2017 ASHS Annual Conference

Pawpaw (Asimina triloba), a North American native fruit, is emerging as an alternative high-value niche crop to tobacco among Kentucky farmers. Pawpaw is thought to require cross-pollination however, there is some evidence of self-compatibility in few varieties. The objective of this study was to determine the level of self-compatibility and its impact on fruit and seed set in pawpaw. Two pawpaw varieties ‘Sunflower’, and ‘Susquehanna’ were examined in this study at Kentucky State University’s Research and Demonstration Farm. The flowering branches were bagged with Tyvek-made pollination bags on 25th March. Unfortunately, the flowers inside pollination bags died, so 1000 crosses, including 250 self and cross pollinations for each variety, were carried out with open flowers in April, 2016 and were tagged with different colored flags. Since pawpaw tends to flower at different times, the flower buds observed after pollination were removed in May. The fruit clusters along with fruit number were then recorded on three dates, first on 24th May, second on 9th June and third on 22nd August. The seeds from each treatment were collected and stored at chilling temperature (40C) with wet peat moss for 110 days. The stratified seeds, 60 of each cross, were then randomly transferred to growth chamber at 210C for 10 weeks for germination. The leaf of parent material and the roots of newly germinated offspring were collected for DNA extraction. Parentage analysis was done using microsatellite (SSR) DNA markers. The data analysis indicates that the highest fruit set recorded was 65.2% in self-pollination of Susquehanna whereas the lowest was 31.2% in cross pollination of Susquehanna to Sunflower. The average seed set ranged from 6 to 8 per fruit. Although the data were not significantly different, self-pollination tends to set more fruit than cross-pollination. However, there was a trend of higher fruit drop with time in self-pollination than cross-pollination.
Horticulture, fruit, new crops