Leveduras no controle de Colletotrichum truncatum e seu efeito na produtividade da soja

Abstract

Anthracnose is a disease that is difficult to control, requiring alternatives for proper management, and among these, biological control through yeasts may be an alternative. The aim of this study was to evaluate yeast isolates for their potential antagonist against Colletotrichum truncatum 'in vitro', its control over the incidence of the pathogen and its influence on crop productivity. The yeast isolates of the genera Candida spp., Cryptococcus spp., Pichia spp., Rhodotorula spp., Sporidiobolus spp., Sporobolomyces spp. and Zygoascus spp., were subjected to in vitro tests, namely: non-volatile compounds (yeasts x C. truncatum), volatile compounds and the effect of yeast culture filtrates. With the best in vitro treatments, treatments for field experiments were determined. The treatments used for the field experiment were: Control (water), Bion® (positive control), Saccharomyces cerevisiae (positive control), Rhodotorula glutinis, Sporidiobolus johnsonii, Zygoascus hellenicus. The incidence of anthracnose in pods in the upper and lower halves of the plants was evaluated. From these results, the area under the anthracnose incidence progress curve for the lower (AUAIP-L) and upper (AUAIP-U) half was calculated. The production components were determined: number of pods per plant (NPP), number of grains per pod (NGP), weight of a thousand grains (WTG) and productivity (PROD). The greatest performance in controlling the pathogen obtained in in vitro prospecting was with the isolates R. glutinis (AH 18-1), S. johnsonii (AH 19-2), S. johnsonii (AH 19-3), Z. hellenicus (AH 07-2) and Z. hellenicus (AH 14-1) For the field results, in relation to the incidence of disease, the treatments S. cerevisiae, R. glutinis (AH 18-1), S. johnsonii (AH 19-2) and Z. hellenicus (AH 14-1) significantly reduced AUAIP-L and AUAIP-U. Regarding the production components, compared to the control (water), significant results for NPP were obtained with Bion®, S. cerevisiae and R. glutinis (AH 18-1); for NGP and WTG they were obtained with Bion®, S. cerevisiae, R. glutinis, S. johnsonii, Z. hellenicus and for productivity they stood out R. glutinis, S. cerevisiae and Bion® Yeasts L22 Rhodotorula glutinis (AH 18- 1), L27 Sporidiobolus johnsonii (AH 19-2), L28 Sporidiobolus johnsonii (AH 19-3), L33 Zygoascus hellenicus (AH 07-2) and L35 (Zygoascus hellenicus (AH 14-1)), showed potential to control C. truncatum The yeasts Rhodotorula glutinis (AH 18-1), Sporidiobolus johnsonii (AH 19-2) and Zygoascus hellenicus (AH 14-1) decreased by 61.7, respectively %, 58.7% and 41.3% for the incidence of anthracnose in the lower half (AUAIP-L) and 49%, 43.8% and 33.9% for the upper half (AUAIP-U) in soybean culture. In the incidence of anthracnose, Rhodotorula glutinis (AH 18-1) and S. cerevisiae contributed to an increase of 44.4% and 41.5%, respectively, in soybean grain productivity.