Mendes-Rodrigues Clesnan, Oliveira Paulo Eugênio, Ranal Marli Aparecida
Programa de Pós-graduação em Ecologia e Conservação de Recursos Naturais, Instituto de Biologia, Universidade Federal de Uberlândia, Caixa Postal 593, 38400-902 Uberlândia, Minas Gerais, Brazil.
Rev Biol Trop. 2011 Dec;59(4):1915-25.
Pseudobombax tomentosum and P. longiflorum are common trees in the Cerrado region, but the former species is more common in forest edges while the later is present in open cerrado areas. This work aimed to investigate differences in seed germination and seedling growth in these species, from seed collected from Cerrado areas in Central Brazil. For this, a seed germination experiment was designed and included four replicates with 25 seeds per species; seeds were randomly distributed in the germination chamber. To evaluate initial seedling growth, seedlings height was measured up to 67 days after seedling emergence; besides, some of these seedlings were grown for biomass evaluation during nine months. Results showed that seeds of the two species had the same germinability (near 100%) and mean germination time (ca. 12 days). However, P. longiflorum showed a more spread seed germination through time, with higher values of coefficient of variation in germination time and uncertainty index; and lower values of synchronization than P. tomentosum. The two species showed basically the same growth pattern, but lower values for height of apical meristem, diameter of underground structures (mostly roots), dry mass of shoots, underground structure and total mass of seedlings in P. tomentosum were obtained, compared to P. longiflorum. Both species allocated more dry mass to underground structures in detriment of shoot. This probably allows resprouting behavior which prevents hydric stress and detrimental fire action typical of the open Cerrado areas.
绒毛假木棉和长花假木棉是塞拉多地区常见的树木，但前者在林缘更为常见，而后者则生长在开阔的塞拉多地区。这项工作旨在研究从巴西中部塞拉多地区收集的种子在这些物种中的种子萌发和幼苗生长差异。为此，设计了一个种子萌发实验，每个物种有四个重复，每个重复25粒种子；种子随机分布在发芽室中。为了评估幼苗的初始生长情况，在幼苗出土后67天内测量幼苗高度；此外，将其中一些幼苗培养九个月以评估生物量。结果表明，这两个物种的种子具有相同的发芽率（接近100%）和平均发芽时间（约12天）。然而，长花假木棉的种子萌发在时间上分布更分散，发芽时间的变异系数和不确定性指数更高；与绒毛假木棉相比，同步性值更低。这两个物种表现出基本相同的生长模式，但与长花假木棉相比，绒毛假木棉的顶端分生组织高度、地下结构（主要是根）直径、地上部分干质量、地下结构和幼苗总质量的值更低。两个物种都将更多的干质量分配到地下结构，从而损害地上部分。这可能有利于萌蘖行为，从而防止水分胁迫和开阔塞拉多地区典型的有害火灾影响。
