Arbuscular mycorrhizal fungi in rosewood (Aniba rosaeodora Ducke) and mahogany (Swietenia macrophylla King) in the Manaus region
In the State of Amazonas there are two distinct periods of rainfall distribution, which are concentrated between December and April and a dry period, which runs from June to September. This climate characteristic can interfere in the establishment of the mycorrhizal association in forest species, considering that soil moisture can interfere with the germination of mycorrhizal fungi spores. The soil moisture near the field capacity favors the development of symbiosis, and alternations between dry and rainy periods can favor the sporulation of AMF. However, there are discrepancies among the studies regarding the establishment of mycorrhizal fungi as a function of soil moisture. The restriction of water availability in the months of low precipitation induces in the microorganisms associated with the plant, the activation of adaptation mechanisms, such as increased sporulation. The mycorrhization occurs mainly in thin and new roots, which must be present at the time the AMF are observed, a situation that may vary according to the plant species and their location in the forest system. Mahogany (Swietenia macrophylla King) and rosewood (Aniba rosaeodora Ducke) are native species from the Amazon of high economic value. The cultivation of these plants involves the use of appropriate agricultural practices to obtain productive forest stands. The success of the establishment of these species depends on the ability to withstand edaphoclimatic variations and, consequently, to present high percentages of survival in the field and less need for cultural treatments, therefore, the association with mycorrhizal fungi can be of fundamental importance for the establishment of these species, as it can improve mineral nutrition and water absorption for the metabolism of plants in periods of less precipitation. These factors must be considered: seasonality, edaphic factors, host dependency, host plant ages, the sporulation skills and the patterns of distribution of FMA spores in soils. There are several studies carried out with mycorrhizal associations in the Amazon with annual crops (Miranda, Vilela, & 2005; Silva, Siqueira & Stürmer , 2009), as well as with perennial species (Oliveira, 2001; Oliveira & Oliveira, 2004; Moreira, Oliveira, Maia & Oliveira, 2019b). However, more researches are needed to better understand how mycorrhizal relationships are established in regional plant species. The present study verified the occurrence of mycorrhizal fungi in rosewood (Aniba rosaeodora Ducke) and mahogany (Swietenia macrophylla King) cultivated in two rural properties in the Community of Brasileirinho, in the municipality of Manaus, in three different periods, and to verify how these associations contribute to the nutrition of these two species.