The Effects of Several Environmental Factors on the "Stunted Root" Formation in Rice Plants

Abstract

Experiments were undertaken to test the effects of several environmental factors on the "stunted root" formation in rice plants. The results reported here concern the "stunted root" formation when the plants were subjected to the percolation, the wind, the shading, the heavy nitrogen, and the mechanical stress treatments, respectively. Both the percolation and the wind treatments favorably affected the root growth, leading a decrease in the number of the "stunted roots". On the other hand, the shading, the heavy nitrogen, and the mechanical stress treatments affected unfavorably the root growth, resulting the abundant formation of the "stunted roots", especially in the upper parts of each shoot-unit. The morphological observation of the "stunted roots" thus formed revealed that some of these environmental factors produce their own distinctive patterns of the "stunted roots". Both the percolation and the wind treatments resulted in decreasing the number of "stunted roots" of the deteriolation or the swelling. type; the shading treatment, in increasing that of the tapering type; the heavy nitrogen treatment, in increasing that of the deteriolation, the swelling, or the cessation type, while in decreasing that of the tapering type; and the mechanical stress treatment, in increasing that of the cessation type, respectively. Although the real physiological mechanisms underlying the changes in the external morphology of the "stunted roots" are obscure, yet, these morphological changes may have some diagnostic value in relation to their nutritional and/or toxic effects.