Trade-off strategies of individual clonal reproductive traits in Chinese wildrye (Leymus chinensis (Trin.) Tzvel) under NaCl stress

Soil salinity is a serious abiotic stress negatively affecting crop productivity and threatening the global food security. The extent of salt affected soils is continuously increasing due to poor irrigation, improper agricultural practices, and over-fertilization. This study was conducted to investigate the adaptive characteristics of individual growth and the changes of clonal components against salinity stress. The experiment was comprised of different treatments; control, 100 and 200 mmol L-1 salt stress. The results indicate that increasing concentration of salt stress decreased the individual plant biomass, leaf biomass and underground biomass, and increased stem biomass and plant height. Moreover, at 200 mmol L-1 the diameter and volume of the underground parts showed a small reduction whilst length and area of the underground part increased significantly. Besides this Leymus chinensis reduced the input of leaves and various seed plants, allocated more energy to the underground roots, and adopted the root configuration strategy of fine root extension to increase the length, area and volume of the roots. Under high concentration of salt stress; the underground bud reservoir expanded continuously, but the upward output was slightly decreased. This indicates that bud bank was expanded to prepare for reproduction, but the continuous salt stress seriously interfered with the underground clonal components of L. chinensis, and the nutrients and energy synthesized by cells were insufficient to support the continuous extension of rhizostems and the development of daughter plants. In conclusion, salt stress is majorly contributing to decrease the growth and biomass production of L. chinensis, however, salt had more pronounced negative impacts on upward growth as compared to underground growth.