Relationship between Photosynthetic Capacity and Carbohydrate Content of Mangifera indica cv. Harumanis in Response to Girdling and Paclobutrazol

Girdling and paclobutrazol have been related with the effects on the photosynthetic capacity and carbohydrate content of plants. The physiological changes caused by these methods distress the growth and development of plants in general. A field experiment was carried out from August 2021 to June 2022 on 5 years of open-field Mangifera indica cv. Harumanis trees grown at Malaysian Agriculture Research and Development Institute (MARDI), Serdang, Selangor. The objective of this experiment was to understand the relationship between girdling, paclobutrazol application, combined methods and untreated trees on plant photosynthetic performances and carbohydrate content in the leaves. The treatments were performed on 1st December 2021, and the measurements of leaf gas exchanges and carbohydrate content were performed 4th weeks later on fully expanded leaves shoot, experiencing similar light exposure. In the study, the combination of girdling and paclobutrazol application resulted in a significant decrease in photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (Tr) but significantly increase in intercellular CO2 concentration (Ci) and carbohydrate content.