The frequency, duration, and severity of heat and drought stresses singly or in combination can be aggravated by climate change. Under these stresses, the stored carbohydrates in stems play an important role in grain filling in wheat (Triticum aestivum L.) post-anthesis. This study examines the genetic variation of stem characters in wheat and their role in supporting grain weight under favorable and drought, combined drought, and heat conditions. Field experiments were conducted with seven spring wheat genotypes along with their F1 and F2 progenies. Stem diameter (SD), stem density (SDN), and stem weight (SW) were measured in 21 F1 (half-diallel analysis) and 12 F2 (3 x 4 North Carolina Design II) crosses. Among stem characters, SD was significantly correlated with thousand kernel weight (TKW) and grain yield per spike (GYPS) in all environments in F1 and F2. All characters showed high heritability estimates. For stem characters, the highest heritability was found for SD in both generations. High positive phenotypic and genotypic correlations were found between stem characters and both TKW and GYPS. The correlation between reductions due to stress (%) in stem characters and reduction due to stress in TKW and GYPS confirmed the strong relationships between stem characters and yield attributes in the stressed environments. We conclude that stem characters, especially SD, may play an important role in sustaining grain filling under such conditions. This is possibly due to a greater stem capacity for assimilates storage post-anthesis and subsequent remobilization to the grains