Physiological responces of some barley genotypes (Hordeum vulgare) under dust stress condition

Introduction Cereals are among the most vital agricultural products on a global scale, with an estimated annual production of around 904 million tons. Barley (Hordeum vulgare), a species within the Gramineae family, ranks as the fourth most important grain crop worldwide based on production. It is also the second most extensively cultivated cereal, covering 18% of the total cultivation area. This plant, which is currently at risk, demonstrates a considerable tolerance to non-living stresses. Abiotic stresses influence living organisms in diverse manners. In recent years, dust has emerged as a significant environmental challenge in western and southern Iran, leading to a reduction in soil moisture retention and negatively affecting plant health. Plants, due to their immobility, are particularly vulnerable to the adverse effects of air pollution compared to other organisms. Additionally, dust diminishes soil fertility, contributing to lower agricultural productivity and economic losses. The presence of dust on leaves further complicates these issues by obstructing light penetration, disrupting photosynthesis, reducing biomass production, and ultimately decreasing crop yields. This research seeks to analyze the impact of dust on the physiological characteristics of different barley genotypes. Materials and methods The research was conducted during the agricultural year 2022-2023 at the Faculty of Agriculture's research greenhouse at Ilam University. A factorial design was employed within a randomized complete block structure, incorporating three replications. The experimental factors included micro-dust treatments at two levels (with and without dust) and a selection of ten barley genotypes sourced from the IPK Institute's seed bank in Germany. To simulate dust stress, soil was collected from the Mehran region, sieved through 53-micron screens, and analyzed for physicochemical properties (refer to Table 2). A plastic chamber measuring 150 x 2.20 x 3.40 meters (length x width x height) was constructed to mimic conditions of a dust storm. Dust was applied during the seedling phase, and physiological traits such as leaf chlorophyll content, leaf soluble protein concentration, leaf proline content, and leaf soluble carbohydrates were evaluated ten days after the dust application. Following the assessment of these traits, variance analysis and mean comparisons were conducted using SAS 9.4 software, while graphs were generated using the GraphPad program. Mean comparisons were performed using the LSD (least significant difference) test at a 5% probability level, and correlation comparisons along with principal component analysis were executed using JMP software. Results and discussion The results of this research highlighted the importance of the cultivar×dust interaction in influencing the levels of chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, ion leakage, relative water content (RWC), proline, catalase, and sugars, all at a significance level of 1%. In contrast, neither dust nor dust treatment showed a significant effect on protein content. Exposure to dust resulted in decreased levels of chlorophyll, ion leakage, relative water content, and protein, while it caused increases in proline, catalase, and soluble sugars. Correlation analysis revealed a positive relationship among photosynthetic pigments, whereas their association with relative water content was negative. Furthermore, a strong positive correlation (r = 1) was identified between protein and carbohydrates. Factor analysis conducted on the examined traits identified three factors with eigenvalues exceeding one, which collectively accounted for 99.72% of the total data variation. Notably, relative water content exhibited a significant positive correlation with protein (r=0.758) at the five percent significance level. Conclusion The findings indicate that dust stress negatively impacted photosynthesis, ion leakage, relative water content, and protein levels, while simultaneously elevating carotenoids, proline, catalase, and soluble carbohydrates. The effects of dust stress varied across different cultivars, with certain traits in specific cultivars showing increased vulnerability. Remarkably, the HOR6964 genotype demonstrated a higher level of resilience in comparison to other genotypes.