Influência da temperatura, salinidade e Ph no crescimento de fungos da caatinga com potencial para promoção de crescimento vegetal

Abstract

In arid and semi-arid environments, resources, vegetation and the diversity of microorganisms go through times of variable abundance. These areas live a continuous process of soil degradation and it is in this context that fungi appear presenting adaptations that, in addition to providing them with a higher survival rate, can also benefit the organisms that are around them. In this sense, this study aimed to investigate the growth of Caatinga’s fungi under different physicochemical conditions to use them in the future in the production of a consortium for the formulation of a bioinoculant. The experiments carried out in this study were conducted with fungi isolated from soil samples collected in may 2018, in areas of the Aroeira farm, located in the city of Irauçuba. Seven morphotypes were tested, five from the soil sample from the exclusion area and the other two from the natural area. For the thermotolerance test, the strains were incubated in PDA medium at 15, 30, 35, 40, and 45°C, for the halotolerance test, PDA + NaCl medium was prepared so that media with the following salt percentages were used: 0%, 0,9%, 2%, 4%, 8%, and 10%, finally, for the pH tolerance test, the PDA medium with adjusted pH to the following values was used: 4,0, 5,6, 6,0, 7,0, and 8,0. All morphotypes submitted to the thermotolerance experiment grew at 15, 30, and 35°C, the last temperature at which colonies presented the most considerable areas, no strain showed growth at temperatures of 40 and 45°C. The seven fungi used in the halotolerance test, except NIRA 04 which did not show growth at a concentration of 10%, grew in the six media with different percentages of NaCl. All strains submitted to the pH tolerance experiment grew at pHs 4,0, 5,6, 6,0, 7,0, and 8,0 , with pH 4 being the one in which the colonies presented the smallest areas. The results presented show the influence that the three variables used in this study, temperature, salinity, and pH, have on the radial growth of fungi from different soil samples in an area susceptible to desertification in the Caatinga. Finally, more studies must be carried out to evaluate the influence of other variables on the growth of these microorganisms, in addition to testing the potential properties of these strains, to select the most promising in the future and use them as a bioinoculant applicable in the recovery of degraded soils.