Thiourea supplementation mediated reduction of grain arsenic in rice (Oryza sativa L.) cultivars: A two year field study.

The present study delineates the interactions of arsenic (As), a carcinogenic metalloid, and thiourea (TU), a non-physiological reactive oxygen species (ROS) scavenger, in rice plants grown in As contaminated fields in West Bengal, India. The study was performed for four consecutive seasons (two boro and two aman) in 2016 and 2017 with two local rice cultivars; Gosai and Satabdi (IET-4786) in a control and two As contaminated experimental fields. Thiourea (0.05% wt/vol) treatment was given in the form of seed priming and foliar spray. Thiourea significantly improved growth and yield of rice plants and reduced As concentration in root, shoot, husk and grains in both cultivars and fields. The reduction in As concentration ranged from 10.3% to 27.5% in four seasons in different fields. The average (four seasons) increase in yield was recorded about ~8.1% and ~11.5% in control, ~20.2% and ~18.6% in experimental field 1, and ~16.2% and ~24.1% in experimental field 2, for gosai and satabdi, respectively. Mean hazard quotient (HQ) and incremental lifetime cancer risk (ILCR) values of As reduced upon TU supplementation for both cultivars as compared to that of non-TU plants. Hence, TU can be effectively used to cultivate rice safely in As contaminated fields.

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