Salinity Influence on <i>Leymus chinensis</i> Characteristics in a Temperate Meadow Ecosystem

Abstract

Salinity is an important restrictive factor for plant growth and ecosystem productivity. However, the endogenous mechanisms by which salinity constrains plant growth are not well understood. To determine the mechanism by which soil salinity suppresses plant growth under salt stress, the effect of soil salinity on hormones in the leaves of Leymus chinensis and the plant density, height and biomass were examined in Songnen meadow steppe. The plants with rhizosphere soil were collected in the growing season (May, June, July, September, October) from the field at different salt levels. The shoot density, height and biomass accumulation of L. chinensis highly decreased with the increase in the soil salinity. Salinity significantly reduced the synthesis of the hormones gibberellic acid (GA₃) and indoleacetic acid (IAA), but it increased the concentration of abscisic acid (ABA). Significant negative correlations between the soil electrical conductivity and plant leaf hormones (GA₃, r = -0.853, P < 0.05; IAA r = -0.971; P<0.01) related to plant growth and positive correlation with ABA (r = 0.931, P<0.01) were observed. Significant positive correlations between the plant hormones related to plant growth (GA₃ and IAA) were observed, but negative correlations were found between ABA and plant density (r = -0.872, P<0.05) and height (r = -0.833, P<0.05). The results suggest that soil salinity might restrict plant growth and biomass accumulation by reducing the synthesis of GA₃ and IAA and increasing the synthesis of ABA under salt stress.