Rapid growth in clonal Juglans nigra L. is most closely associated with early foliation, robust branch architecture, and protandry

The advantages of clonal forestry have been well described, but little progress has made in the identification phenotypes best suited to this method high-value hardwood species. genetic variation within, repeatability (broad-sense heritability) of, and Pearson's correlations among phenological, morphological, physiological, growth traits (N = 22) black walnut (Juglans nigra L.) were investigated using 25 grafted genotypes. trees grown at wide spacing (4.6 m × 6.1 m) an intensively managed plantation north-central Indiana, USA. Clonal effect was significant (p < 0.05) for most except gas exchange variables. Many phenological showed high (Rc2 > 0.70), including foliation dates, first female bloom, pollen shed, crown retention rate (autumnal defoliation). Some moderate (0.35 Rc2 0.7), such as branch angle, frequency, tree diameter, height, anthracnose severity, foliar carbon nitrogen concentration. Net CO2 assimilation stomatal conductance had low 0.35). We observed a previously unreported association between sexual morph stem growth, i.e., protandrous generally grew faster than protogynous trees. This may be evolutionary consequence differences reproductive costs versus trees, needs tested other monoecious woody Overall, our analyses indicated that following are associated with rapid growth: 1) early foliation; 2) male flowering or late flowering, more likely variety; 3) large average diameter; 4) frequency; 5) small (more vertical) angle; 6) leaf fall; 7) later-season concentration; 8) number fruits seeds. These used, further testing, define biomass ideotype J. nigra.