Inhibition of photosynthesis by flowering in mango (Mangifera indica L.). A study by gas exchange methods.
Shivashankara K. S., Mathai C. K.
Author Affiliation: Tree Physiology Laboratory, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore, 560 089, India.
Scientia Horticulturae 83 : 205-212
Abstract : A regular (cv. Thothapuri) and an irregular (cv. Langra) bearing cultivar of mango were selected to study the gas exchange parameters such as photosynthesis, stomatal conductance and internal carbon dioxide concentrations in flowering and non-flowering branches. Experiments were conducted on 14-year-old trees at Bangalore. Photosynthetic rates at different carbon dioxide concentrations were also recorded in both types of branches to calculate the carboxylation efficiency by generating CO2 response curves. Photosynthetic rate and stomatal conductance were higher in non-flowering branches than in the flowering ones, in both cultivars. The reduction in photosynthetic rate was not due to variation in the water status of the leaves, since relative water content of the leaves in both types of branch was not significantly different. Hence, the reduction in photosynthetic rate could be mainly due to the reduction in carboxylation efficiency. Such a reduction in carboxylation efficiency could be due to the presence of inhibitors in the leaves of flowering branches.