Long-Term Effect of Herbicides on Weed Diversity Indices in Rice-Wheat Cropping System

Abstract

A long-term experiment on rice-wheat cropping system has been in operation at Department of Agronomy of CSKHPKV, Palampur from 2000 till 2018. The soil of the test site was silty clay loam in texture, acidic in reaction and low in available N, P and K. The nine treatments so tested included farmers' practice, continuous use of herbicides (butachlor + 2,4-D) with 100% N through inorganics or 25%N substitution through fresh Lantana leaves in rice followed by continuous use of isoproturon + 2,4-D or alternate use of isoproturon and clodinafop along with 2,4-D in wheat, alternate use of butachlor with pretilachlor with 100% N through inorganics or 25% N substitution through fresh Lantana leaves in rice followed by continuous use of isoproturon + 2,4-D or alternate use of isoproturon and clodinafop along with 2,4-D in wheat. Lower weed diversity was recorded in both the crops where herbicide application was done during both the year of study. Herbicide application greatly influenced the population of the weeds as compared to Farmer's practice. The value of Shannon winer and Simpson index was lower in chemical treated plots as compared to Farmer's practice.