This research was set as a pot experiment,the sorghum variety Liaonuo 10 was used as the experimental material,and the conventional nitrogen application rate(300 kg/ha)was used as the control(N0),N1-N3 treatments showed a 10％gradient decrease in nitrogen fertilizer application rate(270,240 and 210 kg/ha),N4-N6 treatments were combined with 3％3,4-dimethylpyrazole phosphate(DMPP)on the basis of N1-N3,the application rates of phosphorus and potassium fertilizers were both 75 kg/ha.The results showed that,with the reduction of nitrogen fertilizer application,relative chlorophyll content(SPAD value),dry matter accumulation,total nitrogen accumulation,dry matter production efficiency,nitrogen dry matter production efficiency,nitrogen agronomic efficiency,and nitrogen fertilizer utilization rate gradually decreased.After the application of DMPP,the growth and development of sorghum returned to the level of conventional fertilization.Compared with the N0,the total nitrogen accumulation of N5 treatment(20％nitrogen reduction+3％DMPP)increased by 4.67％;the grain weight per ear and 1000-grain weight increased by 3.72％and 5.58％,respectively;the dry matter production efficiency increased by 8.77％;the nitrogen dry matter production efficiency increased by 1.14％,and the nitrogen agronomic efficiency increased by 5.75％;the nitrogen fertilizer use efficiency and nitrogen fertilizer agronomic efficiency increased by 15.47％and 45.12％,respectively.In conclusion,when the nitrogen fertilizer application rate was reduced by 20％,adding 3％DMPP of the normal nitrogen application rate could improve the dry matter production efficiency and nitrogen utilization rate in sorghum,and had a certain potential for increasing yield.
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