The effect of boron fertilization on mangosteen (Garcinia mangostana L.) fruit quality

The production of Indonesian mangosteen increased from 72,634 t in 2006 to 97,487 t in 2011. However, the export in 2010 was only 11,388 t or 13.5% of the total production. The low proportion of exported fruit is caused by several fruit quality problems, especially yellow latex and pericarp scaring. Yellow latex incidence is related to low calcium and boron content on the pericarp. The objective of this research was to study the effect of boron application on fruit quality, especially on yellow latex (gamboges) incidence. The research consisted of two experiments, boron application into the soil, and spray application of boron. The first experiment consisted of application of 0, 15, 30, or 45 g boron (B₂O₃) per plant. The results showed that soil boron applications significantly reduced the incidence of yellow latex on the pericarp by 20-33% but had no effect on yellow latex in fruit flesh. Boron application also significantly increased fruit weight and diameter as well as total soluble solids, but had no effect on pericarp hardness and thickness, total titratable acid, or vitamin C content. In the second experiment, boron was sprayed at 0 and 1, and 2 and 3 g L^-1 at 1 and 2 months after anthesis. Results showed that spray application of boron had no significant effect on incidence of gamboges in the pericarp and flesh, fruit scaring, fruit hardness, vitamin C, total soluble solid, total titratable acid, fruit diameter and weight, or fruit drop.