Determination of residual effect of herbicides through bioassay technique

A laboratory experiment was conducted on herbicides sprayed on Lantana camara during spring and autumn seasons, 2023 at Department of Agronomy, College of Agriculture, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur, to study the residue of different herbicides through bioassay. Fourteen weed control treatments including metsulfuron methyl (4 g/ha and 8 g/ha), imazethapyr (150 g/ha and 300 g/ha), chlorimuron ethyl (9 g/ha and 18 g/ha), metribuzin (1400 g/ha), 2,4-D amine (2500 g/ha), oxyfluorfen (235 g/ha), glufosinate ammonium (500 g/ha), glyphosate (1500 g/ha and 2000 g/ha), indaziflam + glyphosate (1390 g/ha) and control were evaluated in completely randomized block design with three replications. Wheat, rice, oats, mustard and cucumber were used as indicator plant in bioassay to test the residual effect of herbicides in the soil of treated plots. Two growth parameters i.e. shoot length and root length were measured for all plant species. Germination count of seedlings and phytotoxic effects on crops were also recorded. Soil samples were collected at 3 and 5 months after spray and analyzed for residue using bioassay. The results revealed that shoot length and root length of all the five indicator plants were not significantly affected by residue of various herbicides during the period of investigation. Therefore, all the five indicator crops viz. wheat, rice, oats, mustard and cucumber successfully be grown under field condition after the application of these herbicides.