Elvio Bellini,1 Stefania Nin,2 and Maurizio Cocchi3
ADDITIONAL INDEX WORDS. Asimina triloba, breeding, cultivars, selections, varietal characterization, in vitro culture
SUMMARY. The Horticulture Department of the University of Florence has been studying the pawpaw (Asimina triloba) since 1990 through collaboration with Italian fruit grower Domenico Montanari, who currently hosts the largest pawpaw orchard and variety collection in Italy. Research efforts are focused mainly on the development of new varieties and selections with desirable ornamental characteristics. New variety selection is based on high tree productivity, large fruit size, good organoleptic quality and improved fruit postharvest handling. The breeding program has resulted in 3,000 seedlings that are currently being evaluated in Tuscany, Italy. In addition to breeding efforts, 15 commercially available varieties were evaluated in replicated trials in 2000 and 2001, with selections characterized for vegetative, reproductive and pomological traits. In 2000 and 2001, the varieties ‘Prima 1216’ and ‘Prolific’ had high yields and should be suitable for production in Italian fruit-growing areas. Experiments to establish explants of pawpaw in culture were also performed testing a range of genotypes, disinfestation procedures, and methods to induce callus culture. Protocols for the propagation of pawpaw in vitro would offer many advantages for mass multiplication of desirable plants; however, the propagation of pawpaw in vitro has so far been met with limited success.
The north american pawpaw is receiving increasing attention for its potential as a landscape tree, fruit crop, and as a source of important secondary products with anti-tumor and pesticidal properties (Bellini and Montanari, 1992a, 2000; Layne, 1996; McLaughlin, 1997; Pomper et al. 1999). Due to attractive tree form and fall color, as well as cold hardiness for the Italian climate, pawpaws are suitable for ornamental and biodiversification efforts in parks and gardens in Italy. Furthermore, the species has a very low susceptibility to pests and disease (Peterson, 1991) and produces fruit with a unique flavor and a high nutrient content (Peterson et al., 1982), thus also representing an alternative to traditional fruit crops for organic fruit production (Bellini and Montanari, 1992a, 2000).
In Italy, experimentation with pawpaw began in 1983 in Faenza, Italy at the farm of Domenico Montanari, which now hosts the largest Italian pawpaw orchard and collection. Initially, Montanari evaluated a range of American varieties under Italian climatic conditions (Bellini and Montanari, 1992b).
Breeding and selection efforts were initiated with the development of a seedling population of more than 1,000 individuals obtained from seed coming from the U.S., from open pollination of the variety ‘Sunflower’, and from a number of seedling selections.
Department of Horticulture, Florence University, 50019 Sesto Fiorentino (FI), Italy.1Professor of pomology and fruit tree science, author to whom reprint request should be addressed; e-mail: elvio.bellini@unifi.it.
2Grant researcher.
3Undergraduate student.