Salt Tolerance of Muskmelons as Affected by Various Salinities in Sand Culture

Abstract

Muskmelons (Cucumis melo L.) were grown in sand to determine the salt tolerance as affected by salinization of sea water, NaCl, Na₂SO₄ and MgCl₂ in Experiment I, and MgSO₄ in Experiment II at osmotic potentials of -0.95 (MgSO₄ only), -1.20, -1.70 and -2.70 bars as compared to a control of -0.70 bars of base nutrient solution. Fruit fresh weight and whole plant dry weight were greatest in the control and decreased in each salinity with decreasing osmotic potentials of treatment solutions. At -2.70 bars fruit fresh weight in the control was 37.3, 31.4, 11.8, 24.8 and 17.0% in the sea water, NaCl, Na₂SO₄, MgCl₂ and MgSO₄ series, respectively. No plant died in the sea water and NaCl series. A few plants at -2.70 bars in the MgCl₂ series withered by harvest. All plants died within 60 days after transplanting at -2.70 bars in the Na₂SO₄ series and at -1.70 and -2.70 bars in the MgSO₄ series. The growth in decreasing order was control>sea water_??_NaCl>MgCl₂> Na₂SO₄_??_MgSO₄. The addition of single salts or sea water to the base nutrient solution increased the content of the respective added ions in leaves and soil solutions (SSa) and EC of SSa, and decreased osmotic potentials of SSa. Ca in leaves decreased in the Na₂SO₄, MgCl₂ and MgSO₄ series with decreasing osmotic potentials of treatment solutions. The result seemed to suggest specific effects of Mg and SO₄ ions on muskmelons.