Water but not photosynthates integration exists between mother and daughter ramets of a root-derived clonal shrub

Abstract

Clonal integration in rhizomatous and stoloniferous clonal plants has been studied for many years, but the mechanisms of clonal integration of root-derived plants remain largely unknown. Alhagi sparsifolia is a typical root-derived clonal plant in the extremely dry land of the Taklamakan desert, and it usually cannot reproduce sexually in natural and non-irrigated environments; clonal reproduction is the primary way for this plant to maintain and extend its populations. After determining that A. sparsifolia clonally integrates its ramets, we tested whether that capability could enhance the species’ survival in dry conditions, using both a spacer-severed group and a control spacer-connected group, by applying both supplementary water and 13C labeling to mother ramets and old daughter ramets. Our results showed that the midday water potential of both mother and daughter ramets increased significantly after spacer severance. The water potential of the mothers significantly increased after water supplementation, under both the spacer-severed and spacer-connected treatments. The water potential of daughter ramets in the spacer-connected treatment group also increased significantly, but that of the spacer-severed treatment group did not. Leaf relative water content and increases in height, crown width, number of branches, and basal diameter of the daughter ramets in the spacer-connected group were significantly higher than those in the spacer-severed group. δ13C values of mother (and of old daughter) ramets significantly increased after 13C labeling, but δ13C values of neither mother, old daughter nor young daughter ramets changed. We concluded that clonal integration of water takes place between mother and daughter ramets of A. sparsifolia and that the mother can transfer water to daughter ramets through the spacers, but that no clonal integration of photosynthates occurs among the ramets of A. sparsifolia. These results have important implications for vegetation restoration and the utilization of water resources in this area.