T. Akter*, M. S. Alam and K. T. Kobra
*Corresponding author’s e-mail: tahmina_sauento@yahoo.com
An experiment was conducted in the experimental area of Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka during the period from April to August 2017 to evaluate the effect of different doses of nitrogen on the incidence of sucking insect pest of rice. BRRI dhan43 were used as the test crop in this experiment. The experiment comprised of the following nitrogen dosses as treatment- T1 Top dressing of Nitrogen per hectare (T2=50, T2 = 60, T3 = 70, T4 = 80 and T5 = 90 from urea at three equal splitting application; also and T6 = Untreated control. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Data was recorded on insect pests incidence, number of healthy, infested plants leaf or tillers due to different insect pests and infestation level and also yield contributing characters and yield of BRRI dhan43 from different treatments. It was revealed that three common species of sucking insect pests such as brown plant hopper, green leaf hopper and rice bug were found in rice field and they belonged to three families under two orders. Among the insect species one species belonged to the family Delphacidae. Insect population for five selected hills per plot were observed with sucking insect pests such as brown plant hopper, green leaf hopper and rice bug which were found to be the highest in number from T5, whereas the lowest number of these insect pests were observed from T3 treatment. In case of tillers, leaf and panicle infestation in different crop stages caused by different rice sucking insect pests, the lowest infestation was recorded from T3, whereas the highest from T3. In consideration of yield contributing characters and yield of BRRI dhan43, the maximum number of filled grains per panicle (93.38%) was recorded from T3, while the minimum number of filled grains per panicle (73.36%) from T5. The highest grain yield (4.25 t/ha) was recorded from T3 , while the lowest (1.24 t/ha) from T6 which was then flowed by (2.55t/ha) from T5. Among the different nitrogen doses 70 kg N per hectare (T3) was superior to the other doses.

Keywords: Doses of nitrogen, Incidence, Sucking insect pest, BRRI dhan43.

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