Indian Journal of Weed Science

A field experiment was carried out at the experimental area of Punjab Agricultural University, Ludhiana during 1998 and 1999 to study the competitive behaviour of transplanted rice with variable plant densities (22, 33 and 44 hills m⁻²) receiving different nitrogen levels (120, 150 and 180 kg ha⁻¹) having the infestation of Echinochloa crusgalli. The field under the experiment was sandy loam in texture with 72.7% sand, 11.1% silt and 16.0% clay and was under continuous rice-wheat rotation since last eight years. During 1998, seed yield of rice increased significantly with each increment in N level, however, during 1999 application of 180 kg N ha⁻¹ significantly increased seed yield of rice than 120 and 150 kg N ha⁻¹ and the differences in the latter treatments were found to be non-significant. Similarly, seed yield of rice increased significantly with increase in plant population from 25 to 41 plants (hills) per sq. m during both the years. Higher plant density increased seed yield by 17.7 and 19.0% than the recommended (33 plants m⁻²) and 48.1 and 62.5 than 3/4th of recommended (25 plants m⁻²)during 1998 and 1999, respectively. Higher dose of nitrogen (180 kg ha⁻¹) and higher plant density of 41 plants m⁻² resulted in significant reduction in dry matter accumulation by weeds as compared to recommended N (120 kg ha⁻¹) and plant density of 33 plants m⁻² during both the years.