||Elevated carbon dioxide increases nectar production in Epilobium angustifolium L.|
||Andreas Erhardt, Hans-Peter Rusterholz, Jürg Stöcklin|
||Oecologia Online First (DOI: 10.1007/s00442-005-0182-5)|
Effects of elevated CO₂ and nutrient availability on nectar production and onset of flowering in five different seed families (genotypes) of Epilobium angustifolium were investigated in a greenhouse experiment. Elevated CO₂ significantly increased nectar production per day (+51%, p<0.01), total sugar per flower (+41%, p<0.05), amino acid concentration (+65%, p<0.05) and total amino acids per flower (+192%, p<0.001). All other parameters tested, i. e. nectar sugar concentration, proportion of glucose/fructose and proportion of sucrose/(glucose + fructose), were not significantly affected by elevated CO₂ and/or fertilization. However, elevated CO₂ caused a marginally significant trend for earlier flowering in highly fertilized plants. No significant family × CO₂ interaction was found in any of the tested parameters, but the response in nectar production varied considerably among seed families (+10% - +104%) and was significantly positive in two of the five seed families investigated. Our results are not consistent with earlier studies on effects of elevated CO₂ on nectar production and flowering phenology in other plant species. It seems instead that CO₂ effects on nectar production are species- and genotype-specific. Hence no general conclusions about effects of elevated CO₂ on these floral traits can be drawn at present, but it must be cautioned that elevated CO₂ might not only increase floral rewards as in E. angustifolium, but might also lead to shifts or even disruptions in fine tuned plant-pollinator interactions.
||elevated CO2 ·flowering phenology ·nectar sugar ·nectar amino acids
||Jürg Stöcklin: email | webpage | list of publications|