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Subject: Agronomy × Author: BAHIRGUL SABIRY × Start date: 2014 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    WEED MANAGEMENT IN RAINFED MAIZE (Zea mays L.) THROUGH EARLY POST-EMERGENT HERBICIDES
    (University of Agricultural Sciences Dharwad, 2015-06) BAHIRGUL SABIRY; Dr. RAMESH BABU
    A field experiment was conducted during kharif season of 2014-15 at MARS, UAS, Dharwad to take up investigation on “Weed management in rainfed maize (Zea mays L.) through early post-emergent herbicides”. The treatments comprised of early post-emergent herbicides viz., topramezone, atrazine and 2,4-D Na salt at 100% of their recommended dose when used alone and tank mixtures viz., topramezone + atrazine and topramezone + 2,4-D at 50% of their recommended dose and they were applied at 20 DAS. These treatments were compared with recommended weed management practice (Pre emergent application of atrazine + one intercultivation+one hand weeding). The experiment was laid out in Randomized Complete Block Design with three replications. Experimental results revealed that at 30 DAS, tank mixtures viz., topramezone 12.5 g/ha + atrazine 625 g/ha and topramezone 12.5 g/ha + 2,4-D 500 g/ha recorded significantly lower weed density (8.67 and 11.67 g/0.5m2, respectively) and weed dry weight (5.59 and 6.60 g/0.5 m2, respectively) and were on par with recommended practice (10.00/ 0.5 m2). At 60 DAS, significantly higher weed control index (86.11%) and lower weed index (4.38%) was recorded in topramezone 12.5 g/ha +atrazine 625 g/ha which was on par with recommended practice, weed free and topramezone + 2,4-D. Grain yield was significantly higher with this treatment (6791 kg/ha) which was on par with application of topramezone 12.5 g/ha + 2,4-D 500 g/ha (6609 kg/ha), recommended practice (6882 kg/ha) and weed free (7103 kg/ha). These herbicide mixtures were also significantly higher with respect to nitrogen uptake by the crop. The same trend was noticed with net returns (` 97259/ha and ` 91740/ha, respectively) and benefit: cost ratio (4.00 and 3.88, respectively). The dehydrogenase activity was significantly reduced with atrazine and 2,4-D when used alone and it was higher with topramezone 12.5 g/ha + atrazine 625 g/ha at 7 and 15 DAS after herbicide application.