THE EFFECT OF DIFFERENT DOSES OF NITROGEN FERTILIZER (UREA) ON THE INCIDENCE OF SUCKING INSECT PESTS OF RICE

Abstract

The 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 2016, to evaluate the effect of different doses of nitrogen fertilizer (urea) 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 doses as treatment- T1 = Top dressing of Nitrogen fertilizer (urea) @ 50kg/ha at three equal split application; T2 = Top dressing of Nitrogen fertilizer (urea) @ 60kg/ha at three equal split application; T3 = Top dressing of Nitrogen fertilizer (urea) @ 70kg/ha at three equal split application; T4 = Top dressing of Nitrogen fertilizer (urea) @ 80kg/ha at three equal split application; T5 = Top dressing of Nitrogen fertilizer (urea) @ 90kg/ha at three equal split application and T6 = Untreated control. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Data was recorded on insect pest incidence, number of healthy, infested plants, leaf and 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 3 common species of sucking insect pests such as brown plant hopper, green leaf hopper and rice bug were found in rice field. Insect populations for 5 selected hills/plot were observed and sucking insect pests e.g., brown plant hopper, green leaf hopper and rice bug were investigated. 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 infestation was observed from T5. In consideration of yield contributing characters and yield of BRRI dhan43, the maximum number of filled grains/panicle (93.38%) was recorded from T3, while the minimum number of filled grains/panicle (73.36%) from T6. The highest grain yield (4.25 t/ha) was recorded from T3, while the lowest grain yield (1.24 t/ha) was recorded from T6 followed by T5 (2.55t/ha). Among the different nitrogen doses; 70 kg N/ha applied in T3 treatment was superior to other nitrogen doses.