Effects of AMF on nutrient and stoichiometric characteristics in different organs of sunflower

Abstract

In order to explore the effects of arbuscular mycorrhizal fungi (AMF) on growth and nutrient absorption for ornamental sunflowers, explain the related physiological mechanism, four species of AMF Acaulospora scrobiculata (AS), Diversispora spurca (DS), Funneliformis mosseae (FM) and Diversispora versiformis (DV) were selected, and inoculated into potted ornamental sunflower seedlings under greenhouse condition. Effects of AMF on growth, nutrient absorption and ion balance of ornamental sunflower were analyzed. Results showed that four different AMF could infect sunflower roots. In which, DS inoculation has the highest mycorrhizal colonization; whereas, the mycelial length of DV treatment in rhizosphere soil was significantly higher than the other three AMF treatments. Four kinds of AMF markedly decreased the fresh weight in roots and leaves, but significantly increase the fresh weight in flower discs. Furthermore, the four different AMF increased the nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) contents in roots, leaves and flower discs of sunflower in varying degrees, meanwhile reduced the N:P and N:K in root and the flower discs. In addition, the four different AMF significantly reduced the sodium ion (Na+) concentration but significantly increased K+/Na+, Ca2+/Na+ and P/Na+ in flower discs. The correlation analysis showed that there was a significant positive correlation between the mycorrhizal infection rate and the content of P or K in roots, or P, K, Ca in leaves, or N, K in flower discs in various organs of sunflower. In short, AMF could promote ornamental sunflower growth by ameliorating nutrient absorption and transport, adjusting the distribution of mineral elements in organs and the balance between ions, to enhance adaptability and ecological benefits.