Effect of increased alkalinity on Na⁺ and K⁺ contents, lipid peroxidation and antioxidative enzymes in two populations of Populus cathayana

Abstract

We compared two populations of Populus cathayana Rehder, originating from altitudes 2 840 m and 1 450 m, to determine whether trees from different altitudes exhibit different tolerance to alkalinity. The tree cuttings were exposed to nutrient solutions with pH 7.9, 8.8, 9.8 and 10.4 and the salt concentration 200 mM. Na + and K + contents, and Na + /K + ratios in leaves and roots were greatly affected by pH values. At pH 10.4, the Na + /K + ratios in both leaves and roots sharply dropped in the higher altitude population but were maintained at higher levels in the lower altitude population. The patterns of pH-induced changes in contents of malondialdehyde and free proline, and antioxidative enzyme activities indicated that the higher altitude population exhibits greater tolerance to alkalinity stress than does the lower altitude population.Additional key words: free proline, malondialdehyde, poplar, salt-alkali mixed stress.

Effect of sodium carbonate-induced salinity–alkalinity on some key osmoprotectants, protein profile, antioxidant enzymes, and lipid peroxidation in two mulberry (Morus alba L.) cultivars

“…Sujanpuri. Results showing NaHCO 3 -induced enhanced activities of different antioxidant enzymes as observed in two mulberry cultivars are in parallelity with those reported earlier in the same species under salt stress (Sudhakar et al 2001;Harinasut et al 2003;Ahmad et al 2012b) and in P. cathayana under NaHCO 3 stress (Lu et al 2009). …”

“…Sujanpuri. Similar findings have been reported in two diverse populations of P. cathayana (Lu et al 2009). …”

“…S146. Such a NaHCO 3 -induced decrease in growth has earlier been reported in two populations of a tree species, P. cathayana (Lu et al 2009). The growth inhibition caused by salt stress has been reported in Triticum aestivum (Guo et al 2010), Leymus chinesis (Sun & Hong et al 2011), Medicago ruthenica , Brassica juncea (Javid et al 2012), and variety of tree species e.g.…”

“…Alkalinity is known to suppress growth and yield of most plants, but its effects due to high pH have been reported to be more severe than those of salt stress (Lu et al 2009;. In our studies, we found out that sodium carbonate-induced alkalinity caused a marked inhibition in the growth of two mulberry cultivars appraised as shoot fresh and dry weights and shoot length, but this reduction in growth was more pronounced in cv.…”

“…However, relatively few studies have been undertaken on the effects of alkaline soils on plant growth and productivity. The investigations carried out on the effects of alkalinity developed by NaHCO 3 on two populations of Populus cathayana (Lu et al 2009) have revealed that increasing pH of the saline growth medium causes more damage to cell membranes. The alkalinity at the same time severely upsets the mechanism of ion uptake in both populations.…”