The impact of a seaweed-derived biostimulant (Kelpak®) on the tolerance of lettuce plants (Lactuca sativa) to cadmium pollution
Abstract
Lettuce is an important leafy vegetable containing beneficial bioactive compounds. Meanwh i le, lettuce can absorb cadmium in areas of man-made soil contamination. Concentrations of 10 and 20 mg/L CdCl 2 in irrigation water resulted in noticeable changes in plant vital signs. The presence of cadmium in the irrigation water at a concentration of 10 mg/L had no significant effect on the productivity of the above-ground portion of lettuce. A 14% reduction in biomass was observed when the cadmium concentration in the irrigation water was doubled. Growth inhibition and a decrease in photosynthetic pigment content were observed. The chlorophyll a content of lettuce leaves decreased by 28.6% and 35.7%, respectively, due to an increase in cadm i um chloride content in the irrigation water from 10 to 20 g/L. The carotenoid content of leaves decreased proportionally to the increase in cadmium content in irrigation water. At the same time, the presence of lipid peroxidation products in plant tissues increased. Foliar treatment with the seaweed-derived biostimulant in our case study had a visible effect only on plants growing in the soil, while under conditions of cadmium contamination of the soil, the weight of plants treated with Kelpak ® was almost identical to the weight of untreated plants. Application of Kelpak ® resulted in chlorophyll a and b content in the 20 ml/L CdCl 2 +BS concentration variant slightly lower than in the 10 m L /L CdCl 2 +BS concentration. An increase in carotenoid content by 15.5 – 27.3% in variants contaminated with cadmium indicates a mitigation of the negative impact of the toxicant on plants. Foliar treatment of plants with a biostimulant reduced the stress response to cadmium pollution in the form of de c reas e in the MDA production by 14 – 22%. A strong negative correlation was established between MDA content in lettuce leaves and biomass growth, chlorophyll a, and carotenoid content.References
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