Effects of salt stress on root morphology, carbon and nitrogen metabolism, and yield of Tartary buckwheat

This study aims to clarify the effects of different concentrations of sodium chloride on the carbon and nitrogen metabolism and yield of Tartary buckwheat. The salt-sensitive cultivar Yunqiao 2 was pot-grown and treated with four salt concentrations including 0, 2, 4, and 6 g kg(−1). The root morphology index increased from seedling stage to maturate stage. The content of soluble protein in the leaves reached the maximum at the anthesis stage, and the other substances content and the enzymes activity related to carbon and nitrogen metabolism reached the maximum at the grain filling stage. The root morphology index, root activity; invertase, amylase, sucrose synthase, and sucrose phosphate synthase activities; nitrate-nitrogen, ammonium nitrogen, and soluble protein content; and nitrate reductase and glutamate synthase activities increased first and reached the maximum at 2 g kg(−1) treatment and then decreased with increasing salt stress concentration. The content of soluble sugars and sucrose and the activity of glutamate dehydrogenase increased continuously with increasing salt concentration, and reached the maximum in the 6 g kg(−1) treatment. The grain number per plant, 100-grain weight, and yield per plant increased first and reached the maximum at 2 g kg(−1) treatment and then decreased with increasing salt stress concentration. In summary, moderate salt stress (2 g kg(−1)) can promote the root growth, increase the content of carbon and nitrogen metabolism-related substances and enzyme activity, and increase the yield per plant of Tartary buckwheat.