The changes in C/N, carbohydrate, and amino acid content in leaves during female flower bud differentiation of Juglans sigillata

This study was conducted to investigate the relationship between carbon and nitrogen nutrition with physiological and morphological differentiation stages of Juglans sigillata, which could provide an important theoretical basis for improving walnut output and its quality. The results showed that the female flower bud differentiation of J. sigillata was finished in 2 years and the total duration was nearly 1 year. At the physiological differentiation stage, higher carbon-to-nitrogen ratio (C/N) due to an increase in the soluble sugar content, heterocyclic, aromatic, and hydrophobic amino acids, and proline (Pro) and alanine (Ala) initiated the differentiation of the female flower bud. After initiation of flower bud differentiation, nitrogenous compounds, such as alkaline amino acids and heterocyclic imino acids, especially arginine (Arg), Pro, Ala, and l-cysteine (Cys), and a higher content of soluble sugars favored its morphological differentiation. These results could provide a theoretical basis and reference for controlling the ratio of male and female flower buds in production to improve iron walnut yield.