Impact of Water Regimes on Minimizing the Accumulation of Arsenic in Rice (Oryza sativa L.)

Shehzad, Muhammad Tahir; Ṣābir, Muḥammad; Saifullah,; Siddique, Abu Bakkar; Rahman, Mohammad Mahmudur; Naidu, R.

Impact of Water Regimes on Minimizing the Accumulation of Arsenic in Rice (Oryza sativa L.)

2022

Arsenic (As) is very common pollutant of the environment categorized as class-I human carcinogen. Rice crop is inherently efficient at accumulating As that is also triggered by conventional cropping methods (flooded conditions). A pot experiment was conducted with the objectives to (i) determine the accumulation of As in rice grains and shoots and As species in rice grains, (ii) determine the effect of As concentrations on physiological and agronomic characteristics of the rice crop, and (iii) assess the changes in fractions of As within the soil under different water regimes. Water regimes included flooding, intermittent, intermittent + aerobic, and aerobic irrigation. Grain As concentration from flood-irrigated rice was significantly (P ≤ 0.05) reduced in rice grown in 10 and 50 mg kg⁻¹ As-contaminated soil with less applied irrigation. Water management techniques have influenced As speciation in rice grains. As the irrigation techniques were shifted from flooding to intermittent, intermittent + aerobic, and aerobic irrigation, a significant decrease in concentration of inorganic species (11.98–76.81% at 10 mg kg⁻¹ and 66.04–93.61% at 50 mg kg⁻¹) was observed. Aerobic irrigation has effectively reduced the concentration of arsenic in rice grain as compared to other irrigation techniques in both the As-contaminated soils. This study indicated that irrigation management techniques other than flood irrigation have significantly affected the As (total and speciation) concentration within the rice grains and non-significantly affecting crop yield and this must be considered if regulations are based on inorganic As percentage of total As concentration.

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