Effect of Nitrogen and Plant Population Levels on Competition of Maize (Zea mays L.) with Weeds

Field experiments were conducted at the experimental area of Punjab Agricultural University, Ludhiana during kharif seasons of 2000 and 2001 in order to study the competitive ability of maize with weeds as influenced by nitrogen levels and plant densities on loamy sand soils. Higher plant population of 90000 plants ha−1 significantly reduced dry matter accumulation by weeds during 2000 as compared to the recommended plant density (75,000 plants ha−1) but these differences were non-significant during 2001. Higher level of nitrogen (175 kg ha−1) resulted in significant increase in grain yield than the recommended dose i. e. 125 kg ha−1, whereas higher plant population (90,000 ha−1) resulted in significant reduction in grain yield than 75,000 plants per hectare during both the years. On an average of two years, pre-emergence application of atrazine at 1 kg ha−1, atrazine 0.75 kg ha−1+straw mulch and two hand weeding treatments increased grain yield by 39.4, 38.2 and 36% than unweeded control.