Competitive ability of rice cultivars against Echinochloa species under varied nitrogen regimes

Abstract:

A surprising fact about Echinochloa crus-galli the world's worst rice weed is that it can absorb nitrogen faster than many rice cultivars, turning a farmer's fertiliser investment into a weed problem. This research evaluated the competitive ability of four rice cultivars (Swarna, MTU 7029, IR 36, Jaya) against Echinochloa under two nitrogen regimes (60 and 120 kg N ha⁻¹) at Rani Lakshmi Bai Central Agricultural University, Jhansi, during kharif 2022. MTU 7029 showed the strongest weed suppression (72.1% at high N) through rapid canopy closure and early vigour. High nitrogen consistently favoured rice over Echinochloa, with weed suppression 22-27 percentage points higher at 120 kg N than at 60 kg N. Rice cultivars with faster early leaf area expansion were better competitors regardless of nitrogen level. These findings suggest that combining competitive cultivars with optimised nitrogen timing can reduce herbicide dependency in rice.