Abstract:

To clarify the flowering characteristics and the impact of breeding systems on Bougainvillea glabra 'Mrs. Eva', so as to promote its hybrid breeding and garden application, field observation method was adopted to investigate its flowering phenology, as well as the dynamic process of flowering and morphological characteristics of its flowers. FDA staining method and liquid culture medium method were used to determine its pollen viability and in vitro germination rate. The breeding system was determined through a combination of morphological observation, aniline blue staining method, and field hybridization experiments. The results showed that: (1) the floral tube structure of B. glabra 'Mrs. Eva' was unique, cylindrical with upper part wrinkled and both ends swollen, which hamper most insect pollination. (2) The pollen grains of B. glabra 'Mrs Eva' were round or elliptical in shape, with reticulate patterns; the total pollen count per flower was 1375, and the suitable temperature for pollen germination was 28℃; the pollen exhibits group germination effect. (3) The ratio of pollen quantity to ovule was 11000, and the hybridization index was 4. Based on the results of field bagging and artificial pollination experiments, it can be concluded that the main breeding system of B. glabra 'Mrs. Eva' is cross-pollination type and requires pollinators. The research results are of certain significance for resource utilization and germplasm innovation of B. glabra ‘Mrs. Eva’.

Key words: Bougainvillea, flowering biology, pollen germination rate, breeding system, hybridization breeding