INTEGRATION OF SOME ALLELOPATHIC SPECIES FOR WEED MANAGEMENT IN SPRING PLANTED HYBRID MAIZE UNDER DIFFERENT TILLAGE REGIMES.

A two-year study was conducted on integrated weed management in maize under different tillage regimes at Agricultural Research Station Swabi Khyber Pakhtunkhwa, Pakistan during Spring 2014 and subsequently repeated in 2015. The experiment was laid out at silt loam soil in Randomized complete block design (RCBD) with a split plot arrangement having three replications. Tillage regimes ((minimum, conventional and deep tillage) were kept in main plots (Factor A) and allelopathic plant residues (sorghum, sunflower and parthenium) as surface mulched in various combinations and their water extracts @ 15L each + atrazine @ ?th of recommended dose were assigned to the sub-plots (Factor B), for weed management in maize. Data during both years (2014 and 2015) were recorded and analyzed for dry biomass of weeds 30 DAS, kernels ear-1, ear length (cm), kernel yield (kg ha-1) and cost benefit ratio. Foliar application of Sorghum + parthenium water extracts at 15 L integrated with a quarter recommended dose of atrazine (pre emergence) under conventional tillage regimes suppressed total weed dry biomass by 34 and 42% at 30 DAS during 2014 and 2015, respectively which increased maize kernel yield by 52 % over the weedy check and was almost equivalent to the label dose of atrazine (0.50 kg a.i ha-1) and also had the highest CBR (1:20.4). Among the soil mulch treatments, Sorghum + sunflower +parthenium each at 4 Mg ha-1 under deep tillage regimes suppressed weed dry biomass by 69 and 75 % at 30 DAS during 2014 and 2015 respectively, pooled data of both years (2014 and 2015) indicated increase in maize kernel yield by 54 % over control with CBR (1:15:2). However, the mulch treatments and the cost of deep tillage were uneconomical. Hand weeding under deep tillage regimes increased maize kernel yield by 46 % as compared to the weedy check. Based on current studies, it is concluded that foliar application of Sorghum + parthenium aqueous extract integrated with reduced atrazine dose are economical and eco-friendly having the highest CBR. Consequently, reliance on atrazine could be reduced by 75% resulting in environmental safety and sustainability, however further studies are suggested to fine tune our findings. [ABSTRACT FROM AUTHOR]