Root Training by Plastic Tubes II. Geotropic Reaction of the Roots of Several Species 1

In the greenhouse, the difference in ability of roots of different species to grow upward was appraised by growing plants in U‐shaped tubing. In the field, plants grown in straight tubes were inserted vertically into the prepared plow layer. In curved tubes, cabbage and rape plants rapidly returned their fibrous root systems to their crowns; in the field, they bent upward from the impenetrable plow pan and permeated the plow layer. Other species, such as oats, showed little ability to grow upward in the soil.