Effects of Nitrogen Application Rate on Sugar Metabolism after Anthesis and Grain Yield of Dryland Wheat
Nitrogen(N)fertilizer application is one of the current measures to increase agricultural pro-duction,and appropriate application rate is of great importance to wheat yield formation.Pool planting experi-ment was performed from 2020 to 2021 in the wheat experimental station of Shanxi Agricultural University in the southeast of the Loess Plateau.Four treatments with pure N application rate as 0(N0),90(N90),150(N150)and 210(N210)kg/hm2 respectively were set,and their effects on aboveground growth,sugar me-tabolism after anthesis and yield of dryland wheat were analyzed,in order to explor the suitable N application rate for yield increase and the physiological mechanism of sugar metabolism.The results showed that compared with the control(N0),applying N fertilizer significantly increased plant height and leaf area index of dryland wheat at each growth stage,and activities of sucrose synthase(SS)and sucrose phosphate synthase(SPS)in flag leaves after anthesis,and the differences were significant at 15～30 days after anthesis.For yield and its components,the yield,spike number,grain number per spike and 1 000-grain weight increased by 13.45%～42.18%,7.68%～22.33%,2.14%～3.45%and 2.48%～13.54%,respectively.The total starch content in-creased by 1.8～8.8 percentage points,especially the amylopectin content increased significantly.For the dy-namic trend,with the increase of N application rate from 90 kg/hm2 to 210 kg/hm2,the leaf area index at each growth stage,the activities of SPS and SS in flag leaves at 10～30 days after anthesis and the starch con-tent in grain at 10～30 days after anthesis increased first and then decreased,and reached the highest value under N application rate at 150 kg/hm2.Finally,the yield of dryland wheat was the highest in N150 treat-ment,while the starch content was the highest in N210 treatment which was not significantly different from N150 treatment.In conclusion,150 kg/hm2 of N application rate promoted the aboveground growth of dryland wheat,enhanced the activity of sugar metabolism enzymes in flag leaves at 10～30 days after anthesis,in-creased sucrose and starch contents in grain,and finally the yield increasing effect was the best.
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