Analysis of combining ability and heterosis based on controlled pollination populations of eucalypt

Artificial hybridization remains the most effective method for genetic improvement of eucalypt, though limited research exists on the genetic basis of heterosis for interesting traits in Chinese eucalypt. We attempted to use Python in combined with SAS and SPSS to explore the relationship between parental combining ability and heterosis in controlled pollination populations of eucalypt. Our results indicated that E. urophylla had the highest general combining ability (GCA). The special combining ability (SCA) of U3423 x 3327, 06H16 x LL131, and H0733 x U6 were the highest. H0733 x U6, H0733 x P9060, and (E. urophylla x E. grandis) x 06H241 had the strongest mid-parent heterosis (MPH). U3423 x 3327, U952 x C2232, and (E. urophylla x E. grandis) x 06H241 had the strongest high-parent heterosis (HPH). We found that completely controlled by non-additive effects were (E. tereticornis x E. urophylla) x (E. urophylla), E. urophylla or (E. urophylla x E. grandis) x (open pollination). Fully controlled by additive effects were (E. tereticornis x E. urophylla) x E. camaldulensis or E. grandis, (E. urophylla) x (E. pellita x E. tereticornis), (E. urophylla x E. grandis) x E. pellita or E. tereticornis. All the findings in the present research explained the genetic basis of heterosis in eucalypt growth, and enriched the theory of hybrid breeding in eucalypt.