Effects of Different Levels of Salinity and Nitrogen Fertilizer on Physiological and Biochemical Characteristics of Two Salt Sensitive and Salt-Tolerant Wheat Cultivars

The objective of this experiment was to determine the effects of different levels of nitrogen (N) and salinity on biochemical mechanisms of two wheat genotypes. A field experiment was carried out in a three replicate RCBD split factorial experiment in salinity station of College of Agriculture, Ferdowsi University of Mashhad, Iran in 2007-2008 and 2008-2009. Three levels of salt stress (1.3, 5, 10 dS/m) served as main plots and a combination of three levels of sulfate ammonium (50, 100, 150 kg N/ha) and 2 genotypes namely, Bam (resistance) and Toos (susceptible to salt stress) served as subplots. Results indicated that the effect of year on most characteristics was significant. Also under salinity stress, N application (100 and 150 kg N/ha) caused a significant effect on both genotypes with respect to biochemical and yield attributes [soluble proteins, SOD, CAT and APX activity]. Also the highest and the lowest MDA content was observed at 10 dS/m salinity level with 50 and 150 kg N/ha, respectively. The salt-tolerant and sensitive genotypes exhibited maximum value for physio-biochemical and yield attributes at 100 and 150 kg N/ha, respectively. These results suggest that application of N may improve most of the traits and is demonstrated to have physiological benefits and/or reduce the injurious effects of salt stress in wheat.