Stigma Receptivity, Stigma Morphology and Fruit Set of Yantai Sweet Cherry (Cerasus avium)
烟台甜樱桃柱头的可授性、形态特征与坐果率

Stigmatic receptivity is a limiting factor of flower receptivity and fruit set in Cerasus avium. This study investigated stigma receptivity, morphological characteristics and fruit setting under defined developmental stages by scanning electron microscopy, benzidine testing, H2O2 testing and bagging experiments. Stigma receptivity occurs 1 day before blossoming and is retained for 5 to 7 days. Stigma receptivity is associated with collapse of papillae and production of cellular exudates. The loss of receptivity is accompanied by nigrescence and stigma shrinking, including severe stigma degeneration. The stages of bell-like flowers and flattened flowers showed increased stigma receptivity. As compared with emasculation and bagging, hand pollination could produce greater fruit set, and fruit set was maintained even at the stage of petal abscission. Successful pollination was 60.50% at the balloon-like stage, 58.33% at the petal unfurling stage, 62.08% at the fully open stage, 57.14% at the flattened petal stage, and 39.13% at the petal falling stage. Open pollination could produce pollination levels between 30% and 42%. The best pollination opportunity mainly occurs when petals are unfurling and when petals flatten. A longer receptivity period is helpful for stigmas to be visited and pollinated successfully by bees and gives cultivators the opportunity to apply remedial measures such as artificial pollination to increase pollination rates and fruit set.