| Adquate application of nitrogen and potassium fertilizer is benefical for crop yield increase,improvement of wheat quality and adaptability to the environment.However,the fertilizer application is generally high and fertilizer utilization rate is dispointingly low,which leads to the waste of resources and the pollution to the environment.In this study,Youngmai 29(red-skinned strong gluten spring wheat)was selected as the research material.In 20202021,the nitrogen and potassium fertilizer of wheat were reduced by 10%(N/K-10%)and 15%(N/K-15%)respectively compared with the conventional dosage(N:240 kg/hm2,K:120 kg/hm2,CK).In 2021-2022,20%(N/K-20%)and 25%(N/K-25%)experiments were added to investigate the effects of the reduced application of nitrogen and potassium fertilizer on the yield,quality,soil nutrients and nitrogen efficiency of spring red-skinned strong gluten wheat after rice,and to explore the relationship between reduced application of nitrogen and potassium fertilizer and high yield,high quality,high nutrient utilization efficiency and high yield.The results are as follows:1.The treatments of different nitrogen and potassium reduction have different impacts on yield formation.The yield of N-10%and N-15%was higher than that of CK treatment.Among them,the yield of N-10%(2020-2021)and N-15%treatment(2021-2022)was the highest,and the yield of N-20%and N-25%treatment was lower than that of CK.In the two years,the tiller number,dry matter accumulation,grain-leaf ratio and higher leaf area index in N-10%and N-15%treatments were significantly higher,indicating better photosynthetic performance.The effects of the different potassium-reduction treatments on the yield formation increased with decreasing potassium application,with the highest yield in K-10%(2020-2021)and K15%(2021-2022)treatments,and lower yield in K-20%and K-25%treatments than CK.The tiller number,dry matter accumulation,grain-leaf ratio and LAI in Both K-10%and K-15%treatments were suitable.The reasonable population structure and good photosynthetic performance in the four fertilization treatments(N-10%,N-15%,K-10%and K-15%)were realized,resulting in high yield with reduced fertilizer.2.There was a correlation between nitrogen or potassium uptake,transport and nutrient efficiency of wheat and the amount of nitrogen and potassium application.Compared with the conventional dosage of CK,the nitrogen agronomic efficiency and apparent utilization of the two annual nitrogen reduction treatments were the highest in the N-10%treatment,which had lower or similar nitrogen accumulation and higher nitrogen fertilizer apparent utilization,with slight inter-annual variation;However,N-15%treatment significantly reduced nitrogen accumulation and nitrogen apparent utilization rate.The nitrogen accumulation,nitrogen apparent utilization rate,nitrogen agronomic efficiency and nitrogen physiological efficiency were all significantly reduced in the N-20%and N-25%treatments,and the greater the degree of nitrogen reduction,the greater the decrease.The K2O accumulation and potassium apparent utilization rate was lower than those of CK in the K-10%and K-15%treatments.The apparent utilization rate,agronomic efficiency and physiological efficiency of potassium all increased and then decreased with the reducation of potassium application rate.The difference was significant.When the potassium application rate continued to be reduced to 20%and 25%,the K2O accumulation,the apparent utilization rate and the agronomic efficiency would be significantly reduced.3.The nitrogen reduction treatment regulated the utilization of nitrogen by regulating the activity of key enzymes in nitrogen metabolism.The activity of glutamine synthetase(GS)in flag leaf increased and then decreased with the decrease of nitrogen application after anthesis.It was significantly reduced with nitrogen reduction of more than 20%.The activity of glutamate synthase(GOGAT)in flag leaf after anthesis also increased and then decreased with the decrease of nitrogen application rate.The activity of GOGAT in N-10%treatment was the highest,followed by the conventional nitrogen application treatment(CK).It is indicated that the moderate reduction of nitrogen was beneficial to improve the activities of GS and GOGAT enzymes in flag leaves after anthesis,but the excessive reduction of nitrogen was not conducive to the nitrogen assimilation catalyzed of GS and GOGAT enzymes in flag leaves after anthesis.4.The effects of nitrogen reduction on different quality indexes of wheat grains were different.The grain bulk density of N-10%treatment was the highest.The grain hardness of each treatment changed little,and the value was above 60.The treatment of N-10%and N-15%was higher but with large differences between the annual types.The flour yield of each treatment changed little in the two years,with the highest value in N-10%treatment.The wet gluten content of the treatments varied between the two years and was significantly influenced by the year type,in which the wet gluten content of each treatment in 2020-2021 was above 28%,meeting the quality index of medium and strong gluten wheat varieties(GB/T173202013).In 2021-2022,the wet gluten content decreased with the decrease of nitrogen application rate.Except for N-25%,the wet gluten content of each treatment was above 26%,which met the quality index requirements of medium gluten wheat varieties.The sedimentation value increased and then decreased with the decrease of nitrogen application rate.The protein content decreased with the decrease of nitrogen application rate in two years,and the highest was CK in conventional treatment.The grain protein content of N-10%treatment was above 13%in both years,which met the quality index requirements of medium and strong gluten wheat varieties.Similarly,the potassium reduction also regulated the changes in different quality indicators of wheat grains.There were significant differences in grain weight among the treatments,with the highest grain weight in the K-10%treatment.The grain hardness varied less among treatments with values above 60,with the highest values in the K-15%and K-20%treatments,varying significantly among the annual types.The flour yield also varied less among treatments,with the highest values in the K-10%treatment.The wet gluten content of each treatment was varied and significantly influenced by the year type,where the wet gluten content was above 28%in 2020-2021,meeting the quality index requirements of medium and strong gluten wheat varieties,and the wet gluten content in 2021-2022 decreased with decreasing potassium application,but the wet gluten amount was above 26%in all treatments,meeting the quality index requirements of medium-gluten wheat varieties.The settling value increased and then decreased with the decrease of potassium application,and the protein content increased and then decreased with the decrease of potassium application in both years,and the grain protein content of K-15%treatment was above 13%,which met the quality index requirements of medium-strength wheat varieties.5.The nitrogen reduction affected the characteristics of soil nutrient supply during the wheat season.The nitrogen reduction of 10%,15%,20%and 25%did not reduce the soil available nitrogen(increased or basically stable)and available phosphorus content(increased)at wheat maturity stage,and the nitrogen reduction of 25%significantly increased the soil available nitrogen content at wheat maturity stage.The nitrogen reduction treatment had no effect on soil available potassium content.The soil nitrogen loss under different nitrogen reduction conditions showed differences,as soil nitrogen deficit was significantly reduced in all nitrogen reduction treatments,with relatively small positive values in N-10%and N-15%treatments,and negative values in N-20%and N-25%treatments.It shows that under the condition of high soil fertility in this experiment,the moderate reduction of nitrogen application is conducive to promoting plant nitrogen absorption,reducing excessive accumulation of nitrogen in soil,reducing nitrogen loss,and maintaining soil nitrogen balance.However,the excessive nitrogen reduction will consume nitrogen in the soil,which may cause soil nitrogen deficiency in the long run.6.The nitrogen reduction affects greenhouse gas emissions in the wheat season.The emission rate of CO2 in winter wheat farmland were all positive as a source of CO2 emissions.The CO2 emission flux under N-10%and N-15%treatment in 2020-2021 showed N-15%<N-10%overall,while N-10%<N-15%in 2021-2022;under the different nitrogen reduction treatments,the CH4 emission flux of wheat field tended to be negative as a whole.Compared with the CK treatment with conventional fertilization,the N-10%and N-15%could reduce the CH4 emission flux of wheat field and the N2O emission flux of wheat field.The reduced nitrogen application of 10%and 15%had no significant effect on the total GWP(warming potential)of wheat fields.In 2020-2021,the nitrogen-treatment had no significant effect on the greenhouse gas in GHG intensity compared to the conventional nitrogen application treatment CK,as the N-10%and N-15%treatments could improve wheat yields by 19.33%and 23.44%,respectively,compared to CK;the nitrogen-treatment had no significant effect on the greenhouse gas.There was no significant effect of N-treatment on greenhouse gas intensity in wheat fields in 2021-2022.7.N-10%and N-15%treatments and K-10%and K-15%treatments of medium-strength wheat were more beneficial for high-quality and high-yielding wheat groups;with better leaf area index,group quality.The higher yields and the mutual coordination of yield,quality and nitrogen efficiency could be archeived,with less impact on the environment. |
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