Recent Topics Posters
Gulzar, Salman , Moinuddin, Muhammad , Siddiqui, Hina , Hameed, Abdul , Edwards, Gerald E. , Khan, M .
Differences in photosynthetic adaptations of coastal and inland salt marsh grasses in Pakistan.
We compared the photosynthetic responses of four perennial salt marsh grasses when grown under varying levels of salinity (0 to400 mM NaCl). Under increasing salinity the coastal grasses Aeluropuslagopoides and Sporobolus tremulus had lower leaf water content but higher relative water content and leaf thickness than inland grasses Paspalumpaspalodes and Paspalidium geminatum. Leaf osmolality increased with increasing salinity; this was most pronounced in A. lagopoides, and lower for inland species at moderate salinity. Osmolalities of species from natural habitats correlated well with soil electrical conductivity (ECe1:5).Chlorophyll content decreased (except for S. tremulus), while carotenoids were higher in the inland grasses. Photosynthetic rates, stomatal conductance and transpiration rates declined under higher salinities except forP. paspalodes. Under saline conditions the intercellular CO2concentrations (Ci) increased in S. tremulus and P. geminatum indicating a biochemical limitation on photosynthesis, Ci decreased in P. paspalodes at 400 mM NaCl suggestive of stomatal limitation, while Ci remained unchanged in A. lagopoides.Salinity did not affect water use efficiency (WUE) in A. lagopoides and S.tremulus, increased WUE in P. paspalodes and caused a substantial decrease in WUE in P. geminatum.Salinity caused photo inhibition in A. lagopoides, but not in the other species. The yield of PSII in the light (phi PSII) and qP were higher in coastal grasses under moderate salinity (200 mM NaCl), but decreased significantly in coastal and inland species under high salinity (400 mMNaCl). Comparison of the efficiency of PSII for O2 evolution to carboxylation efficiency showed a dramatic increase in alternate electron sinks under medium to high salinity. The dissipation of excess solar energy as heat (NPQ)was lower in the coastal than inland grasses and appeared to be correlated with higher leaf temperatures. Analysis of C isotope composition of plant biomass, a potential measure of WUE, showed there was little effect of salinity treatments(0 to 400 mM) but some differences compared to field grown plant. Also,relative yield parameters from fluorescence data showed lower yield of NPQ in coastal than inland grasses. Higher SOD activities may indicate a greater role of the Mehler reaction linked to alternative electron flow than NPQ in coastal salt secreting grasses.
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1 - University Of Karachi, Institute Of Sustainable Halophyte Utilization, Off. University Road, Gulsha-e-Iqbal, Karachi, Sindh, N/A, 75270, Pakistan
3 - Washington State University, School of Biological Sciences, Pullman, WA, 99164
4 - UNIV OF KARACHI, Ins. Sustain. Halophyte Utli., PO BOX 8452, KARACHI, N/A, 75270, Pakistan
Presentation Type: Recent Topics Poster
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM