EFFECT OF THE ROOT SYSTEM ON TOMATO STEM GROWTH

Abstract

The root system of tomato plants was divided into 2 separate parts, of which one was kept submerged in a Hoagland nutrient soln., and the other kept in different surroundings. In this way it was found that if all the roots of a tomato (or Cosmos) plant be submerged in a nutrient soln. of pH 6 or higher, aeration cannot prevent chlorosis and especially a drop in the growth rate of the stems, although root growth is satisfactory. As soon as a portion of the root system develops in moist air, however, growth of the stem becomes maximal. All expts. point toward the conclusion that the part of the root system which develops in moist air supplies one or more factors (tentatively named caulocaline) required for stem growth and prevention of chlorosis. Thus, in intact plants the aeration of roots seems to be of relatively greater importance for their caulocaline production that for salt uptake.