Study On Leaf Nutritional Diagnosis Of Citrus In Chongqing Three Gorges Reservoir Area

Leaf nutritional diagnosis is an important basis for decision making in orangery fertilization.Most of the current diagnostic criteria based on the characteristics of high-yield populations.This study is based on 14-year-old of citrus sinensis osbeck?Newhall Navel Orange‘.There are a total of 80 representative orange orchards of Yunyang navel orange orchard and Citrus Research Institute Dagou orchard of Newhall Navel Orange in the Chongqing three gorges reservoir area.To determine leaf mineral nutrition elements,yield and fruit quality parameters in different phenological stages.Principal component analysis was used to establish citrus fruit yield and quality comprehensive parameters evaluation factor,and using compositional nutrient diagnosis（CND）and recommendation integrated system（DRIS）and deviation from optimum percentage（DOP）three methods for leaf nutritional diagnosis,to improve the Newhall Navel orange of the high quality and comprehensive indicators evaluation factors of leaf nutrition diagnosis standard and to provide a basis for high-yield and high-quality fertilization scheme for citrus.The main findings are as follows:1.A simplified expression of the comprehensive evaluation factors of yield and quality of Newhall Navel orange citrus fruits was established by principal component analysis and partial least squares analysis（PLS）.The parameters of fruit yield and quality of Newhall navel orange was selected from 12 indicators:fruit shape index（FSI）,titratable acid（TA）,solid acid ratio（TAR）,peel thickness（PT）,and peel brightness（L）and the peel red-greendifference（A）6factorsestablishtheexpressionas F=0.46FSI-0.45TA+0.39TAR+0.31PT-0.22L+0.25A,and the R²Y and Q² values of the model reached 0.98 and 0.98,respectively.2.Based on the correlation analysis of the imbalance index of CND and DOP nutrition diagnosis methods,the key phenological periods of citrus fruit yield and quality were screened out.The correlation between the nutritional diagnostic imbalance index CNDr²（or NBIm）and the comprehensive parameters of yield and quality（F）,yield factor（Y）and quality factor（f）were calculated by CND and DOP analysis methods.The results indicated that the key period of Newhall Navel orange production was the second physiological fruit drop period,and the correlation coefficients were-0.16 and-0.24,respectively.The key period of quality impact was fruit expansion period,and the correlation coefficients were-0.44^**and-0.41^**,respectively.The key period of the comprehensive parameters of yield and quality of Newhall Navel orange was the second physiological fruit drop and expansion period,and the correlation coefficients were-0.55^**and-0.39^**,respectively.3.According to the CND method,the diagnostic criteria mineral nutrient elements in the key period of Newhall Navel orange were established.The diagnostic criteria for high yield of Newhall navel orange were N（1.85-2.09）%、K（0.82-1.23）%、P（0.14-0.20）%、Ca（33.71-41.96）g.kg^-1 DW（dry weight）、Mg（1.52-2.34）g.kg^-1 DW、Cu（3.27-5.17）mg.kg^-1DW、Fe（68.03-122.85）mg.kg^-1 DW、Mn（29.59-50.21）mg.kg^-1 DW and Zn（7.72-13.55）mg.kg^-1 DW,respectively.The diagnostic criteria for high quality of Newhall navel orange were N（2.20-2.54）%、K（1.02-1.50）%、P（0.15-0.23）%、Ca（27.27-37.71）g.kg^-1 DW、Mg（1.70-2.42）g.kg^-1 DW、Cu（2.98-5.08）mg.kg^-1 DW、Fe（56.47-86.96）mg.kg^-1 DW、Mn（19.85-39.50）mg.kg^-1 DW and Zn（5.02-8.80）mg.kg^-1 DW,respectively.4.According to CND,DRIS and DOP,it is recommended to apply leaf nutrition diagnosis and fertilization to orchards in low production level subpopulation in different regions.The fertilization order of the second physiological fruit drop period of the low-yield plot in the Dagou orange orchard in Citrus Research Institute,by CND method:Ca>Zn>Mn>Cu>Mg,by DOP method:Zn>Ca>Mn>Mg,by DRIS method only needs to be increased Ca fertilizer.The Yunyang low-yield plot by CND method:Mn>K>P>Fe>Zn;by DOP method:Mn>Fe>K>P;by DRIS method:Mn>Zn>Ca;the Fertilization order of the expansion period low-quality plot in the Dagou orange orchard in Citrus Research Institute,by CND method:Ca>Mg=Mn>Fe,by DOP method:Mn>Ca,by DRIS method:Ca>Mn>Mg,and Yunyang low-quality plot by CND method:P>K>Mn>Fe;by DOP method:P>K>Mn;by DRIS method needs to increase P fertilizer.Through the comprehensive analysis of the three methods,it was found that the overall nutritional status was lacking micr-fertilizer in the Dagou orange orchard in Citrus Research Institute and the nutrient balance of Yunyang navel orange orchard was poor.Every region had a great potential of production.5.Screen and establish an automatic generation algorithm model for the nutritional diagnosis of adult Newhall navel orange based on the CND inflection point model,and combine the DOP method to achieve automatic feedback of nutritional diagnosis results and fertilization recommendations.The results showed that the CND inflection point method was used to establish the nutritional diagnostic criteria for the key phenological stage of citrus,and the diagnosis results of leaf DOP were reasonable.The results provide a precise management of citrus orchard nutrient management and intelligent decision-making system for algorithm model and theoretical basis.