Vol. 14 No. 1
Bioassay for detecting flucetosulfuron residue in wetland rice soils
Author(s): S. R. ARYA, E. K. SYRIAC AND S. K. RAJ
Abstract: In order to assess the residue of flucetosulfuron in wetland rice soils, bioassay was conducted in two parts viz., identification of suitable indicator plants for flucetosulfuron and assessment of herbicide residue in post experiment soil using selected indicator plant. To identify indicator plant for flucetosulfuron, pot culture experiments were conducted using four test plants viz.,barnyard millet, cucumber, sunflower and maize. Each plant species was allowed to grow in 8 different concentrations of flucetosulfuron viz., 0, 0.01, 0.05, 0.1, 0.5, 1, 10, 50 and 100 μL L-1. The effect of different concentrations of flucetosulfuron on germination percentage, shoot length, root length, shoot fresh and dry weight of each indicator plant species were recorded. Based on statistical analysis, sunflower was selected as the most sensitive indicator plant for assessing the residual effect of flucetosulfuron, since it recorded the highest regression co-efficient for the parameters tested. Among the various parameters compared, shoot length of sunflower was selected as the most suitable parameter to detect the residue of flucetosulfuron in soil. Logarithmic linear regression equation developed for shoot length of sunflower was Y=4.309788-0.64968 ln (X), R2= 0.946. Field experiments were carried out with 3 different concentrations (20, 25 and 30 g ha-1) of flucetosulfuron at 3 different times of application (2- 3, 10-12 and 18-20 days after sowing) for the Kharif and Rabi seasons of 2016-‘17. After each filed experiment, bioassay was conducted in post experiment soil and results revealed that there is no toxic residue of flucetosulfuron in the soil of the experimental plots indicating the safety of the chemical.
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