Articles
THE CHANGES OF PHOTOSYNTHETIC CHARACTER IN CYMBIDIUM FABERI ROLFE DURING THE STAGES OF RECOVERY AFTER HIGH LIGHT STRESS
Article number
766_37
Pages
283 – 290
Language
English
Abstract
The photosynthetic characteristics of C. faberi were studied by gas exchange and chlorophyll fluorescence after high light stress in summer and during the recovery under room light conditions.
The light compensation point of C. faberi was about 30 µmol·m-2·s-1 and the saturation point about 300 µmol·m-2·s-1, which suggested that C. faberi should be a typical shade-acclimated plant.
After 1 day treatment with high light (600-1300 µmol·m-2·s-1), net photosynthetic rate (Pn) and apparent photosynthetic quantum yield (AQY) declined remarkably, and light compensation point doubled.
Although the light saturation point hardly changed, the maximum Pn at the saturation point decreased by about 60% of the original value, which indicated that subjecting C. faberi to high light stress could result in marked photoinhibition.
During recovery under room light (100-300 µmol·m-2·s-1), the light compensation points decreased and Pn gradually increased, reaching its original level in 8 d.
The changes of Pn were in accordance with those of stomatal conductance (Gs), which suggested that the decline of Pn might be due to the lower Gs.
However, further studies showed that intercellular CO2 concentration (Ci) actually increased while Gs declined, which indicated that the decline in Gs could not result in the short supply of CO2. Perhaps the photosystems were temporarily hampered and could not use CO2, resulting in higher Ci.
The minimal fluorescence intensity (Fo) increased by about 44% after 2 days under room light following high light stress and then decreased.
The maximum fluorescence intensity (Fm) and photochemical efficiency (Fv/Fm) decreased obviously after high light stress and then increased gradually during the recovery under room light.
Fo, Fm and Fv/Fm all recovered in 8 d under room light.
The results indicated that the photosynthetic apparatus of C. faberi were temporarily hampered by high light that caused the decline of Pn, but fully recovered following several days under room light conditions.
The light compensation point of C. faberi was about 30 µmol·m-2·s-1 and the saturation point about 300 µmol·m-2·s-1, which suggested that C. faberi should be a typical shade-acclimated plant.
After 1 day treatment with high light (600-1300 µmol·m-2·s-1), net photosynthetic rate (Pn) and apparent photosynthetic quantum yield (AQY) declined remarkably, and light compensation point doubled.
Although the light saturation point hardly changed, the maximum Pn at the saturation point decreased by about 60% of the original value, which indicated that subjecting C. faberi to high light stress could result in marked photoinhibition.
During recovery under room light (100-300 µmol·m-2·s-1), the light compensation points decreased and Pn gradually increased, reaching its original level in 8 d.
The changes of Pn were in accordance with those of stomatal conductance (Gs), which suggested that the decline of Pn might be due to the lower Gs.
However, further studies showed that intercellular CO2 concentration (Ci) actually increased while Gs declined, which indicated that the decline in Gs could not result in the short supply of CO2. Perhaps the photosystems were temporarily hampered and could not use CO2, resulting in higher Ci.
The minimal fluorescence intensity (Fo) increased by about 44% after 2 days under room light following high light stress and then decreased.
The maximum fluorescence intensity (Fm) and photochemical efficiency (Fv/Fm) decreased obviously after high light stress and then increased gradually during the recovery under room light.
Fo, Fm and Fv/Fm all recovered in 8 d under room light.
The results indicated that the photosynthetic apparatus of C. faberi were temporarily hampered by high light that caused the decline of Pn, but fully recovered following several days under room light conditions.
Publication
Authors
Tao Jun, Zhu Lihua, Yu Ju, Wei Jun
Keywords
Cymbidium faberi Rolfe, net photosynthetic rate, apparent photosynthetic quantum yield, stomatal conductance, chlorophyll fluorescence
Online Articles (67)