Laboratory screening of aluminum tolerance in Jatropha curcas L.

Jatropha curcas L. (jatropha) has recently received great attention for its utilization in biofuel production and rehabilitation of wastelands. Jatropha grows in tropical and subtropical regions where large extensions of acidic soils with high aluminum content are present. It is therefore important to screen the tolerance of jatropha germplasm to this metal. We assessed aluminum tolerance levels in eight genotypes by means of a laboratory seed germination/root elongation toxicity test. The plant material was exposed to solutions of different aluminum concentrations in sand medium. Days to germination, root length, shoot length, shoot dry matter, and leaf chlorophyll content were measured. Aluminum exposure of plant material significantly influenced the days to germination, root length and leaf chlorophyll content. The aluminum influence on these three traits was combined in an index, which revealed genetic differences among the tested genotypes. Potential aluminum tolerance was identified in G8, whereas G1 and G5 showed the highest aluminum sensitivity. However, the level of aluminum tolerance identified in the laboratory needs to be validated under field conditions.