Cadmium and lead excess differently affect growth, photosynthetic activity and nutritional status of Trigonella foenum-graecum L.

Abstract

Context Heavy metal contamination of soils is a serious environmental problem worldwide. Cadmium (Cd) and lead (Pb) are considered among the most important types of pollutants. Aim To investigate the response of a local fenugreek cultivar against lead and cadmium. Methods Physiological changes were studied under different concentrations (0, 100, 200, 300 and 400 μM) of PbCl2 and CdCl2. Key results Fenugreek growth decreased gradually with increasing Cd and Pb supply. This decrease was accompanied by a gradual decline in shoot and root length and photosynthetic parameters. However, Cd treatments showed pronounced effects in fenugreek seedlings as compared to Pb. The tolerance index was between 0.41 and 0.81, which suggests relative tolerance of this cultivar to Pb and Cd. This species was also able to maintain stable water status. Nevertheless, in presence of high Cd concentration (400 μM), this species showed substantial decrease in CO2 assimilation (86%), transpiration rate (87%), stomatal conductance (57%), chlorophyll content (35%) and carotenoid content (53%). Shoot proline content was increased significantly under 200 and 300 μM Cd, and slightly under 100 and 200 μM Pb. Furthermore, Cd and Pb induced a decrease in shoot magnesium and phosphorus content. Conversely, shoot iron content was increased. Data showed that fenugreek accumulated Cd, and translocated to the harvestable parts (up to 20 mg/kg DW under 400 μM). However, Pb was mostly accumulated in roots. Conclusions Our results revealed that the relative tolerance of fenugreek to Pb excess was coupled to a remarkable accumulation of this element in root, which favourite the phytostabilisation process. Implications FM, FL, SJ and OTZ execute the manipulation and the culture of plants. FM, OTZ, IN and KZ analyse and examine obtained results. FM, OTZ and KZ write and preparethe manuscript. IN, HM and KZ prepare the conception and the realisation ofthis work.