Identifying potential seedless citrus accessions through floral structure and pollen performance

Seedless character is one of important traits for fresh fruit citrus. Since there are many mechanisms to obtain seedless fruit, it is important to identify which mechanism is possibly used in it. The first to be observed is usually the pollen characteristic. Abnormality in pollen could lead to seedless fruit production. In this study, we observed several potential seedless citrus accessions in the germplasm collection to obtain the information on the floral structure and pollen characteristics supporting the production of seedless fruits. The study was conducted at Plant Breeding Laboratory of Indonesian Citrus and Subtropical Fruits Research Institute, Batu, East Java in 2019. The flower and pollen were observed on their structure, morphology, viability, and germination percentage. The result showed that at anthesis, the anther position could be located below, above and parallel with the stigma. Flowers with anthers located below the stigma have lower chance to be self-pollinated and in the absence of pollinators it increases the opportunity to produce seedless fruit. Pollen morphology observations indicated that most accessions had elliptical shape with either acute, circular or rectangular apices. Pollen viability ranged from 64–95% with pummelo accession Bageng showed the highest percentage, and lime accession Nipis Borneo was the lowest. In addition, Nipis Borneo also has the lowest germination percentage, around 17.69%, while the highest one was observed on lemon Montaji Agrihorti which was 57.52%. This study showed that Nipis Borneo has the highest potential as seedless citrus just based on at its pollen performance, while on the other hand, Montaji Agrihorti has the highest possibility of producing seedy fruit. For more comprehensive information, further study needs to be conducted especially on the interaction of pollen and pistil.