Studies On The Influence Of Soil And Leaf Nutrient On Citrus Fruit's Output And Quality

Citrus industry is the long-term mainstay industry of Three Gorges reservoir area, it will play important role in agricultural production and everyday life of farmers, espesically immigrants. This study took 20 representive citrus orchards of Zhongxian as the research objectives. This paper studies the influence of soil and leaf nutrient on citrus fruit's output and quality in Zhongxian County of the Three Gorges reservoir area, so as to offer scientific basis for nutrition diagnosis and rational fertilizing. The main conclusions of this study are as follows:1. Soil nutrition situation of citrus orchardsResult shows that available N & K were seriously deficient, quick P was low, and however available Ca,Mg,Fe,Mn,Cu were superfluous, available Zn was in optimum range. The pH range of Citrus orchards soil was 4.05～7.90. Extremely significant negative was found between the contents of available N,available Fe,Mn,Cu and pH values in soil. Extremely significant positive was found between the contents of available Ca,Mg and pH values in soil. Meanwhile, there was extremely significant positive correlation between available N,P, the contents of available Fe,Mn,Cu,Zn and soil organic matter of citrus orchard, and a extremely significant negative correlation between the contents of available Ca and soil organic matter of citrus orchard. Results indicated that improving soil organic matter is helpful to soil nutrient status.2. Nutrition levels of citrus leavesThe mineral nutrient status of citrus was studied by leaf analysis. Result indicated that P , N and Ca contents were in optimum status, and K was deficient, however Mg was excess , but Fe,Cu,Zn were optimum, and Mn was inadequate . There were extremely significant negative correlation between pH values in soil and the contents of leaf N and Mg, and significant negative correlation was found between pH values in soil and the contents of leaf Mn, but significant positive correlation and the contents of leaf Ca. There were significant negative correlation between the contents of soil organic matter and leaf Ca,but significant positive correlation between the contents of soil organic matter and leaf N and Fe.Ca and extremely significant leaf Mg.3. Influence of nutrient of soil on nutrient levels in leavesSignificant Correlation was between mass fractions of mineral nutrient elements in leaves and mass fractions of a few of nutrient of soil. Results indicated that their relation was complexity. Leaves N,soil N and available Mn were extremely positive correlation. Leaves Ca and soil available Ca were extremely positive correlation. Leaves Ca and soil available Fe,Cu were negative correlation. Leaves Mg and soil available Ca were extremely negative correlation. Leaves Mg and soil available Fe were extremely positive correlation. Leaves Fe and soil P,available Fe were extremely positive correlation. Leaves Mg and soil available Ca were extremely negative correlation. Leaves Fe and soil available Mn were positive correlation. Leaves Cu and soil available Fe,Cu were positive correlation.4. Influence of nutrient of soil on output and quality of citrus fruitThe soil pH value and organic matter significantly influenced output of citrus fruit. The N,P,K,Ca in soil significantly influenced output of citrus fruit.The micro nutrient had less influence on output of citrus fruit. Weight of single fruit and soil were extremely negative correlation. Weight of single fruit and soil organic matter were extremely positive correlation. Weight of single fruit and available Fe were extremely positive correlation. TTS and soil pH value were extremely negative correlation. TTS and soil organic marten available Fe were extremely positive correlation. Acid and soil pH value were extremely negative correlation. Acid and soil organic matter,available Mg,Cu,Zn were extremely positive correlation. Fruit Vc and soil pH value,available K were positive correlation. Fruit Vc and soil organic matter,other nutrient elements were negative correlation. Fruit Vc and soil available Mg were extremely negative correlation.5. Influence of nutrient levels in leaves on output and quality of citrus fruit Leaves N,K,Ca,Mg,Fe,Cu,Zn significantly influenced output of citrus fruit.That is, nutrient levels in leaves can reflect nutrient requirements of output of citrus fruit. Weight of single fruit and leaves Mg were extremely negative correlation. TTS and leaves K were extremely negative correlation. Acid and leaves N,Zn were extremely positive correlation. Fruit Vc leaves nutrient elements were no significant correlation.6. Identification of appropriate soil nutrient and leaves nutrition diagnosis indexes of excellent citrus orchardsThe field of soil available nutrition elements content were that pH value was 4.1～7.6, organic matter was 0.42～1.24g/Kg, available N was 6.5～14.5mg/Kg, available P was 2.5～38.4 mg/Kg, available K was 52.4～114.4 mg/Kg, available Ca was 4277.2～5345.6 mg/Kg, available Mg was 72.6～253.3 mg/Kg. The field of leaves nutrition elements content were that N was 2.18%～2.63%, P was 0.12%～0.14%, K was 0.62%～1.14%,Ca was 2.27%～4.87%, Mg was 0.69%～1.13%.