Application Research On Quantitative Fertilization Of Main Shape Jujube Tree And Near Infrared Spectroscopy Analysis Of Nitrogen Nutrition

In this study,the trunk-shaped gray jujube tree was used as the research object,and the fertilizer utilization efficiency was improved by controlling the fertilization ratio at different growth stages of gray jujube.The effects of 16 different fertilization treatments on the growth,nutrient utilization and fruit quality of the trunk-shaped gray jujube tree under three combinations were studied.Based on the principal component analysis,the best fertilization scheme was calculated,and the near-infrared spectrum of nitrogen was constructed to provide a theoretical basis for labor-saving and efficient cultivation.The results of this study are as follows:（1）Applying more nitrogen fertilizer in the early stage of germination can effectively improve branch growth and leaf photosynthesis.Nitrogen has a significant contribution to the growth and development of fruit trees and the formation of canopy.In the early germination stage（S1 combination）and young fruit expansion stage（S2 combination）,the SPAD value of leaves was the highest under single factor nitrogen fertilizer treatment,but excessive nitrogen supply would consume too much carbohydrate in plants,which was not conducive to biomass accumulation.Therefore,in the early stage of germination,H2 treatment with moderate concentration of three fertilizers and the highest principal component analysis was selected.Nitrogen fertilizer(460.77 g/plant^-1),phosphorus fertilizer(489.13 g/plant^-1)and potassium fertilizer(588.23 g/plant^-1)could promote the growth and development of jujube branches and accumulate a certain amount of nutrients.（2）The fruit external quality of the three combinations of H1 fertilization treatment was better,and in terms of appearance quality,the treatment effect of single factor was generally lower than that of multi-factor fertilization treatment.Fertilization had no significant effect on fruit shape index and edible rate of jujube fruit.In terms of the effect on jujube fruit texture,the S1 combination（H4-H6 treatment）increased with the increase of potassium application in multiple factors,and the cohesion and fruit elasticity also increased.In the combination of S1 and S2,with the increase of single factor potassium fertilizer application amount,the soluble sugar content also gradually increased.In the combination of S2and S3,the soluble sugar content of H6 treatment with higher potassium fertilizer content was also higher,reaching 13.88%and 13.2%.The vitamin C content also had a positive response to the application of potassium fertilizer.The vitamin C content of S1 combination H6 treatment was the highest,which was351.35 g/kg.The benefits of the three fertilization combinations and ratios on the internal nutrition of the fruit are as follows:potassium fertilizer>phosphorus fertilizer>nitrogen fertilizer.（3）A quantitative prediction model for rapid detection of nitrogen content in jujube leaves in southern Xinjiang was constructed by using Fourier transform near infrared spectroscopy.In the experiment,the leaves of Huizao jujube in southern Xinjiang were selected as the research object.The special bands of 4315.91～4 335.19 cm^-1,4 4967.7～5 176.00 cm^-1and 7 104.47～7 189.32 cm^-1were selected in the full band range of near infrared spectroscopy 10 000～4 000 cm^-1.The number of samples was 192,and the standard deviations of calibration set and validation set were 0.31 and 0.39,respectively.The pretreatment method of SNV+original spectrum+SG was considered as the optimal method combination,and the principal component was removed from 7 problem samples due to 7 words and Mahalanobis distance.In the prediction model of nitrogen content in jujube leaves,the correlation coefficient was 0.86 406,the RMSECV was 0.0 176,and the RMSEP was 0.0 178.The absolute deviation between the predicted value and the actual value of the model is small,and the model prediction ability is good.The difference between RMSEP and RMSEC is 0.0 002,and the difference is small.The model is accurate.（4）Under the conditions of this experiment,the recommended fertilization ratio for S1 and S2 stages was H2 treatment:nitrogen fertilizer(460.77g·plant^-1),phosphorus fertilizer(489.13g·plant^-1),potassium fertilizer(588.23g·plant^-1).In the later stage,jujube trees gradually transformed into reproductive growth,and the amount of potassium fertilizer needed to be increased.Therefore,H4 treatment with higher potassium fertilizer content was recommended in the S3 stage:nitrogen fertilizer(524.57g·plant^-1),phosphate fertilizer(326.08 g·plant^-1),potassium fertilizer(882.35g·plant^-1).