a1_The aim of this work was to study the acclimation of photosynthesis in a boreal grass (Phalaris arundinacea L.) grown in controlled environment chambers under elevated temperature (ambient + 3.5°C) and CO2 (700 μmol mol-1) with varying soil water regimes. More specifically, we studied, during two development stages (early: heading; late: florescence completed), how the temperature response of light-saturated net photosynthetic rate
(Psat), maximum rate of ribulose-1,5-bisphosphate carboxylase/oxygenase activity (Vcmax) and potential rate of electron transport (Jmax) acclimatized to the changed environment. During the early growing period, we found a greater temperature-induced enhancement of Psat at higher measurement temperatures, which disappeared during the late stage. Under elevated growth temperature, Vcmax and Jmax at lower measurement temperatures (5-15°C) were lower than those under ambient growth temperature during the early period. When the measurements were done at 20-30°C, the situation was the opposite. During the late growing period, Vcmax and Jmax under elevated growth temperature were consistently lower across measurement temperatures. CO2 enrichment significantly increased Psat with higher intercellular CO2 compared to ambient CO2 treatment, however, elevated CO2 slightly decreased Vcmax and Jmax across measurement temperatures, probably due to down-regulation acclimation. For two growing periods, soil water availability affected the variation in photosynthesis and biochemical parameters much more than climatic treatment did. Over two growing periods, Vcmax and Jmax were on average 36.4 and 30.6%, respectively, lower with low water availability compared to high water availability across measurement temperatures. During the late growing period, elevated growth temperature further reduced the photosynthesis under low water availability., a2_Vcmax and Jmax declined along with the decrease in nitrogen content of leaves as growing period progressed, regardless of climatic treatment and water regime. We suggest that, for grass species, seasonal acclimation of the photosynthetic parameters under varying environmental conditions needed to be identified to fairly estimate the whole-life photosynthesis., Z.-M. Ge ... [et al.]., Obsahuje poznámky, and Obsahuje bibliografii
This paper describes the technical information and performance of a new multi-objective chamber system enabling the control of environmental variables (e.g., temperature, CO2, air humidity, wind speed, and UV-B radiation) for understanding plant responses to climate change. Over a whole growing season, four different climate scenarios were evenly programmed into the system’s 16 chambers as ambient environment (AMB), elevated temperature (ET), elevated CO2 concentration (EC) and elevated temperature and CO2 concentration (ETC). Simultaneously, the chamber effects were assessed regarding the physiological responses and growth of a boreal perennial grass (reed canary grass, Phalaris arundinacea L.). During the growing season, the chamber system provided a wide variety of climatic conditions for air temperature (T a), relative humidity (RH) and CO2 concentration (C a) in the AMB chambers following outside conditions. The target temperature (+3.5°C) was achieved to a good degree in the ET and ETC chambers, being on average 3.3°C and 3.7°C higher than ambient conditions, respectively. The target concentration of CO2 (700 ppm) was also well achieved in the EC and ETC chambers, being on average 704 ppm and 703 ppm, respectively. The stable airflow condition inside all of the chambers provided a homogeneous distribution of gases and temperature. The decreases in RH and increases in vapour pressure deficit (VPD) in the elevated temperature chambers were also maintained at a low level. Chamber effects were observed, with some physiological and growth parameters of plants being significantly lower in the AMB chambers, compared to outside conditions. The plant growth was negatively affected by the reduced radiation inside the chambers., X. Zhou ... [et al.]., and Obsahuje bibliografii