PERFORMANCE OF DIRECT SEEDED SALI RICE UNDER TWO DIFFERENT CROP ESTABLISHMENT METHODS AND WEED MANAGEMENT PRACTICES
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Date
2020-06
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AAU, Jorhat
Abstract
A field experiment entitled “Performance of direct seeded sali rice under two
different crop establishment methods and weed management practices” was carried out
at the Instructional-cum-Research (ICR) Farm, Assam Agricultural University, Jorhat
during the sali season of 2018-19 with a view to study the growth and yield behaviour
of direct seeded sali rice under two different crop establishment methods and to find out
the appropriate weed management practices for direct seeded sali rice. The experiment
was laid out in a factorial RBD with three replications. The treatments consisted of two
methods of sowing i.e., dry seeding (M1) and wet seeding (M2) and seven different
weed management practices viz., two hand weedings at 20 & 40 DAS (W1), preemergence
herbicide application of pretilachlor @ 0.75 kg a.i./ha (W2), pre-emergence
herbicide application of pretilachlor @ 0.75 kg a.i./ha + one hand weeding at 40 DAS
(W3), pre-emergence herbicide application of pyrazosulfuron ethyl @ 20 g a.i./ha (W4),
pre-emergence herbicide application of pyrazosulfuron ethyl @ 20 g a.i./ha + one hand
weeding at 40 DAS (W5), weed free check (W6) and weedy check (W7).
The experimental field was infested with different types of grasses viz., Panicum
repens, Leersia hexandra and Eragrostis unioloides, sedges viz., Cyperus rotundus L.,
Fimbristylis littoralis, and broad leaved weeds viz., Ageratum conyzoides, Alternanthera
philoxeroides., Ludwigia decurrens and Acmella ciliate. The method of sowing brought
significant influences on weed density and weed dry weight in all the growth stages.
The wet seeding proved statistically superior in regards to growth attributes i.e. number
of tillers/m2 and plant height at all growth stages compared to dry seeding. Similarly,
wet seeding recorded significantly highest yield attributes i.e. number of panicles/m2
(160.11), panicle length (26.32 cm), number of filled grains/panicle (118.83) of sali rice
followed by dry seeding. The wet seeding also recorded significantly highest grain yield
(31.27 q/ha) and straw yield (49.04 q/ha). Higher uptake of nitrogen, phosphorus and
potassium in grain, straw and total uptake by sali rice and lower uptake by weeds were
recorded in wet seeding.
Among the different weed management practices, weed free plot recorded the
lowest weed density and weed dry matter, highest weed control efficiency and highest
weed control index at all growth stages as well as recorded the highest growth
characters, yield attributes, grain yield and straw yield. Results indicated that apart from
the weed free plot, pre-emergence herbicide application of pretilachlor @ 0.75 kg a.i./ha
+ one hand weeding at 40 DAS and pre-emergence herbicide application of
pyrazosulfuron ethyl @ 20 g a.i./ha + one hand weeding at 40 DAS shown the lowest
weed density, dry weight, highest WCI, highest WCE at 45, 60 DAS and at harvest
stage as well as it recorded the highest yield attributes, grain yield and straw yield. At
30 and 60 DAS, lowest uptake of nutrients by weeds were recorded in weed free check
followed by two hand weedings at 20 & 40 DAS. At harvest, lowest uptake by weeds
were recorded in weed free check followed by pre-emergence herbicide application of
pretilachlor @ 0.75 kg a.i./ha + one hand weeding at 40 DAS. Significantly higher
uptake of nitrogen, phosphorus and potassium in grain, straw and total uptake by sali
rice was recorded in weed free check followed by pre-emergence herbicide application
of pretilachlor @ 0.75 kg a.i./ha + one hand weeding at 40 DAS and pre-emergence
herbicide application of pyrazosulfuron ethyl @ 20 g a.i./ha + one hand weeding at 40
DAS.
The treatment combination of wet seeding (M2) combined with the weed free
check recorded the highest grain yield (41.33 q/ha) and straw yield (59.33 q/ha) and it
was statistically at par with the treatment combination of wet seeding along with preemergence
herbicide application of pretilachlor @ 0.75 kg a.i./ha + one hand weeding at
40 DAS. An economic analysis showed that treatment combination of wet seeding
combined with pre-emergence herbicide application of pretilachlor @ 0.75 kg a.i./ha +
one hand weeding at 40 DAS (M2W3) recorded the highest net return (Rs. 63,089/ha)
and benefit cost ratio (1.76).