EVALUATION OF PRE AND POST-EMERGENT HERBICIDES IN AEROBIC RICE (Oryza sativa L.)
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Date
40865
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University of Agricultural Sciences GKVK, Bangalore
Abstract
A field experiment entitled “evaluation of pre and post-emergent
herbicides in aerobic rice” was conducted during Kharif 2010 at Main
Research station Hebbal Bengaluru. The experimental site was uniform
in topography and sandy loam in soil texture. The soil pH was neutral in
reaction and medium in available Nitrogen, phosphorus and potassium.
The experiment consisted of 12 treatments laid out in randomized
complete block design with three replications consisting five preemergent
herbicides, two post emergent herbicides, two combination of
pre and post-emergent herbicides, passing of cycle hoe at 15, 30 and 45
DAS and compared with two hand weedings at 20 and 40 DAS and
unweeded check. The predominant weed flora observed in the
experimental field in association with the aerobic rice includes
Echinochloa colonum, Digitaria marginata, Elusine indica, Chloris barbata,
Cynadon dactylon, Ageratum conyzoides, Commelina benghalensis,
Spilanthus acmella, Acanthospermum hispidum, Stachytarpheta indica,
Celosia argentia, Parthenium hysterophorus and Cyperus rotundus. The
results revealed that pre-emergence application of bensulfuron methyl @
60 g + pretilachlor @ 600 g a.i. ha-1 recorded significantly higher grain
and straw yield (4100 and 4961 kg ha-1 respectively), lower weed
population and their dry weight (72.00 No. m-2 & 3.65 g 0.25 m-2,
respectively). The plant growth and yield components viz., plant height
(85.80 cm), leaf area (2306 cm2 hill-1), total dry matter production (64.00
g hill-1), number of productive tillers hill-1 (21.32), weight of panicle (2.81
g), filled spikelets per panicle (88.23) and 1000 grain weight (21.80 g)
were significantly higher with the same treatment. Further the nutrient
uptake by the crop (79.30, 13.90 and 58.40 Kg NPK ha-1) was maximum
and the net returns and B:C ratio was also high with the pre-emergence
application of bensulfuron methyl @ 60g + pretilachlor @ 600 g a.i. ha-1.