光和磷对苔草属植物胡萝卜状根形成及分布格局的影响

为了了解光照和土壤中磷对苔草属植物胡萝卜状根形成及分布格局的影响，2006年夏季在加拿大麦吉尔人工气候室内，对北美苔草属植物进行了不同光照强度和磷浓度组合的处理，以诱导苔草属植物胡萝卜状根的形成。结果发现：（1）苔草属植物的胡萝卜状根主要在低磷条件下形成，其中54％的植株在低磷条件下形成胡萝b状根，而高磷条件下只有4％的植株形成；（2）在相同的光照和磷处理条件下，处理时间对苔草属植物胡萝b状根的形成无显著影响；（3）遮荫影响苔草属植物胡萝b状根的形成，其中在“低磷＋全光照”条件下形成胡萝b状根的植株占处理植株总数的52％，而在“低磷＋遮荫”条件下形成胡萝卜状根的植株只占22％；（4）在苔草属植物中，胡萝卜状根只发生在苔草亚属（Subgen．CaYex）植物中，其中23组81种苔草亚属中78％的种类形成胡萝卜状根，而在二柱苔草亚属（Subgen．Vignea）植物中，5组9种苔草植物均无胡萝卜状根形成。可见，胡萝卜状根的形成不仅受环境因素（养分、光照）的影响，而且还与其系统发育有关。

Impact of phosphorus supply and light on dauciform root development and the occurrence pattern of dauciform roots among Carex species

In order to understand the impact of phosphorus supply and light on dauciform-root development and the occurrence pattern of dauciform roots among Carex species,inducement of phosphorus(P) and light treatment on Carex species were conducted in McGill University phytotron in summer,2006.Several results were found as follows:first,the development of dauciform root of Carex species strongly depended on P availability,especially on P deficiency;44% of the plants under low P treatment formed dauciform roots,while only 2% of the plants under high P treatment developed dauciform roots;second,the time under same P and light treatment had no significant effect on development of dauciform root;third,shade decreased the number of Carex plants which developed dauciform roots,in which 52% of the plants with low P and high light treatment developed dauciform roots,while 22% of the plants with low P and low light had dauciform roots;fourth,dauciform root only occurred in Subgen.Carex,not in Subgen.Vignea among genus Carex species.Among 23 sections 81 species of the Subgen.carex,78% species developed dauciform roots,however,no dauciform root occured in 5 sections 9 species of the Subgen.Vignea.Therefore,the induction of dauciform roots in Carex is allied with phylogeny,rather than the influence of the environment(nutrition and light).