Morphological and biochemical evaluation of salinity tolerance of barley cultivars in central regions of Iran

One of the biggest challenges of agriculture in the present era is environmental stresses, especially drought and salinity stress and its destructive effect on food security. In this regard, this experiment was conducted with the aim of selecting of tolerant cultivar of barley to salinity stress and identifying tolerance mechanisms in new and old barley cultivars.

This experiment was carried out during the two years of 2016-17 in the Milshbar Ardakan region located in Yazd province-Iran. Experimental treatments included 9 six-rowed barley cultivars including Nik, Mehr, Khatam, Reyhan, Goharan, Nosrat, Morocco, Afzal and Fajr 30 cultivars in three levels of irrigation water salinity including 4, 10 and 14 dS.m-1 were evaluated as a split plot experimental design so that water salinity as the main plots and cultivars as a sub-plots were randomly placed. The studied traits included yield and yield components as well as sodium and potassium levels, oxidizing enzymes and photosynthetic pigments.

The results showed that salinity treatment had a significant effect on day to emergence, day to tillering and grain yield. Salinity stress reduced grain yield components but this reduction was not significant. The effect of cultivar on plant phenology and day to emergence, tillering and ripening was significant, but on yield and yield components became insignificant. However, among the studied cultivars, Nik, Mehr, Khatam and Reyhan cultivars had higher yields and yield components. Among the salinity treatments, the highest grain yield was obtained at salinity of 4 dS m-1 with 5770.64 kg ha-1. With increasing salinity of irrigation water to 10 and 14 dS m-1, grain yield decreased by 18.04 and 27.55%, respectively, and reached 4729.29 and 4180.87 kg ha-1. The results of interaction showed that the interaction effect of year × salinity on grain yield components was significant and also the interaction of year × cultivar on 1000-Kernel weight and grain yield and year × salinity × cultivar on grain yield was significant. With increasing salinity stress, the amount of sodium ions in the shoots increased and potassium decreased, so the ratio of K/Na decreased. This mechanism was more effective in tolerant cultivars and in salinities of 4 and 10 dS m-1. With increasing salinity stress, the amount of oxidizing enzymes increased, so that with increasing salinity from 4 to 10 and 14 dS m-1, the amount of peroxidase enzyme was increased 1.59 and 2.23 times, catalase 1.52 and 1.95 times, and guaiacol peroxidase 1.47 and 2.89 times, respectively. With increasing salinity stress, all photosynthetic pigments increased. Among the cultivars, the amount of chlorophyll a and b in Morocco, Nik and Mehr was higher than other cultivars.

Based on the results of this experiment, it seems that tolerant cultivars, in addition to having high production potential, should have high potassium uptake mechanisms and high gene expression to produce enzymes that protect against oxidative stress in order to tolerate low to medium salinity stress.