Mustard productivity in Bangladesh remains low due to the continued cultivation of low-yielding varieties. To identify high-performing cultivars suitable for cultivation in post-T. Aman fallow lands utilizing residual soil moisture, a field experiment was conducted under farmers’ field conditions during the rabi season (November 2019 to February 2020) at Sotero, Shiberbazar, Sylhet. Seventeen rapeseed–mustard varieties comprising BARI, BINA, and local cultivars were evaluated in a randomized complete
block design with three replications. Significant varietal differences were observed for all growth and yield attributes. BARI Sarisha-11 produced the tallest plants, whereas BARI Sarisha-8 recorded the shortest. BARI Sarisha-14 produced the highest number of branches per plant (4.40), followed by BARI Sarisha-10 (3.80), while Tori-7 produced the fewest (1.53). Safal produced the highest fresh biomass, whereas BARI Sarisha-13 recorded the lowest. Tori-7 produced the highest plant population, while BARI Sarisha-13
had the lowest. BARI Sarisha-10 recorded the highest number of siliquae per plant (45.40), followed by Daulat (40.27), whereas BARI Sarisha-17 produced the fewest (15.00). BINA Sarisha-10 produced the highest number of seeds per siliqua (18.33), while Daulat recorded the lowest (10.73). BARI Sarisha-17 exhibited the highest 1000-seed weight while Tori-7 was the lowest. The highest seed yield was obtained from BARI Sarisha-15
(1.43 t ha⁻¹), followed by Agroni (1.23 t ha⁻¹), Safal (1.20 t ha⁻¹), and BARI Sarisha-11 (1.14 t ha⁻¹), whereas BINA Sarisha-10 produced the lowest yield (0.68 t ha⁻¹). Overall, the findings indicate that BARI Sarisha-15, BARI Sarisha-11, Agroni, and Safal are promising varieties for mustard cultivation under Sylhet conditions due to their superior yield performance and adaptability under the experimental conditions.