Abstract:

Based on the Liriodendron interspecies hybridization study by professor Ye Peizhong,according to the satisfying and exact mating system and field design,the reciprocal cross with extensive genetic background of Liriodendron tulipifera Linn., the backcross and F₁ crossing which had never been made, and the genetic analysis of heterosis of the hybrid tulip tree were carried out.The results are as follows:(1)One-year-old hybrid seedlings of plus crossing,minus crossing,BC₁ and F₂ universally showed notable positive growth heterosis.Growth characters of the seedlings had extremely significant difference among families and expressed great variation among individuals of family.Growth performance of BC₁ families was particularly excellent.Thus family selection,individual selection and utilization of BC₁ and F₂ hybrids had tremendous potential.(2)The paper preliminarily put forth the photosynthetic superiority hypothesis regarding as the theoretical explanation of heterotic mechanism of the hybrid tulip tree and other forest-tree hybrids.(3)Some important genetic parameters were calculated simply.

Key words: The hybrid tulip tree, Heterosis, Genetic analysis, Photosynthetic superiority hypothesis