^{Genetic improvement on bi-clonal seed orchard of Chinese fir clone Long-15 and Min-33}

Key words: 
• forest tree breeding /
• Chinese fir（Cunninghamia lanceolata） /
• seed orchard /
• bi-clonal seed orchard /
• improvement gain /
• genetic analysis

Abstract: With both the unimproved Cunninghamia lanceolata （Chinese fir） trees（ck1） and the multiple-clonal seed orchards （ck2；i.e.，first generation，one-and-half generation，and second generation seed orchards） as experimental controls，we studied the genetic improved gain，direct and reciprocal crossing effects，and genetic effects of a bi-clonal Chinese fir seed orchard（clones Long-15 and Min-33）. We measured qualities of seeds collected in four consecutive years，planted seedling in two consecutive years at four different locations with five replications，and analyzed inheritance traits in the progenies. The results showed that compared to ck1，seeds from the bi-clonal seed orchard increased 6.76% － 20.44% quality gains；compared to ck2，thousand-seed weight，seed viability，and seed vigor were superior. The six-year-old progenies derived from the bi-clonal seed orchard had an increase of 46.14% volume gain than ck1，an increase of 10.63% － 21.10% than ck2. Both effects of direct crossing and reciprocal crossing on progeny growth，height-diameter ratio and crown diameter were similar；but height，diameter at breast height（DBH） and volume growth were mostly controlled by the gene additive effect；and thousand-seed weight，germination index and seed vigor showed a super dominant effect.［Ch，2 fig. 4 tab. 16 ref.］