Mycorrhization stimulant based in formononetin associated to fungicide and doses of phosphorus in soybean in the cerrado

Abstract

Arbuscular mycorrhizal fungi (AMF) are obligatory biotrophics, which complicates the feasibility of producing inoculants. Thus, the discovery of substances capable of stimulating mycorrhizal colonization, like the isoflavone formononetin emerges as a promising alternative to explore the benefits of AMF native soil in extensive crops system. The aim of this study was evaluate the application of the isoflavone formononetin (7-hydroxy-4'-methoxy isoflavone) andfungicide via seed in Cerrado soil in no-tillage system and fertilization with two doses of phosphorus in soybean under field and controlled conditions. In the field experiment the treatments were three levels of formononetin (0, 0.5 and 1.0 mg Formononetin seed -1 ) in the absence and presence of fungicide (Carbendazim + Thiram commercial mix) applied to seeds with two doses of phosphorus (100 % and 33% of the recommended fertilization). The study was conducted until the maturation of soybeans. The greenhouse conditions experiment was implemented with the same treatments used in the field research and the flowering stage of the soybean plant was simulated water stress during 10 days, returning to normal irrigation until to harvest the soybean grain. Applying of formononetin stimulated the increased of mycorrhizal colonization, number of nodules, vegetative growth and soybean production in the greenhouse. In the field research the treatments contributed to attenuate the negative effect of the fungicide Carbendazim + Thiram in soybean reflecting increased soybean production and adequate supply of soil phosphorus besides high density of propagules of natives AMF that contributed to reduce the benefits of stimulating mycorrhizal (formononetin) in this research.

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.…”

“…Techniques that mitigate these problems are extremely important for the best performance of these crops. 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).…”

“…Although there is no specificity between arbuscular mycorrhizal fungi and host plant, the soil management and use may cause changes in the diversity of native arbuscular mycorrhizal fungi (Ferreira et al 2012) and select less efficient arbuscular mycorrhizal fungi, what will result in the need for greater input of fertilizers to maintain the crop yield. Therefore, it is important to know the diversity and the symbiotic and infective potential of native arbuscular mycorrhizal fungi in the Brazilian ecosystems, especially in the Brazilian Savannah biome (Cordeiro et al 2015). However, for being obligate symbionts, the use of arbuscular mycorrhizal fungi has been limited, due to the high production cost of inoculants.…”

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

“…This crop has high economic and social importance in Brazil, the greatest soybean producer worldwide. In Brazil, soybean is predominantly cropped in soils characterized by low availability of N and P, making these nutrients the main limiting factors to the growth and agricultural productivity of soybean (CORDEIRO et al, 2015;YAMADA;ABDALLA, 2004). Because soybean can form symbiosis with N 2 -fixing bacteria belonging to the genus Bradyrhizobium, the plant demand for N may be completely supplied by biological nitrogen fixation SIQUEIRA, 2006).…”