The experiment was conducted at the Field Laboratory of the Department of Crop Botany, Bangladesh Agricultural University during the period of December to May (Boro season) 2017–2018. The experimental field was located at 24°43'9.6' N, 90°25 '29.7' E, and an altitude of 18 m above sea level. The experimental area belongs to the non-calcareous dark grey soil under the Old Brahmaputra Floodplain Agro-ecological Zone (AEZ 9) of Bangladesh. The region covers a large area of the Brahmaputra river-borne sediments which were laid down before the river-shifted into its Jamuna Channel about 200 years ago (UNDP/FAO, 1988). The agro-climatic conditions i.e. monthly values of maximum, minimum and average temperature (°C), relative humidity (%), monthly total rainfall (mm) and sunshine (h) received at the experimental site during the study period. Two-hybrid rice cultivars viz. Ishpahani-2 and Saru Madina- 2 were used as experimental materials. Seeds (certified) were collected from the local market. Three transplanting dates viz. 1st January, 15th January, and 30th January, were used as experimental treatments. The experiment was laid out in a factorial randomized complete block design with three replications. The size of a unit plot was 4.0 m × 2.5 m. Healthy sprouted seeds were sown in a nursery bed on 1 December, 15 December, and 30 December 2017 with proper care. The field layout was made on 25th December according to experimental specification immediately after final land preparation. Recommended doses of Triple superphosphate (TSP), Muriate of potash (MoP), Gypsum, and Zinc sulphate (ZnSO4) were applied at the rate of 90 kg, 150 kg, 115 kg, and 12 kg ha–1, respectively at the time of final land preparation (BRRI 2017). Urea (@ 260 kg ha–1) was top-dressed in three equal splits at 15, 30, and 45 days after transplanting (DAT). Thirty-day-old seedlings were transplanted on 1 January, 15 January and 30 January 2018, respectively in the well-puddled plot. Transplanting was done by using two seedlings hill–1 with 25 cm × 15 cm spacing between rows and hills, respectively. Different intercultural operations namely gap filling, thinning, weeding, irrigation, drainage, and bund repairing were done whenever needed. Data on yield contributing characters and yield were recorded from five randomly selected hills from each plot. The yield parameters recorded are plant height (cm), number of totals, effective and non-effective tillers hill–1, length and width of flag leaf, panicle length (cm), number of totals, filled and unfilled grains panicle–1, length and number of primary branches panicle–1, number of filled and unfilled grains in a primary branch, length and number of secondary branches in a primary branch, number of filled and unfilled grains in secondary branch and 1000-grain weight (g). The grain yield (g 10-hill–1) and straw yield (g 10-hill–1) were recorded, and biological yield (g 10-hill–1), grain yield (t ha–1), straw yield (t ha–1), and harvest index (%) were calculated. Harvest index (%) was calculated using the following formula: HI = YE/YBX 100; Where, HI Harvest index (%), YE, and YB designate economic and biological yields (t ha–1), respectively. Data were analyzed statistically following the analysis of variance (ANOVA) technique, using Statistix 10 software package, and means were separated by Duncan’s new multiple range test (DMRT) at a 5% level of significance (Gomez and Gomez, 1984).