Informatics Publishing Limited

T. Ramprakash ¹, M. Madhavi ¹, M. Yakadri ¹, A. Srinivas ¹

Affiliations
1 AICRP on Weed Control, Rajendranagar, Hyderabad, IN

Abstract

A field experiment on direct-seeded rice was conducted during kharif 2011 and 2012 at the College Farm, ANGRAU Hyderabad, to study the influence of different doses of bispyribac sodium 10% SC (10, 15, 20, 25 and 40 g a.i/ha) on physical, physico-chemical and fertility properties of the soil. Persistence of the herbicide in soil from application to harvest of the crop and the residues in plant samples at harvest were also studied. No significant changes in physical (texture, bulk density, particle density, pore space, maximum water holding capacity), physico-chemical (pH, EC, CEC, organic carbon) and fertility properties of the soil (available N, P₂O₅ and K₂O) were noticed at any of the applied doses. Bispyribac sodium dissipation in soil followed a first-order decay process. Half-life (DT₅₀) of bispyribac sodium was 13.10 days, 10.21 days and 9.93 days at 40 g/ha, 25 g/ha and 20 g/ha doses respectively. DT₉₀ values were also calculated. No detectable residues of bispyribac sodium were found in the straw or grain at the time of harvest.

Keywords

Bispyribac Sodium, Herbicide, Direct Seeded Rice, Half-Life, Soil Properties.

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T. Ramprakash ¹, M. Madhavi ², M. Yakadri ¹

Affiliations
1 AICRP on Weed Control, ANGRAU, Rajendranagar, Hyderabad-30, IN
2 Department of Agronomy, College of Agriculture, Rajendranagar, Hyderabad, IN

Abstract

Propaquizafop is a new graminicide herbicide recommended for control of grassy weeds in all dryland and ID crops. A field experiment was conducted during Kharif 2012 at the College Farm, ANGRAU, Hyderabad, on a Alfisol, to study the dissipation and persistence of varying doses of propaquizafop (25, 50, 62.5, 100 and 125g a.i/ha) in soil and turmeric. The influence of the herbicide on soil physical, physico-chemical and fertility properties was also assessed. Residues of the propaquizafop in soil and soybean were estimated on GC-ECD. Recovery of the herbicide in soil was 91.8-92.6%. In the rhizome and plant, the recovery was 88.6-92.1% and 93.6-93.8%, respectively. Limit of quantification was 0.01 mg/kg. No significant changes in physical (texture, bulk density, particle density, pore space, maximum water holding capacity), physico-chemical (pH, EC, CEC, organic carbon) and available nutrient status of the soil (available N, P₂O₅ and K₂O) were noticed in any of the applied doses of the herbicide. Application of propaquizafop @62.5 g/ha resulted in highest bio-efficiency. Propaquizafop dissipation in soil followed a first-order decay process. Half-life of the herbicide in soil increased with increasing dose. At sub-optimal doses, 50.0 g/ha, residues of propaquizafop persisted in the soil upto 15 DAA, (days after application) with a half life (DT₅₀) of 15.12 days. At the recommended dose (62.5 g/ha) half-life of propaquizafop was 17.67 days and residues reached below detectable limit (BDL) beyond 30 DAA. At doses above recommended level (100.0 and 125 g/ha), herbicide residues in the soil persisted for a longer period (45 and 60 DAA respectively) with DT₅₀ of 21.29 and 29.36 DAA, respectively. No detectable residues of propaquizafop were detected in the turmeric rhizomes or plant at the time of harvest.

Keywords

Propaquizafop, Turmeric, Herbicide Persistence, Half-Life, Soil Properties.

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