Objective The objective of this study is to investigate the effective detection method and variation law of stigma receptivity of chestnut ‘Yanshanzaofeng’ and hybrid pollen viability, and to screen the optimal pollination time of chestnut ‘Yanshanzaofeng’, so as to provide a theoretical basis for the realization of efficient hybrid breeding.

Method The main chestnut variety ‘Yanshanzaofeng’ in Qianxi County, Hebei Province of northern China was selected as the female parent, and varieties ‘Wangqiandali’, ‘Duanzhiyabian’ and ‘Santunhongli’ were selected as the male parents with feature such as multi-seed and dwarf, and the artificial pollination experiments were carried out at different time of flowering periods. Firstly, benzidine-hydrogen peroxide and MTT staining were used to determine stigma receptivity, TTC, I₂-KI and magenta acetate staining and in vitro germination method were used to determine pollen viability, and then on this basis, samples were taken every 2 h from 08:00 to 18:00 on a single day during the full flowering period. The optimal pollination time of ‘Yanshanzaofeng’ was explored by analyzing the variation law of stigma receptivity and pollen viability, fruit setting rate and seed setting rate.

Result (1) Benididine-hydrogen peroxide and MTT staining were used to detect the stigma receptivity of ‘Yanshanzaofeng’, the former had a rapid response and a large number of bubbles appeared on the stigma, and the latter took a long time for stigma to change color. (2) Magenta acetate staining had the best effect on pollen viability, with the pollen viability above 75%, followed by I₂-KI staining, and the effect of other methods was not obvious. (3) The stigma receptivity and pollen viability were best from 10:00 to 12:00 in the full flowering period. (4) Among different hybrid combinations, the highest seed setting rate occurred during the pollination period from 08:00 to 12:00, and the seed setting rate of ‘Wangqiandali’ and ‘Santunhongli’ as the male parents was the highest.

Conclusion The most suitable hybrid pollination time for chestnut ‘Yanshanzaofeng’ is 10:00−12:00 on a single day during the full flowering period. The results of this study will provide theoretical guidance for the success of artificial cross-breeding of chestnut, and great significance for analyzing the reproductive biological characteristics and reproductive mechanism of chestnut.