The Influence of Mineral Nutrition on the Root Development of Trees

Abstract

Sitka spruce seedlings were grown with divided root systems in sand culture and the application of N, P, and K was varied while maintaining a complete supply of other nutrients. There was a localized stimulation of the growth of roots to which nutrients were applied and N produced the greatest stimulation; P was also important but K did not enhance growth. Measurements of Ca and Mg concentrations in the roots showed that differential root growth, which is influenced by the concentration of N and P in the bathing medium, could not be adequately explained by the effect of N or P on the uptake of the immobile cations. The two parts of the divided root system appeared to compete for assimilates; the enhanced growth of one root was accompanied by reduced growth in the other, and vice versa.