EFFECT OF SALINE SUBSTRATE ON HOURLY LEVELS OF CARBOHYDRATES AND INORGANIC CONSTITUENTS OF BARLEY PLANTS

Abstract

Barley plants were grown in sand-cultures supplied with a base nutrient, with base nutrient plus 100 mg. equiv./l. of chloride, and with the base nutrient + 200 mg. equiv./l. of sulfate. The plants were sampled at 4-hr. intervals over a 24-hr. cycle and analyzed for mineral constituents and carbohydrates. Regardless of treatment, there was no measurable effect of time of day on the conc. in the dry matter of Ca, Mg, Na, K, SO4, Cl, and total-N. There were, however, large fluctuations in the conc. of sugars (primarily sucrose) and starch. The "salt plants" contained higher percentages of sugars on a fresh wt. basis than did the control plants. The addition of both chloride and sulfate salts (24-hr. averages) reduced Ca concs. relative to the control plants, left Mg unchanged, caused a marked increase in Na, a marked decrease in K, and had little effect on total-N and PO4 concs. There was a greater proportionate increase in the SO4 content of the "SO4 plants" than of Cl content of the "Cl plants." The accumulation of carbohydrates with salt accumulation, indicates that the salts interfered with the utilization of carbohydrates in cellular elaboration rather than with photosynthetic activity.