An ideal leaf spraying strategy of brown sugar for edible medicinal plants of Viola inconspicua

The typical edible medicinal plants of Viola inconspicua were compared with leaf-green, biomass, metabolomes, and bacterial communities, after leaf-spraying water (A), brown sugar water (B), brown sugar, urea, and KH₂PO₄ water (C), or KH₂PO₄ and urea water (D). The plants sprayed with C solution presented relatively normal leaf-green and the highest biomass. In contrast of A group, B, C, and D groups were found with 72, 94, and 104 leaf differently accumulated metabolites (DAMs) and 105, 88, and 92 root DAMs, respectively. Typically, relative abundances of amino acids were elevated in C and D groups, while those of leaf flavonoids were increased in B group. Noticeably, leaf DAMs of C group versus A group had strong correlations with one to more phylum- or/and genus-dominant bacteria of C group. Taken together, leaf-spraying brown sugar, urea, and KH₂PO₄ water are ideal for holding leaf-green and biomass in V. inconspicua plants.