PRODUCTIVITY OF WET-SEEDED RICE (Oryza sativa L.) UNDER DIFFERENT PLANT DENSITY AND WEED CONTROL
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Date
2011
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Birsa Agricultural University, Kanke, Ranchi, Jharkhand
Abstract
Rice (Oryza sativa L.) is the most important crop of south-east Asia popularly
referred to as the rice bowl of the world. In India rice is cultivated in 45 million hectares
with production of 124.40 million tonnes having productivity of 2930 kg/ha (Rao et al,
2007). The importance of rice in India is such that even a minor fluctuation in
productivity brings about major change in Indian economy. If the rice productivity of
India in general and Jharkhand in particular is raised by cultural methods, it can bring
about tremendous change in agricultural scenario and on rural economy. A wet seeded
rice crop may be sown at the start of monsoon or after a few weeks when soil is more
saturated. Seed rate plays an important role which is kept usually to minimize weed
menace in increasing rice productivity and herbicides are also effective to control of
weeds in wet seeded rice.
A field experiment was conducted during kharif 2010 at the Agricultural Farm,
Birsa Agricultural University, Jharkhand on acidic (pH5.7) sandy-loam soil (61% sand,
22% silt and 17% clay) having low in organic carbon (0.37%), available nitrogen
(242.23 kg/ha) and exchangeable potassium (123 kg/ha) and medium in available
phosphorus (14.43 kg/ha) to study the productivity of wet-seeded rice (Oryza sativa L.)
under different plant density and weed control. The treatment comprised of four seed
rates viz. 60, 80, 100 and 120 kg/ha and five weed control methods viz. butachlor 1.5
kg/ha (PE), pyrazosulfuron (PoE) 0.02 kg/ha, almix (PoE) 4 g/ha, Weed free and Weedy
check. The experiment was laid out in randomized block design with three replications.
Results revealed that rice crop sown with 100 kg seed/ha significantly reduced
population of grassy weed by 64.49 and 80.27%, broad leaved weeds by 48.03 and
42.63% at 40 and 60 days after sowing respectively compared to 60 kg seed/ha.
Application of pyrazosulfuron (PoE) 0.02 kg/ha significantly reduced grassy weed
population by 54.57 and 21.31% at 20 and 40 DAS, broad leaved weeds by 86.57, 50.40
and 54.29% at 20, 40 and 60 days after sowing respectively and sedges population by
84.11 and 73.88% at 40 and 60 DAS as compared to weedy check . 100 kg seed/ha
significantly reduced dry matter accumulation to the tune of 71.57 and 64.96% at 40
DAS and 89.75 and 82.52% at 60 DAS by grasses as compared to 60 and 80 kg seed/ha
and 84.59 and 75.66% significantly reduced dry matter accumulation at 40 and 60 DAS
respectively by sedges as compared to 60 kg seed/ha. Application of pyrazosulfuron
(PoE) 0.02 kg/ha registered significantly reduced dry matter accumulation by grassy
(74.51,93.97 and 85.00%), BLW (69.04,93.61 and 91.45%) and sedges (89.60,88.42 and
60.21%) at 20, 40 and 60 DAS as compared to weedy check. The dry matter
accumulation by total weeds was significantly reduced to the tune of 76.94% by 100 kg
seed/ha as compared to 60 kg seed/ha thereby registering maximum weed control
efficiency i.e, 59.42, 66.60 and 58.61% at 20, 40 and 60 DAS respectively while
application of pyrazosulfuron (PoE) 0.02 kg/ha recorded 76.18, 93.08 and 79.46%
significantly reduced total weed dry matter accumulation as compared to weedy check
thereby registering maximum weed control efficiency i.e, 67.56, 93.24 and 78.52 at 20,
40 and 60 DAS respectively.
Rice crop sown with 100 kg seed/ha recorded 30.46 and 8.35% significantly
higher total tillers/m2 at maturity compared to 60 and 80 kg seed/ha, 67.94 and 38.00%
significantly higher dry matter accumulation by rice plant at maturity as well as
maximum crop growth rate 5.77, 9.14, 8.45, 9.07 and 1.73 g/day/m2 at 20 days interval
from 20 DAS respectively upto maturity thereby recording maximum panicle length
(19.35 cm), effective tillers, higher filled grains/panicle resulting in higher grain and
straw yield (2784 and 3639 kg/ha). 100 kg seed/ha recorded significantly higher gross
return (Rs 33298/ha), net return (Rs 16628/ha) and benefit-cost ratio (0.99) as compared
to that recorded under 60 and 80 kg seed/ha. Among herbicide application of
pyrazosulfuron (PoE) 0.02 kg/ha registered 41.94% higher tillers/m2 at maturity, 28.58%
higher dry matter accumulation by rice plant thereby producing 29.5% higher panicle
length, 40.06% higher effective tillers (317/m2) and lower number of unfilled grains as
compared to weedy check. This resulted 51.19% significantly higher grain yield (3046
kg/ha) and 56.54% higher straw yield (3741 kg/ha), 54.36% higher gross return (Rs
32583/ha), 100.22% higher net return (Rs 17115/ha) compared to weedy check.
Application of pyrazosulfuron (PoE) 0.02 kg/ha also generated 33.46 and 25.10% higher
gross return, 64.85 and 46.26% higher net return and 65.45 and 45.45% higher benefitcost
ratio as compared to butachlor 1.5 kg/ha (PE) and almix (PoE) 4 g/ha respectively.
On the basis of above findings it is concluded that 100 kg seed/ha was the most
optimum seed rate for effective suppression of weeds, higher productivity and
profitability of rice grown as direct seeded under wet condition and among weed control
methods application of pyrazosulfuron 0.02 kg/ha (PoE) was found to be most effective
herbicides in suppressing weeds throughout the growing season of rice thereby
facilitating higher grain yield production and generating higher net return and B:C ratio.
Description
PRODUCTIVITY OF WET-SEEDED RICE (Oryza sativa L.) UNDER DIFFERENT PLANT DENSITY AND WEED CONTROL
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