Ecological Stoichiometry Homeostasis of Six Microelements in Leymus chinensis Growing in Soda Saline-Alkali Soil

Abstract

Soil salinization poses severe threats to grassland ecosystems in various parts of the world, including the Songnen Plain in northeast China. Severe impairment of plant growth in this soil is generally attributed to high soil pH, total alkalinity, and sodium (Na) contents. This paper focuses on the ecological stoichiometry of microelements, which has received much less attention than relations of macroelements, in the soil and plants (specifically Leymus chinensis) growing in it. The results show that the soil’s manganese (Mn), zinc (Zn), iron (Fe), copper (Cu), nickel (Ni) and molybdenum (Mo) contents are lower than average in Chinese soils, but only Mn and Zn are severely deficient in L. chinensis. With increases in soil pH, total alkalinity, and Na, the Mo contents in both soil and L. chinensis slightly increase, while contents of the other microelements decline. Homeostasis indices obtained for the six microelements—and Fe/Zn, Fe/Ni, Fe/Cu, and Cu/Zn ratios—were all between 0.82 and 3.34 (ranging from just below the “plastic” threshold to “weakly homeostatic”). Despite Zn deficiency in the soil, Zn appears to have the highest homeostasis of the six elements in L. chinensis (homeostasis indices of Zn, Cu, Ni, Mn, Fe and Mo were 3.34, 2.54, 1.86, 1.76, 1.52, and 1.33, respectively). In addition, the Cu/Zn ratio had the highest homeostasis index (1.85), followed by Fe/Zn (1.02), Fe/Cu (0.95) and Fe/Ni (0.82). Appropriate application of Mn and Zn fertilizers is recommended to promote the growth and development of L. chinensis in soda saline-alkali soil.

Cu and Na contents regulate N uptake of Leymus chinensis growing in soda saline-alkali soil

“…Soils of the study area have a loose texture with a higher proportion of non-capillary pores than capillary pores, and exhibit poor retention of water and fertilizer. Detailed descriptions of the study area can be found in previously published research [ 5 ].…”

“…Soil pH was measured in 1:2.5 (w/v) soil distilled water extracts. Detailed descriptions of the testing methods can be found in previously published research [ 5 , 30 ].…”

“…It is an important region of agricultural production and animal husbandry within China but it also has one of the highest concentrations of soda saline-alkali soil in the world [4]. L. chinensis, the dominant grassland plant in this region, is highly tolerant of saline-alkali conditions [5]. Moreover, it achieves high yields and is valuable in both ecological and economic terms-the former because of its ability to stabilize grasslands, the latter because of its usefulness as fodder [6].…”

“…L . chinensis , the dominant grassland plant in this region, is highly tolerant of saline-alkali conditions [ 5 ]. Moreover, it achieves high yields and is valuable in both ecological and economic terms–the former because of its ability to stabilize grasslands, the latter because of its usefulness as fodder [ 6 ].…”

“…) in Matlab[5] (R2016a, The Math Works Inc. Natick, MA). The results were visualized using Sigmaplot 12.5 (Systat Software, Inc. Germany).…”