Analysis of the Outcrossing Ratio of German Chamomile (Matricaria recutita L.) using SSR-markers

Abstract

German chamomile (Matricaria recutita L.) is one of the most ancient and widely used medicinal plant species. Plant breeding efforts for desired agronomic traits have existed for over sixty years; however, the breeding programs for chamomile are small in comparison to other crop plant species. The objective of this thesis was to examine the variability of chamomile’s outcrossing ratio based upon multiple environmental factors in order to provide a basic understanding of pollination biology to inform the breeding of chamomile. Two studies were conducted to achieve this objective. The first study evaluated the outcrossing ratio at multiple geographical locations throughout central Germany. The second study evaluated greenhouse compared to field conditions, as well as, potential temperature effects on the outcrossing ratio. Chamomile exhibited a wide range of outcrossing frequencies in the crosses regardless of both location and ploidy. The results did not show a statistical difference between geographical locations; however, in all crosses there appeared to be an effect associated with crossing direction. In many crosses, the frequency of outcrossed progeny was considerably higher in one cross direction than the other. The greenhouse and field comparison could not be made due to progeny germination difficulties. The greenhouse crosses could have been negatively affected by poor pollination, seed dormancy, and unfavorable temperature conditions during germination. Although this study had technical issues, and the outcrossing ratio could not be analyzed as expected, valuable knowledge was gained for the direction of future research in chamomile.