马尾松生长性状交配效应的遗传分析及杂交组合选择

Effects of Mating Manners on Growth Traits of Pinus massoniana and Selection of Cross Combinations

利用2份6×6全双列交配设计子代测定林材料,对马尾松生长性状的配合力、杂种优势和自交效应等进行分析。结果表明:2份测定材料的树高、胸径和材积等生长性状的一般配合力、特殊配合力和正反交效应都极为显著,这些性状的遗传是由加性和非加性基因共同控制,其中非加性效应起主导作用,加性基因效应相对较小,而基因上位效应材料Ⅰ(1992年制种)明显大于材料Ⅱ(1993年制种)。马尾松生长性状的特殊配合力效应明显大于一般配合力效应,这可能与亲本来源于不同地理种源和经过一般配合力间接选择有关。马尾松生长性状普遍存在自交衰退现象,2份材料中各亲本树高、胸径和材积的平均自交衰退程度分别为-17.8%^-18.4%、-23.3%^-27.7%和-44.3%^-50.6%,一般配合力小的亲本自交衰退程度呈明显增加趋势。马尾松不同交配组合间的杂种优势差异巨大,正反交杂种优势在总体上大致相似。以材积为评选指标,2份材料各选出10个优良杂交组合,其平均材积增益分别为测验群体的59.41%和41.76%,是对照的100.58%和74.61%。

Two groups of filial generation derived from 2 different Pinus massoniana complete-diallel cross were analyzed. Results showed that general combining ability（GCA）, specific combining ability（SCA） and reciprocal effects were significant for some growth traits including height, DBH and volume index. The heredity of these growth traits was controlled by both additive and non-additive genes, with the non-additive genes playing a dominant role. The epistatic effect was greater in groups Ⅰ （crossed in 1992） in comparison with group Ⅱ （crossed in 1993）. The SCA of P. massoniana growth traits was significantly greater than GCA, which would be due to different geographical provenances of parents and an indirect pre-selection undergone by GCA. Inbreeding depression was commonly observed for P. massoniana growth traits, and the extent of inbreeding depression was - 17.8% ～ - 18.4% , - 23.3%～ - 27.7% and - 44.3% ～- 50.6% for height, DBH and volume index respectively. It was observed that parents with small GCA value exhibited greater extent of inbreeding depression. Huge differences in hybrid vigor of different crosses were observed, and the difference between original cross and reciprocal cross was not significant. Based on volume index, ten fine crosses were selected from each of the two groups, and the average increment of volume index was 59.41% and 41.76% respectively in comparison with the average of testing groups, and was 100.58% and 74.61% in comparison with local commercial variety.