Changes in mineral element contents of ‘Newhall’ navel orange (Citrus sinensis Osb.) grafted on two different rootstocks under boron deficiency

The hydroponic method was used to study the changes in boron (B), zinc (Zn), calcium (Ca), magnesium (Mg) and potassium (K) concentrations of Newhall navel orange (Citrus sinensis Osb.) grafted on citrange［C. sinensis (L.) Osb. Poncirus trifoliate (L.) Raf.］ or trifoliate orange ［Poncirus trifoliata (L.) Raf.］ under B deficiency. The results show that under the B deficiency, B concentrations of trifoliate orange-grafted plants and Zn concentrations of citrange-grafted plants are significantly decreased, which may be one of the reasons why trifoliate orange-grafted plants are easy to appear symptom of B deficiency and citrange-grafted plants are easy to appear symptom of Zn deficiency under the B deficiency. Compared to the normal B treatment, Ca concentration in leaves of trifoliate orange-grafted plants is increased obviously under the B deficiency, and K concentration in root of trifoliate orange-grafted plants is much higher than that of citrange-grafted plants. These results indicate trifoliate orange-grafted plants are more sensitive to the B deficiency. There are not significantly differences in Mg concentrations between trifoliate orange-grafted and citrange-grafted plants under the B deficiency.