空心莲子草对水分变化的形态适应研究

在人工栽培空心莲子草并控制其立地水分条件，使之形成相应三种生境类型——旱生型、挺水型、漂浮型的条件下，初步研究了空心莲子草对水因子变化的形态适应机理。对节间长度、不定根数、不定根长度、叶形指数、抽枝率、节间最大周长等六个形态学指标进行的单因素方差分析和因子分析的结果表明：水分条件的变化对全部形态参数都有极显著影响；旱生型空心莲子草以地上部迅速占有空间的生长为主，其次是地下部生长；与旱生型空心莲子草相比，漂浮型的生长趋势中茎的增粗生长和根的数量生长上升到重要位置，然后才是茎与根的伸长生长；挺水型的第一位生长具有旱生型与漂浮型的双重特点，第二位生长在一定程度上具有与漂浮型相同的特征。按旱生型—挺水型—漂浮型逐级过渡，节间长度、不定根数极显著增加；第一公共因子中不定根数的重要性逐步升高，而且抽枝率始终是重要参数，但其均值在漂浮型中最小。所以，对旱生型与挺水型空心莲子草的治理应以抑制其抽枝为主要手段，对于漂浮型则应以抑制其生根为主。后续的相关研究应该以寻找其根和茎的发育机理为主，并以此为突破口采用适当的方法治理该种的蔓延。

MORPHOLOGICAL ADAPTATION OF ALTERNANTHERA PHILOXEROIDES(MART.)GRISEB TO THE CHANGE OF WATER

The paper studied the mechanism of adaptation of Alternanthera philoxeroides (Mart.) Griseb to the change of water factor, by cultivating them in three groups of slots and manipulating their water condition to make them form three kinds of habitat types namely terrestrial, emergent, and floating types; Implementing One-Way Anova analysis and factor analysis to the following morphological parameters-length of internode, maximum-circumference of internode, branching frequency, number of adventitious roots, length of adventitious roots, leave ship index, it is revealed that the change of water factor affected all the parameters significantly. On the part of the terrestrial type, the growth of the overground parts was predominant for occupying spaces, and then of underground parts secondly; However, as for the floating type, the widenning growth of the stems and the increase of roots go up to a vital position, and the lengthening growth of them is secondary. For the emergent type , the number one growth involves double features of the former two, but the number two growth ,to a much degree, is similar to the floating type. Along the line as terrestrial type-emergent type- floating type, the role of the parameter, the amount of adventitious roots, protrudes gradually. Branching frequency is always the important element to consist the first common factor, but its mean value was the smallest in floating type. Therefore, it should be a proper way to control the branching for harnessing the terrestrial and the emergent type, while to constrain the rooting for the floating type, and the relatively successive study should be based on searching for the mechanism of branching and rooting.