干热河谷木棉科三种植物根茎叶水分传输的解剖结构比较研究

Comparison of moisture transmission anatomical structure of three kinds of Bombacaceae plants in the dry-hot valleys

木棉科的许多植物在热带雨林的湿润气候和极端干旱的干热河谷环境下均能长成高达30m以上的大乔木,其水分传输相关的解剖结构值得研究,且不同种间树高和树体大小也存在差异。为揭示这种情况与水分传输结构的相关性。文中采用石蜡切片和光学显微镜技术,运用隶属函数法,对干热河谷木棉(Bombax ceiba)、长果木棉(Bombax insigne)和吉贝(Ceiba pentandra)三种植物根茎叶进行解剖比较观察,探索水分传输结构与植物抗旱性关系。结果表明:不同植物叶片大小形态间存在明显差异,长果木棉叶片显著大于木棉和吉贝。长果木棉中柱鞘细胞分化能力较木棉和吉贝高,长果木棉根木质部面积占横切面积比率的55.24%,木棉和吉贝分别为13.43%和27.21%。长果木棉和木棉茎皮层细胞高度肉质化,且木棉皮层中存在大量腺体。长果木棉叶片栅栏组织厚度与海绵组织厚度比值达99.30%,木棉和吉贝分别为64.93%和47.59%。吉贝海绵组织厚度最大为78.69 um,分别是长果木棉和木棉的1.30倍和1.77倍。长果木棉主叶脉维管束呈半圆形,木棉和吉贝形成"V"字形。经测定根茎叶27个指标中有13个指标种间差异显著,可作为评定的理想指标。通过隶属函数法综合分析三种木棉科植物的抗旱能力为长果木棉>木棉>吉贝,这与干热河谷三者的树高和树体大小的顺序相一致。

Many Bombacaceae plants can grow up as big trees to more than 30 meters, either in humid rain forest or in the extremely dry environmental; but tree height and tree body size exist differences among different kinds of trees. In order to investigate whether these differences were related to water transportation structure of different trees, comparative study of anatomy structure of Bombax ceiba, Bombax insigne and Ceiba pentandra that grow in the dry- hot valleys （DHV） were taken by using paraffin method and optical microscope technology. Results showed that there are significant differences in leaf morphology of three kinds of plants. The differentiation ability of B. insigne pericycle cells was higher than B. ceiba and C. pentandra, and the radio of Xylem/root area of B. insigne （55.24%） were respectively 4.11 times and 2.03 times of B. ceiba （ 13.43% ） and C. pentandra （27. 21% ）. Stem cortex ceils of B. insigne and B. ceiba are highly succulent, and there are many glands in cortex cell of B. ceiba. The radio of palisade tissue and spongy tissue of B. insigne （99.30%） was higher than B. cei- ba （64.93%） and C. pentandra （47.59%）. Sponge tissue thickness of C. pentandra reach the maximum of 78.69 urn, which was 1.30 times and 1.77 times of B. insigne and B. ceiba respectively. The main vein vascu- lar bundle of B. insigne presents a semicircle, and that of C. pentandra and B. ceiba form ＂V＂. There are 27 indicators of root, stem and leaf to be analyzed, and there were 13 indices reached significant difference among species and can be used as ideal indicators to evaluate drought resistance. Drought resistance ability that was comprehensive analyzed by the subordinate function value method was B. insigne 〉 B. ceiba 〉 C. pentandra, and this sequence is line with the trends of the height and size of the trees in the DHV.