Sensibilidade de Metarhizium anisopliae à temperatura e umidade em três tipos de solos

Abstract

The aim of this research was to evaluate the effect of soil temperature and soil water saturation on Metarhizium anisopliae survival in three soil types. The fungus survivorship was determined in the following soils types: Oxissol with clay texture, Oxissol with medium texture and Alfissol with medium sandy texture. The temperatures tested were 21.5; 26.8 and 31.5°C and the soil water saturation were 35, 65 and 100%. The fungus survivorship was evaluated at zero, 20, 40, 60, 80, 100, 120 days after soil incubation in each temperature accessed. In the assay for water saturation studies, the survival was evaluated after zero, 14, 28, 42, 56, 70, 84, 96, 112 days of incubation at 27.0±1.0°C. In both the assays, the colonies forming units (CFU) was determined in Petri dishes. The fungus survival was significantly influenced by the soil temperature and soil moisture. An increase in the number of CFU was observed in soil held at 26.8 and 21.5°C. The highest temperature (31.5°C) was more detrimental to fungus growth and survival than the lowest ones. The fungus grew quickly in the 65% soil water saturation but afterwards a decrease in the soil fungal population in the three soil types was observed. The 35 and 100% soil water saturations favored the fungus survivorship in the soil but was less favorable for the fungus growth.