Comparative Study on Inbreeding Depression of Biclonal and Three-line Seed Orchards of Cunninghamia lanceolata

In Suichang of Zhejiang province, 3 blocks of biclonal (2000-2002) and 2 blocks of three-line (2019-2021) seed orchard of Cunninghamia lanceolate were selected for inbreeding depression. The experiment revealed that inbreeding changed with the parents’ progenies and parental materials in the biclonal seed orchard. It also related with the flowering phase of male and female of different lines. It showed that the progenies of the parents in the three-line seed orchards had no inbreeding depression and showed a certain hybridization advantage compared with the progenies in the multi-line seed orchards under the condition of matched flowering phase. Propositions were put forwarded of further research on the flowering phase of the parents in the higher generation breeding orchard.