Revisiting ramet connection under homogeneous water availability environments

Abstract

There is little consistency on effects of ramet physical connection in homogeneous environments. To revisit this issue, we chose Cynodon dactylon (Linn.) Pers. (Bermuda grass) as a model plant to establish three experiments. In the water availability experiment (I), stolon severing had no significant effects on plant biomass; however, it significantly affected plant morphology by increasing main stolon length of C. dactylon grass under the homogeneous high water (i.e., less stress) condition, possibly due to an escape strategy from disturbance (stolon severing). Apical dominance and root competition are common factors shaping these plant performance measures. We followed these results with two additional experiments to test if such results could be explained by the partial release of apical dominance or root competition. In the apical dominance release experiment (II), biomass and number of branches of distal sections were significantly increased. However, at the whole clonal fragment level, main stolon and inter-node length were both significantly decreased after apical ends were disconnected. In the root competition experiment (III), no significant effect was found indicating weak root competition in homogeneous environments. We concluded that stolon connection had no significant effects on the biomass of C. dactylon while it affected plant morphology in homogeneous environments. Secondly, clonal architecture is partially determined by the presence of ramet connection and apical dominance. Removal of the apical end may have enhanced development of the distal sections, but the loss of stolon connection with distal sections inhibited the performance of apical sections leading to negative effects to the whole clonal fragment. Apical dominance seems more important than root competition for plant performance of C. dactylon under homogeneous environments, but this is only one clonal species in one environmental condition.