Study On Nitrogen Fertilizer Application And Nitrogen Nutrition Diagnosis Based On SPAD Value Of ’Fubaiju’

In recent years,with the continuous improvement of people’s quality of life,health drinks such as tea chrysanthemum are becoming more and more popular,while the unscientific supply of nitrogen fertilizer in chrysanthemum cultivation brings problems such as nitrate accumulation and soil water pollution,which limits the development of the industry and the improvement of economic benefits.In this paper,‘Fubaiju’,a geographical indication product from Macheng,Hubei Province,was selected as the material to compare the traditional nitrogen application and the four nitrogen treatment（115%,85%,70%,55%）on the basis of traditional nitrogen application.And set five topdressing ratios of N₁（base fertilizer:topdressing=8:2）,N₂（base fertilizer:topdressing=7:3）,N₃（base fertilizer:topdressing=6:4）,N₄（base fertilizer:topdressing=5:5）and N₅（base fertilizer:topdressing=3:7）.By comparing the yield of fresh flowers per plant and the functional content of dried flowers,the best nitrogen application level and the ratio of base fertilizer and topdressing were selected.At the same time,the SPAD value of leaves was used to explore the feasibility of rapid diagnosis of nitrogen nutrition in the field of’Fubaiju’,so as to provide a basis for efficient nitrogen fertilizer management in the whole growth period of’Fubaiju’.The main results are as follows:1.The biomass of each organ of‘Fubaiju’under five nitrogen levels in four growth stages was compared.it was found that the biomass of chrysanthemum plant was the highest at115%N level in seedling stage and branching stage;the biomass of chrysanthemum plant was the highest at 70%N level at bud stage and the smallest at 55%N level;at flowering stage,the biomass of chrysanthemum plant was the highest at 70%N level.From the aspect of fresh flower yield per plant,the yield at 70%N level was 1085.69g/plant,which was not significantly different from that of traditional nitrogen application（CK）.In addition,70%N was 13.19%,23.37%and 48.74%higher than the total flavonoids,chlorogenic acid and luteolin of dried flowers with traditional nitrogen application（control）,respectively.However,when nitrogen is reduced to 55%N,the number of diseased plants will increase.In addition,compared with the economic benefits of five levels of nitrogen fertilizer supply,the net income of 70%N is the highest.To sum up,70%of the traditional nitrogen supply is the best fertilization level.2.Comparing the biomass of organs of‘Fubaiju’at four growth stages under five nitrogen bases and topdressing supply ratios,it was found that the biomass of chrysanthemum plant was the highest under the fertilization scheme of N₁（8:2）at seedling stage,the highest under the fertilization scheme of N₁（8:2）and N₄（5:5）at branching stage,and the highest under the fertilization scheme of N₃（6:4）and N₄（5:5）at flowering and budding stage.In terms of flower yield per plant,the yield of N₃（6:4）,N₄（5:5）and N₅（3:7）fertilization scheme was 38.03%,37.44%and 35.76%higher than that of N₁（8:2）fertilization scheme,respectively.In terms of quality,chlorogenic acid and isochlorogenic acid An of flowers under N₃（6:4）fertilization scheme were 19.51%and 15.57%higher than N₁（8:2）,respectively.The contents of total flavonoids,chlorogenic acid,luteolin and isochlorogenic acid An in flowers under N₄（5:5）fertilization scheme were 16.44%,87.8%,14.28%and58.4%higher than those under N₁（8:2）fertilization scheme,respectively.The content of the above indexes under N₅（3:7）fertilization scheme was 10.44%,13.41%,18.57%and 37.34%higher than that of N₁（8:2）fertilization scheme,respectively.In addition,compared with the economic benefits of the five fertilization schemes,the output value of N₃（6:4）and N₄（5:5）was the highest,while the labor cost of N₃（6:4）was lower and the net income was higher.3.The SPAD values of upper,middle and lower leaves of‘Fubaiju’at different growth stages were measured,and their correlations with leaf total nitrogen content,leaf total nitrogen content,plant total nitrogen content and fresh flower yield per plant were analyzed.the results showed that the correlation coefficients between upper leaves and leaf total nitrogen content at seedling stage,branching stage,bud stage and leaf total nitrogen content were 0.951**,0.9473**,0.9218**,respectively.The correlation coefficients between the middle leaf and leaf total nitrogen content at seedling stage,branching stage and budding stage were 0.9319**,0.9015**and 0.8731**respectively,and the correlation coefficients between lower leaf position and leaf total nitrogen content at seedling stage,branching stage and budding stage were 0.617**,0.8104**and 0.7199**,respectively.The correlation coefficients between upper leaves and plant total nitrogen content at seedling stage,branching stage and budding stage were 0.9811**,0.966**and 0.9239**respectively,while those of median leaves with plant total nitrogen content at seedling,branching and budding stage were0.9727**,0.9422**and 0.8421**respectively.The correlation coefficients between lower leaf position and plant total nitrogen content at seedling stage,branching stage and budding stage were 0.4941**,0.7136**and 0.5878**respectively.In addition,the correlation coefficients between SPAD value of epigynous leaves and flower yield at seedling stage,branching stage and budding stage were0.9261**,0.8708**and 0.9164**,respectively.while the correlation coefficients between middle leaves and flower yield at seedling stage,branching stage and budding stage were 0.967**,0.8672**and 0.9184**respectively,and those of lower leaves were 0.7127**,0.7872**and 0.6209**times,respectively.To sum up,the SPAD values of upper,middle and lower slices of‘Fubaiju’at different growth stages were significantly positively correlated with leaf total nitrogen content,plant total nitrogen content and fresh flower yield per plant,and the upper leaf had the highest correlation coefficient among the three leaf positions.its SPAD value at seedling and branching stage plays a guiding role in judging plant nitrogen abundance and deficiency,guiding nitrogen application and yield prediction of‘Fubaiju’.