Influence of Rhizosphere Oxygen Concentration on Rice Root Growth

Abstract

The growth of rice root needs oxygen, which is consumed in root respiration and contained in soil also influencing the ecological environment of rhizosphere. Although rice plant can transport atmospheric oxygen from its shoot through its continu-ous aerenchymatous system to its roots, rice can not grow well in submerged, anoxic soil; there exists affinitive relation between the aeration condition of soil and the growth of rice plant. In this study, various rice cultivars were cultivated in hydropotic to study the influence of rhizosphere oxygen concentration enhanced by aeration on rice root growth. The results showed that aera-tion significantly increased the oxygen concentration of hydroponic solution during the whole plant growth stage. Rice plant had the highest oxygen absorption ability at heading stage, compared to the no rice planting treatment, the oxygen concentration at this stage was decreased 73.62% for Guodao 1 and 68.50% for Shanyou 63, and the decrease extent was more than that at booting stage and grain filling stage. Compared to control, length of single root, length of the longest root of rice planted in higher oxygen concentration solution were longer, the dry weight percent of rice root ranging from 10 to 20 cm and longer than 20 cm from root base to tip increased accordingly, and the number of roots per plant was less. While in the treatment with anoxic condition, the number of rice root increased and the length decreased. Genotype difference existed in the influence of rhizosphere oxygen con-centration on root vitality. Under aeration condition, the root active absorption area per plant and root vitality of hybrid rice Guo-dao 1 and Shanyou 63 increased significantly at full heading stage; the root vitality of conventional rice genotype Xiangzaoxian 11 and Yongjing 18 which had high root vitality also increased significantly, while the root vitality changed little in low root vital-ity genotype Xiangzaoxian 24 and Chunjiang 06. When rice growed in anoxic condition, root vitality decreased.