Acquisition of ephemeral module in roots: a new view and test.

Abstract

The terminal root branch orders composed mainly of primarily-developed tissues are increasingly recognized as an ephemeral module specialized for resource absorption. This root module is crucial in driving a range of ecosystem processes such as belowground productivity, carbon and nutrient cycling. Traditionally, acquisition of the ephemeral root module is achieved by separating these primarily-developed branch orders with forceps. However, obtaining this root segment with forceps approach is labor-intensive which may not be applicable for studies with an appreciable amount of root samples. To address this challenge, we developed a new idea to obtain the ephemeral root module. In this new view, root samples were tenderly kneaded by hand and the detached roots are considered as the ephemeral root module. To test this idea, four species with contrasting growing environment were selected and a range of chemicals were determined including C, N, P, Ca, S, Mg, Ba, Zn, Mn, Pb, Cu, V and Li. We found no or little difference of these chemicals in roots by hand-kneading approach from roots by forceps approach. These results suggested that hand-kneading method could be a convenient way to acquire ephemeral root module.