HYDRATION LEVELS ON CONIDIAL PRODUCTION OF Metarhizium rileyi (Ascomycota) IN SOLID GROWING MEDIUM

Abstract

This study aimed to evaluate the conidial production of Metarhizium rileyi in rice with different water volumes. The bioassay was composed by completely randomized design (CRD), with four treatments (20, 30, 40 and 50 mL of distilled water), being added 100 g of rice thin and long, making a total of 10 plastic bags per treatment, which were autoclaved for 15 minutes at 1.0 atm pressure, to 120 ºC. After the cooling of the rice, were added in each plastic bag, 2.0 mL of suspension containing 1 × 108 conidia mL-1. Then the bags were incubated for ten days in a germination chamber (BOD type) at 25 °C (±1 °C), 80% (±10%) relative humidity and 12h photoperiod to promote conidial germination and growth of the fungus, being performed a mild agitation every two days. The use of higher water volume resulted in greater conidial production and greater number of viable conidia. However, the highest rate of conidia germination was obtained with the use of 30 mL of water, is this the volume of water that corresponds to the best results.