The Developmental Pattern in a Group of Therophytes
1972; Elsevier BV; Volume: 161; Issue: 1-2 Linguagem: Inglês
10.1016/s0367-2530(17)32053-4
ISSN1618-0585
Autores Tópico(s)Mediterranean and Iberian flora and fauna
ResumoThe occurence and characteristic features of dormancy in ten species of therophytes (Allysum calycinum L., Arenaria serpyllifolia L., Calamintha acinos (L.) Clairv., Lamium amplexicaule L. Lithospermum arvense L., Medicago minima (L.) Grufbg., Myosotis hispida Schlecht., Thlaspi perfoliatum L., Veronica dillenii Cr., Veronica praecox All.) in xerothermic grasslands has been studied. The laboratory experiments were extended by detailed phenological observations in natural habitats on slopes of the Bohemian Karst and České Středohoří Hills. The experiments revealed the occurence of seed dormancy in all investigated species, with exception of Calamintha acinos. The prevailing type of dormancy seems to be the physiologically unripened embryo. The requirements for after-ripening of about three months duration was established in the following species: Alyssum calycinum, Arenaria serpyllifolia, Lithospermum arvense, Myosotis hispida, Thlaspi perfoliatum Lamium amplexicaule, Veronica praecox. Another two types of dormancy are represented by the impermeability of the seed coats (Medicago minima) and most probably by the presence of germination inhibitors (Veronica dillenii). The dormancy was broken by puncturing the seed coats in the first case, and by gibberellic acid treatment in the second one. According to our phenological observation and experimental data, dormancy lasts throughout the hot summer season and may be thus considered an important developmental adaptation to fit the local climatic pattern.
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