以落羽杉〔Taxodium distichum （Linn.） Rich.〕和墨西哥落羽杉（T. mucronatum Tenore）及其3个杂交后代品系‘中山杉405’（‘Zhongshansha 405’）、‘中山杉406’（‘Zhongshansha 406’）和‘中山杉407’（‘Zhongshansha 407’）2年生盆栽扦插苗为研究对象，对株高和地径的年增长量、总叶面积、株高和地径的增长量动态变化、株高和地径的生长期进行了比较分析，并根据地径增长量分析了3个杂交后代品系的杂种优势。结果表明：3个杂交后代品系的年株高增长量介于父本与母本之间但无显著差异，而三者的年地径增长量和总叶面积则明显高于父本和母本。墨西哥落羽杉与3个杂交后代品系的株高和地径生长期均一致，分别为5月11日至10月5日和6月1日至11月9日；而落羽杉的株高和地径生长期分别为5月11日至8月10日和6月8日至11月16日。5月份至10月份，墨西哥落羽杉的株高持续增长，而3个杂交后代品系的株高不连续增长，落羽杉的株高则在8月10日之后停止生长；生长初期和生长末期，3个杂交后代品系的地径增长量均高于父本和母本；秋季3个杂交后代品系均能快速进行地径生长，而此时父本和母本的地径增长量均下降。除夏季的少数时间段外，‘中山杉405’在整个生长季都表现出明显的杂种优势，而‘中山杉406’和‘中山杉407’在整个生长季总体上表现出杂种优势，且它们的杂种优势最大值均出现在生长后期，说明供试的3个杂交后代品系在秋季也能快速生长。研究结果显示：供试的3个杂交后代品系均遗传了落羽杉地径生长迅速和墨西哥落羽杉株高生长期长的特性，秋季3个杂交后代品系的地径和株高增长量总体上均高于父本和母本，表现出明显的杂种优势。

Taking two-year-old potted cutting seedlings of Taxodium distichum （Linn.） Rich.， T. mucronatum Tenore and their three hybrid progeny lines of ‘Zhongshansha 405’， ‘Zhongshansha 406’ and ‘Zhongshansha 407’ as research objects， annual increments of height and basal diameter， total leaf area， dynamic changes in increments of height and basal diameter， and growth periods of height and basal diameter were compared and analyzed， and heterosis of three hybrid progeny lines were analyzed according to basal diameter increment. The results show that annual height increments of three hybrid progeny lines are between male and female parents， but there is no significant difference， while their annual basal diameter increments and total leaf areas are obviously higher than those of male and female parents. Growth periods of height and basal diameter of T. mucronatum are consistent with those of three hybrid progeny lines， which are from May 11th to October 5th and from June 1st to November 9th， respectively， while those of T. distichum are from May 11th to August 10th and from June 8th to November 16th， respectively. From May to October， height of T. mucronatum keeps growing， while that of three hybrid progeny lines grows discontinuously， and that of T. distichum stops growing after August 10th. During early and late growth periods， basal diameter increments of three hybrid progeny lines are higher than those of male and female parents. In autumn, basal diameter keeps increasing quickly in three hybrid progeny lines， while it decreases in male and female parents at the meantime. Except a few time segments in summer, ‘Zhongshansha 405’ exhibits obvious heterosis over the whole growing season. By contrast, ‘Zhongshansha 406’ and ‘Zhongshansha 407’ generally show heterosis over the whole growing season. For all three hybrid progeny lines, their highest heterosis values appear in late growth period， indicating that they also grow fast in autumn. This study shows that these three hybrid progeny lines tested inherit characteristics of fast growth of basal diameter of T. distichum and long growth period of height of T. mucronatum. In autumn, increments of both height and basal diameter of three hybrid progeny lines are totally higher than those of male and female parents， indicating obvious heterosis.