Growth of lemongrass (Cymbopogon citratus (DC) Stapf) inoculated with arbuscular mycorrhizal fungi (Rhizophagus clarus and Claroideoglomus etunicatum) under contrasting phosphorus levels

Abstract

'Cymbopogon citratus' (DC) Stapf (lemongrass) has many industrial applications. Various factors affect the metabolism of this plant. Specifically, its association with arbuscular mycorrhizal fungi (AMF) increases water absorption and nutrient uptake, mainly phosphorous (P). This study aimed to assess the AMF symbiotic effects on nutrient uptake and growth in 'C. citratus' inoculated with the Rhizophagus clarus and Claroideoglomus etunicatum AMF under different levels of P applied to the substrate. The treatments were prepared in a sterile substrate with high (200 mg kg-1) and low (20 mg kg-1) P levels, with and without AMF inoculation. The experiment was conducted in a greenhouse for six months. A 3 x 2 (3 mycorrhizal x 2 levels of P) factorial experiment in a completely randomized design (eight repetitions) was used in this study. The variables spore density and root AMF colonization, basal soil respiration, microbial biomass carbon, shoot, root and total dry mass, nitrogen (N) and P content in the plant were analyzed. No significant AMF symbiotic effects (p > 0.05) on lemongrass growth were observed for the P levels. P and N content in the shoots, and total P, increased in treatments with AMF and at the high P level, particularly in the inoculation with 'R. clarus'. Spore density, root colonization, and microbial biomass carbon were higher with AMF inoculation. It was observed that AMF inoculation increased the content of P and N in 'C. citratus', but did not affect plant growth. AMF inoculation can improve soil quality and, combined with a higher P level, can increase P and N uptake by lemongrass plants, modifying the plant metabolism.