Experimental site and soil: The field trial was conducted during July to November 2016 at the Agronomy Field laboratory of Bangladesh Agricultural University, Mymensingh. The experimental field is located at 24.75 oN latitude and 90.50 oE longitude at an altitude of 18 m above the mean sea level. The experimental area belongs to the agroecological zone of the Old Brahmaputra Floodplain (AEZ-9). The experimental field was a medium high land having silt loam soil (sand-20%, silt-67% and clay-13%) with particle density of 2.60 (g cc-1), bulk density of 1.35 (g cc-1) and pH value of 6.40. The soil contained 1.67% organic matter, 0.10 % total N, 26.0 ppm available P, 0.14 meq 100 g-1 available K, 13.90 ppm S and 0.5 ppm available Zn. The experimental area is under the sub-tropical climate, which is characterized by high temperature, humidity and rainfall with occasional gusty wind in the Kharif season (April – September), and moderately low temperature, humidity and scanty rainfall during the Rabi season (October – March). Experimental treatment and design: The experiment comprised four rice varieties such as Binadhan-7 (V1), Binadhan-12 (V2), Binadhan-16 (V3) and Binadhan-17 (V4) and five plant spacing viz. 25 cm × 20 cm (S1), 25 cm × 15 cm (S2), 20 cm × 20 cm (S3), 20 cm × 15 cm (S4), and 15 cm × 15 cm (S5), and used a split-plot design with three replications allocating the variety in main plot and plant spacing in sub-plots. The unit plot size was 4 m × 3 m. The space between blocks and plots were 1.0 m and 0.5 m, respectively. Crop husbandry: Thirty-day old seedlings were transplanted on well puddled land on 6 August 2016 allocating two seedlings per hill. Experimental plots were fertilized with N, P2O5, K2O, S, Zn and B @ 95, 23, 42, 11, 2 and 1 kg ha-1 through urea, triple super phosphate (TSP), muriate of potash (MoP), gypsum, zinc sulphate and boron fertilizers, respectively. All fertilizers except urea were applied as basal dose. Urea was applied in three equal installments at 15, 25 and 40 days after transplanting (DAT). A pre-emergence herbicide, Pretilachlor (Commit 500 EC) was applied @ 1.0 L ha-1 at 4 DAT to check the weed infestation. The crop was harvested at full maturity (when 90% of the grains became golden yellow in colour). Binadhan-7 and Binadhan-16 were harvested on 25 October 2016 while Binadhan-12 and Binadhan-17 were harvested on 6 November 2016. Data recording: Data on weed density were collected from each plot at vegetative growth stage of rice plant (45 DAT) using a 0.25 m x 0.25 m quadrate (Cruz et al, 1986). The quadrate was randomly placed lengthwise at three spots in each plot. Weeds were uprooted, washed, identified, counted, clipped to ground level and packed species wise and separately oven dried at 70 o C for 72 hours to record weed biomass. Weed density and biomass were expressed as no. m-2 and g m-2, respectively. Weed control rating was done at 45 DAT based on visual observation using European Weed Research Society (EWRS) developed 1 to 9 scale, where, 1= total control, 9= no effect on weeds (Delchev and Barakova, 2018). Five rice hills were randomly selected from each unit plot and uprooted before harvesting for recording necessary data on growth and yield attributes. After sampling, harvesting was done from central 3.0 m x 2.0 m area of each plot to record the grain and straw yield. The harvested crop from each plot were separately bundled, properly tagged and then threshed by pedal thresher and the fresh weight of grain and straw were recorded plot-wise. The grains were cleaned and sun dried, and straws were also sun dried properly. Finally, grain and straw yields were recorded in t ha-1. Grain yield was adjusted at 14% moisture content. Statistical analysis of data: Data were compiled and tabulated for statistical analysis and then subjected to “Analysis of variance” test as per split-plot design following computer package “Statistix 10”. Significant differences among means were adjudged by Tukey’s HSD test at p = 0.05 using the same statistical package programme.