Ecophysiological adaptation of green roof plant Sedum lineare to temperature variation
To investigate physiology of S. lineare planted in adverse environment, we conducted measurements of gas exchange and chlorophyll fluorescence parameters in leaves of S. lineare that grew in roof and was cultivated in a light incubator for temperature experiment We also measured carbon isotope ratio (δ13C) in different organs of S. lineare grown in the incubator under different temperatures for 30 days. Main results were as follows:Long term treatment of high/low temperature,high diurnal temperature difference between day and night and high leaf boundary layer conductance altered by wind force could lead to inactivation of photosystem II in leaves of S. lineare and to the switch of C3 photosynthetic pathway to CAM,indicating that S. lineare was a facultative CAM plant;Short term chilling caused irreversible inactivation of photosystem II in leaves of S. lineare ;Rehydration would help the recovery of photosystem H,but such recovery would be delayed under dry condition. Planted in an adverse temperature environment would bring about defoliation, and the chlorophyll contents and chlorophyll fluorescence parameters would increase in the re-maining leaves of S. lineare. When planted with sufficient water supply, mature leaves of S. lineare did not show a temperature-sensitivity,but the young leaves would;The measured δi3C showed decrease of leaf stomatal conductance of young leaves,but no effect on that of old leaves caused by high temperature. The stems,though containing chloro-phyll, did present significant photosynthetic capacity.
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