Controlled Pollination to Assess Intraspecific Compatibility Among Passiflora incarnata Genotypes from Different Provenances

Passiflora incarnata L., commonly known as maypop, is a wild passion fruit native to many areas of the eastern and southern United States where the climate ranges from subtropical to temperate. Although P. incarnata has had little attention paid to it for breeding purposes, it could be used in breeding for fruit production and possibly contribute cold hardiness genes in combination with other Passiflora species. The study was performed in 2018, 2019, and 2021 at the Mississippi State University South Mississippi Branch Experiment Station in Poplarville, MS, United States. Passiflora propagules were collected from various locations: Florida (FL), Illinois (IL), Mississippi (MS), Missouri (MO), and Oklahoma (OK). Of the 122 flowers across the five P. incarnata genotypes from differing locations, none of them produced a fruit or had any indication of successful or partially successful fertilization when selfed, indicating strong self- incompatibility. If self-compatibility does exist in nature, it is likely to be rare. However, certain combinations of P. incarnata from different locations produced successful fruiting, including IL × MO (52% success), FL × MO (85%), FL × OK (80%), MS × OK (40%), MO × IL (50%), MO × OK (40%), and OK × MO (80%). The differences across provenances show that incompatibility exists within P. incarnata but can depend on location. Overall, fruit weight, fruit size, and soluble solids content measured in this study were similar to and, in some cases, greater than those previously reported. These differences help to illustrate the diversity within P. incarnata and the still-untapped potential for breeding improvements. The problem of self-incompatibility is complex and there is much to learn about how Passiflora species, especially P. incarnata, function. Much of the U.S. domestic market is not familiar with passion fruit, especially as a table fresh product. This could be a barrier to adoption, but it could also prove to be an opportunity to create a niche within the present market and expand it. Although maypop fruit quality is not equal to that of Passiflora edulis Sims, selecting superior wild genotypes with desirable attributes to be used in future intra- and interspecific breeding is possible based on the results of this study.