The tolerance to saline–alkaline stress was dependent on the roots in wheat

Saline–alkaline stress is one of the most serious global problems affecting agriculture, causing enormous economic and yield losses in agricultural production. Wheat, one of the most important crops worldwide, is often subjected to saline–alkaline stress. In this study, two wheat cultivars with different saline–alkaline tolerance, XC-12 (non-tolerance) and XC-45 (tolerance), were used to investigate the influence of saline–alkaline stress on photosynthesis and nitrogen (N) metabolism through hydroponic experiment with aim of elucidating the mechanism of resistance to salt-alkali. These results showed that saline–alkaline stress significantly reduced biomass accumulation, chlorophyll content, photosynthetic ability and N absorption but increased N utilization efficiency. There was no significant difference in photosynthesis between XC-12 and XC-45 under saline–alkaline stress. In addition, XC-45 had lower ratio of Na+/K+ in leaves and Na+-K+ selection rate and higher N absorption ability than XC-12, thereby improving physiological metabolism. Moreover, the roots exhibited greater growth performance in response to saline–alkaline stress as a result of increasing glutamine synthetase activity in roots, thus promoting N metabolism in roots. By coordinating the synergistic effect of increasing soluble protein in root, XC-45 exhibited greater tolerance to saline–alkaline stress. All data pinpoint that the root physiological function was more responsible for resistance to saline–alkaline stress in wheat.