Boron deficiency alters cell wall anatomy and reduces hydraulic conductance in Macrotyloma uniform a quantitative morpho-anatomical study

Boron (B) deficiency is an important micronutrient limitation that can adversely affect plant growth and vascular development. This study evaluated the effects of B deficiency on germination, early growth, biomass accumulation, tissue water status, and quantitative anatomy of Macrotyloma uniflorum (horse gram) under controlled hydroponic conditions using three independent experimental replicates. B deficiency significantly reduced germination, vigor, plant height, fresh weight, and dry weight compared with B-sufficient plants. Quantitative anatomical analysis showed pronounced alterations in vascular and ground tissues, including reduced xylem vessel dimensions, decreased xylem cell wall thickness, swollen root tips with enlarged cortical cells, and frequent vascular abnormalities. B-deficient plants also exhibited higher tissue water content than B-sufficient plants. Based on the Hagen–Poiseuille relationship, the observed reduction in xylem vessel radius corresponded to a theoretical 95.6% reduction in hydraulic conductance. These findings suggest that B deficiency disrupts cell-wall organization and vascular development, potentially limiting water-transport capacity and contributing to impaired early plant growth. The study provides a quantitative morpho-anatomical framework for understanding B deficiency responses in M. uniflorum and suggests that xylem vessel dimensions may have potential as a morphological indicator for screening B-use efficiency.