INFLUENCE OF ACIDITY, CALCIUM AND MAGNESIUM ON GROWTH OF XANTHI TOBACCO IN WATER-CULTURE

Abstract

Water-culture expts. with oriental Xanthi tobacco in the greenhouse were carried out to determine the effect of acidity (initial pH 4.6 and 7) on the Ca and Mg requirements of the plant. Trace-element impurities were at a level sufficiently low to permit production of moderate symptoms of Zn, Cu, and B deficiency. 2.5-gallon containers with a fixed charge were used and only water replenished. No difficulty was experienced with iron nutrition if the solns. were vigorously stirred semi-weekly so that the roots became covered by a heavy coating of the precipitated iron, phosphate, etc. The relative freedom from toxic quantities of trace-element impurities was also conducive to good iron nutrition. The absence of a major effect of acidity on the Ca and Mg requirements at the 5% level of variance was also attributed to the absence of deleterious quantities of trace-element impurities. A definite trend was indicated by a 5.8% increase in avg. yield in the Mg series; and a 5.6% decrease in avg. yield in the Ca series at the acid level.