Abstract
In high-mountains, cold spells can occur at any time during the growing season and plants may be covered with snow for several days. This raises the question to what extent sexual processes are impaired by low temperatures. We tested pollen performance and fertilization capacity of high-mountain species with different elevational distribution in the European Alps (Cerastium uniflorum, Gentianella germanica, Ranunculus glacialis, R. alpestris, Saxifraga bryoides, S. caesia, S. moschata) during simulated cold snaps in the laboratory. Plants were exposed to 0 °C (the temperature below the snow) for 12, 36, 60 and 84 h. In S. caesia, the experiment was verified in situ during a cold snap. Sexual processes coped well with large temperature differences and remained functional at near-freezing temperatures for a few days. During the cooling-down phase a high percentage (67–97%) of pollen grains germinated and grew tubes into the style. At zero degrees, tube growth continued slowly both in the laboratory and in situ below the snow. Fertilization occurred in up to 100% of flowers in the nival species and in G. germanica, but was strongly delayed or absent in the alpine species. During rewarming, fertilization continued. Overall, progamic processes in high-mountain plants appear fairly robust toward weather extremes increasing the probability of successful reproduction.
Highlights
Anthesis is one of the most critical phases in the life cycle of a plant and extremely vulnerable to unfavorable climatic conditions
We addressed the following questions: (1) to what extent are sexual processes during anthesis impaired by low temperatures in high-mountain plants—are they decelerated, temporarily interrupted, or irreversibly impaired; (2) in the case of deceleration or interruption, do processes continue in the normal way when temperature conditions become more favorable again; and (3) if so, how long can sexual processes be delayed or interrupted and remain functional?
A cold snap simulation experiment consisted of a 7 h cooling-down phase from 14 to 0 °C, a cooling phase at 0 °C (12, 36, 60, 84 h, respectively), and a 5 h warm-up phase from 0 to 20 °C plus a further 4 h at 20 °C
Summary
Anthesis is one of the most critical phases in the life cycle of a plant and extremely vulnerable to unfavorable climatic conditions. Flowers of high-mountain species have to cope with large diurnal temperature oscillations but with cold spells, which can occur at any time during the growing season. Pollen germination and pollen tube growth was slow from the beginning and, except for one species (Gentianella germanica), fertilization did not occur within the maximum exposure time of 50 h. Seven plant species (Table 1), which differ in their elevational distribution range, were exposed to temperature conditions as they occur during summer cold snaps in high-mountains. To this end, flowers were pollinated with allopollen, gradually cooled down to 0 °C (the temperature below the snow), and kept at this temperature for up to four days. Since nival plants regularly have to cope with subzero night temperatures we expected them to perform better during cold snaps than alpine species
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
