Comparative analysis of two-rowed and six-rowed barley genotypes: impacts of water stress and nitrogen fertilizer on yield and stress responses

Water stress is a critical abiotic stress factor with profound implications for agricultural productivity and global food security. This research explores the complex relationships between water stress and the application of nitrogen fertilizer in two-row and six-row barley genotypes with the aim of comprehending their performance and mechanisms for responding to stress. The study was performed over two years, employing a randomized complete block design with varying irrigation levels, nitrogen treatments, and barley genotypes. The results showed significant differences in various agro-morphological, physiological and biochemical traits between the two-row and six-row barley genotypes under different conditions. Water stress led to significant decreases in grain yield, shoot dry weight, leaf area index, and relative water content across all genotypes. It also caused an increase in electrolyte leakage, malondialdehyde content, and hydrogen peroxide levels, indicative of cellular membrane damage and oxidative stress. However, antioxidant enzyme activities such as glutathione peroxidase, ascorbate peroxidase, and catalase, along with DPPH radical scavenging activity, escalated as a defense response. Furthermore, nitrogen fertilizer application generally enhanced grain yield and shoot dry weight while decreasing oxidative stress indicators. However, under water stress conditions, nitrogen application exacerbated the negative effects of water stress, leading to reduced crop yield and stress resistance. As a result, this study emphasizes the critical role of genotype selection and proper use of nitrogen fertilizer application in optimizing the performance of two-row and six-row barley crops under different humidity conditions.