Synergistic and Antagonistic Effects of Salinity and pH on Germination in Switchgrass (Panicum virgatum L.)

Yuan Liu,Quanzhen Wang,Jian Cui,Bao Xie,Yunwei Zhang,Haitao Liu,Chunhui Wu,Guo Chen,Keith R Davis

doi:10.1371/journal.pone.0085282

Abstract

The effects of salt-alkaline mixed stress on switchgrass were investigated by evaluating seed germination and the proline, malondialdehyde (MDA) and soluble sugar contents in three switchgrass (Panicum virgatum L.) cultivars in order to identify which can be successfully produced on marginal lands affected by salt-alkaline mixed stress. The experimental conditions consisted of four levels of salinity (10, 60, 110 and 160 mM) and four pH levels (7.1, 8.3, 9.5 and 10.7). The effects of salt-alkaline mixed stress with equivalent coupling of the salinity and pH level on the switchgrass were explored via model analyses. Switchgrass was capable of germinating and surviving well in all treatments under low-alkaline pH (pH≤8.3), regardless of the salinity. However, seed germination and seedling growth were sharply reduced at higher pH values in conjunction with salinity. The salinity and pH had synergetic effects on the germination percentage, germination index, plumular length and the soluble sugar and proline contents in switchgrass. However, these two factors exhibited antagonistic effects on the radicular length of switchgrass. The combined effects of salinity and pH and the interactions between them should be considered when evaluating the strength of salt-alkaline mixed stress.

Highlights

Salt-affected soils are present in a large portion of the marginal land, and millions of hectares of marginal cropland are limited by the high concentrations of salts in the soil [1,2]
The correlation coefficients of the germination percentage (GP), germination index (Gi), plumular length (PL) and radicular length (RL), as well as the contents of soluble sugar (SS), MDA and proline are illustrated as functions of the salinity and pH
The salinity significantly negatively correlated with the germination percentage (r = 20.548), germination index (r = 20.638), plumular length (r = 20.622) and radicular length(r = 20.806), while it significantly positively correlated with the contents of soluble sugar (r = 0.271), MDA (r = 0.266) and proline (r = 0.744)

Summary

Introduction

Salt-affected soils are present in a large portion of the marginal land, and millions of hectares of marginal cropland are limited by the high concentrations of salts in the soil [1,2]. Switchgrass (Panicum virgatum L.), an important species of tall prairie grass, is a warm-season C4 perennial rhizomatous grass that is native to North America [7,8]. This grass has been classified into two main ecotypes based on its morphology and habitat, upland and lowland [9]. Switchgrass is considered a potential source of biomass feedstock for renewable energy production in marginal areas that would not compete with food production due to its broad adaptability, rapid growth rates, high yields, growth in less productive soils and high water use efficiency [12,13,14,15]

Objectives

Methods

Results

Discussion

Conclusion