BIO-EFFICACY OF HERBICIDE COMBINATIONS FOR WEED MANAGEMENT IN DRY DIRECTSEEDED RICE (Oryza sativa L.)
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Date
2018-10-10
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
A field experiment entitled “Bio-efficacy of herbicide combinations for weed
management in dry direct-seeded rice (Oryza sativa L.)” was conducted during kharif
2016 and 2017 at Main Research Station, University of Agricultural Sciences, Hebbal,
Bengaluru, involving twelve treatments laid out in RCBD design with three replications
using MAS 946-1 variety. The treatments comprised of nine pre- and post-emergence
herbicide combinations, hand weeding, mechanical weeding and weedy check. Major
weeds observed were Cyperus rotundus, Cynodon dactylon, Commelina benghalensis
and Alternanthera sessilis. Pooled analysis indicated that hand weeding at 20, 40 and 60
DAS recorded highest grain (5.50 t ha-1
) and straw yield (7.22 t ha-1
) and it was on par
with bensulfuron methyl + pretilachlor fb bispyribac sodium (5.39 and 7.16 t ha-1
,
respectively) and bensulfuron methyl + pretilachlor fb triafamone + ethoxysulfuron (5.29
and 7.03 t ha-1
, respectively). Significantly lower total weed density, dry weight and weed
index was recorded in hand weeding at 20, 40 and 60 DAS (17.7 m-2
, 4.3 g m-2
and 0.00,
respectively) followed by bensulfuron methyl + pretilachlor fb bispyribac sodium (19.8
m-2
, 4.6 g m-2
and 2.11 %, respectively) whereas, it was significantly higher in weedy
check (108.2 m-2
, 35.8 g m-2
and 74.49 %, respectively).The higher net returns and
benefit cost ratio was achieved in bensulfuron methyl + pretilachlor fb bispyribac sodium
(Rs. 59,275 ha-1
and 2.93, respectively) closely followed by bensulfuron methyl +
pretilachlor fb triafamone + ethoxysulfuron (Rs. 57,533 ha-1
and 2.88, respectively)
without any phytotoxicity on rice crop. Unweeded control recorded significantly lower
grain yield (1.40 t ha-1
), straw yield (2.32 t ha-1
), lower net returns (Rs.-1,912 ha-1
), lower
B:C ratio (0.93). Considering the present labour scarcity and drudgery, herbicides
combination was found to be efficient weed management strategy for rice cultivation in
dry-direct seeded situations along with least effect on soil microflora and residual black
gram crop.