EFFECT OF GLYPHOSATE HERBICIDE ON PHOSPHORUS AVAILABILITY AND SUBSEQUENT GROWTH AND YIELD OF WHEAT

Abstract

A field experiment was conducted in Grey Terrace soils under Madhupur Tract Agro-Ecological Zone (AEZ-28) during 2019-2020 to observe the effect of glyphosate on wheat growth applied before crop establishment to the soil. The experiment was tested by applying glyphosate 2 and 7 days before land preparation. The soils under two different phosphorus doses (minimum phosphorus and high dose of phosphorus) and three glyphosate doses (no glyphosate, recommended dose of glyphosate and high dose of glyphosate). Twelve treatments were studied in split-split plot design with three replications. The growth and yield parameters of wheat, weed biomass and P concentration were varied due to the plant back period, glyphosate and phosphorus doses applied to the soil before crop establishment. When glyphosate applied 2 days before, emergence, germination and plant growth were hampered in compared to 7 days before application. Application of high glyphosate dose with high P significantly reduce yield and yield contributing characters of wheat crops. The phosphorus concentration in clay loam soil was also the highest recorded in the high glyphosate combined with high P dose. When glyphosate was applied at the recommended dose 7 days before land preparation, the yield and yield contributing characters were not hampered compared with high dose of glyphosate. The key result from the experiment was the interaction of plant back period and high rate of glyphosate with high dose of P fertilizer, leading to a negative effect on wheat phenotypic and yield characters in clay loam soil. The interaction of recommended dose of glyphosate and phosphorus reduce the weed biomass and increase the phosphorus availability in clay loam soil, and thus reducing the total cost of production for wheat. However, most of the effects were observed at the initial stage of crop growth.