The determination of pitaya shoot maturity relevant to the competence of receiving long day length induction by CPPU

For studying the flower physiology of pitaya plants (Hylocereus sp.), determining the maturity of current shoots is essential. N-(2-Chloro-4-pyridyl)-N′-phenylurea (CPPU), a synthetic cytokinin, functions as a competitive inhibitor of cytokinin oxidase and was used to amplify the function of endogenous cytokinins. Spraying 100 mg•L−1 CPPU on the current shoots of different ages 7.5 weeks after the spring equinox (WASE) may result in budding within 1 week. In our study, typical floral buds emerged on the mature shoots but not immature shoots. Furthermore, the critical shoot age for the pitaya plant to be competent for receiving long day length stimulus at spring equinox was line between 13.5 and 15.5 weeks of pre-growth. Application of CPPU to the shoot older than 1 year at 5.5 WASE resulted in precocious flowering by 2 weeks. © 2022