Effect of Nitrogen, Phosphorus and Potassium (NPK) Application on Insect Pests Infesting Transplanting Aman Rice (Oryza sativa L.)

Abstract

The study was conducted in the experimental area of Sher-e-Bangla Agricultural University (SAU), Sher-e-Bangla Nagar, Dhaka-1207, Bangladesh, during the period from July to October 2016 to find out the effect of different levels of NPK on insect pests in transplant aman rice. BRRI dhan33 was used as the test crop in this experiment. The experiment comprised of different NPK (Nitrogen, Phosphorus and Potassium) fertilizers doses as treatment where, T0 = absolute control, no NPK fertilizers, T1 = NPK @ 45, 50, 40 kg/ha, T2 = NPK @ 70, 25, 40 kg/ha, T3 = NPK @ 70, 50, 20 kg/ha, T4 = NPK @ 70, 50, 40 kg/ha, T5 = NPK @ 70, 50, 60 kg/ha, T6 = NPK @ 70, 75, 40 kg/ha and T7 = NPK @ 95, 50, 40 kg/ha. The experiment was laid out in a Randomized complete block design (RCBD) plot with three replications. Data were recorded on different types of insect pests that were identified for the entire growing period with their number and incidence on rice plants. During the entire growing period 5 selected hills/plot were monitored with clear observation on yellow stem borer, leaf folder, rice hispa, grasshopper, brown planthopper, green leafhopper and rice bug insects and pests. The lowest number of infestation of insects and pests was observed from T5, whereas the highest number was found in T7 treatment. In case of incidence percent of dead heart, data were observed at 25th, 45th and 65th days after transplanting (DAT), respectively. Data recorded from each plot revealed that the lowest incidence of dead heart was observed in T5 (3.64%, 4.23% and 4.47% at NPK 70, 50, 60 kg/ha), while the highest incidence of dead heart was found in T7 (10.37%, 13.56% and 14.73%, respectively) treatment. In terms of white head incidence, at 60, 70 and 80 DAT, data recorded from each plot revealed that the lowest incidence of white head was found in T5 (2.35%, 2.66% and 3.12%, respectively), whereas the highest incidence of white head was observed in T7 (7.57%, 8.26% and 8.64% at NPK @ 95, 50, 40 kg/ha).