Introduction: Extensive global research has been conducted on the phenomenon of allelopathy, yielding a wealth of results. Materials and methods: The present study aimed to evaluate the effects of wheat and corn straw extracts, as well as distilled water (control), on seed reserve mobilization and seedling growth in five rapeseeds (Brassica napus L.) varieties: Talayeh, Hayola401, Mahtab, LG-Anniston, and Angelica. The experiment was conducted in a factorial arrangement based on a randomized complete block design (RCBD) with three replications. Significant simple and interactive effects of the treatments on the measured traits were observed. Due to the significance of the interaction effects, further analyses were conducted to assess the impact of the irrigation solutions. Results and Discussion: The results demonstrated that, overall, the inhibitory effects of corn straw extract on the measured traits were much more pronounced compared to wheat straw extract. Regarding the transfer of seed reserves, LG-Anniston exhibited the lowest sensitivity to wheat straw extract, while Mahtab displayed the highest. Similarly, LG-Anniston was the least affected by corn straw extract, showing lower sensitivity compared to the other varieties. This trend was also observed for seed reserve depletion percentages. In some varieties, straw extract significantly improved seed reserve utilization efficiency. For example, in Mahtab, the efficiency values for distilled water, wheat straw extract, and corn straw extract were approximately 0.78, 0.71, and 0.74, respectively. Considering the reduction in seedling dry weight (normal seedlings) under wheat straw extract irrigation compared to the control, Mahtab was identified as the most sensitive variety, with a 65.50% reduction, while LG-Anniston was the most resistant, with only a 21.84% reduction. Other varieties exhibited reductions ranging from 31.9% to 45.6%. Conclusion: The inhibitory effect of corn straw extract was so severe that it completely prevented the emergence of normal seedlings in Talayeh, Hayola401, and Angelica. However, Mahtab and LG-Anniston were able to produce weak seedlings, with growth reductions of 91.1% and 82.8%, respectively, compared to the control.
