Pecan is a highly heterozygous outcrossing species, which shows wide variation in nut and tree quality when propagated from seed (Sparks, 2005). Establishment of orchards of superior genotypes is critical for pecan as a cultivated crop. Much research has been conducted for pecan propagation, such as clonal propagation by stem cuttings (McEachern and Storey, 1972; Wolstenholme and Allan, 1975), root cuttings (Nelson and Gustafson, 1982), mound layering (Wood, 1989), in vitro propagation (Avila-Trevino et al., 2013; Corteolivares et al., 1990; Hansen and Lazarte, 1982, 1984; Renukdas et al., 2010), and grafting and budding (Wood et al., 1994). Since propagation by tissue culture or vegetative cuttings has not been perfected, the commercial pecan industry is still dependent on conventional propagation by grafting and budding (Nesbitt et al., 2002).
Currently, four main grafting and budding techniques have been commonly used, including whip grafting, inlay bark grafting, four-flap grafting, and patch budding (Wells, 2007). The successful use of these grafting and budding techniques proved to be a milestone for the pecan industry (Wood et al., 1994). Four-flap grafting is ideal for small diameter rootstocks and branches of larger trees (Taylor and Drews, 1983). Rootstocks of 1, 2, and 3 years old with diameter up to 2.5 cm may be grafted by whip grafting (Wells, 2007). Patch budding may be used on small tree trunks or branches 0.9 to 3.8 cm in diameter (McCraw, 2007). Inlay bark grafting is often used for rootstocks that are too large for other grafting techniques (Drews et al., 1981). The disadvantage with all of these, however, is that the seedlings generally require two to three seasons of growth before their diameter is large enough to be grafted or budded, thus increasing the cost of the product and tying up land in the nursery.
Grafting performed on germinated seeds has proven to be successful in other fruit crop trees, such as chestnut [Castanea sativa (Serdar, 2009)], mango [Mangifera indica (Kaur and Malhi, 2006)], nutmeg [Myristica fragrans (Haldankar et al., 1999)], and walnut [Juglans regia (Gandev and Arnaudov, 2011; Suk-In et al., 2006)]. The objective of this study was to test if epicotyl grafting can be an alternative, short-term reproduction method to produce grafted pecan trees.
Avila-Trevino, J.A., Arreola-Avila, J.G., Rodriguez-de la O, J.L., Trejo-Calzada, R., Valdez-Cepeda, D. & Borja-de la Rosa, A. 2013 Morphogenic response in the in vitro propagation of pecan (Carya illinoinensis [Wangenh] K. Koch) Revsta Chapingo Serie Ciencias Forestales y del Ambiente 19 469 481
Gandev, S. & Arnaudov, V. 2011 Propagation method of epicotyl grafting in walnut (Juglans Regia L.) under production condition Bulgarian J. Agr. Sci. 17 173 176
Haldankar, P.M., Nagwekar, D.D., Desai, A.G. & Rajput, J.C. 1999 Factors influencing epicotyl grafting in nutmeg J. Medicinal Aromatic Plant Sci. 21 940 944
Kaur, G. & Malhi, C. 2006 Effect of age of rootstock and growing medium on the success of epicotyl grafting in mango Indian J. Hort. 63 244 247
McCraw, D. 2007 Patch budding pecans. Div. Agr. Sci. Natural Resources Oklahoma Coop. Ext. Serv. 6206
Nelson, K.L. & Gustafson, W. 1982 A propagation technique for producing clonal rootstocks of pecan, Carya illinoensis (Wang) K. Koch, by root cuttings Annu. Rpt. Northern Nut Growers Assn. 73 134 137
Nesbitt, M.L., Goff, W.D. & Stein, L.A. 2002 Effect of scionwood packing moisture and cut-end sealing on pecan graft success HortTechnology 12 257 260
Renukdas, N.N., Manoharan, M. & Garner, J.O. 2010 In vitro propagation of pecan [Carya illinoinensis (Wangenh) K. Koch] Plant Biotechnol. 27 211 215
Suk-In, H., Moon-Ho, L. & Yong-Seok, J. 2006 Study on the new vegetative propagation method ‘Epicotyl grafting’ in walnut trees (Juglans spp.). Proc. Fifth Intl. Walnut Symp. 705:371–374
Taylor, G. & Drews, D. 1983 The four flap graft: A dependable technique for the grafting of smaller diameter pecan stocks Pecan Qrtly. 17 6 9
Wells, L. 2007 Pecan propagation, p. 9–18. In: L. Wells and P. Conner (eds.). Southeastern pecan growers’ handbook. Univ. Georgia Coop. Ext. Bul. 1327
Wood, B.W., Payne, J.A. & Grauke, L.J. 1994 An overview of the evolution of the US pecan industry, p. 1–11. In: C.R. Santerre (ed.). Pecan technology. Springer, New York, NY