MECHANICAL STRENGTH OF STEMS IN AQUATIC MACROPHYTES
MECHANICAL STRENGTH OF STEMS IN AQUATIC MACROPHYTES
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DOI：
10.5586/asbp.2009.022
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发表时间：
2009-01-01
影响因子：
1
通讯作者：
Szmeja, Jozef
中科院分区：
文献类型：
--
作者：
Bociag, Katarzyna;Galka, Agnieszka;Szmeja, Jozef
在沉水植物种群中，个体是根据对水动力作用的抵抗力来选择的。本研究的目的是检查是否个人在河水中生长的拉伸和弯曲阻力比植物发生在不暴露于流动应力的地方。我们测定了四种水生植物（Potamogeton natans，P. pectinatus，Batrachium fluitans和Chara fragilis）的极限抗拉强度，它们发生在两种环境变量中：流动（流速为0.1-0.6 m/s（-1））和停滞水中。此外，研究了来自两种环境变体的苦草的弯曲。此外，还确定了所研究植物茎中强化结构的类型和排列方式，其中游泳眼子菜茎最耐拉伸（15.6 +/- 4.7 N），而栉孔藻（3.3 +/- 1.0 N）和水线蕨（2.6 +/- 0.8 N）的茎的耐拉伸性较差。脆弱轮藻（0.6 +/-0.3 N）的茎抗性最低。如果它们出现在河流中，则Batrachium，Chara和P. pectinatus更能抵抗拉伸，而P. natans，在停滞的湖水中。湖泊中的苦草茎的极限弯矩（9.75.10（-3）-4.25.10（-3）Nm）也远大于河流中的苦草茎（2.12.10（-3）-1.00.10（-3）Nm）。一方面，在所有研究的Cormophyta物种中，抗性更强的茎（在死水中的P. natans中，在其他自来水中）更厚，并且其特征在于在整个茎横截面中的空气空间的贡献更高。另一方面，茎保留其物种特异性结构，并具有类似比例的强化元素。
In populations of submerged macrophytes, individuals are selected in terms of resistance to the effect of hydrodynamic forces. The aim of this study was to check whether individuals growing in river water are more tensile and bending resistant than plants occurring in places not exposed to flow stress. We determined the ultimate tensile strength of steins in four macrophyte species, Potamogeton natans, P. pectinatus, Batrachium fluitans and Chara fragilis, which occur in two environmental variants: in running (current velocity of 0.1-0.6 m/s(-1)) and stagnant water. In addition, flexure of P. natans stems from both environmental variants was examined. What is more, the type and arrangement of strengthening structures in stems of the plants under study were determined.Potamogeton natans stems are the most resistant to stretching (15.6 +/- 4.7 N), while stems of P. pectinatus (3.3 +/- 1.0 N) and Batrachium fluitans (2.6 +/- 0.8 N) are less resistant. Chara fragilis (0.6 +/- 0.3 N) has the least resistant stems. Batrachium, Chara and P. pectinatus are more resistant to stretching if they occur in a river current, whereas P. natans, in stagnant lake water. Ultimate bending moment of P. natans stems from lakes is also much greater than of stems from a river (9.75.10(-3)-4.25.10(-3) Nm as compared to 2.12.10(-3)-1.00.10(-3) Nm).The resistance of stems to breaking is directly proportional to the stem and thallus cross sectional areas. On the one hand, in all the studied Cormophyta species, the more resistant stems (in P. natans from stagnant water, in the others from running water) are thicker and characterised by a higher contribution of air spaces in the overall stem cross-section. On the other hand, the stems retain their species specific structure and have a similar proportion of strengthening elements.