In vitro development of green manures: phytotoxicity and remediation of 2,4-D / Desenvolvimento in vitro de adubos verdes: fitotoxicidade e remediação de 2,4-D

Abstract

Evaluation of phytoremediation capacity under aseptic, controlled conditions can be achieved with the use of plant tissue cultures as a model, eliminating interference from the physical environment. Herein, we developed an in vitro culture protocol for green manures of Crotalaria juncea, C. spectabilis and Canavalia ensiformis, each of which contributes to a sustainable cropping system. In particular, we studied their behavior in the presence of the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid). Disinfection of C. juncea seeds was efficient, and plantlets presented the best development of roots, stem and leaves. Thus, subsequent experiments were conducted only with C. juncea. For 2,4-D tolerance tests, C. juncea seedlings were transferred to Murashige and Skoog (MS) solid media under the following concentrations of 2,4-D: 0 (control), 0.2, 0.5 and 1.0 mg L-1 for a 30-day period. After this period, MS culture media for C. juncea was analyzed by HPLC for quantification of residual 2,4-D. C. juncea development was observed to be sensitive to 2,4-D toxicity; however it was observed 2,4-D reduction in the media. Nonetheless, field assays are still necessary to evaluate the feasibility of using it as a phytoremediator, as well as determine the influence of environmental and plant density variables on 2,4-D absorption capacity from soil.