利用已进入正常开花结实期的截干矮化马尾松二代无性系种子园,以研究其开花结实的遗传变异规律.结果表明,种子园雌、雄球花量及球果数在无性系内分株间差异不显著,但在无性系间均达极显著水平,其遗传变异系数变化在37.85%～53.50%,无性系重复力皆在0.71以上.根据开花结实的调查结果,种子园无性系主要聚为雌多雄少(偏雌)、雄多雌少(偏雄)、雌雄均多(偏中)和雌雄均少(偏少)4种类型,其分别占总无性系的25.00%、29.55%、38.64%和6.82%,种子园中20%的高产无性系提供了开花结实总量的41.27%～49.15%.相关分析结果认为,理想的截干矮化马尾松二代高产无性系母树的主要形态特征为:冠幅宽、分枝长、分枝角大、树冠宽卵圆形或圆球形.在种实性状上,除种子千粒质量外,球果大小和出籽性状在母树树冠阴面与阳面间差异极显著,且均以树冠阳面高于阴面,说明充足的光照有利于提高种子园种子产量.%A survey was conducted to study the genetic variation of flowering and fruiting of Pinus massoniana in the dwarfed second-generation clonal seed orchard which had entered the stages of normal flowering and seed setting. Results showed that extremely significant differences were observed in strobilus and cone production among different clones, but insignificant differences among clonal ramets. The genetic variation coefficient varied from 37.85％ to 53.50％, and the clonal repeatability was over 0.71. The clones could be clustered into four types, namely partial female type, partial male type, neutral type and few type according to the law of flowering and fruiting, accounting for 25.00％, 29.55％, 38.64％ and 6.82％ respectively. Strobilus and cone produced by 20 percent of high yield clones accounted for 41.27 percent to 49. 15 percent of the whole seed orchard production. Correlation analysis indicated that the optimal morphological characteristics of mother trees from the high yield dwarfed second-generation seed orchard clones were as follows: larger crown, longer branch, flatter branch angle and wide egg-shaped crown or spheroidal crown etc. Except for thousand kernels weight, significant differences in cone size and seed traits were observed between shade crown and sun crown, and cone size and seed traits for the sun crown were superior to those for the shade crown, indicating that abundant light would help to improve the yield of seed orchard.
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