Evaluation Of Nitrogen Efficiency Difference In Different Maize Varieties And Analysis Of Nitrogen-saving Potential

In order to ascertain the differences in nitrogen absorption,utilization efficiency and nitrogen-saving potential of different maize varieties,it provides theoretical and technical reference for the selection of Guizhou nitrogen efficient maize varieties.According to the studies in 2019,in Weining County,Bijie City,and Puding County,Anshun City,Guizhou Province,selecting Huaxingdan 88,Jinyu 838,Xianyu1171,Jinguidan 3,and Andan 3 as materials,using the two-factor split plot design,nitrogen fertilizer dosage as the main zone,setting 4 levels?respectively for 0,100,200,300?/ha?,5 maize varieties as secondary zone.The effects of different nitrogen application levels on growth characteristics,dry matter and nitrogen accumulation and distribution,yield and yield components of each variety were studied to evaluate the nitrogen uptake and utilization efficiency of each variety and analyze the nitrogen-saving potential of each variety.The main findings are as follows:1.Under this test condition,the output of each variety had a parabolic relationship with the amount of nitrogen applied downward.The yield of each variety was highest when the nitrogen application rate was 200?/ha,an average increase of 31.05%compared with the control.Appropriating application of nitrogen fertilizer can increase the number of spikes and the weight of thousand kernels and shorten the length of bald tips.The variety Jinyu 838 had the highest yield at various nitrogen levels,with an average of 13572.70?/ha,The binomial regression of yield and nitrogen application level was carried out,and the appropriate nitrogen application rate was 206.65?/ha.2.This study shows that increasing the amount of nitrogen application significantly increased the total root length,total root surface area,average root diameter and total root volume of each variety of each variety during the heading and spinning stage.With the increase of nitrogen fertilizer level,the root and shoot ratio increased first and then decreased and then increased again.The plant height,stem thickness,ear height,leaf area,and LAI of various maize varieties at different growth stages increased first and then decreased with the increase of nitrogen application,and the SPAD gradually increased with the increase of nitrogen level.The net photosynthetic rate,stomatal conductance,and transpiration rate of each variety during the heading and spinning stage increased first and then decreased with the increase of nitrogen application level,and the intercellular CO₂concentration varied among different varieties.Under the same conditions,Jinyu 838 and Jinguidan 3 have a larger photosynthetic area and better root morphology,and can more fully absorb and utilize nitrogen fertilizer.3.Studies have shown that the dry matter accumulation,stage dry matter accumulation,crop growth rate,relative growth rate,and nitrogen accumulation of each variety were the highest when the nitrogen application rate was 200?/ha.The grain dry matter and nitrogen accumulation amount of mature grains varied with the nitrogen application the increase has increased by 4.74%and 62.67%respectively.Under different nitrogen levels,Jinyu 838 had the most dry matter and nitrogen accumulation during the mature period.The dry matter was 11.23%and 9.81%higher than that of Huaxingdan 88,Xianyu 1171,Jinguidan 3,and Andan 3,respectively0.25%,5.01%,nitrogen accumulation was 10.82%,22.89%,0.93%,and 6.00%higher,and the dry matter and nitrogen accumulation amount allocated to the grains at maturity were also significantly higher than other varieties,accounting for the total dry matter respectively and the total nitrogen accumulation was 54.34%?63.79%,and71.14%?72.35%,the dry matter accumulation,crop growth rate and relative growth rate were the largest in the jointing stage-big trumpet stage,male head spinning stage-mature stage.It shows that the growth and material accumulation of variety Jinyu838 at various nitrogen levels are superior to other varieties.4.The results showed that nitrogen efficiency,nitrogen absorption efficiency,nitrogen utilization efficiency,apparent nitrogen utilization efficiency,nitrogen fertilizer physiological utilization efficiency,nitrogen fertilizer agronomic utilization rate,nitrogen fertilizer partial productivity and the nitrogen dry matter production efficiency increased with the nitrogen application rate.The difference in nitrogen harvest index was not significant under different nitrogen levels,but the difference among different varieties was significant,with a difference of 0.64?0.73.The nitrogen requirement for 100?grain increased with the nitrogen application rate,an increase of 4.29%?45.01%.Jinyu 838 has the highest nitrogen efficiency,nitrogen absorption efficiency,and nitrogen fertilizer partial productivity at various nitrogen levels.The nitrogen efficiency was 6.67%?19.00%higher than that of Huaxingdan 88,Xianyu 1171,Jinguidan 3,and Andan 3,nitrogen absorption efficiency was 1.37%?21.31%,nitrogen fertilizer productivity was 5.25%?15.26%,and each the production for 100 kg grain requires less nitrogen,and the nitrogen dry matter productivity is greater.Through correlation analysis,17 trait indicators were screened as corn nitrogen efficiency evaluation indicators.The comprehensive evaluation of nitrogen efficiency of various varieties through principal component analysis and membership function method shows that:Jinyu 838 and Jinguidan 3 have strong absorption and utilization capacity of nitrogen fertilizer,which belongs to nitrogen-efficient varieties;Andan 3 has general performance and belongs to nitrogen effective type varieties;the varieties Huaxingdan 88 and Xianyu 1171 are the worst and belong to low nitrogen efficiency varieties.5.Taking the yield of each variety without nitrogen application as a control,calculate the nitrogen-saving potential and percentage of the corresponding variety.The results show thatthe nitrogen saving potential of each variety is the highest when the nitrogen application level is 200?/ha,and the smallest at 300?/ha;Compared with the yield of the same variety without nitrogen application,Jinyu 838has the largest nitrogen-saving potential and has a nitrogen saving of 63.79%potential,the average nitrogen-savingis 62.22?173.85?/ha,the percentage of nitrogen-saving potential is 28.88%?41.70%;The nitrogen-saving potential of Andan 3was the weakest,and the average nitrogen-saving potential was negative.Through comprehensive analysis of the yield of various varieties,plant growth characteristics,accumulation and distribution of dry matter and nitrogen,nitrogen efficiency,and nitrogen-saving potential,Jinyu 838 is a high-yield,high-efficiency and high-nitrogen-saving variety;Huaxingdan 88 and Xianyu 1171 are middle-class Low-efficiency,medium-nitrogen-savingvarieties;Andan3isa low-yielding,medium-efficiency,low-nitrogen-saving variety;Jinguidan 3 is a high-yielding,high-efficiency,medium-nitrogen-saving variety.Under the conditions of this experiment,Jinyu 838 has the advantages of high yield and high efficiency,the plants grow better,It can be considered as the high yield and high efficiency nitrogen saving variety.