SOME EFFECTS OF SODIUM SALTS ON THE GROWTH OF THE TOMATO

Abstract

Marglobe tomatoes were grown in sand cultures using a nutrient soln. with NaCl and Na2SO4 as the added salts. Two series were set up with 5 treatments each control, 40, 80, 120, and 160 m.e.Na/1. To segregate supplementary effects of the anions, series A had Na supplied as 25% Cl- and 75% SO4=, series B as 75% Cl- and 25% SO4=. The plants were grown to maturity to obtain data on flowering and fruit production. The osmotic conc. of the substrate appears to be a primary factor in growth inhibition, although secondary effects of the Cl- and SO4 are noted. The principal effects of high conc. of the substrate were: a) reduction in height and diam. of stems and fresh and dry wt. of vines, b) reduction in cambial activity, maturation of cells of smaller size, and relatively thicker walls in xylem elements and mechanical cells, c) inhibited floral development and reduced set of fruit, d) reduction in total yield of fruit and in size and wt. per fruit, e) increase in osmotic conc. of the vegetative and fruit juices. The accumulation of Ca, K, Mg, and N in the juice of the ripe fruit was greater at high osmotic concs. of the substrate although those elements were supplied in equal amts. for all treatments. The accumulation of Cl, SO4, and Na in the vegetative and fruit juices increased with increasing increments of salt in the substrate. Flavor did not appear to be impaired by salt treatments. The incidence of blossom-end rot appeared to be related to wide fluctuations in water stress. High accumulation of K may be a contributing factor.