NUTRIENT INTERRELATIONS IN LIME-INDUCED CHLOROSIS

Abstract

Analyses of leaves of pear, apple, peach, and cherry trees affected with lime-induced chlorosis indicated a correlation between the Ca/K balance and the degree of chlorosis. Chlorotic leaves were usually high in K and somewhat low in Ca and Mg. The Fe content of chlorotic leaves was sometimes low, but in some cases it was higher than that of green leaves. N, P, and Mn were not found to be correlated with lime-induced chlorosis. When leaves were extracted successively with water, ether, 0.1 N HC1, 0.5 N HC1, and 1 N HC1, only the 0.5 N HC1 fraction was found to be consistently low in Fe in the chlorotic leaves. In both green and chlorotic leaves, K was found to be mostly water soluble. Mg and Mn were either water soluble or easily dissociated by 0.1 N HC1 (except a small amt. of Mg present in the ether fraction). Ca, P, and Fe were distributed more generally in all of the fractions. Over half of the Fe in the leaves was present in a form insoluble in 1 N HC1; presumably as iron-hematin, iron nucleoprotein, or in other complex organic compounds. The data suggest that in calcareous soils, when Fe approaches a limiting level, an upset in the Ca/K balance may induce chlorosis by preventing the formation of an iron-containing enzyme which functions in chlorophyll synthesis.