Effects of High Salt Concentrations on Growth of Bean Plants

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Abstract
Red kidney bean plants were grown to the flowering stage in aerated soln. culture with basal nutrient soln. and in this soln. with various amts. of Na2S04, NaCl, CaCl2, MgCl2, or MgSO4 added. The effect of these separate salts on plant growth was studied in concs. of 1.5, 2.5, 3.5, and 4.5 atms. osmotic concn., including the 0.5 atm. conc. of basal nutrient. At isosmotic concns., similar amts. of growth occurred in the NaCl, CaCl2, and Na2SO4 series, but there was a marked depression of growth with MgCls or MgSO4. For most salts and mixtures of salts there tends to be a linear relationship between growth and osmotic conc., expressed in atmospheres. High concs. of Mg salts produce symptoms of toxicity in the bean plant. This toxicity is evidenced by a necrosis of root primordia and by the appearance of necrotic areas in the pulvini of the trifoliate and primary leaves, and in extreme cases by necrotic lesions on the petioles, internodes, and even the hypocotyl.