淹水胁迫下北美鹅掌楸幼苗形态和生长的响应

为探索不同家系北美鹅掌楸的耐淹性差异，采用盆栽苗模拟淹水法对Louis（L），Kent（K）和Penn（P）3个家系的2年生幼苗进行处理，研究皮孔、膝根、绿叶等指标的变化情况。结果表明：膝根形成是北美鹅掌楸淹水胁迫的应激反应，同一家系随胁迫水位高度的增加膝根长度和粗度分别呈增长和增粗的趋势，不同家系膝根生长量存在差异，L家系膝根最长、最细，P家系增粗最快，K家系居中；通气组织皮孔的形成增高了北美鹅掌楸的耐淹性，皮孔数L家系＞K家系＞P家系；在淹水条件下植株表现为枯死及绿叶数减少，其中K家系绿叶数最多，不同家系表现存在差异；水中穿孔根的生长提高了地上/地下部分比值，增加吸氧表面积而提高耐淹性能，是一种应激反应。3个家系耐淹性强弱依次为L家系＞K家系＞P家系，膝根长度和皮孔数量与北美鹅掌楸耐水能力直接相关。

Response on Morphology and Growth of Seedlings of Liriodendron tulipifera Under Submergence

In order to explore the different resistance of Liriodendron tulipifera under submergence, the study made 2 year old potting Liriodendron tulipifera seedling, from 3 families of 3 provenances（Louis （L）, Kent （K） and Penn （P）） as material and treated by submergence, studied the variation of lenticels, knee roots and leaves of seedlings. The results showed that, knee roots formation was a stress response for Liriodendron tulipifera to adapt to submergence. In a same family, the length and coarseness of knee roots were increased with aggravated submergence height, while knee roots increment existed differences in different families, such as knee roots of L family was the longest and thinnest, the thickening of P family was fastest, while K family was in the medium. Lenticels formation increased the resistance of Liriodendron tulipifera under submergence, the order of lenticel quantity from high to low were L family, K family and P family. Under submergence condition, plants withered and green leaves reduced, but different families existed differences, and green leaves quantity were the most. The growth of living roots under water improved the ratio of aboveground and underground part, expanded superficial area for oxygen absorbed, and then increased the resistance to submergence, and therefore, it was a stress response. According to index, the order of resistance to submergence in three families was L＞K＞P. Knee roots length and lenticels quantity were direct correlation with submergence tolerance of Liriodendron tulipifera