Biológicos no controle de doenças, indução de resistência e promoção de crescimento na cultura da soja

Abstract

The growing concern about sustainability and the reduction in the use of chemical pesticides has sparked growing interest in the use of biological control agents (or biologicals) as an alternative in the integrated management of diseases. The objective of the present study was to evaluate the potential of the commercial product Pardella® based on Trichoderma harzianum, Trichoderma asperellum and Bacillus amyloliquefaciens, as a biocontrol agent, resistance induction and growth promotion in soybean crops. For this, seven experiments were carried out: (1) Direct pairing and mycelial growth test of the fungi Sclerotinia, Rhizoctonia, Macrophomina, Mhomopsis, Fusarium; (2) electron microscopy of pathogen versus biological structures; (3) soybean germination in the presence of a biological control agent; (4) physiological performance of soybeans in the presence of biological control agents; (5) potential use of a biological control agent on powdery mildew in soybeans; (6) induction of resistance in soybeans by biological control agents; (7) effect of biological control agents on end- of-cycle diseases (CLDs). All experiments were conducted in the laboratories, greenhouse and experimental area of the Federal Technological University of Paraná (UTFPR), Campus Dois Vizinhos-PR and Campus Pato Branco-PR, using soybean seeds from the cultivar P96Y90RR. The R statistical programming environment was used for data analysis. To evaluate the mycelial radial growth of pathogenic fungi, the Verhulst Logistic Growth Model was adopted. The biological control agents tested in this study showed high in vitro potential as inhibitors for some phytopathogenic fungi, including Sclerotinia, Rhizoctonia, Macrophomina, Phomopsis, Fusarium, which cause important diseases. in soybean cultivation. Among the mechanisms involved in control are competition and mycoparasitism, through mechanical inhibition by strangulation, coiling and thinning of hyphae, and rupture of septa. The application of the commercial product based on Trichoderma harzianum, Trichoderma asperellum and Bacillus amyloliquefaciens did not provide gains in the physiological quality parameters of seeds and in the physiological performance of soybean plants under natural environmental conditions. There was no effect of the biological control agent on powdery mildew in soybeans in an experiment in pots under greenhouse conditions. Biological control agent, with the activation of the chitinase enzyme in plant tissues. The biological control agents present in Pardella® had a positive effect on reducing the severity of end-of-cycle diseases (CLDs) under field conditions. In general, biological control with species of Trichoderma and Bacillus amyloliquefaciens proved to be suitable for application aimed at controlling pathogens, with a consequent contribution to reducing dependence on fungicides.