Effect of Foliage Calcium Spray on Potassium, Calcium, Magnesium Contents and Fruit Quality of Mango Plants

Effect of spraying calcium-containing solutions of varied concentrations on fruit quality as well as potassium (K), calcium (Ca) and magnesium (Mg) contents in the fruits and leaves of mango plants werestudied to determine the possible benefit of theapplication. Tainung No 1 mangotrees were subjected to the spraying of Ca solutions at the concentration of 0 (CK), 0.5, 1.5, 2.5, and 3.5g/L on the leaves at the time before flower induction, of early fruiting stage, during fruit growing stage, or before harvesting. It was found that the Ca contents in the leaves, as well as thepeel, pulp and stone of the fruits increased due to the treatmentswithin the tested range of Ca concentrations. Ca in the fruits was significantlylower than that in the leaves. The correlation on K/Ca/Mg contents between the 1^st tip leaf and the fruits was more significant than that between the 2^nd leaf and the fruits. On the 2^nd leaf, itsK and Mg contents decreased, while Ca increased, after thetreatments.Interestingly, the spraying increased the sugar/acid ratio, significantly decreasedtitratable acid, and heightened vitamin C content resulting in an improved eating quality of the fruits. However, spraying athigh Ca concentration tended to reduce the soluble solids and sugars in the fruits. It was concluded that, within the tested concentration range, spraying the Ca-containing solutions on the mango plants could upgrade the fruit quality, withthe greatest effect observedat a Ca concentration of 0.5 g·L^-1.