FURTHER EVIDENCE THAT BORON IS ESSENTIAL FOR THE GROWTH OF LETTUCE

Abstract

A deficiency-disease of lettuce resulting from an insufficiency of B is described and illustrated. The effectiveness of several B compounds in preventing or correcting the deficiency disease is given. The concentrations of soluble B compounds that result in B deficiency, normal growth, and toxicity were ascertained. The physical condition of the plant was modified by the concentration of soluble B in the nutritive solution. The effect of the less soluble B compounds was modified by the reaction of the culture, the volume, and, through the plant itself, by climatic and seasonal conditions affecting the rate of growth. Boro-silicate was the most satisfactory compound for incorporation in sand cultures. Increase in the B content of the nutrient solutions up to concentrations that resulted in the death of the seedlings increased the B content of the leaf tissue.