Effect of Soil Acidity and Magnesium on Muskmelon Leaf Composition and Fruit Yield

Abstract

The response of muskmelons ( Cucumis melo L.) to Mg fertilization and soil pH was studied on a Princeton loamy sand that contained 34 kg·ha −1 available Mg at pH 4.8. Calcitic limestone was used to adjust the soil to pH 5.4 in 1984 and 5.8 in 1985. Magnesium was added for 2 years at 0, 56, 112, and 168 kg·ha −1 . Lime application increased exchangeable soil Ca and decreased exchangeable Mn. Liming had no effect on exchangeable Mg, but Mg application increased exchangeable Mg linearly. Plants developed Mg deficiency in plots receiving no Mg treatment regardless of soil pH and Mn toxicity in unlimed plots at pH 4.8. Leaves developed Mg deficiency symptoms when the Mg concentration in leaf tissue was 0.30%. Magnesium application increased leaf tissue Mg and reduced leaf tissue Mn concentrations. Application of calcitic limestone increased leaf tissue Ca and reduced leaf tissue Mg and Mn concentrations. Muskmelon fruit yields were increased both by liming and Mg applications. Yield increases due to liming were attributed to reduced Mn levels in plant tissue.