部分菊科入侵种种子(瘦果)的萌发能力和幼苗建群特性

对入侵种种子生物学各方面的了解有助于更好地预测入侵趋势和评估可持续管理的策略.研究通过对部分菊科入侵种种子(瘦果)进行的室内萌发实验和土壤埋藏实验,通过与相关研究的对比和分析,对这些入侵种的萌发能力和幼苗建群特性进行了研究.10个入侵种种子室内萌发实验的结果表明,在25℃、12h光照的情况下,除钻形紫菀和一年蓬以外,被研究的其它8个种的终萌发率超过了50%,而且都显示出早期快速萌发的特点.用SPSS的曲线拟合工具对10个种的累积萌发趋势进行了曲线回归分析,对应的最佳模型均为三次曲线方程.不同土壤埋藏深度下幼苗出苗实验的结果表明,菊科8个入侵种的种子在表土的出苗率均最高,随着覆土厚度的增加,种子的出苗率逐渐降低,当覆土厚度超过3 cm以上时,所有种子均不能出苗.种子在不同的埋藏深度的出苗情况与种子的大小有关,较大种子破土能力相对较强;种子在不同的埋藏深度的出苗情况与种子本身的萌发能力也相关.土壤埋藏期限的实验结果表明,随埋藏时期的增加,小蓬草、苏门白酒草和一年蓬3个人侵种种子的活力逐步降低,在土壤中埋藏12个月后,其活力分别为21.34%、18.15%和27.38%.这些入侵种较广的种子萌发温度适应范围和高萌发率为防除工作带来了困难.在生产上,可通过不同时期的翻耕、将种子深埋等措施减少这些入侵种的危害.

The germination potential of seeds (achenes) and establishment attributes of seedlings of some invasive species of Asteraceae

Understanding seed biology of invasive plant species will be helpful to predict future invasions, and to develop a strategy on sustainable management of invasive species. In this study, we assessed germination characteristics of seeds (achenes) of ten inva-sive species of Asteraceae sown in soils at different depths and seeds of these species that had been buried in the soil for different durations, and establishment attributes of the seedlings. The results of the germination experiments showed that, except for Aster subulatus and Erigeron annuus, percentages of germinating seeds were all above 50% at 25 ℃ and a daily light period of 12 h, and that germination was rapid. Cumulative germination of each of the ten species after sowing was fitted to cubic curves. The results of burial experiments showed that seedling emergence rates decreased with increasing depth of seed burial, and that all of the eight in-vasive species in these experiments had the highest seedling emergence rates when sown on the soil surface. When seeds were buried deeper than 3 cm, no seedlings emerged. The seedling emergence rate of seeds buried at different depths was positively associated with the size of seeds, and also with the germination abilities of the seeds. The results of the burial duration experiment in Conyza canadensis, C. Sumatrensis and Erigeron annuus demonstrated that the viability of seeds decreased with increasing duration of burial. When seeds had been buried for 12 months, the viabilities for the three species were 21.34%、18.15% and 27.38%, respectively. The high germination rates under a wide spectrum of environmental conditions are likely to make it difficult to control these invasive plants. However, one potential option to decrease the harmfulness of these invasive species would be to deeply bury their seeds by turning over the soil.