Impact of row spacing and reduced herbicide doses along with ajuvant on weeds in maize (Zea mays L.)

In agriculture herbicides have enormous role and enhance crops yield by suppressing weeds and reducing weed crop competition. An experiment was conducted at Agronomic Research Area, University of Agriculture, Faisalabad during summer 2014 to evaluate the effect of reduced row spacings and atrazine + mesotrione + halosulfuron methyl (Land Mater 58% WDG) alone and with alkyl ether sulphate as adjuvant on weeds growth and yield of maize (Zea mays L.). The experiment was layout in randomized complete block design with factorial arrangement having three replications. Treatments comprised weedy check, atrazine + mesotrione + halosulfuron methyl at labelled dose (719.2 g a.i per ha), 75% of label dose (539.4 g a.i per ha) and 50% of labelled dose (359.6 g a.i per ha) alone and in combination with alkyl ether sulphate @ 396.8 mL per ha. The herbicides were applied after emergence of weeds and maize with knapsack hand sprayer fitted with flat fan nozzle. The results showed that reduction of row spacing in maize from 75 cm to 60 cm did not influence weed density and dry weight for all weeds 14 DAS and 30 DAS except Convolvulus arvensis L. and Coronopus didymus L. 14 days after spray. It significantly influenced ear height of maize. Although the number of grains per cob and grain weight were increased with wider row spacing but due to lower plant population at this spacing the grain yield per unit area was found non- significant. With herbicide and adjuvant treatments the maximum reduction in weeds density (81 % and 82%) and weed biomass (84% and 88%) two weeks after spray while (77%) and (81 %) at harvest was observed with atrazine + mesotrione + halosulfuron methyl at 75% of label dose (539.4 g a.i per ha) + alkyl ether sulphate @ 396.8 mL per ha and atrazine + mesotrione + halosulfuron methyl at labelled dose (719.2 g a.i per ha) treatments, respectively under both row spacings. The highest ear height (85.33 cm) was recorded in atrazine + mesotrione + halosulfuron methyl @ 719.2 g a.i per ha. Atrazine + mesotrione + halosulfuron methyl @ 539.4 g a.i. per ha (75% of labelled dose) + alkyl ether sulphate sodium salt @ 396.8 mL per ha gave the highest grain yield (8.18 t per ha) and was statistically similar with atrazine + mesotrione + halosulfuron methyl @ 719.2 g a.i per ha (labelled dose). Based on present findings it is concluded that atrazine + mesotrione + halosulfuron methyl @ 539.4 g a.i. per ha + alkyl ether sulphate sodium salt @ 396.8 mL per ha resulted in the maximum weed control and increased yield (32%) of maize when compared with weedy check.