OPTIMIZATION OF WEED MANAGEMENT THROUGH AGRO-TECHNIQUES IN AEROBIC RICE (Oryza sativa L.)
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Date
2019-10-14
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UNIVERSITY OF AGRICULTURAL SCIENCES, GKVK BENGALURU
Abstract
The weed management investigations were carried out on red sandy loam soil
with medium in available NPK during summer 2017 and 2018 at Zonal Agricultural
Research Station (ZARS), Bengaluru, consisting of two different field experiments which
were laid out in a Randomized Complete Block Design. The results of the experiment on
standardization of the agro-techniques for weed management in aerobic rice revealed that
application of pyrazosulfuron ethyl 10 % WP @ 35 g a.i. ha-1 as pre-emergence spray
followed by bispyribac sodium 10 % SC @ 30 ml a.i. ha-1 as early post-emergence spray
recorded significantly lower weed density, weed dry weight and weed index (3.80 %) due
to higher weed control efficiency (90.52 %). This helped in obtaining higher rice grain
and straw yield (5800 & 9786 kg ha-1, respectively), plant height (58.42 cm), total dry
matter production (149.84 g plant-1), productive tillers hill-1 (40.32), panicle length (24.53
cm), 1000 grain weight (25.35 g), net returns (`62424 ha-1) and B:C ratio (2.59). Another
experiment on weed management in aerobic rice through intercropping recorded higher
crop biomass and higher weed suppression. Sole rice was densely infested by weeds and
also had higher weed biomass compared to the intercrops. However, intercrops
suppressed efficiently the weeds, increased crop growth and rice equivalent yield over the
sole rice crop. The intercropping system of rice with leafy palak vegetable (spinach) was
the most suppressive of weeds. Among the treatments, rice + leafy vegetable palak
recorded significantly lower weed density (138.4 NO. m-2), dry weight at harvest (148.04
g m-2), higher weed smothering efficiency (46.95 %), higher rice grain, rice straw and
palak leaf yield (7651; 9687 and 25508 kg ha-1, respectively), higher rice equivalent yield
and land equivalent ratio (16153 kg ha-1 and 2.13, respectively), besides the higher gross
returns (`2,56,842 ha-1), net returns (`2,12,860 ha-1) and B:C ratio (5.84) over the sole
rice.