*Corresponding author’s e-mail: tahmina_sauento@yahoo.com
Abstract
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.
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