LAUSR

To select maternal parents with high fertility and high combining ability during cross breeding of Populus tomentosa Carr., the ploidy level of 75 female clones was determined using flow cytometry. In addition, genetic variations and phenotypic correlations of seed traits and early growth traits, as well as the general combining ability (GCA) for seedling height (SH) and basal diameter (BD) of all diploid half-sib families were examined. A total of 26 natural triploid clones were identified. For all diploid families, family effects were significant for inflorescence length (IL), thousand kernel weight (TKW), seedling emergence rate (SER), and for SH and BD. There was a positive correlation between TKW and other traits, excluding IL. The seed-bearing coefficient (NS × SER) ranged from zero to 32.4%. Clones 3-10-2, 2-8, 3119, 3206, and 3-10-1 had the best performance of the GCA for SH and BD. Based on the fertility and GCA for SH and BD, clone 3-10-2 and clone 3119 could be used as female parents for controlled cross-breeding of P. tomentosa.