Abstract:

The aim of this study was to clarify the root morphological adaptation strategies of Rumex hanus in response to salt-alkali stress. The profile excavation method was used to collect the roots of R. hanus in saline-alkali soil at Shihezi city， Xinjiang Province and the root distribution and morphological characteristics of R. hanus in different months were analyzed and the root morphological distribution and the adaptation strategy in the saline-alkali environment were explored. It was found that the roots of R. hanus significantly reduced soil electrical conductivity around the root system， and this effect was significantly correlated with root length and root biomass. Root length， root biomass and root volume showed a decreasing pattern with increase in soil depth. From July to October， the root volume grew the fastest in the 0-20 cm soil depth， increasing by 71.26%. The roots at a horizontal distance of 25-35 cm from the plant grew slowly and less densely compared with those within a 5-25 cm radius of the plant. In this way new root growth was concentrated in low conductivity soil closer to the plant， avoiding high-salt areas and improving nutrient absorption. Fine roots （d≤2 mm） accounted for more than 90% of the total root length. In summary， the roots of R. hanus exhibited a morphological adaptation strategy to resist stress and enhance their resistance to saline-alkali soils. The main phenomenon was that the roots more strongly colonized a soil zone within a 25 cm radius of the plant where soil conductivity was lower to approximately 40 cm soil depth. In this zone roots were the most dense and rapidly increased their length from 0-15 cm horizontally to the plant. The results illustrate one available strategy for configuration of salt-tolerant plants for saline-alkali soil in arid regions and potentially provide a foundation for the development of new management practices.

Key words: root morphology, saline-alkali soil, Rumex hanus, root distribution