one shoot developed on most trench layered pawpaw plants limiting the plant production potential of this system; on several plants two shoots on some did form. Since the original seedling tree of most commercially available cultivars no longer exists, we are attempting to propagate cultivars budded onto a seedling rootstock. A goal of the USDA-NCGR is to propagate these cultivars, and other valuable germplasm, on their own roots. With trench layering, the scion would be more distant from the rootstock, and so it would be easier to differentiate which shoots emerged from the scion, and which shoots emerged from root suckers or the base of the plant beneath the graft, which would not be the genotype desired to propagate. Scion shoots would consist of mature tissue, likely more ontologically advanced than the oldest seedlings used in this study; however, this study does suggest that trench layering has potential for establishing a limited number of self rooting cultivars.

Wounding alone did not promote rooting. It was found that girdling was essential to rooting in pecan, with girdled shoots that were not treated with any auxins capable of producing roots (Wood, 1989). However, this does not appear to be the case with pawpaw, as girdled shoots with no auxin treatments were not capable of rooting. There is a possibility that shoots were not completely girdled using the sandpaper method, although every effort was made to completely girdle the shoots and disrupt the cambial layer each year.

Juvenility did affect rooting characteristics of pawpaw shoots. Only in 2002 was plant maturity shown to greatly influence rooting percentage, but both experiments suggested that age of the mother plant affected number of roots formed per shoot and average adventitious root length of shoots. Source plant maturity has been shown to have a strong influence on adventitious rooting in pawpaw in previous studies (Finneseth, 1997; Geneve, unpublished data). Odilo and Rafael (1976) found that only juvenile Annona cherimola cuttings produced roots. However, upon examining the 2003 data, it appears that perhaps the adventitious rooting-inhibiting effects of maturity could be overcome somewhat by applying very high levels of IBA to shoots. Utilizing increased concentrations of IBA that year, more mature shoots were induced to root.

Auxin application promoted rooting characteristics in pawpaw, as has been shown in previous studies of other fruit and nut crops, such as apple (Delargy and Wright, 1979),