Institut National de la Recherche Agronomique, UMR "Écologie des Forêts de Guyane," Kourou, French Guiana;
Am J Bot. 2007 Jun;94(6):901-11. doi: 10.3732/ajb.94.6.901.
To investigate the existence of coordinated sets of seedling traits adapted to contrasting establishment conditions, we examined evolutionary convergence in seedling traits for 299 French Guianan woody plant species and the stress response in a shadehouse of species representing seed size gradients within five major cotyledon morphology types. The French Guianan woody plant community has larger seeds than other tropical forest communities and the largest proportion of hypogeal cotyledon type (59.2%) reported for tropical forests. Yet the community includes many species with intermediate size seeds that produce seedlings with different cotyledonal morphologies. A split-plot factorial design with two light levels (0.8% and 16.1% PAR) and four damage treatments (control, seed damage, leaf damage, stem damage) was used in the shadehouse experiment. Although larger-seeded species had higher survival and slower growth, these patterns were better explained by cotyledon type than by seed mass. Even larger-seeded species with foliar cotyledons grew faster than species with reserve-type cotyledons, and survival after stem grazing was five times higher in seedlings with hypogeal cotyledons than with epigeal cotyledons. Thus, to predict seedling performance using seed size, seedling morphology must also be considered.
为了研究适应不同建植条件的幼苗特征的协调集合是否存在，我们检验了 299 种法属圭亚那木本植物物种的幼苗特征的进化趋同，以及在遮荫棚中代表五个主要子叶形态类型内种子大小梯度的物种的胁迫反应。法属圭亚那木本植物群落的种子比其他热带森林群落大，而且是报告的热带森林中具有最大比例地下子叶类型（59.2%）的群落。然而，该群落包含许多种子大小中等的物种，这些物种产生的幼苗具有不同的子叶形态。在遮荫棚实验中，采用了双因素裂区设计，两个光照水平（0.8%和 16.1%PAR）和四个损伤处理（对照、种子损伤、叶片损伤、茎损伤）。尽管大种子物种的存活率更高，生长速度更慢，但这些模式更多地由子叶类型而不是种子质量来解释。即使是具有叶性子叶的大种子物种的生长速度也快于具有贮藏性子叶的物种，而具有地下子叶的幼苗在茎被放牧后的存活率比具有地上子叶的幼苗高五倍。因此，要使用种子大小来预测幼苗性能，还必须考虑幼苗形态。
