Autotoxic inhibition of seed germination by Typha latifolia: an evaluation.

Seeds of Typha latifolia were exposed to leaf extracts, leaf pieces, and soil water from adult plants of T. latifolia. In liquid culture, only extracts of concentration greater than or equal to 3% (dry weight to volume) inhibited seed germination. Adding soil to the liquid cultures increased the inhibition of seed germination by extracts. The inhibitory effects of extracts were correlated with the development of water molds in the cultures; prior to the development of water molds, even 15% extracts were not inhibitory to germination. In contrast to results from extracts; neither 3% concentrations of senesced leaf pieces nor soil surface water from one year old pots of T. latifolia had any detrimental effects on germination. Seeds sown into pots containing established T. latifolia germinated as well as seeds sown into control pots. These results do not support the contention that T. latifolia inhibits the germination of its seeds by the release of allelopathic substances.