Comparison of flowering induction by vernalization and high temperatures in root-chicory (Cichorium intybus L. var sativum)
(2016) doctoral school Plant Science — Location: Bruxelles (9.June.2016)
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- Chicory is a biennial plant with a need of vernalization for flowering initiation. In previous experiments, we have shown that high temperature (> 35°C) could also induce bolting independently of vernalization (Mathieu et al., 2013). So the aim of our experiment was to compare the induction of flowering by high temperatures and vernalization and to analyze the resulting inflorescence and flower development. Two temperature regimes (17°C vs. 35°C) were combined with two vernalization treatments (vernalized vs. no-vernalized). The seedlings of root chicory cv. Melci were vernalized during 6 weeks at 4°C or not. After 3 weeks at 17°C (for the no-vernalized plants) or 1 week at 17°C (for the vernalized plants), the plants were exposed to high temperature (35°C for the high temperature condition or 17°C for control condition) for 14 weeks. The rate of bolting was followed during the growing period and 11 weeks after the start of the treatment, the number of nodes on the floral stem, the number of flowers per inflorescence, the number of pollen grain per flower, the flower pollen viability and the stigma receptivity were measured. The dry weight of the floral stem was also quantified at the end of the experiment. High temperature increased the flowering rate in non-vernalized plants (25% vs. 0%) while it decreased it in vernalized plants (35% vs. 100%). High temperature also induced a loss of apical dominance. The number of flowers per inflorescence and the number of nodes on the floral stem were similar whatever the treatment. However, in both vernalized and no vernalized plants, high temperature decreased the weight of the floral stem, the number of pollen grains per flower, the pollen viability and the stigma receptivity compared to vernalized plants in control conditions. Since ethylene can substitute the need of vernalization to induce flowering in chicory (Joseph et al., 1985), we also investigated the ethylene production in vernalized and no-vernalized seedlings exposed to high temperature. So, we show an increase of ethylene production in no-vernalized plants exposed to high temperatures compare to vernalized plants. Our results show that high temperature induces flowering independently of vernalization and reduces the flowering induction due to vernalization in root chicory. High temperature had a negative impact on the subsequent development of the reproductive system.
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Mathieu, A.-S., Quinet, M., & Lutts, S. (2016). Comparison of flowering induction by vernalization and high temperatures in root-chicory (Cichorium intybus L. var sativum). doctoral school Plant Science, Bruxelles. https://hdl.handle.net/2078.5/72181