Growth and development patterns in Mustard (Brassica spp.) as influenced by sowing time

Mustard is Bangladesh's leading oil crop, produced only during the winter (rabi) season. The sowing date is a key factor determining mustard's optimum growth and development. Because of global warming, gradual changes in season and weather parameters over time is creating a challenge in mustard cultivation. Thus, the present investigation assessed the role of different planting dates on several modern mustard varieties to disclose the optimum growth indicators necessary for elevated biological yield (BY) and harvest index (HI). Three planting times, viz. 31st October (D1), 10th November (D2), 20th November (D3) and six varieties viz. Binasarisha-4 (V1), Binasarisha-9 (V2), Binasarisha-10 (V3), BARI Sarisha-14 (V4), BARI Sarisha-16 (V5), BARI Sarisha-17 (V6) were put on a replicated factorial randomized complete block design (RCBD) during rabi 2019 at BINA Sub-station farm, Magura. At the final harvest stage, outcomes depicted that highest and lowest total dry mass (g/plant) was produced by treatment D3× V5 (64.03) and D1× V1 (15.34), maximum and minimum absolute growth rate (mg/plant/day) by D1× V5 (2389.10) and D2× V1 (184.50), most and least relative growth rate (mg/g/day) in D1× V4 (53.34) and D2× V1 (3.55), maximum and least crop growth rate (g/m2/day) with D1× V3 (55.60) and D3× V4 (20.04). BY was the peak (8.13, 8.71, 8.77 t/ha) under all plantings (D1, D2, D3) with V5 variety, but HI (44.96%) was most in variety V4 with D2 sowing. Therefore, correlation studies showed a significant positive relationship between biological yield and harvest index. Overall, BARI Sarisha-16 performed well in all three sowing times, and remarkably, BY was rising with delayed planting in the case of Binasarisha-9, Binasarisha-10, and BARI Sarisha-14. This implies that delayed planting might not hamper yield but boost yield to some extent.