Assessment of Growth and Tolerance of Indigenous Shrubs Ricinus communis (L.) and Senna occidentalis (L) Soil Spiked with Different Concentrations of Lead Sulphate (PbSO4)

Abstract

Heavy metals such as Lead (Pb) are highly toxic and can have possible implications for human health even at low concentrations. The aim of this research was to assess the potential of castor (Ricinus communis) and senna (Senna occidentalis) to grow in Pb contaminated soil. Pot experiments were conducted in the screen house located in the Center for Dyryland Agriculture, Bayero University Kano, New Site. The set up consisted of pots containing in 2 Kg of agricultural soil spiked with 2.5 mg/kg, 5 mg/kg and 10 mg/kg of Lead sulphate (PbSO₄) for each plant and replicated four times with four seeds per pot. The pots were labeled and placed in completely randomized design. Number of leaves and root length were assessed at 45 and 90 days after planting (DAP). The soil was sandy loam and slightly acidic with low heavy metals content. Growth parameters were generally higher in control plants. In castor plants, there were significantly higher (p<0.05) mean values for height and root length in control castor plants than those in treated soil at 45 DAP. The control had mean plant height of 16.85cm compared to 11.25 cm for 2.5 mg/kg: 10.75 cm for 5 mg/kg and 10.38 cm for 10 mg/kg treatments. Likewise an average root length of 17.35 cm of was recorded compared to 9.5 cm for 2.5 mg/kg: 10.12 cm for 5 mg/kg and 7.75 cm for 10 mg/kg treatments. Senna plants in control had significantly higher mean values for height at 45 DAP (16.38 cm) and 90 DAP (29.5 cm) than those grown in the contaminated soils. Root length of Senna at 90 DAP was significantly higher in control (24.0 cm) than in all other treatments. The results indicated tolerance of castor and Senna to soils contamination by lead.