Biologi dan kawalan echinochloa crus-galli (l.) beauv. dalam tanaman padi tabur terus
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Date
1994
Authors
Man, Azmi
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Abstract
Field surveys conducted in the granary areas of Peninsular
Malaysia identified 16 spesies of grasses, 20 sedges, 35
broadleaved weeds and 7 aquatic weeds. Eight species were
common to a 11 rice granaries of which E. crus-ga 7 7 i was
the dominant weed. Detai 1 ed studies were conducted from
1989 to 1993 at MARDI Rice Research Centre, Seberang Perai
including varietal identification of Echinoch7oa crusga77i
and its life cycle, seed longevity, competition at
various densities of this weed against direct seeded rice
(DSRL critical period of weed competition, influence of
rice variety, time of flooding and control methods.
Echinoch7oa crus-ga77i was the dominant weed for six
consecutive seasons of DSR in Seberang Perai. The studies
in Kemubu, Kelantan revealed that £. crus-ga77i was
pronounced after DSR was adopted. Ech i noch 7 oa crus-ga 7 7 i
var. formosensis has longer seed longevity than var. crus-
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ga77i. Variety crus-ga77i also showed drastic reduction in
germination percentages in the rice field (with exception
2nd season which had 6. 4% germination) with 2. 94% (1st
season) to 0.02% (6th season). Variety formosensis
exhibited a similar trend in germination percentages from
7. 33% (1st season) to 0. 08% (6th season). Most of the
seeds germinated during the first three weeks after sowing
of rice. Survival test showed that after six seasons, all
var. crus-ga 7 7 i seeds were not vi ab 1 e wh i 1 e about 7% of
buried seeds of var. formosensis survived.
Echinoch7oa crus-ga77i at different densities vary in
their competitive ability with rice. Competition was more
intense at high densities than at low densities. Only 10
plants/m2 were required to cause significant yield
reductions of about 18.7% and 19.9% (i.e. 1 t/ha) for main
season 1988/89 and off season 1989 respectively. Negative
relationships between panicle;m2 and rice yield and dry
weight and rice yield were obtained. A rectangular
hyperbo 1 a re 1 at i onsh i p was estab 1 i shed when DSR competed
at high densities of E. crus-ga77i. Economic thresholds of
this weed was estimated at 1-3 pl ants;m2 . Critical period
of competition between E. crus-ga77i with rice, and mixed
weeds with rice in main season 1988/89 and off season 1989
respectively are at 15 to 30 DAS. Further, verifications
of critical period for weed control in DSR were also
carried out. Twelve rice varieties with different plant
types and maturation periods were tested in main season
1989/90 under two weed control regimes, weed free at
cri t i ca 1 stage and weed competition t i 11 harvest. Weed
control at critical period significantly reduced weeds
regrowth at 60 DAS. Yield increase in the range of 22.15 -
66. 51% was recorded. Under fu 11-season weed competition,
Bahagia (tall plant with droopy leaves) was tolerant to
weed competition with a lower improvement in yield
production (22%).
Studies showed that early flooding in off season 1990 at
three and six DAS reduced the problem of E. crus-ga 7 7 i
infestation. However, crop stands were thin and weak with
reduced number of productive tillers. Delayed flooding
espec i a 11 y after 15 DAS enhanced serious infestation of
various weeds resulting in high yield loss. However,
delayed flooding improved crop anchorage and weed free
condition at cri t i ca 1 period, enhanced t i 11 er production
and higher yields.
Several methods of weed control were tested in off season
1990 and main season 1990/91 in order to suppress weeds at
the critical period. Among treatments that gave
si gni fi cant yield increase were manual weeding at 15 and
30 DAS, bensulfuron applied at 10 DAS followed by manual
weeding at 30 DAS, pretilachlor sprayed at 4 DAS followed
by manual weeding at 30 DAS and combination of molinate +
bensulfuron applied at 10 DAS. Delaying the manual weeding
at 30 DAS could cause physical injury to crop.
Description
Keywords
Echinochloa crus-galli , Padi tabur terus