Comparative Growth Response of Three Jatropha Species on Heavy Metal Contaminated Soil

Abstract

A B S T R A C TThis study investigated the comparative phytotoxcity effect of heavy metal contamination on Jatropha curcas, Jatropha gossypifolia and Jatropha multifida in contaminated soil from a dump site in Ibadan Nigeria. Seeds of J. curcas, J. gossypifolia and J. multifida were planted in a germination tray and later transplanted into polythene pots filled with 2kg of either control soil or heavy metal contaminated soil, a 3 × 2 factorial experiment laid out in complete randomized design (CRD) replicated four times was adopted; treatments imposed include T1 -J. curcas/Control Soil, T2 -J. gossypifolia/Control Soil, T3 -J. multifida/Control Soil, T4 -J. curcas/Contaminated soil, T5 -J. gossypifolia/Contaminated Soil, and T6 -J. multifida/Contaminated Soil. Weekly variation in growth parameters: the plant height, leave production and stem diameter were measured over the course of 12 weeks. The growth parameters were dependent on a combination of both specie type and level of heavy metal contamination of soil. J. multifida (T3) (36.93cm) performed best, comparable with J. gossypifolia (T2) (34.1cm) after 12 weeks while J. multifida (T6) had the lowest mean plant height (7.23cm) which is not significantly (p<0.05) different from other species on the contaminated soil; for leave production, J. gossypifolia (T2) produced the highest mean number of leaves (9.67) which is comparable with J. multifida (T3) (9.00) and less so with J. curcas (T1) (6.67) with significant leave losses on the contaminated soils after 12 weeks; variation in stem diameter shows that J. curcas (T1) had the highest stem girth (1.96 mm) which is comparable to the value obtained for J. curcas (T4) (1.95mm), while J. multifida (T6) had the lowest stem girth (1.09 mm). J. gossypifolia (T2) and J. multifida (T3) had comparable stem girth of 1.57mm and 1.47mm respectively. Toxicity of heavy metals in the contaminated soil greatly affect the growth parameters of the Jatropha.

Comparative Heavy Metal Uptake and Phytoremediation Potential of Three Jatropha Species

“…It was observed that the post-harvest soil heavy metals for all the species was reduced correspondingly to what is reported in other studies [8,9,22], albeit not significantly in all the post-harvest pots. The low and insignificant reduction may be due to the high level of contamination in the soil as the plants may need more time beyond the three months the plants were monitored to get acclimatized to the toxic environment, the phytotoxic effect of the heavy metals on the three Jatropha species is already documented [23]. The analysis of heavy metals in the Jatropha plant's part shows that the Jatropha spp were found to be able to efficiently remove the studied metals in varying degree, cadmium, however, was not detected in the plant parts of the three Jatropha species.…”