ABSTRACT
Effect of Pochonia chlamydosporia on soil microbial activity and accumulation of macro- and micronutrients in soybean infected with Meloidogyne javanica

Raiane P. Schwengber1, Cláudia R. Dias-Arieira1, Angélica S. Melo1, Carolina Y. Futigami1, Guilherme Tarini1, Marcelo A. Batista1, Angélica Calandrelli1*, and Simone M. Santana-Gomes1, 2
 
Meloidogyne javanica induces the formation of specialized feeding sites in host roots, affecting nutrient absorption by the plant. Biological control agents, such as Pochonia chlamydosporia, may mitigate the damage caused by nematodes. We hypothesized that the fungus contributes to plant nutrient absorption and soil microbial activity, thereby reducing the negative impacts of nematode infection. This study aimed to assess the influence of P. chlamydosporia on M. javanica reproduction, soil respiration, vegetative development, and accumulation of macro- and micronutrients in soybean. Experiments were conducted in a greenhouse using plants inoculated with M. javanica and treated with P. chlamydosporia, uninoculated plants treated with P. chlamydosporia, untreated plants inoculated> with M. javanica, and uninoculated untreated plants (absolute control). The inoculum consisted of 2000 eggs and second-stage juveniles of M. javanica, and the treatment consisted of 5.2×107 chlamydospores g−1 at a dose of 2.5 kg ha−1. Water was used as control. At 60 d after treatment, P. chlamydosporia reduced M. javanica reproduction by 40.3% and plant height was highest in inoculated treated plants. Soil microbial biomass C reached the highest level in nematode-inoculated soil (3665 mg C kg-1), whereas basal respiration was stimulated by P. chlamydosporia treatment (0.51 mg CO2-C kg-1 h-1). The microbial metabolic quotient peaked in soils with both nematodes and the fungus. Regarding nutrition, P. chlamydosporia enhanced P (+46%) and K (+69%) accumulation in leaves, while M. javanica infection increased Zn content.
Keywords: Alternative control, nematophagous fungus, plant nutrition, soil respiratory activity.
1Universidade Estadual de Maringá, Departamento de Agronomia, Maringá, Paraná, Brasil.
2Universidade Estadual de Maringá, Departamento de Ciências Agrárias, Umuarama, Paraná, Brasil.
*Corresponding author (a.calandrelli@hotmail.com).