Foliar Supplied Boron Can Be Transported to Roots as a Boron-Sucrose Complex via Phloem in Citrus Trees.

ABSTRACT: Although foliar boron (B) fertilization is regarded as an efficient way to remedy B deficiency, the mechanisms of foliar B transport from leaves to roots are still unclear. In this study, performed with 1-year-old "Newhall" navel orange (Citrus sinensis) grafted on trifoliate orange (Poncirus trifoliata) plants, we analyzed the B concentration in leaves and roots, B-sucrose complex in the phloem sap after foliar application of ¹⁰B, girdling, and/or shading treatments. Results indicated that ¹⁰B concentration was significantly increased in roots after foliar ¹⁰B treatment. On the other hand, both girdling the scion stem and shading over the plants with a black plastic net significantly reduced the B and ¹⁰B concentration in roots. LC-MS analysis revealed that foliar ¹⁰B-treated plants had higher concentration of sucrose and some sugar alcohols in the phloem sap as compared to foliar water-treated plants. Combining with the analysis in the artificial mixture of B and sucrose, a higher peak intensity of the ¹⁰B-sucrose complex was found in the phloem sap of foliar ¹⁰B-treated plants compared to the control plants. Taken together, it is concluded that foliar B can be long distance transported from leaves to roots via phloem, at least by forming a B-sucrose complex in citrus plants.

SUBMITTER: Du W 

PROVIDER: S-EPMC7076173 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature