Effect of different ratios of nitrate and ammonium on photosynthesis, and fatty acid composition of canola under saline conditions

In order to evaluate effects of different ratios of ammonium and nitrate, on photosynthesis, respiration and fatty acid composition of canola under conditions of salt stress a greenhouse experiment was conducted in Agriculture Research Center of Eastern Azerbaijan, Iran on 2009. The experimental design was completely randomized design arranged in factorial. The first and second factor included four differing ratios of nitrate to ammonium namely 0:100, 25:75, 50:50 and 75:25 and salinity stress namely 0 and 200 mM NaCl, respectively. The results demonstrated that the highest wet and dry weight, leaf area, relative water content, photosynthesis ratio, transpiration ratio and leaf potassium content were obtained from those plants which were treated with nitrate and ammonium in 50:50 ratio under non saline condition. Salinity significantly decreased wet and dry weight, leaf area, relative water content, photosynthesis and respiration ratio and leaf potassium content. It seems that 50:50 ratio protects plants from salinity stress. On the other hand fatty acids content increased on account of salinity stress. In addition, in high ammonium ratios fatty acid content were considerably more than high nitrate ratios. Furthermore, the highest fatty acid content was obtained from 25:75 ratios in other word high ammonium treatments.