Objective Self-incompatibility (SI) in Corylus leads to low pollination and fruit set and consequently the slow breeding progress caused by, this study aimed to screen for chemical reagents capable of effectively overcoming SI and to determine their optimal concentrations, thereby providing theoretical and technical support for efficient hazelnut production and germplasm innovation.

Methods Based on unpollinated pistils of the cultivar 'Dawei', prior to self-pollination, pistils were treated with different concentrations of seven chemical reagents: sodium chloride + boric acid, gibberellin (GA), 6-benzylaminopurine (6-BA), acetone, a pollen extract from 'Liaozhen No. 7', ethanol, and ammonium sulfate. The effectiveness of each treatment in overcoming SI was assessed using the stigma penetration rate of self-pollen tubes as the key indicator.

Results Among the seven reagents, acetone, GA, and 6-BA promoted self-pollen tubes penetration through the stigma, indicating effectively alleviation of SI. The most pronounced effects were observed with the application of 5% acetone or 40 mg·L⁻¹ 6-BA for 5 minutes prior to self-pollination, which yielded pollen tube stigma penetration rates of 54.545% and 54.386%, respectively.

Conclusion Short-term chemical pretreatment of pistils prior to self-pollination, particularly with 5% acetone or 40 mg·L⁻¹ 6-BA, provides a simple and highly effective approach to overcoming SI in Corylus. These results offer a solid theoretical foundation and practical guidance for resolving self-incompatibility issues and accelerating the hazelnut breeding process.