Investigating of salinity stress tolerance in barley (Hordeum vulgare) genotypes originating from Iran

Introduction The combination of the effects of drought stress and soil salinity causes a severe limitation in the production of agricultural crops. Irrigation with saline water has caused the expansion of more saline lands. Salt tolerant genotypes are very important in the development of agricultural systems suitable for saline lands. Soil salinity through soil amendment and or the cultivation of tolerant crops can be adjusted. Of course, soil amendment is a costly process and the cultivation of tolerant species and varieties is the most practical solution in conditions where soil salinity is low. It is clear that the genotypes show a significant difference in response to salinity stress. One of the ways to deal with salinity is to select and find salinity-tolerant cultivars through the use of breeding methods. It is also possible to select and modify salinity-tolerant species in some fodder plants of temperate regions. This research was modified, with the aim of evaluation of selected barley genotypes from past years' experiments, under salinity stress conditions and identification and introduction of tolerant genotypes and direct and indirect use of them in breeding programs. Materials and methods In this experiment, the genotypes were evaluated during two crop years in the form of a rectangular lattice design with three replications at the research station of South Khorasan Agriculture and Natural Resources Research Center, Birjand. The experiment was conducted under normal conditions and salt stress separately. In order to compare these genotypes with modified cultivars, six cultivated barley cultivars, including two salinity-tolerant controls, including Mehr and Khatam cultivars and the semi-sensitive Yusuf control, were also included in the experiments (Table 1). In addition to evaluating the phenological traits of days to flowering and days to maturity, the traits of plant height, seed yield, and 1,000-seed weight were recorded. Stress indices including stress tolerance index (STI) were calculated based on grain yield in barley genotypes. Results and discussion The combined analysis of phenological, morphological and agronomic traits in the evaluated genotypes in two cropping years and two normal conditions and salinity stress showed that the interaction effect of year, salinity stress and genotype on the traits is significant. This showed that the reaction of genotypes was different in different years and different salinity conditions, so the results in different years were analyzed separately. In the salt research station in the first year of the experiment, genotypes number 31 (TN4006), 30 (TN3947), 50 (TN5008) and 28 (TN3646) along with Yusuf, Nusrat and Gohran cultivars, in terms of agronomic traits and stress indices were superior. While in the second year, the top genotypes were genotypes No. 44 (TN4904), 25 (TN3477), 23 (TN3470) and 32 (TN4104) along with Nimroz and Mehr cultivars. Conclusion The information related to the trend of temperature changes and rainfall in different months in Birjand showed that the amount of rainfall was significantly higher in the first year of the experiment. In addition to reducing the salinity of the soil by adjusting the temperature, it reduces the amount of evaporation and transpiration and the intensity of the salinity stress. Therefore, it seems that the level of salinity stress was milder in the first year and more intense in the second year, and this was also observed in the stress intensity index. Based on this, the difference in the results in the two years of the experiment can be justified, in other words, in the first year, tolerant genotypes were introduced in mild stress and in the second year, tolerant genotypes were introduced in severe stress. Overall, these results showed that climate changes in different years have a great impact on the response of genotypes to salinity stress.