Synergy between Glomus fasciculatum and a beneficial Pseudomonas in reducing root diseases and improving yield and forskolin content in Coleus forskohlii Briq. under organic field conditions

Abstract

Root rot and wilt, caused by a complex involving Fusarium chlamydosporum (Frag. and Cif.) and Ralstonia solanacearum (Smith), are serious diseases affecting the cultivation of Coleus forskohlii, a crop with economic potential as a source of the medicinal compound forskolin. The present 2-year field experiments were conducted with two bioinoculants (a native Pseudomonas monteilii strain and the exotic arbuscular mycorrhizal (AM) fungus Glomus fasciculatum) alone and in combination under organic field conditions in order to evaluate their potential in controlling root rot and wilt. Combined inoculation of P. monteilii with G. fasciculatum significantly increased plant height, plant spread, and number of branches; reduced disease incidence; and increased tuber dry mass of C. forskohlii, compared to vermicompost controls not receiving any bioinoculants. Increase in tuber yields was accompanied by an increase in plant N, P, and K uptake. Co-inoculation of P. monteilii with G. fasciculatum significantly improved the percent AM root colonization and spore numbers retrieved from soil. This suggests P. monteilii to be a mycorrhiza helper bacterium which could be useful in organic agriculture. The forskolin content of tubers was significantly increased by the inoculation treatments of P. monteilii, G. fasciculatum, and P. monteilii + G. fasciculatum.

Arbuscular mycorrhizal symbiosis and active ingredients of medicinal plants: current research status and prospectives

“…In a study to determine the effect of four different AM fungi and two free living nitrogen fixing bacteria (NFB) on the content of artemisinin in A. annua inoculated alone or in combination, plants co-inoculated with G. mosseae and a Bacillus subtilis strain produced 25.5-103.2 % more artemisinin than in other treatments, indicating a synergistic effect between G. mosseae and B. subtilis (Awasthi et al 2011). Synergy has also been observed between G. fasciculatum and a beneficial Pseudomonas in improving yield and forskolin content of C. forskohlii tubers under field conditions (Singh et al 2013). …”

Efecto de Glomus fasciculatum y su relación con tres abonos orgánicos en dos cultivares de haba

“…Los hongos micorrízicos arbusculares (HMA) actúan como aceleradores del crecimiento al aumentar la absorción del fósforo y ayudan en la protección contra patógenos (Alarcón y Ferrera, 1999Mena et al, 2006;West et al, 2009;Smith y Smith, 2011;Singh et al, 2013); también pueden influir en el proceso estructural y de agregación del suelo (Rilling y Mummey, 2006). Dentro de los HMA se encuentra Glomus con 85 especies, pero la más importante en la agricultura es G. fasciculatum, estudiada en frutales, forestales, hortalizas y leguminosas.…”

“…Dentro de los HMA se encuentra Glomus con 85 especies, pero la más importante en la agricultura es G. fasciculatum, estudiada en frutales, forestales, hortalizas y leguminosas. Existen reportes del efecto positivo de ésta con composta, estiércol o residuo de cosecha (Saif, 1986) al aumentar el potencial del inóculo en el suelo, la colonización y la absorción de nutrientes (Gosling et al, 2006;Wu y Zou, 2010;Singh et al, 2013;Dutt et al, 2013).…”

“…Vermicompost, manure and mushroom residue contribute organic matter (Eghball et al, 2002). Arbuscular mycorrhizal fungi (HMA) act as growth accelerator by increasing phosphorus absorption and help in protecting against pathogens Ferrera, 1999, 2000;Mena et al, 2006;West et al, 2009;Smith and Smith, 2011;Singh et al, 2013); tt can also influence the structural and soil aggregation process (Rilling and Mummey, 2006). Within the HMA is Glomus with 85 species, but the most important in agriculture is G. fasciculatum, studied in fruit, forestry, vegetables and legumes.…”

“…Within the HMA is Glomus with 85 species, but the most important in agriculture is G. fasciculatum, studied in fruit, forestry, vegetables and legumes. There are reports of the positive effect of it with compost, manure or crop residue (Saif, 1986) by increasing the potential of inoculum in the soil, colonization and nutrient uptake (Gosling et al, 2006;Wu and Zou, 2010;Singh et al, 2013;Dutt et al, 2013).…”