Comparison among lettuce, Indian spinach and methi for uptake of low-dose cadmium under hydroponic and soil-based agriculture systems

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Using recycled water (treated wastewater) in agriculture offers a sustainable approach by adding inherent nutrients and moisture to the soil. However, the recycled water contains unwanted contaminants such as heavy metals like cadmium at lower concentrations. This study assessed the comparative response of three bioaccumulative leafy crops - lettuce, Indian spinach and methi, against cadmium exposure under hydroponic and soil-based cultivation. Crops were irrigated with cadmium-spiked water (0, 0.03, 0.06, and 0.09 ppm), using a nutrient film technique for hydroponics and fertilized soil-filled pots for soil cultivation. All crops exhibited a biphasic hormetic response, with growth stimulation up to 0.06 ppm and decreased response at 0.09 ppm. Cadmium accumulation was linearly increasing in crops with cadmium spiking in irrigation water, and higher accumulation was recorded in roots than shoots. The crops' response was significantly varying between the two cultivation systems, with greater cadmium accumulation under the hydroponic system than the soil-based system. Under soil-based cultivation, Indian spinach and methi retained more cadmium in root, limiting the translocation and thus exhibited higher response against cadmium stress than lettuce, which recorded higher shoot cadmium and lower growth response. On the other hand, under hydroponic cultivation, lettuce had lower cadmium accumulation and moderate growth response, while methi and Indian spinach showed higher uptake in respective root and shoot, and better growth response, indicating the growth stimulation effect of low dose cadmium. Despite cadmium accumulation, the human health risk index remained below one, indicating that it is safe to consume these leafy crops. However, under higher Cd concentrations in the irrigation water, there could be an increased risk of Cd accumulation in the crops. This study indicates that the crops grown in a hydroponic system are more susceptible to higher accumulation than those grown in soil-based cultivation. This dataset contains six excel spreadsheets containing data from three different crops, lettuce, Indian spinach and methi, grown under hydroponic (first 3 spreadsheets) and soil (next 3 spreadsheets) cultivation systems. The 1st and 4th spreadsheets contain the crop growth parameters like plant height, number of leaves and dry matter, 2nd and 5th sheets contain data on cadmium accumulation in plant tissues and soil, while 3rd and 6th spreadsheets contain the derived parameters like, bioconcentration factor, translocation factor, daily intake of metals and human health risk index.