Photosynthetic response of Bromus inermis in grasslands of different altitudes

Authors: PANAGIOTA KOSTOPOULOU, MARIA KARATASSIOU

Abstract: In Greece, grasslands constitute an important component of montane areas. The aim of the present study was to evaluate the photosynthetic responses of the forage species Bromus inermis at two montane grasslands (Filippaioi, Grammatiko) and a lowland grassland under differential irradiation and CO2 concentration levels. In each area, gas exchange parameters were calculated under: a) ambient conditions along with the measurement of variable to maximal fluorescence, b) low (300 µmol m^-2 s^-1) and high (1400 µmol m^-2 s^-1) radiation, and c) ambient (380 µmol mol^-1) and high (800 µmol mol^-1) CO2 concentrations. In addition, assimilation response curves to different levels of irradiation and intercellular CO₂ partial pressure were recorded. The photosynthetic machinery of B. inermis responded better to changes in irradiation in the montane area of Filippaioi, while it was more sensitive to changes in CO₂ concentration in the lowland area. Photosynthesis in the montane area of Grammatiko could be subject to novel ecological pressures shaped by lower grazing intensity. No effect of altitude on physiological responses of B. inermis was found. Instead, plants from each area may use different adaptive mechanisms to persist and thrive in the environmental conditions of each area.

Keywords: Assimilation rate, elevation, intercellular CO₂ concentration, light, smooth brome, stomatal conductance

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