Effect of Sequential Application of Herbicides on Dry Matter Production and Nutrient Uptake in Maize

A field experiment was conducted during Kharif 2013 atthe Main Agricultural Research Station, University of Agricultural Sciences, Dharwad to study the effect of sequential application of pre and post-emergence herbicides in maize under rainfed situation. The experiment consists of ten treatments which were laid out in Randomized Complete Block Design with three replications. The results revealed that the lower number of grassy weeds (5.91), broad leaved weeds (4.14), sedges (2.13) and total number of weeds (5.05) at harvest were observed in treatment Atrazine @ 1 kg a i/ha +2IC+1HW (T₈) as compared to other herbicide treatments but it was on par with Farmers practice 2IC +2HW. Similarly, significantly lower total weed dry weight at harvest (2.53 g/m²) and higher total dry matter accumulation in maize (246.17 g/plant) was recorded in same treatment (T₈) over the other herbicide treatments. Significantly less uptake of nutrients at harvest (3.14 kg N, 1.96 kg P. and 2.04 kg Pha⁻¹)by weeds with Atrazine @ 1 kga.i. ha⁻¹ + 2 IC + 1 HW which was on par with Farmers’ practice i.e. 2 IC + 2 HW, Glyphosate @ 2.5 kg a.i. ha⁻¹ and Paraquat @1 kg a.i.ha⁻¹. Nitrogen, phosphorus and potassium uptake by maize was significantly higher with treatment Atrazine @ 1 kg a.i. ha⁻¹ + 2 IC + 1 HW (128.14 kg N, 34.33 kg P and 110.03 kg K ha⁻¹, respectively) which was on par with Glyphosate @ 2.5 kg a.i.ha⁻¹(124.60 kg N, 31.04 kg P and 100.74 kg K ha⁻¹, respectively), Paraquat @1 kg a.i.ha⁻¹ (121.26 kg, 28.80 kg and 97.59 kg ha⁻¹, respectively).