Optimizing the sowing date and cultivar selection of Corchorus olitorius L. for sustainable fiber production in moderately saline coastal regions of Bangladesh

Jute ( Corchorus olitorius L.) is a sustainable fiber crop with strong potential for cultivation in saline-prone coastal regions of Bangladesh, where large areas remain fallow during the kharif season. To identify the optimal sowing time and suitable varieties for these conditions, a three-year field study (2022–2024) was carried out at the Jute Research Substation, Kalapara, Patuakhali, on moderately saline soils. The experiment followed a split-plot design, with sowing date as the main plot and cultivar as the subplot. Three cultivars, BJRI Tossa pat 5, O-9897, and BJRI Tossa pat 8, were evaluated on four sowing dates. In 2022–2023, sowing occurred on 31 March, 7 April, 14 April, and 21 April, whereas in 2024, the dates were adjusted to 14 April, 21 April, 28 April, and 5 May to assess the impact of delayed planting. In addition to conventional ANOVA, advanced genotype × environment interaction analyses, including AMMI stability indices (ASV, WAAS, YSI) and GGE biplot modeling, were applied to quantify cultivar adaptability and stability across sowing environments. Across years, mid-April sowing (14–21 April) consistently produced the highest fiber and stick yields. BJRI Tossa pat 5 presented the highest yield stability, while interaction effects indicated that O-9897 produced the maximum fiber (3261.1 kg ha⁻¹) and stick (7474.4 kg ha⁻¹) yields under slightly delayed sowing (April 28, 2024) but lower stability, and BJRI Tossa pat 8 presented the poorest performance. AMMI-GGE biplot analyses revealed that BJRI Tossa pat 5 was the most stable and high-yielding cultivar, whereas O-9897 performed best under delayed sowing. Principal component analysis revealed that fiber weight, stick weight, and biomass traits drove most of the variation, whereas correlation analysis revealed that they were strongly positively associated with plant height, base diameter, and green biomass. The study suggests that mid-April is a suitable sowing window for achieving relatively high and stable yields in coastal areas, whereas sowing after early May should be avoided because of overlap with transplanted Aman rice cultivation.