摘要
支持物倾角的变化将引起攀援植物“自遮荫”程度的改变 ,从而影响植物的生长和行为。以攀援植物栝楼 ( Trichosantheskirilowii)为材料 ,通过实验生态学的方法 ,研究了 4种支持物倾角下植株的生长和觅食行为的差异。结果表明 :( 1 )不同生长发育期栝楼植株形态对自遮荫差异的可塑性反应程度不一 ,不同角度攀援生长植株在生长前期均比生长后期有较敏感的形态可塑性反应。 ( 2 )自遮荫程度随支持物倾角的增大而增强 ,较强自遮荫环境下植株比较弱自荫环境下的植株有更大的形态可塑性。 ( 3)比主茎长、比叶面积、生物量对叶片和叶柄的配置在 4种攀援生长形式间差异均不显著。不同角度攀援植株主要通过改变分枝数量、分枝形态和分枝生物量配置以适应支持物倾角的变化 ,这说明 ,自遮荫对植株形态和生物量配置仅产生有限的影响。 ( 4 )分枝能力、分枝数量以及分枝生物量配置均在大角度攀援生长中最大 ,且与小角度攀援生长植株间有显著差异。 ( 5 )水平攀援生长植株主要通过增大主茎生物量投资以充分占有生境 ,而大角度攀援生长植株则主要通过分枝茎扩展以占据有利生境 ,不同攀援生长植株有不同的觅食行为。
Climbing plants differ from non-climbing and self-supporting plants in many growth characteristics, which mainly result from biomechanical constraints. External supports, whose status determines the strategies of climbing plants to search sunlight and other external supports, are important resources for climbing plants. The morphology and growth of climbing plants may be affected by external supports to a large extent. However, the climbing plants are often shaded by their own shoots when they grow on the supports, and changing support angles might induce different shading effects. We called this phenomenon as self-shading. It has reported in many literatures that plants would adapt themselves to different light conditions through altering biomass allocation and growth behaviors. It is therefore hypothesized that self-shading would influence growth and morphology of climbing plants through changing morphology and biomass allocation. We tested this hypothesis in a garden experiment, carried out in the Ecological Garden of Southwest China Normal University with a perennial herbaceous climbing species Trichosanthes kirilowii. On 17 May 1999, the seedlings of Trichosanthes kirilowii with the same size were planted in 40 figuline containers filled with cultivated soil, one seedling per pot. Seedlings were directly offered external support made of iron line(Φ4mm) at the beginning of the experiment. All plants were divided into 4 groups, and each group was offered external supports with given angles (i.e. 0°, 20°, 40°and 80°). The direction of supports was northward. Each plant was supplied with the same quantity of water and nutrient during the experiment. The following parameters were measured at intervals of 14 days from June 6 to August 20: stem length; stem diameter; internode length; leaf number; shoot number; single leaf area; petiole diameter and petiole length. At the end of the experiment, all the plants' above-ground parts were harvested and measured the same parameters above mentioned. The plant was separated into main stem, shoot, lamina, petiole and tendril, and cleaned by tap water. All plant parts were oven-dried for 72h at 84℃ and then weighted separately. The morphological plasticity in different developmental stages of Trichosanthes kirilowii responded to self-shading in varying ways. The plants showed more sensitively plastic responses to self-shading in the early than in the late developmental stages. The degree of self-shading increased with the enlarging of the support angles. The specific stem length and specific petiole length increased with the enlargement of the support angles, and the values of the two parameters at 0°, 20°, 40°and 80°levels were 155.83cm·g -1, 147.34 cm·g -1, 168.37 cm·g -1, 176.92 cm·g -1 and 368.98 cm·g -1, 415.63 cm·g -1, 496.53 cm·g -1, 588.33 cm·g -1, respectively. These results indicate that the plants show stronger responses in morphological plasticity under strong self-shading conditions than under weak self-shading ones. Specific stem length, specific leaf area and biomass allocated to lamina and petioles had no significant differences among four climbing angles. The plants adapted to different support angles mainly through changing the number of shoots, shoot morphology and shoot biomass allocation. These results suggest that the self-shading only had limited effects on plant morphology and plant biomass allocation. The plants climbing on the supports with large angle had stronger branching intensity, more shoots and more shoot biomass allocation than those climbing on the supports with small angle. The shoot number, branching ratios and shoot biomass allocation at 0°, 20°, 40°and 80°levels were 5.60, 7.40, 9.60, 10.60; 2.40 shoot·m -1, 5.40 shoot·m -1, 7.50 shoot·m -1, 5.42 shoot·m -1 and 14.13%, 21.65%, 23.35%, 23.56%, respectively. The plants on small angle-leaned supports occupied the rich-light habitats through increasing stem biomass allocation, while those on large angle-leaned supports sought for rich-light habitats th
出处
《生态学报》
CAS
CSCD
北大核心
2003年第1期1-7,共7页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目 ( 39870 1 60 )~~
关键词
支持物倾角
攀援植物
栝楼
生长
觅食行为
植物形态
climbing plant
external support
growth
foraging behavior
Trichosanthes kirilowii
