Inoculation with arbuscular mycorrhizal fungus Rhizophagus clarus on tomato promotes increasing yield under organic farming inputs

Organic agriculture comprises farming practices that discard synthetic pesticides and fertilizers. Tomato production demands huge amounts of fertilizers and pesticides. Improving efficiency of the inputs allowed for organic tomato production is a challenge to upgrade yields. Thereby, we studied the effects of the inoculation of the arbuscular mycorrhizal fungus (AMF) Rhizophagus clarus, supplying rock thermophosphate and bioactivator, alone or associated, on tomato development and yield. The experiment was achieved in a greenhouse using undetermined tomato cv. BRS-Nagai sown in polystyrene trays and afterwards transplanted to pots. Treatments included R. clarus; thermophosphate (TH) (130 g/pot); bioactivator (PenergeticK® + Penergetic®) (BI); R. clarus + TH; R. clarus + BI; R. clarus + TH+ BI and TH + BI and control (CO). From the flowering onset, plant height, height of insertion of first truss, trusses space, length, and also the diameter and fresh weight of ripe fruits of the three first trusses were assessed. AMF colonization in the roots and macronutrients in leaves and petioles were also measured. Trusses spacing variable was affected by mycorrhiza and thermophosphate. R. clarus inoculation incremented 10 and 31.85% of fresh mass of ripe fruits and mass of ripe fruits per plant, respectively. Soluble solids contents in fruits and N, P and K in the leaves and petioles were similar among treatments. AMF colonization decreased on thermophosphate fertilized plants and increased in bioactivator treatment. Results showed that root inoculation with R. clarus promoted better plant development and yield and may be used as biological inoculant mostly on organic tomato production. RESUMO: A agricultura orgânica preconiza práticas culturais que dispensam o uso de pesticidas e fertilizantes sintéticos. A tomaticultura convencional, por sua vez, demanda grandes quantidades de agroquímicos. Neste contexto, aumentar a eficiência de insumos permitidos em agricultura orgânica consiste em um desafio para a manutenção de altas produtividades. Este estudo objetivou investigar os efeitos, isoladamente e de interação, da inoculação de fungo micorrízico arbuscular (FMA) Rhizophagus clarus e da aplicação de termofosfato e de bioativador no desenvolvimento e na produtividade de tomateiros. O experimento foi conduzido em casa de vegetação com a cultivar BRS-Nagai, genótipo de hábito indeterminado do grupo saladete, semeado em bandejas de poliestireno e posteriormente transplan