title: Efficacy evaluation of selected herbicides on weed control and productivity evaluation of Bt cotton in Punjab.
abstract: Field experiments were conducted during Kharif 2012 and 2013 to evaluate the efficacy of different herbicides for weed management in cotton. Highest seed cotton yield (3537.3 kg ha(-1)) was recorded in weed free plots followed by pendimethalin @1.0 kg a.i ha(-1) as Pre.em.+quizalofopethyl @50 g a.i ha(-1) post-em at 2-4 weed leaf stage + one hoeing (3318.9 kg ha") owing to improved number of bolls per plant and boll weight. Statistically least yield was recorded underweedy check (1435.4 kg ha(-1)). Application of pyrithiobac sodium could not express any visible toxic effect on crop indicating its selectivity for cotton, although none of the tested new chemicals i.e., pyrithiobac sodium@ 62.5g a.i ha(-1) and quizalofopethyl @50g a.i ha(-1) when applied alone could not outperform the existing recommended chemicals for weed management. Yield losses to the extent of 6.2-59.4% were recorded due to weed competition. Weed control efficiency (WCE) was highest under weed free check (86.8%) followed by pendimethalin @1.0 kg a.i ha(-1) as Pre. em.+quizalofopethyl @50g a.i ha(-1), at 2-4 weed leaf stage + one hoeing (73.7%), whereas minimum values were for weedy check (24.7%). Though net returns (r94660 ha(-1)) were highest for weed free check but higher B:C ratio (2:11) was observed for pendimethalin @1.0 kg a.i ha(-1) as Pre em.+quizalofopethyl @50 g a.i ha(-1) post-em at 2-4 weed leaf stage+one hoeing. Therefore, for reasons such as labor shortage besides their timely availability, using these herbicides in combination with cultural practices could be the practical solution foreconomically efficient and effective weed management.
authors.forename: Kulvir
authors.initials: K
authors.lastname: Singh
authors.forename: Pankaj
authors.initials: P
authors.lastname: Rathore
mesh_terms: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics; D018533:Biomass; D004731:Endotoxins / Q000235:genetics; D003368:Gossypium / Q000235:genetics / Q000254:growth & development*; D006460:Hemolysin Proteins / Q000235:genetics; D006540:Herbicides; D007194:India; D030821:Plants, Genetically Modified / Q000254:growth & development; D058728:Weed Control
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D006540:Herbicides; C030956:insecticidal crystal protein, Bacillus Thuringiensis