Flowering and pollination biology of 10 main Camellia oleifera cultivars in Jiangxi Province

Aiming to provide precise guidance for elite cultivar breeding and pollination configuration, the flowering and pollination biological characteristics of 10 main cultivated Camellia oleifera varieties in Jiangxi Province were studied for two consecutive years.

Ten cultivars—‘CL4’ ‘CL40’ ‘CL53’ ‘CL18’ ‘CL3’ ‘GS83-4’ ‘GW2’ ‘GX48’ ‘GW1’ ‘GS84-8’ were evaluated for flowering phenology, floral morphology, and to examine pollen viability, stigma receptivity, and pollen germination dynamics on stigmas.

Flowering duration in most cultivars correlated with annual climatic conditions: high temperatures delayed flowering onset and increased the proportion of peak flowering relative to the total flowering period. Some cultivars exhibited significant inter-annual fluctuations in total flowering duration, whereas ‘CL53’ demonstrated stable flowering timing and duration across both years. Except for ‘GX48’, whose stigma protruded, all cultivars had stigmas enclosed within the stamen cluster. ‘CL53’ showed the largest height difference between pistils and stamens. All cultivars exhibited outcrossing breeding systems, relying predominantly on cross-pollination. ‘GW1’ produced significantly higher pollen quantities per flower than other cultivars. ‘CL4’ displayed frequent anther abortion under climatic stress, drastically reducing pollen germination rates. ‘CL53’ and ‘GW2’ exhibited superior stigma receptivity intensity and duration. Pollen tube growth depended on maternal genotypes: ‘GW2’ as the maternal parent maintained high pollen germination rates, whereas most hybrid combinations with ‘CL40’ as the maternal parent failed to develop pollen tubes to the stylar base.

Integrated analysis of flowering stability, synchronized peak flowering periods, floral architecture, pollen viability, and stigma compatibility identified two optimal configuration models: The optimal pollination cultivars for ‘CL53’ is ‘CL3’, followed by ‘CL40’; The best pollination cultivars for ‘GW2’ is ‘GW1’, followed by ‘GS84-8’; The best pollination cultivars for ‘GX48’ is ‘GW1’, followed by ‘GS84-8’ and ‘GS83-4’; Among self-pollination combinations, ‘CL53’ and ‘GX48’ exhibited relatively high pollen germination rates on their own stigmas, potentially offering fruit setting assurance under unfavorable pollination weather conditions.