Quinoa response to lead: Growth and lead partitioning

Abstract

Chenopods are known for salt and metal ion tolerance. Chenopodium quinoa is a recent introduction in the country but yet to be tested on metal contaminated soils. A pot experiment was conducted to explore growth and phytoextraction potential of four quinoa lines (A1, A2, A7 and A9) against different lead concentrations (0, 50 and 100 mg kg-1). Required lead concentrations were developed in polythene bags filled with sandy loam soil (5 kg) using lead nitrate salt prior to two month sowing and kept sealed up to sowing. Fifteen seeds of each quinoa lines were sown in each treatment bags with three replications. Five plants were kept in each bag after their complete emergence and allowed to grow till yield production (120 days). Results showed that translocation of lead increased from roots to shoots with increase in soil lead concentration in all lines with the following trend: A1 > A9 > A7 > A2. However, A1 accumulated higher in leaf compared to other lines as depicted by translocation factor of 2.34 and 1.34 when grown at soil having 50 and 100 lead mg/kg, respectively. This trend was similar in case of root (A1 > A9 > A7 > A2). There was 25-66% decline in seed yield at 50 mg kg-1 lead level in all lines compared to control. However, growth and yield declined with further increase in lead level. The maximum reduction in yield was observed in A7. More importantly lead concentrations in seed of A2 and A7 quinoa lines were within the permissible value set (0.3 mg/kg DW) by FAO/WHO. It can be concluded that quinoa is suitable for phytoextraction and despite hyper accumulation the concentration in seed remains within safe limit for human consumption.