Relação de massa e localização do escleródio no solo com germinação carpogênica de Sclerotinia sclerotiorum

Abstract

Sclerotia of Sclerotinia sclerotiorum allow the fungus to conserve its pathogenic power for several years on the soil; however, there are incipient studies that relate the sclerotium mass and location on the soil to its pathogenicity. Thus, the aim of this study was to assess if the sclerotium mass and location on the soil can interfere in the carpogenic germination of S. sclerotiorum. Sclerotia were weighed and classified into six classes, (C1) sclerotia with mass inferior to 0.01 g, (C2) 0.01<0.02 g, (C3) 0.02<0.03 g, (C4) 0.03<0.04 g, (C5) 0.04<0.05 g, and (C6) 0.05<0.06 g. Then, they were stored in gerbox containing soil moistened up to 100% saturation and were allocated to the soil surface and buried to a 3-cm depth. Gerboxes were incubated in a BOD chamber, temperature of 20°C and 12 h photoperiod. The percentage of carpogenic germination was higher for sclerotia that were placed on the soil surface in all analyzed classes. Carpogenic germination tended to increase with the increase in the sclerotium mass; for the sclerotia placed on the soil surface, germination was 37.5, 62.5, 75, 87.5, 100 and 100%, while for buried sclerotia, it was 0, 37.5, 37.5, 62.5, 62.5 and 62.5% in C1, C2, C3, C4, C5 and C6, respectively. At the end of evaluations, buried sclerotia had fewer stipites and apothecia. On the soil surface, C4, C5 and C6 sclerotia originated more stipites and apothecia, while for buried sclerotia only C5 and C6 provided larger number of stipites and apothecia per sclerotium.