Effect of llama (Lama glama) manure and Trichoderma strain T1R3 on arsenic uptake by Swiss chard and broad bean crops

Abstract

The town of Pastos Chicos (Jujuy-Argentina), presents arsenic (As) concentrations in soil (49 mgAs kg− 1) and water (1.44 mgAs L− 1) significantly above the maximum allowable limits set by National Laws No 24,585 and N° 24,051. This study aimed to evaluate the effect of llama manure (Lama glama) and Trichoderma strain T1R3 on As uptake and toxicity in Swiss chard (Beta vulgaris var. cicla) and broad bean (Vicia faba L.) crops while assessing potential human health risks. Results indicated that Trichoderma strain T1R3 inoculation stimulated broad bean plant growth by reducing As stress. Swiss chard crops treated with 5% manure and a manure/Trichoderma T1R3 combination reduced As absorption from 32.46 to 64.02% in roots, and from 35.2 to 44.5% in leaves. Broad bean crops inoculated with Trichoderma T1R3 showed significant mitigation of toxicant accumulation in the leaves (67.42%). Also, the manure/Trichoderma T1R3 combination reduced As accumulation (57.46%) in broad bean roots. The efficacy of llama manure and of the llama manure/Trichoderma T1R3 combination in reducing health hazards that derive from As intake by consuming chard leaves was also reflected in Hazard Quotient < 1 values. Although Cancer Risk values decreased considerably, these showed there was a considerable carcinogenic risk for humans consuming chard leaves. These observations reveal that adding llama manure and Trichoderma T1R3 might mitigate As uptake by crops, thus reducing human health risks. This study advanced our understanding of the complex llama manure/Trichoderma strain interactions in As-contaminated soils, which are imperative for developing effective mitigations strategies.