runners, suckering, or tip layering; or plants whose stem cuttings root readily have also been clonally propagated by humans early in agricultural history (Hartmann et al., 1997). Various methods of vegetative, or asexual, propagation have many advantages over seed propagation. First, you can propagate superior genotypes true to type, and maintain desirable qualities such as ornamental value, fruit size and quality, pest resistance, or low vigor for dwarfing capabilities. Clonal propagation also increases uniformity in plantings by decreasing genetic variability, and can shorten the time to flowering and fruit production in fruit crops, if mature tissue is used in propagation (Hartmann et al., 1997). The most common methods of clonal propagation in horticulture are stem cuttings and grafting or budding onto a clonal rootstock, which would often be produced by mound layering or stooling. Other methods of vegetative propagation include tissue culture, root cuttings, and various methods of layering such as air layering, trench layering, or pot layering.

There is currently no feasible method for propagating pawpaw germplasm clonally on its own roots. This is true of many members of the Annonaceae. Most Annona species, including Annona squamosa and A. cherimola, have proven difficult to root and are propagated by grafting or budding onto seedling rootstock (George and Nissen, 1987). Mitra (1986) reported 25% rooting of Annona squamosa softwood cuttings treated with 5000 ppm IBA, and 10% of micropropagated A. squamosa shoots produced roots and survived. An earlier study (Venkataratanam and Satyanaranaswamy, 1956) found A. squamosa very difficult to root, with stem cuttings not exceeding 2% rooting. However, these cuttings were not treated with IBA, indicating the influence of IBA on rooting of A. squamosa. Odilo and Rafael (1976) found that only juvenile Annona cherimola cuttings produced roots, with 25% rooting at 5,000 ppm IBA. George and Nissen (1987) reported ease of rooting in Annona muricata stem cuttings, but noted that most other Annona spp. are difficult to root. Tazzari et al. (1990) concluded that Annona is a low rooting capacity species.

Many propagation methods have been attempted in pawpaw with limited success. Propagation by stem cuttings was attempted by Finneseth (1997), and it was found that juvenility plays a strong role in adventitious rooting capacity of pawpaw. Stem cuttings taken from 7 month old pawpaw seedlings were treated with IBA concentrations ranging