same nitrogen and molybdenum levels were higher than those of the wheat molybdenum high-efficiency cultivar 97003; compared with no nitrogen application, the three levels of nitrogen application could increase both varieties of wheat the upper fresh weight and bending moment, the difference was more obvious when the nitrogen level was 210 kg N/hm2, nitrogen application had a significant effect on the section coefficient and bending stress. The nitrogen level was 0 kg N/hm2 and 210 kg N/hm2 , the bending moment would increase as the amount of molybdenum applied increases; 2) The basal node length of wheat variety 97003 was higher than that of wheat variety 97014 under all Mo and N fertilization levels, while the upper node length and ear length were lower than that of wheat variety 97014; the outer diameter of long axis and the inner diameter of long axis and ear length of wheat molybdenum efficient variety 97003 increased with the increase of nitrogen application level In addition, the outer diameter and inner diameter of long axis, basal stem length and ear length of wheat variety 97014 increased with the increase of nitrogen application level; 3) With the increase of nitrogen application rate, the non structural carbohydrate of wheat stem decreased significantly, and the application of (NH4)2MoO4 1.5 kg/hm2 efficient wheat variety 97003 was observed Ammonium Molybdate / hm2 can reduce the amount of non structural carbohydrate in wheat stem; 4) The cellulose and lignin content in the base of two wheat varieties were different. The cellulose and lignin contents of 97003 wheat variety with high molybdenum efficiency were basically unchanged under all treatment levels. The cellulose content of wheat variety 97003 with low molybdenum efficiency was increased by applying (NH4)2MoO4 1.5 kg/hm2 under four nitrogen levels. The lignin content of basal internode decreased when 0.75 kg/hm2 (NH4)2MoO4 was applied at 210 kg N/hm2 and 120 kg N/ hm2 . 【Conclusion】 The optimal combination of the main physical properties of the two winter wheat lines under different Mo and N application rates were different. The short and thick basal internode, large stem wall thickness, increased total amount of structural carbohydrates and good stalk plumpness were the direct reasons for the high bending resistance, small lodging index and enhanced lodging resistance of winter wheat.