| Late sowing is a common phenomenon in wheat production in Jiangsu Province.Exploring the supporting cultivation measures of high yield,high efficiency and high quality of late sowing wheat has important practical significance for the benign development of Jiangsu agricultural industry.The application of slow release nitrogen fertilizer has the advantages of reducing the number of fertilization and improving the nitrogen use efficiency.A large number of studies have been carried out on the slow release nitrogen fertilizer application technology of suitable sowing wheat,but the slow release nitrogen fertilizer application method suitable for the production of late-sown wheat in Jiangsu Province remains to be further explored.In this study,Yangmai 23 was used as the test variety,Polymer coated urea（PCU）and urea（U）was applied,five fertilization methods including 100%PCU as base fertilizer（A1）,80%PCU+20%U as base fertilizer（B1）,60%PCU+40%U as base fertilizer（B2）,80%PCU as base fertilizer+20%U as jointing fertilizer（Cl）,60%PCU as base fertilizer+40%U as jointing fertilizer（C2）,which derived from three fertilization modes of ’one-time base application of slow release nitrogen fertilizer ’（A）,’ one-time basal application of slow release nitrogen fertilizer mixed with urea ’（B）and ’two times of application including slow release nitrogen as base fertilizer and urea as topdressing fertilizer ’（C）.Set the no nitrogen（ON）treatment and the conventional urea quantitative split application（CK,basal:tillering:jointing:booting as 5:1:2:2）treatment.Effects of different fertilization treatments on yield,quality formation and nitrogen uptake and utilization of late sowing wheat were studied in order to provide technical support for high yield,high efficiency and high quality production of late sowing wheat in Jiangsu Province.The main research results are as follows:（1）Effect of slow release nitrogen fertilizer combined with urea on yield formation of late sowing wheat.The two-year average yield of different application modes was as follows:C>CK>A>B.The average yield of application mode C increased by 5.59%一 7.91%compared with CK treatment,while the average yield of application mode A and B decreased by 6.22%and 8.24%-11.86%compared with CK treatment The two-year average yield of different fertilization treatments was C2>C1>CK>A1>B1>B2,and the two-year average yield of C2 and C1 were 8796.80 kg·hm-2 and 7373.56 kg·hm-2.The main reason for yield reduction in A1,B1 and B2 treatments was reduced spike number and grain weight;the main reason for the high yield of C1 and C2 was that the spike number and grain weight were increased under the premise of stable grain number per spike.The higher spike rate,leaf area index,chlorophyll content and dry matter accumulation of C1 and C2 treatments were the basis for higher spike number and grain weight.Compared with CK,application mode A and B significantly reduced net benefit and input-output ratio,while application mode C significantly increased net benefit and input-output ratio,and C2 treatment was the highest,reaching 13140.80 yuan.hm-2 and 1.61.（2）Effects of slow release nitrogen fertilizer combined with urea on nitrogen uptake and utilization in late sowing wheat.The nitrogen use efficiency of different application patterns was as follows:C>CK>A>B.Compared with CK,the nitrogen partial factor productivity,nitrogen agronomic efficiency,nitrogen physiological efficiency and nitrogen apparent utilization efficiency of application pattern C were increased by 7.21%,14.76%,3.00%and 6.43 percentage points on average,while those of application pattern A and B were decreased by 5.72%,11.7%,1.4%,5.00 percentage points and 9.09%,18.61%,0.59%and 8.61 percentage points respectively.The overall nitrogen use efficiency of different fertilization treatments was C2>C1>CK>A1>B1>B2,and the deficiency of soil nitrogen supply and plant nitrogen absorption from jointing stage to maturity was the main reason for the decrease of nitrogen use efficiency in A1,B1 and B2 treatments.The application of urea（Cl and C2 treatments）at jointing stage was consistent with the peak nitrogen demand of wheat,which was conducive to the absorption and utilization of nitrogen,thereby improving the nitrogen utilization efficiency.（3）Effects of slow release nitrogen fertilizer combined with urea on grain quality of late sowing wheat.The overall grain processing quality and nutritional quality under different application modes were as follows:C>CK>A>B.The test weight,hardness,flour yield,wet gluten content,flour quality parameter,total protein content and total starch content of model C were increased by 0.25%,1.75%,1.68%,1.12%,5.13%,0.83%and 0.98%,respectively,compared with CK.Compared with CK,the application mode A and B decreased by 0.12%,1.20%,0.91%,0.47%,3.42%,0.11%,0.81%and 0.25%,1.99%,1.89%,2.71%,8.94%,1.50%,1.7%,respectively.The grain quality of different fertilization treatments was C2>C1>CK>A1>B1>B2.There were no significant differences in the test weight,hardness,flour yield,wet gluten content,flour quality parameter,total protein content and total starch content between C2 and C1 treatments.The above results showed that either one-time basal application of slow release nitrogen fertilizer mixed with urea or one-time basal application of slow release nitrogen fertilizer mixed with urea was not conducive to the realization of high yield,high efficiency and high quality of late sowing wheat.Two times of application including slow release nitrogen as base fertilizer and urea as topdressing fertilizer ’one base and one topdressing’ was beneficial to the high yield,high efficiency and high quality production of late sowing wheat,and the treatment of 60%PCU combined with 40%U topdressing at jointing stage showed the best comprehensive performance. |
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