Introduction: Wheat (Triticum aestivum L.) is a critical mass crop that is produced in many countries in different regions. However, this benefit is being countered by the effects of high-temperature stress that become more problematic, especially in late-sown conditions. These high temperatures can significantly impact the phenology, growth patterns, and overall yield of various wheat varieties. Understanding how different cultivars respond to these stresses is essential for developing strategies to enhance resilience and ensure food security in the face of climate change. Late seeding in Bangladesh habitually results in wheat exposure to high temperatures during the significant stages of growth and hence interferes with phenology, growth patterns, and yield constituents. The current study hence, aims at explaining the effects of late sowing-induced heat stress on three high-yielding wheat varieties with the intention of determining those genotypes that have increased thermotolerance to enable long-term wheat production in hot climatic conditions.
Methods: An experiment was conducted during the 2020–21 wheat growing season at the Bangladesh Wheat and Maize Research Institute in Dinajpur, Bangladesh. An experimental split-plot design was implemented, incorporating two planting dates—optimal (25 November) and late (5 January)—and three wheat varieties: BARI Gom 21, BARI Gom 26, and BARI Gom 27. Sowing dates were designated as primary plots, while specific cultivars were utilized as secondary plots. Key characteristics, including phenological stages, leaf area index (LAI), plant height, tillers per square meter, spikelets per spike, grains per spike, 1000-grain weight, biomass, harvest index, and grain yield, were quantified and analyzed by variance analysis.
Results: Delayed seeding considerably accelerated phenological development, leading to a shortened interval to phenological maturity and adversely affecting growth and yield. The optimal sowing date of 25 November yielded superior values for tiller density, leaf area index, plant height, spikelets per spike, grains per spike, 1000-grain weight, biomass, and grain yield compared to subsequent sowing dates. BARI Gom 21 exhibited the highest yield among the types, producing 9900 kg ha⁻¹ under optimal sowing conditions and 7424 kg ha⁻¹ with delayed planting. The second-highest yields were recorded for BARI Gom 26 and BARI Gom 27. The interaction between planting dates and varieties had an impact on yield components, with BARI Gom 21 consistently exhibiting superior performance compared to other types in both scenarios.
Conclusions: It has been empirically proven that the date of wheat planting on 25 November in Bangladesh hastens phenological development, enhances vegetative biomass, and augments yields. BARI Gom 21, with its strong heat tolerance and high-yielding capacity, also represents one that can be selected and grown either under optimal or under late-sown conditions. These findings reaffirm the importance of the inclusion of this diversity in breeding programs aimed at generating heat-tolerant wheat lines and, in that way, strengthening the climate resilience of the national wheat production systems.