Growth, Yield Attributes, Yields, and Weed Characteristics as Influenced by Integrated Nitrogen Fertilization and Weed-Control Measures of Maize (Zea mays L.) in Central Rift Valley of Ethiopia

Abstract

                An experiment was conducted during the rainy season of 2003 at Dera and Melkassa, to study the influence of nitrogen fertilizer levels and weed control measures on growth, yield attributes, yields, and weed characteristics of maize (Zea mays L.) under rainfed condition. The experimental treatments were split plot design, comprising four nitrogen fertilizer levels [N0, control, N1, 10, N2, 20, andN3, 30 kg N/ha in main plots and four weed control measures [W0, weedy check, W1, atrazine/s-metolachlor at 3.0 kg/ha (pre-emergence); W2, atrazine/s-metolachlor at 3.0 kg/ha + 2, 4-D at 1.0 kg/ha (pre + post-emergence); and W3, 2, 4-D at 1.0 kg/ha (post-emergence)] in sub–plots and were replicated thrice.

                 Total biomass, straw yield, harvest index, plant height and lodging percentage were increased with an increase in N levels at both sites. Application of 30 kg N/ha was found helpful in reducing the dry matter accumulation by weeds probably because nitrogen requirement of weeds and crop was met at this level and crop could compete better with weeds due to increased growth. Leaf area increased with an increase in nitrogen, being maximum at 30 kg N and minimum in the control at Dera and Melkassa, respectively. Weed control measures not only increased the leaf area, yield attributes and the grain yield of maize but also decreased the weed population and dry matter of weeds. Suppression of weeds by weed-control measures resulted in better growth and development of maize. Weed population and dry matter production of weeds were effectively suppressed with pre and post-emergence application of atrazine/smetolachlor at 3.0 kg/ha + 2, 4- D at 1.0 kg/ ha increased the grain yield of maize by 13.4 % over control non-weeded.