PhD Thesis Defense: Sebastian Nagelmüller
The low temperature growth limit of alpine plants and winter crops
grosser Hörsaal Pharmazie-Historisches Museum, Totengässlein 3
Low temperature is a major limiting factor for growth and productivity for cold adapted wild plants and for winter crops. To assess and understand these low temperature limits for growth, root tips and expanding leaves of alpine plants and winter crops were studied under field conditions. The hypothesis was tested that all cold adapted plant tissues face similar temperature related limitations. The absolute low temperature limit for root growth in alpine plants were found between 0.8 and 1.4 °C and close to 0 °C for leaf growth of monocot and dicot winter crops. In case of roots, such thermal growth limitations are explained by impaired cell elongation and differentiation, as obtained from image analysis of root microscopy. Leaf growth of monocot winter crops was strongly correlated with temperature but genotype specific responses were found. Dicot winter rapeseed leaves showed a diel growth pattern even at low temperature conditions and was co-controlled by vapor pressure deficit, light and putatively by the circadian clock. It is concluded that the low temperature limit for growth in cold adapted plants is similar for both, wild pants and crops, including monocot and dicot varieties. These developmental and cellular explanations of plant growth in the cold are both useful to explain and define the growing season and the distribution limits of arctic-alpine plants, and to assess the performance of cold tolerant winter crops for plant breeding.