Comparison of effects of salt and alkali stresses on the growth and photosynthesis of wheat

Abstract

The seedlings of wheat were treated by salt-stress (SS, molar ratio of NaCl : Na 2 SO 4 = 1 : 1) and alkali-stress (AS, molar ratio of NaHCO 3 : Na 2 CO 3 = 1 : 1). Relative growth rate (RGR), leaf area, and water content decreased with increasing salinity, and the extents of the reduction under AS were greater than those under SS. The contents of photosynthetic pigments did not decrease under SS, but increased at low salinity. On the contrary, the contents of photosynthetic pigments decreased sharply under AS with increasing salinity. Under SS, the changes of net photosynthetic rate (P N ), stomatal conductance (g s ), and transpiration rate (E) were similar and all varied in a single-peak curve with increasing salinity, and they were lower than those of control only at salinity over 150 mM. Under AS, P N , g s , and E decreased sharply with rising salinity. The decrease of g s might cause the obvious decreases of E and intercellular CO 2 concentration, and the increase of water use efficiency under both stresses. The Na + content and Na + /K + ratio in shoot increased and the K + content in shoot decreased under both stresses, and the changing extents under AS were greater than those under SS. Thus SS and AS are two distinctive stresses with different characters; the destructive effects of AS on the growth and photosynthesis of wheat are more severe than those under SS. High pH is the key feature of the AS that is different from SS. The buffer capacity is essentially the measure of high pH action on plant. The deposition of mineral elements and the intracellular unbalance of Na + and K + caused by the high pH at AS might be the reason of the decrease of P N and g s and of the destruction of photosynthetic pigments.

Influences of different iron levels on plant growth and photosynthesis of W. Murcott mandarin grafted on two rootstocks under high pH conditions

“…T2, T3, and T4 were lower than the control plants in terms of plant dry weight. Previous studies have also found that high pH (Yang et al, 2008) and bicarbonate ions (Mengel, 1994;Pestana et al, 2005) decrease plant growth and development. In this study, high pH and low iron had a significant effect on reducing dry weight.…”

Integrated proteomics and metabolomics for dissecting the mechanism of global responses to salt and alkali stress in Suaeda corniculata

“…Comparing alkali stress with salt stress, the high pH environment that surrounds the plant root can cause the precipitation of metal ions and phosphorus, greatly affecting the absorption of inorganic anions and disrupting the ionic balance and pH homeostasis in plant tissues (Shi and Zhao 1997;Yang et al 2007Yang et al , 2008c. It is understood that currently, only a few plant species of alkali-resistant halophytes can survive in saline and alkaline land (Zheng and Li 1999;Yang et al 2008a).…”

“…Photosynthetic capacity has been observed to be much lower under both salt and alkali stresses than in control plants in the glycophytes wheat and barley, and the inhibition was more severe under alkali stress than salt stress (Yang et al 2008c). However, the situation is different in the halophyte Chloris virgata, whose photosynthetic properties were not influenced by salt and alkali treatment below 160 mM (Yang et al 2008a).…”

Comparison of the Effects of Saline and Alkaline Stress on Growth, Photosynthesis and Water-Soluble Carbohydrate of Oat Seedling (Avena sativa L)

“…The results revealed that alkaline stress might damage root functions, including, the absorption of water and ions. These may be the main reasons why the oat RGR was lower for alkaline than saline stress (Yang et al, 2008).…”