Journal of Food, Agriculture and Environment

Gas exchange and chlorophyll fluorescence of salinity-alkalinity stressed Phragmites australis seedlings

Author(s):

Guangxin Zhang ¹, Chunnuan Deng ^{1, 2*}

Recieved Date: 2011-11-18, Accepted Date: 2012-01-03

Abstract:

Increasing salinity and alkalinity in soil and water has drawn much attention over the past two decades. Salinity or alkalinity significantly influences plant growth. When salinity and alkalinity were combined, the effect on photosynthesis of plant was much complex, however, the underlying basis in photosynthetic capacity under combined salinity-alkalinity stress is yet not fully understood. In northeastern China, many Phragmites-dominated wetlands have been markedly salinized and alkalinized due to overexploitation or water resources shortage and climate change. The mechanism of degradation of Phragmites-dominated wetlands has become an important aspect of ecological protection studies within the last two decades. Photosynthesis, stomatal conductance, chlorophyll fluorescence characteristics, chlorophyll content and growth were examined in Phragmites australis seedlings treated with various concentrations of combined salinity-alkalinity stress for 7 days. Combined salinity-alkalinity stress significantly decreased growth rate and chlorophyll content of Phragmites australis. The photosynthesis rates (Pn) were markedly inhibited under middle and high combined salinity-alkalinity stress. The value of F_V/F_M decreased when reed seedlings were stressed by high salinity-alkalinity treatment. The comprehensive photosynthesis performance index (PI_ABS) and the electron transport (ET/RC) were sensitive to salinity-alkalinity stress, and showed a significant decrease under high salinity-alkalinity stress. These results demonstrated the mechanism of combined saline-alkaline stress on the photosystem II of reed. Decreased photosynthesis rate under low salinity-alkalinity condition is associated with the increase of stomatal closure, while decreased photosynthesis rate under high salinity-alkalinity stress is mainly attributed to non-stomatal limitation. Additional research is needed to find management strategies for decrease the adverse effects of salinity-alkalinity stress on wetland plant.

Keywords:

Combined salinity-alkalinity, photosynthesis rate, chlorophyll fluorescence, Phragmites australis, wetland

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Journal: Journal of Food, Agriculture and Environment
Year: 2012
Volume: 10
Issue: 1
Category: Environment
Pages: 880-884

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