Changes in Growth of Egeria densa in Shading Conditions

Abstract

This study aimed to develop a new method to control Egeria densa, which overgrows in agricultural irrigation canals. We conducted two experiments (one in the laboratory and one in the field), focused on changes in light conditions and the growth of E. densa. In the laboratory experiment, the maximum tensile load of the stems was significantly reduced when the light was shaded to about 20 μmol·m^-2·s^-1 (1,400 lx). We discovered that shading exerted a significant negative effect on the number of roots. Furthermore, in the field experiment, which was conducted in an actual agricultural canal, the maximum tensile load on stems was reduced in both the 85-90% and 95-98% shade plots. In particular, in the 95-98% shade plot, the tensile load was reduced to about half of that in the control plot (non-shade) during the high grow season from August to October.