Authors:
Chhay Ngin1, Seng Suon
, Toshiharu Tanaka
, Akira Yamauchi
, Kazuhito Kawakita
, and
Sotaro Chiba |
Abstract:
Field studies with complete randomized design in triplicates were conducted to determine the
impact of mechanically simulated insect-induced defoliation and detillering on irrigated rice
during dry season from January to April 2016 in three locations in Cambodia. Defoliation
treatments were 0% (control), 10%, 25% and 50% defoliation at 30 days after transplanting (dat)
at tillering stage, and 10%, 30% and 50% defoliation at 60 dat at heading stage. The detillering
treatment were simulated at 10%, 20% and 30% at 30 dat and 5%, 10% and 15% at 60 dat
comparing to the control. The parameter examined were: number of tillers/m2
, number of
panicle/m2
, weight of 1000 grains, number of full grain/panicle, and grain yield (kg/ha) were
examined. Results showed that no yield losses occurred up to 50% defoliation at 30 dat and up to
30% defoliation at 60 dat. However, the defoliation of 50% at 60 dat significantly affected the
number of full grain and the grain yield with yield reduction of 13.5% (from 4,422 to 3,824
kg/ha) in average. For simulated stem damages, no difference in rice yield was observed up to
20% tiller removal at 30 dat and up to 10% stems loss at 60 dat. Nevertheless, significant yield
losses occurred when 30% and 15% of tillers were removed at tillering and heading stages,
respectively. These results suggested that the rice plant has the ability to compensate and tolerate
certain levels of foliage and tiller losses at different growth stages. |
