Application of calcium and boron for controlling yellow latex contamination on the mangosteen fruits (Garcinia mangostana L.)

Abstract

Yellow latex originally can be found in all of mangosteen organs, except in the root. When Yellow latex is spilled from its chanenel it will become a serious issue, because it can damage the visual performance of rind and the taste of aryl. Yellow latex contamination in mangosteen occur due to the pressure from the seeds and aril within the time of fruits development, it is also due to the of change of turgor compulsion. The cause of yellow latex bursting is lack of Calcium on the cells epitel membrane. Calcium is important on the developing of membrane’ structure as Ca-pektat in middle lamela. Another element that able to keep the membrane integrity is Boron. In the growth phase, Boron is used on cells division and as regulator for membrane function. The combination of calcium and boron are estimated to affect on controlling of yellow latex contamination in mangosteen. This research was aimed to know the role of calcium and boron application in controlling contamination yellow latex on the mangosteen fruit, Other objectives were to get the best combination calcium and boron in preventing the yellow latex contamination on mangosteen. The research was conducted at the field in Purwakarta West Java, from November 2012 to June 2013. The two factor experiment was designed in a randomized block design with three replications. The rates of calcium were 0.0, 2.5, 5.0, and 7.5 kg/tree. The rates of boron were 0.0, 0.77, 1.55, and 2.32 g/tree. Fertilizer application is done twice, first at 80% anthesis as much as 2/3 of the dose of treatment, and the second giving as much as 1/3 of treatment dose 28 days after the first treatment. Variables measured: (1) Measurement of levels of yellow latex contaminant include: The number of fruit which aryl contaminated with yellow latex, the number of fruit with contaminated pericarp, the number of contaminated aryl segment, score of yellow latex intensity in the aryl and pericarp. (2) the physical properties of the fruit include: fruit weight, pericarp weight, seed weight, aryl weight, edibel portion, longitudinal diameter, transversal diameter, rind hardness, resistance, and observations to the development of pre-harvest fruit diameter. (3) the chemical properties of the fruit are: total soluble solids (TSS), total titrable acid (TTA), nutrient content of Ca, Mg and B in plant tissue and soil, leaf chlorophyll content. Application of dolomite and boron significantly reduce scores and the percentage of yellow latex on the aryl and pericarp, percentage of aryl segment contaminated with yellow latex, increas content of calcium and boron in fruit perikarp. There was interaction between dolomite and boron fertilizer on score and percentage of aryl contaminated with yellow latex. The optimum rate of dolomite and boron to get minimum score and percentage of aryl and pericarp contaminated with yellow latex ranging from 3.7 to 5.0 kg Ca/tree and 0.85 to 1.55 g B2O3/tree. Application of dolomite and boron at 5.0 kg Ca/tree and 1.55 g B2O3/tree can reduce the percentage of fruit which aryl contaminated with yellow latex by 98%, from 66.67% to 1.05%. Fertilizer of boron with a dose of 2.32 g/tree on 20 years old mangosteen in Purwakarta is already beyond the maximum dose, thus increasing the fruit contaminat with yellow latex.