Experimental field The experiment was conducted in the research farm of Wheat Research Center (WRC), BARI, Dinajpur during wheat season (Nov. to April) 2016-17. The geographical position of the area is between 25º44.574" N and 88º40.344" E, and 40 m above sea level. The Agro Ecological Zone (AEZ) of the area is the Old Himalayan Piedmont Plain (AEZ-1). This zone has largest wheat area and also produces largest amount of wheat in the country. Climatic conditions Weather data on weekly average temperature, humidity and rainfall during experimental period, were recorded regularly at the meteorological station of Wheat Research Center (WRC), BARI, Dinajpur. Characteristics of the experimental soil Soils of the experimental sites were analyzed before sowing wheat. The pre-seeding total soil N was 0.08%, indicating a deficiency in soil N. Soil available K was 0.19 meq 100g-1 soil, and available P, S, Zn and B were 17.5, 6.5, 0.78 and 0.16 µg g–1 soil, respectively. Based on the critical level of these plant nutrients, K, S, Zn and B were low, but P was high. Soil pH was 5.4 and organic matter was 1.2%. Experimental design The experiment was conducted in a split-plot design with three replications. Treatments were three sowing dates (Early sowing - 01 November, Optimum sowing - 15 November and Late sowing - 30 December) and three elite existing wheat varieties (‘Shatabdi’, ‘BARI, Gom 27’ and ‘BARI Gom 28’). Three sowing dates were arranged in main plots and three varieties were in subplots.The unit plot size (3 m × 2 m) consisted of 10 rows, each 3 m long, and a row-to-row distance of 20 cm and a block-to-block distance of 1.5 m. Variety, seeding rate, sowing time, seed treatment and insecticide The characteristics of the three wheat varieties used in this research are presented in Table 1. During experimentation, all varieties were sown as per treatments. Seeding rate was 120 kg ha-1 for each treatment. Before sowing, seeds of all varieties were treated with a popular fungicide, Provax-200 WP, which contains carboxin and thiram (marketed by Hossain Enterprise CC Bangladesh Ltd., in association with Chemtura Corp., USA). Furadan 5G (containing Carbofuran, marketed by FMC International S.A. Bangladesh Ltd.) was broadcasted at 10 kg ha-1 for controlling soil-borne insects. Fertilizer, irrigation, mulching and weeding Fertilizer N, P, K, S and B was applied at the rate of 100, 27, 40, 20, 1 kgha-1 as per recommendation of WRC. During final land preparation, two-thirds of N and a full amount of the other fertilizers were applied as basal. The remaining N fertilizer was applied immediately after the first irrigation at 18 days after sowing (DAS) while the second, third and fourth irrigations were applied at 50, 73 and 88 DAS. Mulching was done at 28 DAS and hand weeding at 45 DAS. Data collection Phenological data on days to emergence, days to booting, days to heading and days to physiological maturity were recorded as per sowing dates and varieties. Initial plants m -2 was recorded at 12 DAS. The crop was harvested on 30 March 2017 (for the 2016-17 season). Grain yield and yield related attributes were recorded from a 2 m × 1 m area from the center of each plot. The samples from the harvested area from each plot was bundled separately, tagged and manually threshed on a threshing floor. The bundles were thoroughly dried in bright sunshine before their weights were recorded. Data on plant height (cm), spikes m−2 , spike length (cm), number of spikelets spike−1 , 1000-grain weight (g; TGW), Harvest index (%) and grain yield (kg ha−1 ) were recorded. Grain yield and TGW were recorded at 12% moisture content as described by Hellevang (1995.