Phytoextraction of Cd and Pb and physiological effects in potato plants (Solanum tuberosum var. Spunta): Importance of root temperature

Three consecutive years of field experiments were carried out to investigat e the effect of different root-zone temperatures, induced by the applicatio n of mulches, on the concentration and, accumulation of Cd and Pb and on bi oindicators (chlorophylls, catalase, peroxidase and cell wall fractions) in . different organs of potato plants (roots, tubers, stems, and leaflets). F our different plastic covers were employed (T1, transparent polyethylene; T 2, white polyethylene; T3, white and black coextruded polyethylene, and T4, black polyethylene), using uncovered plants as the control (TO). The diffe rent treatments had a significant effect on the mean root-zone temperatures (TO = 16 degreesC, T1 = 20 degreesC, T2 = 23 degreesC, T3 = 27 degreesC, a nd T4 = 30 degreesC) and induced significantly different responses in the C d and Pb concentrations. and phytoaccumulation, with T2 (23 degreesC) and T 3 (27 degreesC) giving high concentrations of Cd in the roots and low conce ntrations in other organs. In relation to Pb, T2 and T3 reached higher leve ls in the tubers and lower levels in the, roots, stems, and leaves. In term s of phytoaccumulation, the. roots and tubers were the most effective organ s for Cd and Pb. On the other hand, the highest values of peroxidase and ca talase activities were obtained for T3. In addition, most of the carbohydra te fractions in both the roots and the tubers were highest for T3. Meanwhil e, the lowest pigment values were registered for T1 (20 degreesC). For phyt oremediation, it is necessary to ascertain the relevance and control of the thermal regime of the soil to optimize the phytoextraction of pollutant el ements (Cd and Pb).