Chin J Plan Ecolo ›› 2015, Vol. 39 ›› Issue (3): 258-263.DOI: 10.17521/cjpe.2015.0025

• Orginal Article • Previous Articles     Next Articles

Factors influencing the nonrandom abscission of Solidago canadensis seeds

ZHANG Hai-Liang, ZHU Min*(), LI Gan-Jin   

  1. College of Life Sciences, China Jiliang University, Hangzhou 310018, China
  • Received:2014-10-18 Accepted:2014-12-17 Online:2015-03-01 Published:2015-03-17
  • Contact: Min ZHU
  • About author:

    # Co-first authors

Abstract: <i>Aims</i>

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.

<i>Methods</i>

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.

<i>Important findings</i>

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.

Key words: Solidago canadensis, seed, nonrandom abscission, wind dispersal, turbulence