Mycorrhizal Benefits of Salt-Stressed Cinnamomum camphora (L.) Presl. May Be Related to P and Mn2+ Contents in Shoots, Biomass Allocation, and K+/Na+ in Roots and Shoots

Abstract

Arbuscular mycorrhizal fungi (AMF) are taken as bioameliorators to alleviate the detrimental effects of salt stress. However, how AMF affect the performance of Cinnamomum camphora, an economically important species, remains unclear. In this study, we evaluated the interactive effects of AMF and salinity on the growth, nutrient acquisition, and ion ratios of C. camphora. A factorial experiment was implemented in a greenhouse with four fungal regimes (inoculation with sterilized AMF or with Funneliformis mosseae or Rhizophagus irregularis either alone or in combination), and three salt regimes (0, 50, and 200 mM NaCl). Results showed that salinity alone significantly reduced the total dry weight, mycorrhizal colonization, K+ concentration, and ionic homeostasis (particularly K+:Na+, Mg2+:Na+, and Ca2+:Na+) of whole plants. Mycorrhizal inoculation, particularly with R. irregularis, strongly mitigated some of the detrimental effects of salinity, enhancing the salt tolerance of C. camphora. Furthermore, the host plants benefited from the presence of AMF, mainly because they enhanced P and Mn2+ concentrations in the shoots, adjusted biomass allocation, and shifted the selective transporting capacity of K+ over Na+ from roots to shoots. Our results suggested that building mycorrhizal association between C. camphora and R. irregularis may be useful for plant cultivation in coastal areas.