A field experiment was conducted at Main Agricultural Research Station, Dharwad, Karnataka, during 2017-18 to evaluate the effect of seed treatment and foliar application of nano ZnO on growth, yield and economics of Bt cotton. The experiment was laid out in split plot design with three main treatments (S1:seed treatment with chelated ZnSO4 @ 4 g kg-1 seeds, S2: nano ZnO @ 1 g kg-1 seeds and S3:seed priming with 1000 ppm nano zinc solution), four sub plot treatments (Foliar application of nano ZnO @ 500, 750, 1000 and 1250 ppm at square initiation and flowering stage) and three uneven control (C1: RDF + FYM + % EDTA ZnSO4 foliar application at square initiation and flowering stage, C2: C1 + seed treatment with Fe, Zn, Mg and Mn @ 4g each kg-1 seed and C3: Only RDF + FYM @ t ha-1 ) treatments replicated thrice. Among seed treatments, higher seed cotton yield (2842 kg ha-1 ), plant height, number of monopodial and sympodial branches, LAI, LAD, and SPAD chlorophyll meter values were recorded with nano ZnO seed treatment than seed priming with nano zinc solution and chelated ZnSO4 seed treatment. Among different foliar spray concentrations, foliar application of nano ZnO @ 1000 ppm recorded higher seed cotton yield (2718 kg ha-1 ), plant height ( cm), number of monopodial branches (), sympodial branches (), LAI (), LAD (), and SPAD chlorophyll meter value () than other concentrations. Among all treatment combinations, seed treatment with nano ZnO in combination with foliar application of nano ZnO @ 1000 ppm recorded significantly higher seed cotton yield (3221 kg ha-1 ) gross returns ( 1,56,241 ha-1 ), net returns ( 88128 ha-1 ) and B:C ratio () than recommended practices. | Nano zinc seed treatment and foliar application on growth, yield and economics of Bt cotton (Gossypium hirsutum L.)
