Field responses of barley genotypes across a salinity gradient in an arid Mediterranean environment

Salinity is one of the most widespread abiotic stresses affecting crop growth and productivity, particularly when soil and irrigation water are salty. Field experiments were performed in an arid Mediterranean climate to investigate agronomic responses of twenty-one diverse barley genotypes to naturally occurring salinity. Three saline fields (7.72 dS/m) were irrigated with well water of three incremental salinity levels, low (5.25 dS/m), intermediate (8.35 dS/m), and high (11.12 dS/m). The results revealed considerable genotypic variability at the three salinity levels and significant genotype by salinity interaction that could be traced to specific yield components. Increasing salinity level decreased performance of all agronomic traits, but with different patterns, with yield components determined earlier being more affected than traits determined later. Days to heading exhibited a strong and negative relationship with grain yield across all salinity levels, while 1000-grain weight demonstrated the highest association with grain yield, followed by number of grains per spike, plant height, and harvest index, consistently at the three salinity levels. The genotypes were classified based on their yield indices at the three salinity levels into six groups varying from highly salt-tolerant (group A) to highly salt-sensitive genotypes (group F). Genotype-by-salinity interaction was studied based on rankings of performance across salinity levels. Close examination of yield component trends across levels allowed the identification of genotypes with different behaviors, indicating the presence of variation in potentially different mechanisms of response to salinity. This diversity of responses could be used in breeding to improve tolerance over the whole crop cycle, from plant establishment and tillering to grain filling.