Effect of hydrogen sulfide on cadmium and macro- and micronutrients uptake by Leucaena leucocephala.

Cadmium (Cd) levels in agricultural soils are increasing because of industrial expansion and pesticide discharge. There are few plants that tolerate heavy metals particularly Cd. NaHS as hydrogen sulfide (H₂S) donor plays a significant role in Cd tolerance by plants reducing its toxicity. The present research was oriented to evaluate the effect of NaHS in Cd and macro-/micronutrient uptake, as well as some physical and chemical parameters in Leucaena leucocephala plants exposed to this metal. Seedlings were grown in a hydroponic system and exposed to 5 ppm of Cd and NaHS at 1, 10, and 100 μM for 3 days. Inductively coupled plasma optical emission spectrometry (ICP/OES) was used to quantify Cd content and macro-/micronutrients in plant tissues. Results show a significant difference (Fisher's LSD) in radicle length and chlorophyll but did not show effect on carotenoids content. Addition of NaHS to the media shows a significant increase in Cd uptake by root as NaHS concentration in media increased. The maximum Cd uptake (7670 ± 102 mg/kg) was found in the roots of plants exposed to 100 μM of NaHS. A significant reduction in catalase (CAT) activity was observed in the root system, which is due to Cd concentration inside tissues. Results suggested that NaHS helps to decrease the toxic effect of Cd on the growth and development of plants. [ABSTRACT FROM AUTHOR]