Abstract
Description of the subject. Microevolutionary processes in metallophytes established on copper enriched soils can lead to a diversity of plant species showing distinct tolerance capacities among genus. Researches about the relationship between these endangered plants and soil copper concentrations are critical in order to improve ex situ conservation methods in southeastern Democratic Republic of Congo (Katangan Copperbelt). Objectives. The aim of the study was to test the effect of copper on the germination and root elongation of three Crotalaria species naturally occurring along a natural copper gradient. The hypothesis is that copper concentrations have different effects on germination and root elongation according to the species of Crotalaria genus. Method. Three species were selected: Crotalaria cobalticola, Crotalaria peschiana and Crotalaria cornetii, occurring on soils with the highest to the lowest copper concentrations respectively. Germination and root elongation tests were performed in vitro (MS vitamin-enriched medium) in six copper mediums ranging from 0 to 125 µM Cu2+. Results. No significant differences in germination percentage were observed according to the copper concentrations. Crotalaria cornetii had the lowest germination percentage. Root elongation of C. peschiana did not differ with copper concentration, but root elongation of C. cobalticola was higher at the greatest copper concentration (125 µM Cu2+). Conclusions. Even if C. cobalticola presented better growth at highest Cu concentrations, it appeared that C. cobalticola and C. peschiana do not require copper for their early stages of development and could thus be conserved in non-contaminated substrate. Crotalaria cornetii seemed to present a physical seed dormancy.
Highlights
Metalliferous areas present high concentrations of trace metals associated with other environmental constraints including xericity and poor depauperate nutrient content (Ernst, 1974; Kruckeberg, 1985)
Ecosystems established on soils naturally enriched with copper are rare, except in South Central Africa where occurs a large number of copper-cobalt mineralized areas (Duvigneaud et al, 1963; Baker et al, 2010; Chipeng et al, 2010)
We investigated both the germination and the root elongation in the first weeks according to different copper concentrations for three species of the genus Crotalaria (Fabaceae) from the Katangan Copperbelt
Summary
Metalliferous areas present high concentrations of trace metals associated with other environmental constraints including xericity and poor depauperate nutrient content (Ernst, 1974; Kruckeberg, 1985) These harsh abiotic conditions are strong drivers for local adaptation of plant species (Antonovics et al, 1971; Brady et al, 2005) that results in the formation of highly distinctive plant communities (Duvigneaud et al, 1963; Ernst, 1974; Rajakaruna, 2004; Saad et al, 2012). The Katangan Copperbelt, in the Katanga province (South East of Democratic Republic of Congo), extends over 300 km long between Kolwezi and Lubumbashi with more than 150 copper- and cobalt-rich outcrops (François, 1988; Cailteux et al, 2005) These outcrops appear as isolated hills scattered in the Miombo woodland matrix, and available copper concentrations often exceed 10,000 mg Cu.kg-1 at the outcrop summit. Recent studies show that trace metals and related nutrient concentrations play a significant role to structure plant communities along the metal gradient (Saad et al, 2012; Ilunga wa Ilunga et al, 2013; Séleck et al, 2013)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
