Eficiência de fungos micorrízicos arbusculares isolados de solos sob diferentes sistemas de uso na região do Alto Solimões na Amazônia

Abstract

RESUMOOs fungos micorrízicos arbusculares (FMAs) são importantes componentes dos ecossistemas terrestres onde acreditase desempenharem papel fundamental para a sustentabilidade destes. Estes fungos sofrem influência de diversos fatores antrópicos como o uso da terra, que modificam a estrutura e diversidade das comunidades podendo comprometer suas funções ecológicas. No presente estudo avaliou-se o comportamento de FMAs isolados de solos sob diferentes sistemas de uso (SUT). Effectiveness of arbuscular mycorrhiza fungal isolated from soils under different land use systems in the Alto Solimões river region in the AmazonABSTRACT Arbuscular mycorrhizal fungi (AMF) are important components of terrestrial ecosystems where they are believed to play a fundamental role for their sustainability. These fungi are influenced by a number of anthropic factors such as, land use which modifies the structure and diversity of fungal communities and this may compromise their ecological functions. In the present study it was evaluated the behavior of AMF isolated from soils under different land use systems in (LUS). Fifty-one AMF were isolated in trap cultures from soil samples from different SUT tested on cowpea [Vigna unguiculata (L.) Walp] under controlled conditions. It was found that all AMF colonize the cowpea, but in a highly variable intensity. Similar results were found for phosphorus uptake and plant growth. Colonization ranged from 1 to 68%. Growth positive effects ranged from 33 to 148%, being more common in isolates from pasture and crops ecosystems. The enhancement in phosphorus uptake was generalized (95% all fungi), but their growth promoting effects did not followed the same trend. Only 39% of fungal isolated tested were efficient. These more isolated from almost all LUS. Fungal treatments with high efficiency had the following species: A. foveata, Glomus sp.1, Acaulospora sp.1 and a mixture the first two species with A. bireticulata and E. infrequens. The results indicate a wide efficiency diversity of AMF in the Alto Solimões region. Although this characteristic has no direct relationship with the LUS, the proportion of effective isolates varied with their origin.

Effectiveness of Arbuscular Mycorrhizal Fungal Isolates from the Land Uses of Amazon Region in Symbiosis with Cowpea

“…This pattern most likely resulted from the effect of dilution because all of these fungal treatments are among the treatments that promoted the highest production of SDM. This dilution effect on mycorrhized plants has been observed in soybeans (Paula et al 1988), in various tree species (Flores-Aylas et al 2003), and in cowpea (Silva et al 2009). …”

“…Although a direct relationship between the increase in SDM and P content from the soil can not be established, it appears that all the treatments in which inoculation increased SDM resulted in increased P levels in the plant, a fact that has been previously reported (Sanni 1976, Islan et al 1980, Almeida et al 1985, Rohyadi et al 2004, Silva et al 2009). Isolates efficient in absorbing P can reduce P deficits through increased absorption and increased P use by plants (Koide 1991) and by enhancing plant colonization by these fungi (Smith et al 1992).…”

“…Despite the geographic extent and the high plant species richness detected in the Amazon tropical forest, only recently the composition of AMF species from distinct land use systems has been accessed (Leal et al 2009, 2013, Stürmer and Siqueira 2011, Freitas et al 2014) and on the functional diversity of AMF communities (Silva et al 2009). Amazon soils exhibit high richness of AMF species, and 61 morphotypes have been reported to occur in soils under different land uses in the Western Amazon region, of which 30% represent undescribed species (Stürmer and Siqueira 2011).…”

“…Fungal communities originating from distinct land use system in the Brazilian Amazon region screened for their effectiveness had contrasting effectiveness in promoting plant growth and nutrition of cowpea, indicating the presence of efficient fungal lineages within each community that can be selected for inoculation programs (Silva et al 2009). In this study, fungal isolates belonging to distinct genera and species established in single cultures from these communities were compared according to their effectiveness in two types of soils.…”

Ocorrência de fungos micorrízicos em pau-rosa (Aniba duckei kosterm) e mogno (Swietenia macrophylla king) em diferentes épocas de coleta na região de Manaus

“…Há diversas pesquisas realizadas com associações micorrízicas na Amazônia com culturas anuais (Miranda et al, 2005;Silva et al, 2009), bem como com espécies perenes (Oliveira, 2001;Oliveira e Oliveira, 2004;Moreira et al, 2019 a,b).…”