Aplicação de formononetina na colonização e esporulação de fungos micorrízicos em braquiária

Abstract

Resumo -O objetivo deste trabalho foi avaliar o efeito de aplicações de Mycoform na colonização micorrízica e esporulação de 13 isolados de fungos micorrízicos arbusculares em Brachiaria decumbens. O experimento foi conduzido em casa de vegetação, em solo esterilizado, com delineamento experimental inteiramente casualizado, em arranjo fatorial 3x13, com cinco repetições. O produto foi aplicado no plantio e foi ou não aplicado uma segunda vez 60 dias depois, na quantidade de 2 mg kg -1 de solo. Aos 150 dias de crescimento das plantas, foram coletadas amostras de raízes e de solo rizosférico, para a avaliação de colonização radicular e densidade de esporos. Houve estímulo do Mycoform nos parâmetros avaliados, efeito que variou com os isolados estudados. Foi observado efeito significativo da aplicação do Mycoform na colonização das raízes pelos isolados Glomus clarum DCS 09 e DCS 10, Paraglomus occultum DCS 06 e Acaulospora delicata DCS 02 e na esporulação dos isolados G. clarum DCS 09 e DCS 10, P. occultum DCS 06 e DCS 31, Glomus etunicatum DCS 12, A. delicata DCS 30 e Kuklospora colombiana DCS 03. O incremento na esporulação atingiu 89% e, na colonização, 60%, o que confirma os benefícios da formononetina na colonização e na esporulação dos fungos micorrízicos arbusculares.Termos para indexação: Brachiaria decumbens, estimulante de micorriza, multiplicação de FMAs, Mycoform, simbiose radicular. Formononetin application on colonization and sporulation of arbuscular mycorrhizal fungi in BrachiariaAbstract -The aim of this work was to evaluate the effects of Mycoform on both sporulation and colonization of 13 arbuscular mycorrhiza fungi (AMF) isolates in Brachiaria decumbens. The experiment was carried out in greenhouse conditions with sterile soil, in a completely randomized design with 3x13 factorial treatments and five repetitions. The product was applied once at planting and was or was not applied a second time 60 days afterwards, at an amount of 2 mg kg -1 of soil. Plants were allowed to grow for 150 days, when root and rhizospheric soil samples were collected to evaluate the percentage of colonized root segments and the spore density. Mycoform effects were different among the fungal isolates. It had significant effect on colonization for the isolates Glomus clarum DCS 09 and DCS 10, Paraglomus occultum DCS 06 and Acaulospora delicata DCS 02, and on spore density for the isolates G. clarum DCS 09 and DCS 10, P. occultum DCS 06 and DCS 31, Glomus etunicatum DCS 12, A. delicata DCS 30 and Kuklospora colombiana DCS 03. Maximum increases due to Mycoform were 60% for colonization and 89% for spore density. These results confirm formononetin effects on AMF colonization and on AMF sporulation.Index terms: Brachiaria decumbens, mycorrhizal stimulate, AMF multiplication, Mycoform, root symbiosis. IntroduçãoA produção agrícola sustentável está associada ao desenvolvimento de tecnologias que minimizem os impactos ambientais e que poupem insumos não renováveis, como os fertilizantes a base de fósforo. Nesse sentido, há gra...

Arbuscular mycorrhizal fungi and mycorrhizal stimulant affect dry matter and nutrient accumulation in bean and soybean plants1

“…Different responses were also observed with the use of mycorrhizal stimulating in other studies (Novais & Siqueira 2009, Cordeiro et al 2015. However, the mycorrhizal colonization by native arbuscular mycorrhizal fungi was stimulated using the mycorrhizal stimulant (Cordeiro et al 2015).…”

“…However, the mycorrhizal colonization by native arbuscular mycorrhizal fungi was stimulated using the mycorrhizal stimulant (Cordeiro et al 2015). This fact becomes important for the Brazilian Savannah region, for mycorrhizal plants have increased resistance to biotic (pests and diseases) and abiotic (water) stress, as several studies have shown (Novais & Siqueira 2009, Ferreira et al 2012, Cordeiro et al 2015.…”

“…Cordeiro et al (2015) demonstrated that the use of isoflavonoid formononetin provided a 50 % increase in the colonization rate, as well as an increase of over 11 % in the soybean production under drought conditions. Studies on isoflavones, such as formononetin, have been carried out over the years, such as that by Novais & Siqueira (2009). However, the knowledge on its use, management, doses and association with propagules inoculation, among many other issues, still need to be clarified under Brazilian conditions.…”

Formononetin associated with phosphorus influences soybean symbiosis with mycorrhizal fungi and Bradyrhizobium

“…For the area of the first experiment (2010/11), based on the P concentration originally found in the soil (see site characterization above), these three levels of P addition correspond to 0, 75%, and 150% of the P fertilization recommended by Novais et al (1999) for soybean; for the area of the second experiment (2012/13), those three levels of P 2 O 5 addition correspond to 0, 50, and 100% of the recommend P fertilization. The second factor of the factorial scheme consisted of four addition doses of the biostimulant formononetin, 7-hydroxy, 4'-methoxy isoflavone, (0, 25, 50 and 100 g ha -1 ), as the commercial product PHC-506, according to the manufacturers' recommendations (Plant Health Care).…”

“…The discrepancy in the results from both experiments can be probably attributed to differences in the P levels originally found in the soils from each area. Although the same P levels (0, 60, and 120 kg P 2 O 5 ha -1 ) were used in both experiments, according to the recommendations of Novais et al (1999) they correspond to 0, 75, and 150% of the recommend dose for 2010/11; and 0, 50, and 100% for 2012/13. Therefore, in 2010/11 the intermediate level of P addition was already close (75%) to the recommended dose, while the maximum level of P applied was excessive (150%) for this soil.…”