Morphological, anatomical, and physiological leaf traits of Corylus avellana plants growing in different light conditions within the natural reserve "Siro Negri" (Italy) were analyzed. The results highlighted the capability of C. avellana to grow both in sun and shade conditions throughout several adaptations at leaf level. In particular, the more than 100% higher specific leaf area in shade is associated to a 44% lower palisade to spongy parenchyma thickness ratio compared with that in sun. Moreover, the chlorophyll (Chl) a to Chl b ratio decreased in response to the 97% decrease in photosynthetic photon flux density. The results highlighted the decrease in the ratio of Chl to carotenoid content, the maximum PSII photochemical efficiency, and the actual PSII photochemical efficiency (ΦPSII) associated with the increase in the ratio of photorespiration to net photosynthesis (PN) in sun. Chl a/b ratio was the most significant variable explaining PN variations in shade. In sun, PN was most influenced by the ratio between the fraction of electron transport rate (ETR) used for CO2 assimilation and ETR used for photorespiration, by ΦPSII, nitrogen content per leaf area, and by total Chl content per leaf area. The high phenotypic plasticity of C. avellana (PI = 0.33) shows its responsiveness to light variations. In particular, a greater plasticity of morphological (PIm = 0.41) than of physiological (PIp = 0.36) and anatomical traits (PIa = 0.24) attests to the shade tolerance of the species., R. Catoni, M.U. Granata, F. Sartori, L. Varone, L. Gratani., and Obsahuje bibliografii
The rates of net photosynthesis (P^). respiration and growth of Lemna gibba L. were measured as fiinctions of tiine across ranges of temperature, irradiance and carbon dioxide concentrations. on an area basis increased with temperature up to 30 °C but decreased dramatically within a few hours of exposure to elevated CO2, when reported on a dry mass basis. Reductions in the apparent quantum efRciency, photosynthetic capacity and the affinity of ribulose-l,5-bisphosphate carboxylase/oxygenase for CO2 were observed for plants grown at elevated CO2. Starch concentration was not significantly affected by elevated CO2. Although elevated temperature increased metaboiic activity, it only partíally ídleviated the inhibition of P^. L. gibba exhibits a characteristic C3-type response to elevated CO2 and the methodology described is usefiil for fiirther elucidating the mechanism of photosynthetic acclimation to elevated CO2.