Evaluating Black Walnut Planting Stock Quality
Work with hardwood species in the southern and central United States has indicated that root system morphology can be a major determinant of seedling success (or failure) in the field (Kormanik, 1986; Schultz and Thompson, 1990). Survival and shoot growth after transplanting depend to a great extent on the seedling root system and the ability of the seedling to rapidly produce new roots (Farmer, 1975; Sutton, 1980; Burdett et al., 1983; Kormanik et al., 1988; Rietveld and van Sambeek, 1989; Barden and Bowersox, 1989). Especially for stock cultured in bareroot nurseries, the potential for new root production (root growth potential) can be related to the presence of an adequate system of relatively large (> 1 mm proximal to the taproot) permanent first-order lateral roots (FOLR) (Thompson, 1991). FOLR that arise within the portion of the taproot that is lifted are generally able to survive the rigors of lifting, packing, storing, shipping, and planting procedures, and provide sites for initiation of new roots during the seedling establishment phase (Thompson and Schultz, 1995). Periodic seedling excavations have indicated that these roots do persist after planting (e.g. Thompson, 1991).
This is a report from Iowa Agriculture and Home Economics Experiment Station, Project No. 2485 (1995): 17 pp.