Pollination and hybrid affinity of Ottelia acuminata and Ottelia acuminata var. crispa

[Objective] The study aims to reveal the pollination Ottelia acuminata and O. acuminata var. crispa, elucidate the factors affecting successful pollination, and provide theoretical and technical guidance for hybrid breeding between the two species. [Methods] Using O. acuminata and O. acuminata var. crispa as subjects, by observing their flowering dynamics, insect visitation behaviors, and measuring pollen viability, stigma receptivity, and hybrid compatibility index, the study investigated their pollination characteristics and hybrid compatibility. [Results] The flowering dynamics of O. acuminata and O. acuminata var. crispa were fundamentally similar, with each flower lasting 7-11 h. The main pollinating insects include Episyrphus balteatus and Apis cerana. The vitality of the pollen and the receptivity of the stigma both showed an initial increase followed by a decrease. The peak pollen viabilities for O. acuminata and O. acuminata var. crispa were 88.27% and 88.34%, respectively, and the stigmas were all the highest at anthesis Ⅱ. The fruit set rates for direct and reciprocal crosses were 85.71% and 91.33%, respectively, with hybrid compatibility indices both greater than 53. The average number of seeds per fruit for self-pollination were 54 and 69, respectively, and for direct and reciprocal crosses, 73 and 71, respectively. The seed germination rates for self-pollination were 71.7% and 27.3%, respectively, and for direct and reciprocal crosses, 22.6% and 19.7%, respectively. [Conclusion] The flowering dynamics of O. acuminata and O. acuminata var. crispa are fundamentally similar, with each having a short flowering period. There are fewer types of pollinating insects, which affects sexual reproduction, yet there is no significant evidence of hybrid incompatibility.