Cascading Effects of Boron Application Methods on Nutrient Distribution and Metabolite Profiles in Pear Trees

Boron (B) deficiency poses a significant challenge in commercial pear (Pyrus spp.) production, typically addressed through root or foliar supply. However, the impact of these B supply methods on plant nutrition and metabolism in pear trees remains relatively unexplored. This study comprehensively examines three B application treatments: control (no B supply), foliar B supply, and root B supply, with B supplied to pear plants in the form of the stable isotope ¹⁰B. Both foliar and root B applications increased B concentration and accumulation in various plant tissues, with significant variations in distribution patterns. Notably, foliar application enhanced B accumulation in scion tissues and roots, challenging the traditional limitations of B transport. Furthermore, significant interactions between B application methods and mineral nutrients, particularly nitrogen (N), phosphorus (P), calcium (Ca), and magnesium (Mg), influenced nutrient content and distribution. Metabolite profiling of leaves revealed substantial changes in amino acids, organic acids, and fatty acids in response to B applications, whether foliar or root, suggesting impacts on amino acid metabolism, carbohydrate metabolism, and plant resistance mechanisms. This study highlights the effectiveness of both foliar and root B application methods for B supplementation in pear trees, potentially enhancing growth and stress adaptation. In practical terms, combining foliar and root B applications offers a comprehensive approach to correct B deficiency in pear.