University of Tehran perss Journal of Crops Improvement 2008-8337 22 2 2020 06 21 The assessment of weed competition effect on growth and yield of cotton with use chemical and biological fertilizers The assessment of weed competition effect on growth and yield of cotton with use chemical and biological fertilizers 245 255 75981 10.22059/jci.2020.284772.2238 FA Majid Rahimizadeh Assistant Professor, Agronomy Department, Faculty of Agriculture, Bojnourd Branch, Islamic Azad University, Bojnourd, Iran. Journal Article 2019 07 24 A field experiment was conducted to evaluate and compare the effects of N and P chemical fertilizers with biological N and P fertilizers on competition between cotton and weeds with split plot arrangement in a randomized complete block design with three replications during the years 2014 and 2015. The main plots consisted of two levels of weed management practices including weed free and weedy check. Sub plots had five treatments included integrated application of biological and chemical fertilizers:1-Control (Without fertilizer) 2-Urea+Triplesuperphosphate (TSP) 3-Nitroxin+50% urea+100% TSP 4-100% urea+Barvar2 +50% TSP 5-Nitroxin+Barvar2+50% urea+50% TSP. In the first year, control of weeds increased LAI and number of boll per plant to 34 and 22 percent, respectively and cotton yield increased by 67 percent in the first year and 50 percent in the second year. Fertilizer treatments had a significant effect on stem length, LAI, number of sympodial branches and boll per plant, and yield of cotton. Under weed interference condition, use chemical fertilizers alone reduced cotton growth and yield due to increasing competitive ability of weeds. But reducing urea consumption by half and replace it with nitroxin, increased cotton yield by 61% compared to the chemical fertilizer treatment due to increasing number of boll per plant. This result indicates that the use of biological fertilizers reduce the negative effects of chemical fertilizers and increase crop competitiveness against weeds A field experiment was conducted to evaluate and compare the effects of N and P chemical fertilizers with biological N and P fertilizers on competition between cotton and weeds with split plot arrangement in a randomized complete block design with three replications during the years 2014 and 2015. The main plots consisted of two levels of weed management practices including weed free and weedy check. Sub plots had five treatments included integrated application of biological and chemical fertilizers:1-Control (Without fertilizer) 2-Urea+Triplesuperphosphate (TSP) 3-Nitroxin+50% urea+100% TSP 4-100% urea+Barvar2 +50% TSP 5-Nitroxin+Barvar2+50% urea+50% TSP. In the first year, control of weeds increased LAI and number of boll per plant to 34 and 22 percent, respectively and cotton yield increased by 67 percent in the first year and 50 percent in the second year. Fertilizer treatments had a significant effect on stem length, LAI, number of sympodial branches and boll per plant, and yield of cotton. Under weed interference condition, use chemical fertilizers alone reduced cotton growth and yield due to increasing competitive ability of weeds. But reducing urea consumption by half and replace it with nitroxin, increased cotton yield by 61% compared to the chemical fertilizer treatment due to increasing number of boll per plant. This result indicates that the use of biological fertilizers reduce the negative effects of chemical fertilizers and increase crop competitiveness against weeds https://jci.ut.ac.ir/article_75981_caf2d119cbaac4609452559278e1b564.pdf