WEED MANAGEMENT IN DIRECT SEEDED RICE UNDER SEMI-DRY SYSTEM
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Date
1993
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ANDHRA PRADESH AGRICULTURAL UNIVERSITY HYDERABAD
Abstract
The present investigation entitled "WEED
MANAGEMENT IN DIRECT SEEDED RICE UNDER SEMI-DRY SYSTEM"
was conducted on sandy clay loam soil at Agriculture
College Farm, Rajendranagar, during Kharif 1992. The
experiment was laid-out in a randomised block design
(Factorial) with 18 treatments, replicated thrice. The
treatments consisted of two varieties viz., Praaaooa
{V) and Erramallelu (V) and nine weed control
pr!ctices Line weeding_fad hoeing at 20 and 40 DAS,
Anilofos@ 0.2 kg a.i ha at 10 DAS+ lin~1weeding and
hoeing at 30 DAS, AnilofQf@ 0.4 kg a.i ha at 10 DAS,
Anilofos@ 0.4 kg a.i ha at 10 DAS+ lin~1weeding and
hoeing at 40 DAS, Anilofos_f 0.2 kg a.i ha at 10 DAS
+ 2,4-DE~l@ 0.5 kg a.i ha at 30 DAS, Anilofo§1@ 0.2
kg a.i ha at 10 DAS+ 2,4-Q!E@ 0.5 kg a.i ha at 40
DAS, 2,(-DEE@ 1.0 kg a.i ha at 20 DAS+ line weeding
and hoeing at 40 DAS, line ~Ieding and hoeing at 20 DAS
+ 2,4-DEE @ 1.0 kg a.i ha at 40 DAS and unweeded
check).
The weed spp observed during the study were;
Cyperus rotundus, C¥perus difformis (sedges);
Echinochloa crusgalli, Digitaria sanguinallis, Panicum
spp, Cynodon dactylon (grasses); Eclipta alba,
Parthenium hysterophorus, Cessulia auxillaFI's,
Ph~llanthus maderas atensis, Euphorbia hirta and
Trianthema portulacastrum broad leaved weeds).
Lower weed density and weed dry matter {except
at 20 DAS and harvest) was recorded in Prasanna. Weed
control efficiency and weed index was not significant
in between varieties. Plant growth characters like,
plant height, crop dry matter (except at harvest) and
straw yield was higher in Prasanna. While, panicle
weight, 1000 grain weight, total grains per panicle,
harvest index grain yield (7.3%), gross and net returns
and returns per rupee invested were higher in
Erramallelu. However, nutrient uptake by crop and
weeds were not significant between the ~arieties.
Lower weed density, weed dry matter, were
obtained at 40 DAS to harvest with line weeding and
hoeing at 20 and 40 DAS, whereas at 20 DAS the weed
density and_yeed dry matter was lower in anilofos@ 0.4
kg a.i ha (W and W ), mainly due to effective
control of monoc~ts, {7~%) such as Cyperus rotundus,
Cyperus difforrnis, Echinochloa crusgalli and Panicum
spp and_~icots (30%). Anilofos at lower rates {0.2 kg
a.i ha ) was effective on grasses_£nly. Application
of 2,4-0EE {@ 0.5 and 1.0 kg a.i ha ) was effective in
controlling broad leaved weeds (85 to 98%) and to some
extent sedges. Phytotoxic effects were not severe due
to application of herbicides.
Plant growth characters, weed control
efficiency (harvest), yield components, grain yield,
harvest index and gross returns were higher in line
weeding and hoeing at 20 and 40 DAS. However, net
returns and returns per rupee invested were higher in
line we~1ing .and hoeing at 20 DAS with 2,4-DEE@ 1.0 kg
a.i ha at 40 DAS. Integration of physical {line
weeding), mechanical (hoeing) and chemical {herbicide)
methods favoured higher growth and yield than
application of herbicides alone. NPK uptake by crop
was maximum at harvest and weeds at 80 DAS, but rate of
uptake by crop and weeds was higher at 80 DAS. Line
weeding and hoeing at 20 and 40 DAS recorded maximum
nutrienb uptake by crop and minimum by weeds. Reduced
plant ·growth and luxuriant weed growth was recorded in
unweedy check (Wg). Herbicide residue study using
cucumber indicated non-residual nature of the
herbicides. There was no interaction between varieties
and weed control treatments. Line weeding and hoei~i
at 20 DAS with application of 2,4-DEE@ 1.0 kg a.i ha
at 40 DAS is recommended for both varieties to achieve
higher monetary returns.
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