Pecan (Carya illinoinensis) is a deciduous nut tree that is well adapted to loamy bottom land sites (Sparks, 2002). Most pecan seeds are normally germinated and grown in field nurseries for one season, budded the second year, and then dug and sold as bare root trees. The root system predominantly consists of a taproot with weak lateral roots during the first year after pecan seed germination. The taproot will penetrate the soil up to 2 m unless stopped by a water table or an impervious layer by the first season’s end. In contrast, lateral roots are typically limited and will not begin abundant development until the second year. Vertical roots develop from the primary lateral roots at least by the fourth year (Sparks, 2005). Pecan trees, in their native habitats, have been classified as a phreatophyte (a plant that characteristically roots to the water table) (Sparks, 2002). Failure to successfully transplant pecan trees is commonplace and could be a result of the lack of adequate lateral root formation. Newly planted trees may become established promptly, may make a semblance of growth for several years and finally become established, or may fail entirely and die (Laiche, 1980).
Root pruning (Harris et al., 2001; Keever et al., 1986; Laiche, 1980; McCraw and Smith, 1998; Smith and Johnson, 1981; White and Payne, 1982) and growth regulator application (Matta and Storey, 1981) can influence top growth and root branching and therefore increase transplant survival. Previous research has focused on root pruning and transplanting of 2-year-old (McCraw and Smith, 1998) or 3-year-old (Smith and Johnson, 1981; Wood, 1996) pecan trees. Research has not been conducted to determine if pruning the roots shortly after germination stimulates lateral root formation. Similarly, little work has been attempted to consider the effects of taproot pruning in young pecan seedlings back to different lengths on root regeneration. The objective of this study was to determine if root pruning at different periods after seed germination affects pecan seedling root and shoot growth and to evaluate different degrees of taproot pruning on root initiation.
Baraloto, C. & Forget, P.M. 2007 Seed size, seedling morphology, and response to deep shade and damage in neotropical rain forest trees Amer. J. Bot. 94 901 911
Finér, L., Ohashi, M., Noguchi, K. & Hirano, Y. 2011 Fine root production and turnover in forest ecosystems in relation to stand and environmental characteristics For. Ecol. Mgt. 262 2008 2023
Fletcher, E.H. III, Thetford, M., Sharma, J. & Jose, S. 2012 Effect of root competition and shade on survival and growth of nine woody plant taxa within a pecan [Carya illinoinensis (Wangenh.) C. Koch] alley cropping system Agrofor. Syst. 86 49 60
Harris, J.R., Niemiera, A., Fanelli, J. & Wright, R. 2001 Root pruning pin oak liners affects growth and root morphology HortTechnology 11 49 52
Keever, G., Cobb, G., McDaniel, R. & Mukhopaphyay, A. 1986 Response of seedling pecan trees to container size and root pruning. Proc. SNA Res. Conf. 21:81–84
Laiche, A.J., Kilby, W.W. & Overcash, J.P. 1983 Root and shoot growth of field-grown and container-grown pecan nursery trees 5 years after transplanting HortScience 18 328 329
Lynch, D.J., Matamala, R., Iversen, C.M., Norby, R.J. & Gonzalez, M.A. 2013 Stored carbon partly fuels fine-root respiration but is not used for production of new fine roots New Phytol. 199 420 430
Matta, F. & Storey, J. 1981 The effects of container design, BA, and GA3 on root and shoot growth of seedling pecan trees [Carya illinoensis] HortScience 16 652 653
McCormack, M.L., Eissenstat, D.M., Prasad, A.M. & Smithwick, E.A. 2013 Regional scale patterns of fine root lifespan and turnover under current and future climate Global Change Biol. 19 1697 1708
Smith, M. & Johnson, J. 1981 The effect of top pruning and root length on growth and survival of transplanted pecan trees Pecan Qrtly. 15 20 22
White, A.W. Jr 1980 Effects of topsoil-subsoil fertilizer and lime amendments on top and root growth of ‘Stuart’ pecan seedlings in a simulated Norfolk soil profile HortScience 17 380 381