Abstract:Trifoliate orange was used to set the foliar application and root application with H3BO3.The effects of different ways of applying boron on agronomic traits of trifoliate orange,dry matter accumulation,the contents of boron (B),potassium (K),calcium (Ca),magnesium (Mg) in different parts,and contents of the sugar,malondialdehyde (MDA),proline (Pro) and the injured rate in the leaves were studied.The results showed that different fertilization methods led to quite different results.Foliar boron significantly increased dry weight of stem and leaf of trifoliate orange seedling,total dry weight and height,and promoted the growth of root.Concentration of boron in leaves increased by 126.5%.There was 1.3% boron in stems metastasis and accumulation.Foliar applied boron made boron content decrease by 11.1% in trifoliate orange roots.Contents of K,Ca and Mg in leaves under foliar boron were significantly higher than that of CK.Contents of elements were significantly higher by root giving boron than that by foliar boron (except leaf).Contents of sugar,MDA,Pro and injury rates in leaves decreased after applying boron.Foliar boron had a good effect in maintaining the balance of the elements in leaves,carbohydrate synthesis and improving the stress resistance of leaves.It can reduce the content of boron in root and aggravate boron deficiency.