DISTRIBUTION OF ROOTS IN POROUS AND NONPOROUS PLANT CONTAINERS

Abstract

Many years of experience in growing plants in clay pots have taught the horticulturist to judge the needs of his plants by the condition of the root system. The so-called pot-bound condition, in which the root system appears as a mass of interlacing roots between the pot and the soil mass, is a criterion that is applicable only to this type of container, i.e., the porous clay pot. Jones (1) has shown that plants may be grown in nonporous containers and that such plants are equal to those grown in the conventional clay flower pot. The study of root systems in both porous and nonporous plant containers shows a striking difference. In the porous pot, the root system is almost wholly outside the soil mass and the core of soil within may be easily removed. In the nonporous pot, there are relatively few roots on the outside of the soil mass and it is exceedingly difficult to remove the soil from the roots, which ramify throughout the This condition was observed by Whitney and Cameron (7) in 1904 when experimenting with soils in wire baskets covered with paraffin. Such plant containers are nonporous. These investigators state : uInno case has there been found any evidence of any effort on the part of roots to develop toward the sides of the pot. On the contrary, they grow freely throughout the soil. The wire basket covered with paraffin was the outcome of failures to keep the root system within the soil, for in glass tumblers this particular soil contracted, leaving an air space saturated with water vapor between the soil and the wall of the tumbler. These investigators further noted that they obtained an even distribution of soil moisture within these paraffined wire baskets.