Kin Recognition Alters Root and Whole Plant Growth of Split-root Cycas edentata Seedlings

Abstract

Split-root techniques were used to determine if Cycas edentata seedling roots possessed identity recognition capabilities. One compartment of the split-root containers contained a competing half-sibling seedling, and the second compartment contained one of four treatments. When the second compartment contained a half-sibling or C. edentata seedling from the same habitat, root growth did not differ between compartments. When the second compartment contained a C. edentata seedling from a habitat 130 km away or a C. nitida seedling, root dry weight and root length were increased above that of compartments with half-siblings. Whole plant growth also increased in seedlings that experienced competition with the conspecific plant from a distant habitat or from a different species. The results validated the ability of Cycas edentata roots to recognize and then use a plastic response to neighbor root identity. In horticultural settings, planting cycad plants where neighbors are close relatives may reduce plant growth, and planting to ensure neighbors are not close relatives may increase plant growth.