EFFECT OF DIFFERENT LEVELS OF NPK ON INSECT PESTS OF TRANSPLANTED AMAN RICE (Oryza sativa L.)

Abstract

The study was conducted in the experimental field 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 in transplant Aman rice field on it`s insect pests. BRRI dhan33 were used as the test crop in this experiment. The experiment comprised of the different NPK fertilizer dose as treatment- T0= Untreated control (no NPK fertilizers), T1= NPK @ 45, 50, 40 kgha-1, T2= NPK @ 70, 25, 40 kgha-1, T3= NPK @ 70, 50, 20 kgha-1, T4= NPK @ 70, 50, 40 kgha-1, T5= NPK @ 70, 50, 60 kgha-1, T6= NPK @ 70, 75, 40 kgha-1 and T7= NPK @ 95, 50, 40 kgha-1. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Data were recorded on different types of insect pests of rice those were identified recorded during the entire growing period with their number and incidence on rice plants and also different yield contributing characters and yield of rice and analized the statistical differences for different levels of NPK fertilizers. Among the observed insect pests, 2 species were belong to the family Pyralidae and only 1 species for each of Chrysomelidae, Acrididae, Delphacidae, Cicadellidae and Coreidae family. During the entire growing period 5 selected hills/plot were monitored with clean observation and yellow stem borer, leaf folder, rice hispa, grasshopper, brown plant hopper, green leaf hopper and rice bug were recorded the lowest number of those insect pests were observed in T5 trteated plot whereas the highest number was found from T7 trteated plot. In case of incidence of dead heart recorded at 25, 45 and 65 DAT, data recorded from each plot revealed that the lowest incidence of dead heart was observed from T5 (3.64%, 4.23% and 4.47%, respectively), while the highest incidence of dead heart was found from 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 from T5 (2.35%, 2.66% and 3.12%, respectively), whereas the highest incidence of white head was observed from T7 (7.57%, 8.26% and8.64%) treatment. The highest grain yield was recorded from T5 (4.54 ton), while the lowest grain yield was observed from T0 (2.78 ton) treatment. Among the different levels of NPK fertilizers, NPK @ 70, 50, 60 kgha-1 (T5) was the better for the rice cultivation to support its insect pests.