Nitrate reduction and nutrient accumulation in wheat grown in soil salinized with four different salts
2006
Iqbal, N. | Ashraf, M.Y. | Javed, F. | Martinez, V. | Ahmad, K.
The effect of salinization of soil with Na2SO4, CaCl2, MgCl2, and NaCl (70:35:10:23) on the biochemical characteristics of three wheat (Triticum aestivum L.) cultivars ('LU-26S,' 'Sarsabaz' and 'Pasban-90') was investigated under natural environmental conditions. Twenty-day-old seedlings of all three cultivars were subjected to three salinity treatments: 1.3 (control), 5.0, and 10 dSm(-1) for the entire life period of plants. After 120 d of seed sowing, plant biomass production decreased by 49% and 65%, respectively, in response to 5 and 10 dSm(-1) salinity levels. Addition of salts to growth medium also had a significant adverse effect on plant height. Increasing salinity treatments caused a great reduction in nitrate reductase activity (NRA) of the leaf. The inhibitory effect of salinity on nitrate reduction rate was more pronounced at the reproductive stage than at the vegetative stage of plant growth. Wheat cultivars 'LU-26S' and 'Sarsabaz' showed less reduction in NRA due to salinity compared with 'Pasban-90.' Ascending salinity levels significantly reduced potassium (K(+)) and calcium (Ca(2+)) accumulation in shoots, while the concentration of sodium (Na(+)) was increased. Salts of growth medium increased the shoot nitrogen (N) concentration, whereas phosphorous (P) concentration of shoots was significantly reduced due to salinity. Wheat cultivars 'LU-26S' and 'Sarsabaz' proved to be the salt-tolerant ones, producing greater biomass, showing less reduction in NRA, maintaining low sodium (Na(+)), and accumulating more K(+) and Ca(2+) in response to salinity. These two cultivars also showed less reduction in shoot K(+)/Na(+) and Ca(+)/Na(+) ratios than in 'Pasban-90,' particularly at the 10 dSm(-1) salinity level.
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