Reproductive Processes in Senecio fuchsii (Partly in Comparison with Eupatorium cannabinum) as Affected by Temperature, Irradiance and Soil Fertility

Abstract

Summary Field investigations and observations, and a number of related experiments were carried out concerning germination, survival of buried fruits as well as survival and reproduction of seedlings and established plants of Senecio fuchsii. The dry matter allocation during one reproductive cycle to various organs in plants of S. fuchsii was studied in the field. Comparative observations in more or less shaded populations were made. Cold stratification for at least 4 weeks was necessary for higher germination percentages of both species. The rhizomes showed considerable growth during the winter half year. Vernalization stimulated rhizome emergence. The reproductive and dry matter production of plants of S. fuchsii and the less shade-tolerant species Eupatorium cannabinum were studied in a factorial design (radiation intensity - soil fertility). The responses of both species showed marked differences: a higher sensitivity to shading in E. cannabinum , a higher sensitivity to low soil fertility in S. fuchsii . Populations of S. fuchsii from acidic and alkaline soil produce fruits, which are adapted for both soil types.