Nitrogen fertilizer levels and some weed control treatments effects on barley and associated weeds

Abstract

Studies were carried out to investigate the efficiency of nitrogen fertilizer levels (15, 30, 45 and 60 kg/fed) and different postemergence herbicides (metosulam, sulfamoylurea, fenoxaprop-pethyl, clodinafop-propargyl, isoproturon+diflufinican and isoproturon), hand weeding and unweeded check in barley crop at private farms in Shalakan, Kalubia Governorate, Egypt during 2007/2008 and 2008/2009 seasons. Increasing N-levels from 15 to 30, 45 and 60 kg/fed significantly increased number and dry weight of barley weeds after 60 and 90 days from sowing (DFS). Application of 60 kg N/fed recorded the highest number and dry weight of weeds. Metosulam at 0.04 L/fed provided control (95.46-92.83% reduction in dry weight after 60 and 90 DFS) for broadleaved weeds but failed to completely control narrow-leaved weeds. Clodinafoppropargyl at 140 g/fed provided 94.85 and 94.34% reduction in dry weight after 60 and 90 DFS of narrow leaf weeds. Isoproturon+diflufinican came in the first order for controlling total weeds but statistically leveled with isoproturon alone. It recoded number and dry weight of total weeds than unweeded by 90.31 and 91.46% after 60 days from sowing and 89.78 and 90.80% after 90 days from sowing. pplication of nitrogen at 60 kg N/fed recorded the highest value of flag leaf area, plant height, spike length, number of grains/spike, grains weight/spike, spikes number/m2, straw and grain yields as well as grain protein and total carbohydrates percentage. All herbicidal treatments and hand weeding increased significantly growth, yield, yield components and chemical composition of grain barley. Isoproturon+diflufinican was superior treatment for increasing plant height, spike length, grains number/spike, grains weight/spike, spikes number/m2, straw and grain yields as well as grain protein and total carbohydrates percentage. While, hand weeding recorded the highest values of flag leaf area. Application of isoproturon+diflufinican herbicide provided 66.3% more grain yield than weedy check. The interaction between N-levels and weed management treatments had significant effect on total dry weight of weeds, spikes number/m2, grain weight/spike and grain and straw yields. Isoproturon+diflufinican produced the lowest values of total dry weight of weeds after 60 and 90 DFS when 15 kg N/fed was added. While, Application of 60 kg N/fed gave the maximum values of number of spike/m2, weight of grain/spike, grain and straw yields/fed when isoproturon+diflufinican treatment was applied. It could be concluded that using 60 kg N/fed resulted in increment of growth and productivity of barley crop when isoproturon+diflufinican treatment was used.