Bioavailability-based estimation of phytotoxicity of imazaquin in soil to sorghum

Wang, Donghong; Wang, Yun; Yin, Yuanming; Min, Shan; Wang, Shaoyun; Yu, Yunlong

Bioavailability-based estimation of phytotoxicity of imazaquin in soil to sorghum

2015

The injury to sensitive rotational crops caused by residual herbicides from their applications has happened frequently. The assessment of activity of residual herbicide in soil has been of agronomic concern. To accurately determine the toxicity and obtain a comparable concentration that inhibits growth by 50 % (IC50) in different soils, the concentrations of imazaquin in CaCl₂(CCₐCₗ₂) and H₂O (CH₂O) extraction and in in situ pore water (CPW) were adopted for the estimation of IC50 to sorghum. The IC50 values based on CCₐCₗ₂and CH₂Owere 0.06 mg L⁻¹in soil Ansai (AS) to 0.13 mg L⁻¹in soil Huajiachi (HJC), 0.32 mg L⁻¹in soil AS to 0.71 mg L⁻¹in soil HJC, respectively, with variation coefficients of 38.32 and 34.93 %. However, CPW-based IC50 values ranged from 0.90 mg L⁻¹in soil Xiaoshan (XS) to 1.09 mg L⁻¹in soil HJC with a variation coefficient of 6.96 %. This implies that the IC50 based on imazaquin concentration in in situ pore water is almost identical in the five soils. With further studies with more herbicides and plant species, this method might be expanded for the estimation of phytotoxicity of residual herbicide(s) to plant(s).

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