Higher Temperature had Positive Effects on Seed Germination of Glycyrrhiza glabra under NaCl Stress

Abstract

Background: Agricultural soils are affected by secondary salinization due to the fragile ecological environment and lack of scientific management. It is of interest to utilize the germplasm resources of salt-tolerant plants and improve their salinity stress resistance. Seed germination of the medicinal halophyte Glycyrrhiza glabra is affected by soil salt content and temperature during seeding. This study determined the favourable soil temperature for G. glabra seed germination in salinised soil. Methods: Four sodium chloride concentration gradients (control, hyposaline, medium-saline and hypersaline) and 3 temperatures (low- medium- and high temperature) were used for a total of 12 treatments; 30 seeds were utilised in each treatment and each treatment was repeated 3 times. Result: G. glabra seed germination indexes significantly decreased with increased salt concentration. Interestingly, higher temperature could improve the salt tolerance of seeds. Seed germination percentages of hyposaline, medium-saline and hypersaline treatments were higher at elevated temperature than those at low temperature by 33.53%, 127.1% and 41.7%, respectively and were higher than those at medium temperature by 14.1%, 121.6% and 54.6% respectively. Therefore, G. glabra seeds growing in saline habitats should be sown in summer. This study provided a scientific basis for medicinal plant cultivation in salinised soil.