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Effects of buffer capacity on growth, photosynthesis, and solute accumulation of a glycophyte (wheat) and a halophyte (Chloris virgata)

Yang, C.-W., Zhang, M.-L., Liu, J., Shi, D.-C., Wang, D.-L.
Photosynthetica 2009 v.47 no.1 pp. 55-60
Chloris virgata, Triticum aestivum, alkalinization, buffering capacity, halophytes, mixing, pH, photosynthesis, pigments, potassium, seedlings, shoots, sodium, sodium bicarbonate, sodium carbonate, sodium chloride, sodium sulfate, soil, soil solution, solutes, wheat
Two species with different resistances to alkaline pH, the glycophylic Triticum aestivum (wheat) and the halophilic Chloris virgata, were chosen as test organisms. The salt-alkaline (SA) mixed stress conditions with different buffer capacities (BC) but with the same salt molarities and pH were established by mixing neutral (NaCl, Na₂SO₄), and alkaline salts (NaHCO₃ and Na₂CO₃) in various proportions. Growth, photosynthetic characteristics, and solute accumulation of the seedlings were monitored to test the validity of BC as a decisive index of alkali-stress (AS) intensity in SA mixed stress. At the same salinities and pHs, the relative growth rate, the content of photosynthetic pigments, and net photosynthetic rates of wheat and C. virgata decreased, while Na⁺ content and Na⁺/K⁺ ratios in shoots increased with increasing BC. Hence BC was a true measure of AS intensity at mixed SA stress and the alkali-resistance mechanism of plants was easy to interpret. BC of soil solution is an important parameter for estimating the alkalization degree of salt-alkalized soil.