Germination and Seedling Growth of Side and Wafer 'Willamette' Chestnuts

Abstract

Wafer nuts (i.e., central nuts) are often smaller than the outer two when three nuts are produced in Chinese chestnut ( Castanea mollissimaBlume) burs. Because small chestnuts of any type command a low price at retail markets, they are either processed or discarded. Most large chestnuts are sold fresh or for processing, leaving nuts used for propagating trees and seedling rootstocks in short supply. Thus, central and side 'Willamette' ( C. mollissima× dentata Borkh.) chestnuts from 2 to 20 g fresh weight were germinated in a greenhouse in mid March and container-grown in a nursery until early November to determine if nut type or fresh weights influenced germination and seedling growth. Wafer nuts had higher odds for germinating than side nuts, but all chestnuts that weighed ≥ 10 g at harvest averaged more than 87% germination when grown in a greenhouse the following spring. Although shoots emerged most rapidly from side nuts weighing ≤ 9.9 g, mean days to emergence for all chestnuts only varied from 18 to 24 d. Wafer or side nuts weighing ≥ 10 g produced seedlings with large stem diameters (≥ 6.8 mm) that are desirable for grafting. Chestnuts weighing ≥ 14.0 g at harvest generally produced taller seedlings with greater dry weights than those weighing ≤ 11.9 g. Thus, side or wafer chestnuts that are ≥ 10 g can be used to produce rootstocks for grafted chestnut trees and nuts ≥ 14.0 g can be used to produce vigorous seedling trees.