Effects Of Altitude And Slope Aspect On Soil Nutrients And Fruit Quality Of Citrus

Citrus is sweet,juicy and nutritious,with high economic value,and has become an important cultivated economic crop in the south.In recent years,the citrus planting area and total output have been increasing,while the yield is low and the quality is low.Therefore,it aims at improving the quality and efficiency of citrus,saving costs and increasing income,and improving competitiveness and other issues and needs.Taking Hubei,Chongqing,Hunan,Jiangxi,Guangxi,and Guangdong citrus orchard production areas as the research object,the soil nutrients and fruit nutrition status of citrus orchards in different topography parts and their relationship with fruit quality were studied,with a view to citrus orchard soil management and improvement,Provide a basis for rational fertilization and nutrient correction.The main findings are as follows:(1)The soil pH of citrus orchards in the country is generally acidic,the content of exchangeable calcium and magnesium in the soil is low,the available boron content in the soil is at a moderately low level,and the soil organic matter,alkaline nitrogen and available copper,and zinc are at a moderately high level.Soil available phosphorus,available potassium and available sulfur,iron,and manganese are at high levels,and available soil molybdenum is not evenly distributed,and the two-stage differentiation is serious.The comprehensive rankings of the soil fertility of the seven citrus orchard producing areas studied are as follows: Guilin,Guangxi> Chenzhou,Hunan> Yichang,Hubei> Chongqing> Meizhou,Guangdong> Huaihua,Hunan>Fuzhou,Jiangxi.(2)Within a certain range,as the altitude increases,the contents of available potassium,exchangeable calcium and magnesium in the soil gradually decrease,and the contents of soil alkaline nitrogen and available sulfur show a "concave" type change characteristic.The available phosphorus,copper and zinc content in the soil showed a normal distribution with increasing altitude.The soil pH,organic matter,available iron,manganese,and boron content did not show significant changes with increasing altitude.(3)According to the order of sunny slope → semi-yang slope → semi-yin slope→ shady slope,the available sulfur content in the soil is normally distributed,and the contents of soil organic matter,alkali-decomposed nitrogen,available potassium and exchangeable calcium and magnesium are in the form of "concave" Distribution,the available boron content in the soil decreases continuously with the slope from yang to yin.The soil pH and available manganese,phosphorus,iron,manganese,copper,zinc,and boron contents show obvious changes with the slope direction changing from the sunny slope to the shady slope.(4)The content of N,K and Fe in the fruit,as well as the ratio of vitamin C,soluble solids and solid acid is highest in the Guilin citrus orchard in Guangxi,the content of Mg and Mo is the highest in Chenzhou,Hunan,the content of P in the fruit is highest in Chongqing,and the content of Ca The content reached the highest in Yichang,Hubei.The S content of citrus orchards in Fuzhou,Jiangxi,Guilin,Guangxi,Chenzhou,Hunan,and Meizhou,Guangdong was significantly higher than that of Chongqing citrus orchards;Mn,Cu,Zn,B,etc.did not show significant differences in different citrus orchards.The edible rate of the fruit is the best in Fuzhou,Jiangxi.The comprehensive ranking of fruit nutrition in the seven citrus orchards studied is as follows: Guilin,Guangxi> Fuzhou,Jiangxi> Chenzhou,Hunan> Huaihua,Hunan>Meizhou,Guangdong> Chongqing> Yichang,Hubei.(5)Soil nutrients-fruit nutrients and qualities are extremely significantly positively correlated: pH,B-titrable acid;organic matter,K,Ca,Mg,S,Mo-vitamin C;N,K,Ca,Mg-Solid acid ratio;P,Cu,Zn-single fruit weight.Soil nutrients-fruit nutrients and quality are significantly positively correlated: Ca-Ca;Mn-B;Cu-Cu;organic matter-solid acid ratio;S-single fruit weight;Mn,Cu-titrable acid.Soil nutrients-fruit nutrients and quality are extremely negatively correlated: pH-vitamin C,soluble solids and solid acid ratio;organic matter,N,K,Ca,S,Cu,B-edible rate;Ca-single fruit Heavy;S-titrable acid;Mn,Mo-soluble solids.Soil nutrients-fruit nutrients showed significant negative correlations: pH-Mn;organic matter-P;B-single fruit weight and solid acid ratio.