Optimizing Transplanting Time to Mitigate High Temperature Stress and Maximize Yield in Boro Rice Varieties in Barishal Region of Bangladesh

Abstract

Rice yield is highly sensitive to environmental conditions, particularly planting time and temperature. Since rice varieties differ in their tolerance to high-temperature stress, identifying an appropriate transplanting window is essential for ensuring proper tillering, flowering, grain formation, and overall yield. This study examined how high-temperature stress, modulated by different transplanting dates, affects the yield attributes and grain yield of three Boro rice varieties in Barishal. The field experiment was carried out during the 2023–2024 Boro (dry) season at the Sagardi farm of the Bangladesh Rice Research Institute (BRRI), Regional Station, Barishal. The experiment was laid out in a split-plot design with three replications. Six transplanting dates (10 December, 25 December, 10 January, 25 January, 10 February, and 25 February) and three rice varieties (BRRI dhan89, BRRI dhan92, and BRRI dhan102) were evaluated. All three varieties performed best when transplanted on 25 December, producing the highest grain yields: BRRI dhan89 (7233.49 kg ha^-1), BRRI dhan92 (7477.91 kg/ha), and BRRI dhan102 (8097.82 kg/ha). These peak yields were accompanied by maximum tiller and panicle production, higher grain numbers per panicle, and greater thousand-grain weight. Conversely, transplanting on 25^th February led to the highest spikelet sterility, while 25 December showed the lowest, highlighting the strong influence of temperature during reproductive stages. Based on these findings, farmers in the Barishal region are advised to transplant Boro rice seedlings between 10^th December and 10^th January to achieve optimum yield and minimize high temperature-induced sterility. Future research should include a broader range of high-yielding varieties and evaluate similar transplanting schedules across diverse rice-growing regions of Bangladesh to strengthen region-specific recommendations.

Bangladesh Rice J.29(2): 46-54, 2025