Tolerance of an energy crop (Jatropha curcas L.) to zinc and lead assessed by chlorophyll fluorescence and enzyme activity

Zinc and lead toxicity is a serious constraint to the use and revegetation of contaminated soils. The use of tolerant species for remediation of these areas, combined with low-risk products for humans, can be a viable alternative for the management of contaminated soils. In this sense, the present study evaluated Jatropha curcas tolerance to Zn and Pb aiming at the revegetation of contaminated areas. The effect of trace elements on the biomass, absorption and distribution of elements, photosynthetic apparatus and antioxidant enzymes activity were studied. The measurement of the chlorophyll fluorescence detected early Zn and Pb toxicity, showing potential for monitoring areas contaminated by these metals. Jatropha plants were relatively tolerant to the toxicity of the evaluated trace elements. Tolerance was expressed mainly by restricting the element transport to the aerial parts, and by increasing or sustaining antioxidant enzymes activity. Due to this tolerance, Jatropha plants can be useful for revegetation of areas contaminated by these metals. Because it is an oil seed crop species, Jatropha production in these marginal areas may represent an economical alternative by combining phytostabilization with bioenergy production.