WEED MANAGEMENT STRATEGIES AND PLANTING LOCATION EFFECTS ON THE AGRONOMIC PERFORMANCE OF SOYBEAN

Soybean (Glycine max (L.) is an important staple and industrial crop grown in tropical, subtropical and temperate regions of the world. However, its production is constrained by incessant weed competition for nutrient, water and sunlight which reduces output. To minimize the impact of weed competition, this study assessed the effectiveness of different weed management regimes. Soybean seeds were sown in two (2) locations of Delta State (Asaba and Ozoro), and the weed management regimes were T1: No weeding, T2: weeding 3 weeks after planting, T3: weeding 3, 6 weeks after planting, T4: weeding, 3, 6, 9 weeks after planting, and T5: weeding all through. The experiment was a 2 (location) by 5 (weeding regimes) factorial arranged in a randomized complete block design (RCBD) and replicated three times. Data were collected on the agronomic and number of pods produced. Data collected were analysed using analysis of variance and means were separated using least significant differences. At 12 weeks after planting, the plant height, number of leaves and number of pods produced differed significantly and ranged from 24.33±1.02 (Asaba) to 41.46±1.02 (Ozoro), 21.47±1.69 (Asaba) to 48.10±1.69 (Ozoro), and 15.25±1.39 (Asaba) to 24.44±1.39 (Ozoro) between locations, and ranged from 31.90±1.90 (T2) to 37.97±1.90 (T5), 23.93±3.18 (T1) to 41.63±3.18 (T5), and 12.78±2.62 (T1) to 25.01±2.62 (T5) amongst the treatments. Keeping the soybean farm weed-free ensures higher productivity relative to less weeded plots.