Potential impact of nitrogen on population fluctuation of aphid and yield parameters in barley

The present study was carried out on the farmer field under the supervision of the Department of Plant Protection and Quality Control of Pesticides during 2020 and 2021. Barley cultivar ‘Haider-93’ was sown in a randomized complete block design (RCBD) with three replications to examine the effect of two levels ofnitrogen fertilizer, 50 and 100 kg/ha along with control (no fertilizer), on population fluctuation of aphid and on barley yield components like grain protein (%), 1000-grain weight and the barley grain yield. Aphid incidence was recorded throughout the cropping season. The results revealed that peak infestation of aphids per tiller were recorded in the 3rd week of February in successive year. The study indicated a significant relationship between nitrogen fertilizer and aphid population density per tiller. The mean aphid population per tiller was recorded a significantly higher (34.12 ± 0.81 and 28.65 ± 0.17 for the years 2020 and 2021, respectively) at 100 kg/ha of nitrogen level while lowest infestation (14.51 ± 0.20 and 12.30 ± 0.10 aphids per tiller for the year 2020 and 2021, respectively) was recorded at 0 kg/ha of nitrogen fertilizer. Nitrogen fertilizer level at 100 kg/ha gave significantly higher grain protein (12.80 ± 0.17 and 13.70 ± 0.26% for the years 2020 and 2021, respectively) and grain yield (2758.75 ± 60.82 and 2673.79 ± 61.88 kg/ha produce for the year 2020 and 2021, respectively) of the barley crop. However, treatment differences for 1000-grain weight (g) were recorded as non-significant. These findings suggest that the nitrogen fertilizer at 100 kg/ha level produced significantly higher grain protein (%) and grain yield at the same time, also supported the higher infestation of aphids per tiller. Still, this aphid density did not affect the accumulation of grain protein (%) and grain yield of the barley crop. The results of this study might be used for decision-making to apply nitrogen fertilizer for better grain yield of barley crop but at the same time considering the colonizing aphid population.