Dissipation Kinetics of Trinexapac Acid in Paddy Leaves, Grain, Straw and Soil Using Liquid Chromatography Tandem Mass Spectrometry.

Abstract

Field experiments were conducted to investigate the dissipation and persistence residues of trinexapac acid in paddy crop. The treatments consisted of one control and two different concentrations of Trinexapac-ethyl 25% EC (Emulsifiable concentrate) at 30 and 60 g a.i. ha^- 1(recommended and double the recommended dose). Leaf samples were collected at random in each plot separately at 0, 1, 3, 5, 7, 10 and 15 days after foliar application and grain, straw and soil samples were collected at harvest. The mean recovery of trinexapac acid (@ 0.01, 0.05 and 0.1 mg kg^- 1 was more than 75%. At application rate of 30 and 60 g a.i. ha^- 1 (gram of active ingredient per hectare), initial trinexapac acid residues on leaves were 0.29 and 0.44 mg kg^- 1, respectively. Residues were observed even after 15 days of spray. At harvest time, the residues of trinexapac acid in grains were below LOQ (limit of quantification) at 30 g a.i. ha^- 1 treatment whereas, at 60 g a.i.ha^- 1, the residues were found to be 0.02 mg kg^- 1. In straw, trinexapac acid residues were detected to be 0.05 and 0.08 mg kg^- 1 at 30 and 60 g a.i. ha^- 1 treatments, respectively. The soil samples showed 0.04 and 0.08 mg kg^- 1 residue at 30 and 60 g a.i. ha^- 1, respectively. The half life calculated for trinexapac acid came to be 10.10 and 9.09 days revealed the slow dissipation of trinexapac acid in paddy crop. The residue of trinexapac acid reached below LOQ at harvest time. Therefore the recommend dose of trinexapac ethyl is considered safe from consumption point of view.