影响加拿大一枝黄花种子非随机脱落的因素  

Factors influencing the nonrandom abscission of Solidago canadensis seeds

作　　者：张海亮[1] 朱敏[1] 李干金 

机构地区：[1]中国计量学院生命科学学院,杭州310018

出　　处：《植物生态学报》2015年第3期258-263,共6页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(30771434);浙江省公益性技术应用研究计划项目(2010C34003)

摘　　要：为揭示加拿大一枝黄花(Solidago canadensis)种群扩散机制,明确种子的脱落及风传扩散在其种群蔓延中的作用,在人工环境下测定了不同湍流强度、风速和湿度处理下种子脱落的差异,并对脱落种子与未脱落种子进行形态学特征对比。结果表明:加拿大一枝黄花的种子脱落受湍流、风速和湿度等因素的共同影响。水平气流下种子的脱落阈值为5.1 m·s–1,并随着风速增加,种子的脱落率增加。与模拟水平气流相比,模拟垂直气流下种子的脱落阈值显著偏小。相对于层流状态,湍流的存在显著提高了种子的脱落率,平均增幅超过300%;但单纯提高湍流强度对种子脱落率的影响不显著。增加湿度则显著降低种子的脱落率。种子形态学特征对比结果表明,脱落种子的冠毛数量和冠毛夹角显著高于未脱落种子。该研究结果为研究加拿大一枝黄花种子脱落规律和风传扩散机制提供了科学依据,也为其他入侵性杂草种子的扩散机制及入侵过程提供了借鉴。Aims Solidago canadensis is one of the major invasive weeds that impose serious threats to native plants. Seeds possess traits suitable for the long distance dispersal by wind. However, the initialization of wind dispersal and the seed release under the influence of abiotic conditions are poorly understood. Methods Wind tunnel experiments were designed to study the effects of horizontal and vertical wind with different turbulence intensities and humidities on seed abscission in S. canadensis. Four horizontal wind speeds（4, 6, 8 and 10 m·s–1）, five turbulence intensities（0.14, 0.11, 0.08, 0.07 and 0.02） and two relative humidities were used in the wind tunnel experiments. The proportion of seed releases from the inflorescences was measured and calculated in the laboratory. Both attached and falling seeds were measured to test their difference in morphological traits. Important findings The seed abscission in S. canadensis was a nonrandom process, and was influenced by factors such as wind speed, turbulence, humidity and seed maturity, etc. Under the horizontal airflow condition, the seed release threshold was 5.1 m·s–1. However, the seed release threshold under vertical airflow condition was markedly smaller. Compared with the laminar flow condition, turbulence greatly increased the seed releasing rate by more than 300% on average. Under the turbulent conditions, the turbulence intensity alone did not significantly influence the proportion of seed release. High humidity decreased the seed releasing rate from the inflorescences. In addition, falling seeds tended to have greater pappus numbers and flat angles comparing to the attached seeds.

关 键 词：加拿大一枝黄花 种子 非随机脱落 风传扩散 湍流 

分 类 号：S451[农业科学—植物保护]