and lower costs, labor, and materials required. Some disadvantages to propagating plants by seed are that a desirable plant will not be propagated true to type, and many seeds require special treatments such as scarification, chilling, or specific storage requirements. Most vegetables, bedding plants, and agronomic crops are propagated by seed (Hartmann et al., 1997). Some ornamental woody plant species are propagated by seed, and seedling rootstocks may be used in Prunus spp., asian pear [Pyrus pyrifolia (Nakai)], citrus species (Citrus spp.), and several nut species (Webster, 1995). Clonal propagation of rootstocks is generally preferred, but seedling propagation does have some advantages. First, seedling rootstocks may be more economical and easy to mass produce. Clonal rootstocks may be infected with various pathogens, including viruses and root-borne pathogens such as Agrobacterium (crown gall) (Webster, 1995). In some cases, the root systems of seedling rootstocks may grow deeper and more vigorously than rootstocks from cuttings (Hartmann et al., 1997). However, there are many disadvantages to using seedling rootstocks in grafting, such as high variability in vigor and lack of desirable qualities that may be imparted by a rootstock such as dwarfing or drought resistance; and generally clonal rootstocks are preferred in tree fruit production.

The pawpaw industry depends heavily on seed propagation. Many pawpaw seedlings are sold by nurseries, and pawpaw cultivars are grafted or budded onto seedling rootstock. Pawpaw seeds are recalcitrant. Finneseth et al. (1998) found that germination percentages dropped below 50% when seed moisture was dropped to 25%. Pawpaw seeds also must be stratified prior to germination. These authors obtained the highest germination percentage, 84-90%, after 14 weeks of chilling at 5circC. Pawpaw seeds also cannot withstand freezing (Pomper et al., 2000). Hence, storage recommendations for pawpaw are to keep seed at 5circC in moist sphagnum peat moss to prevent desiccation and obtain the necessary stratification (Jones et al., 1998). Pawpaw seeds can be stored for approximately two years before a reduction in viability occurs. Given the recalcitrant nature of pawpaw seeds, it would be desirable to develop a clonal propagation method to reduce the dependence on seedling production.

Vegetative propagation has also been exploited by humans throughout history. For example, there are records of grafting being performed over 2000 years ago in ancient Greece (Webster, 1995); and plants that naturally reproduce vegetatively through