Responses of C:N:P stoichiometry and non-structural carbohydrate contents of Prunus mume seedling to nitrogen addition

Prunus mume (P. mume) is a precocious flowering fruit species valued for its use in forestry and urban greening. Nitrogen (N) is a critical factor affecting early seedling growth and nutrient acquisition. However, the organ-specific responses of carbon (C): N: phosphorus (P) stoichiometry and non-structural carbohydrate (NSC) pools to varying N supply remain unclear in this species. To address this, we examined the effects of five N levels (0, 5, 10, 20 and 40 g N plant⁻¹) on morphological characteristics, C:N:P stoichiometry, and non-structural carbohydrate contents in the leaves, stems, and roots of P. mume seedlings under greenhouse conditions. Results indicated that N addition had a complex impact on seedling growth. While it significantly reduced P content across three organs, it increased total N content in the roots, stems, and leaves of P. mume seedlings. Higher N levels (40 g N plant⁻¹) also resulted in a marked rise in the N/P ratio, especially in stems. In terms of C reserves, N addition significantly increased soluble NSC content, while starch storage significantly decreased. Overall, N addition fundamentally changed the C:N:P stoichiometric balance and C reserve allocation in P. mume seedlings, with the reduction in starch closely associated with the accumulation of soluble sugars. These findings provide a scientific basis for optimizing N fertilizer schedules, thereby supporting high-quality nursery production and the sustainable establishment of P. mume orchards in forestry and agroforestry systems.