Modulation de la force des sources et des puits de carbone sur la croissance du bulbe de l’érythrone d’Amérique, erythronium americanum

Liste des illustrations

• Figure 1.1. Illustration des différents stades phénologiques des parties aériennes de l’érythrone d’Amérique en fonction de la saison. Les individus immatures possèdent une seule feuille, les individus matures en possèdent deux et fleurissent. L’échelle de temps n’est pas respectée pour des fins de clarté.
• Figure 1.2. Illustration représentant le stade de développement d’un bulbe en fin de période de dormance estivale, le développement du nouveau système racinaire au cours de l’automne, la croissance de la nouvelle feuille sous le manteau neigeux au cours de l’hiver, et enfin la formation du nouveau bulbe (en blanc) lors de la période de croissance épigée le printemps suivant chez les individus immatures d’érythrone d’Amérique qui ne produisent ni rhizomes, ni bulbes filles, ce qui était le cas dans la présente étude.
• Figure 2.1. Bulb growth kinetics of E. americanum plants grown at 12/8°C (close symbols) and 18/14°C (open symbols) during the epigeous growth period. Data points represent means ± 1 SE from 7 plants. Harvest 1 corresponds to the time at which plants were harvested in the field. Leaf unfolding occurred simultaneously under both treatments (three days later), as explained in the method section and corresponds to the time of random distribution of potted-plants in each growth chamber. Harvests 2 and 3 took place during leaf growth, Harvest 4 when leaves began to yellow, and Harvest 5 when half the leaf had yellowed. Date of complete leaf senescence is shown by the dot for both treatments. The final harvest took place one week later (Harvest 6).
• Figure 2.2. (a) Two representative E. americanum plants after 24 days of growth at 12/8°C (left) and 18/14°C (right) in 2005. The four plants had a similar size. Nevertheless, Warm Temperature (18/14°C) plants had started to senesce while Cool Temperature (12/8°C) plants continued to grow. (b) Bulbs after complete leaf senescence in 2003. The four bulbs above came from plants grown at 18/14°C. The four plants below were grown at 12/8°C. Bars represent 1 cm.
• Figure 2.3. Digital pictures of two bulb transverse sections of E. americanum taken at the end of the epigeous growth period with a camera fixed on a light microscope (40x). Bulb (a) was grown at 12/8°C (Cool Temperature treatment) and (b) at 18/14°C (Warm Temperature treatment).
• Figure 2.4. Variation of leaf characteristics of E. americanum plants from leaf unfolding to the onset of leaf yellowing (Harvest 1 to 4). Leaf dry mass (solid lines) and leaf area (dotted lines) of plants grown at 12/8°C (closed symbols) and 18/14°C (open symbols) are shown. Data points represent means ± 1 SE of 7 plants.
• Figure 2.5. Variation of bulb starch content (a) and concentration (b) of E. americanum grown at 12/8°C (closed symbols) and 18/14°C (open symbols) during the epigeous growth period (Harvests 2 to 6). The arrows indicate the onset of leaf yellowing. Data points represent means ± 1 SE of 7 plants.
• Figure 2.6. Foliar nutrient concentration (left) and content (right) of E. americanum plants grown at 12/8°C (closed circles) and 18/14°C (open circles) (Harvests 2 to 6). Means ± 1 SE are shown (n=3-7). The arrows indicate the onset of leaf yellowing. The final value of P concentration and content at 18/14°C could not been determined precisely by the equipment (values reported were inferior to 0.1 mg g^-1).
• Figure 3.1. Variation in the mass of E. americanum bulbs during the epigeous growth period, in plants grown at ambient (open symbols) and high [CO₂] (closed symbols) in 2004 (above) and 2005 (below). Means ± 1 SE are shown ( N =7 in 2004 and N =6 in 2005). The arrows indicate the onset of leaf yellowing.
• Figure 3.2. Time course of leaf (a, d) and root (b) mass, and leaf area (c, e) from Day 4 following leaf unfolding to the onset of leaf yellowing, for E. americanum plants grown at ambient (open symbols) and high [CO₂] (closed symbols) in 2004 (a, b and c) and in 2005 (d and e). Means ± 1 SE are shown ( N =7 in 2004 and N =6 in 2005).
• Figure 3.3. Time course of the net photosynthesis rate per leaf area a) in 2004 from day 4 after leaf unfolding to the onset of leaf yellowing and b) in 2005 during the first two weeks after leaf unfolding, for E. americanum plants grown at ambient (open symbols) and elevated CO₂ concentrations (closed symbols). Means ± 1 SE are shown ( N =1 to 12).
• Figure 3.4. Time course of starch concentration (a, c) and starch content (b, d) in the bulb of E. americanum during the epigeous growth period. Data originate from plants grown at ambient (open symbols) and high CO₂ concentrations (closed symbols) in 2004 (a, b) and in 2005 (c, d). Means ±1 SE are shown ( N =7 in 2004 and N =6 in 2005). The arrows indicate the onset of leaf yellowing.
• Figure 3.5. Time course of foliar N concentration (a, d), foliar N content (b, e) and bulb N content (c) for E. americanum plants cultivated at ambient (open symbols) and elevated [CO₂] (closed symbols) in 2004 (a, b, c) and 2005 (d, e). Means ± 1 SE ( N =4) are shown from leaf unfolding to half leaf senescence (Harvests 1 to 5), except for bulb N content where data from completely senesced plants is also presented. The arrows indicate the onset of leaf yellowing.