Effects Of Chemical Fertilizer Partialy Substituted By Organicfertilizer On The Nutrition And Fruit Quality Of Pomelo Trees

‘Guanximiyou' [Citrus maxima(Burm.)Merr cv.Guanximiyou] is the main cultivated pomelo variety in China,mainly planted in Pinghe,Fujian.In recent years,a large number of fruit farmers have been blindly using fertilizer for the pursuit of yield,long-term overuseing chemical fertilizers causes problems such as soil environmental damage and the decline in the quality of pomelo.Organic fertilizers are rich in nutrients and long in fertilizer efficiency,which is beneficial to improving soil environment and fruit quality.‘Sanhongmiyou' [Citrus maxima(Burm.)Merr cv.Sanhongmiyou] is a new variety of ‘Guanxi-miyou'.This experiment uses the ‘Sanhongmiyou' as a test material,with a single application of chemical fertilizer as a control(CK),with organic fertilizer instead of 20% chemical fertilizer(T1),organic fertilizer instead of 40% chemical fertilizer(T2)and organic fertilizer instead of 60% chemical fertilizer(T3),to study the effects of organic fertilizers partly replacing of chemical fertilizers on soil environment,tree nutrition and fruit quality.The main findings are as follows:1.The replacement of some chemical fertilizers by organic fertilizer can improve the soil environment,increase the effective nutrient content of some soils,and help regulate soil nutrient balance.Compared with single application of chemical fertilizers,organic fertilizers partly replace of chemical fertilizers can improve soil organic matter content.T1 treatment can effectively increase soil pH,increase soil available nutrients such as available potassium,exchangeable calcium and available zinc.The soil available phosphorus content is too high,and the exchangeable magnesium content is lacking.T2 treatment is more conducive to regulating soil available phosphorus and exchangeable magnesium content,and promoting this two effective nutrient contents to reach the suitable content range of pomelo growth.2.The replacement of some chemical fertilizers by organic fertilizer is beneficial to regulate the nutrient level of the tree.The nitrogen content of the ‘Sanhong-miyou' leaves treated with single fertilizer is too high,and the magnesium content is low.The replacement of some fertilizer by organic fertilizer can effectively reduce the nitrogen content of the leaves,and increase the magnesium content of the leaves,let this two mineral element contents reached an appropriate level;compared with the single application of chemical fertilizer,T1 treatment can significantly increase the zinc content of the leaves,T2,T3 treatment can significantly increase the calcium and boron content of the leaves.3.The replacement of some chemical fertilizers by organic fertilizer can effectively improve the content of various mineral elements in ‘Sanhong-miyou'.Compared with CK,the treatment of some chemical fertilizers replaced by organic fertilizer can effectively increase the content of potassium,calcium,zinc and boron in fruits.Among them,T2 treatment had the most significant increase in potassium,zinc and boron contents,and T3 treatment had the most significant increase in calcium content.In addition,T2 and T3 treatments are also beneficial to promote the improvement of nitrogen and magnesium contents in fruits.4.The replacement of some chemical fertilizers by organic fertilizer can significantly improve the soluble solid content,total sugar content,sugar-acid ratio and water content of ‘Sanhongmiyou',and reduce the titratable acid content of the fruit,but the Vc content,edible rate of the fruit,single fruit weight,fruit type index and peel thickness did not have a significant effect.T1 treatment is beneficial to improve the activity of cell wall metabolism-related enzymes such as PME,PG and Cx in the ripening process of ‘Sanhongmiyou',it can reduces the slag and granulation of fruit,and improves the fruit quality of ‘Sanhong-miyou'.