Associação de indutores de resistência para o manejo da ferrugem do cafeeiro e análise bioquímica da resposta de defesa induzida

Abstract

Leaf rust is a major coffee disease and farmers are increasingly seeking new alternatives to control this disease. The present work was to evaluate the inductors of resistance associated or isolated for the management of rust in coffee seedlings, and to study the effect of the activation of mechanisms involved in the defense response. To meet the objectives, three experiments were carried out. The first was conducted in a greenhouse with the cultivar Mundo Novo using inductors of resistance and associations: NEFID (coffee leaf extract); NEFID + copper phosphite 5.0 mL L-1, NEFID + manganese phosphite 5.0 mL L-1; NEFID + copper phosphite 2.5 mL L-1 + manganese phosphite 2.5 mL L-1; ECFC (bark extract of coffee); ECFC + copper phosphite 5.0 mL L-1; ECFC + manganese phosphite 5.0 mL L-1; ECFC + copper phosphite 2.5 mL L-1 + manganese phosphite 2.5 mL L-1; copper phosphite 5.0 mL L-1; manganese phosphite 5.0 mL L-1; ASM (acibenzolar-S-methyl) 0.2 g L-1, Viça-Café Plus 7.0 g L-1; fungicide (cyproconazole + azoxystrobin) 1.25 mL L-1, an inoculated and an absolute control. In the second experiment we evaluated the effect of the treatments used in the first experiment in regards to germination of urediniospores of H. vastatrix. The third experiment evaluated the effect of NEFID, manganese phosphite, association NEFID + copper phosphite + manganese phosphite, ASM and the fungicide cyproconazole + azoxystrobin, as these treatments worked best in the first experiment in regards to the activity of enzymes defense, the levels of phenolics and lignin. The NEFID + copper phosphite + manganese phosphite reduced rust severity by 84% and presented 85% of inhibition of the germination of the spores of H. vastatrix. It was observed that all the associations of inductors of resistance plus treatments of NEFID and ECFC provided better growth of seedlings. In the biochemical experiment, it was observed that for the association of NEFID + copper phosphite + manganese phosphite, inoculated, NEFID, without an inoculation, and ASM, inoculated and not inoculated; there was an increase in peroxidase activity. Increased Chitinase activity was observed in coffee leaves treated with ASM and manganese phosphite, not inoculated with H. vastatrix. The association of NEFID + copper phosphite, + manganese phosphite, NEFID, manganese phosphite and and fungicide cyproconazole + azoxystrobin promoted increased of β-1,3-glucanase activity in uninoculated leaves of coffee. As for the lignin content, there was no significant difference in treatments. It was also noted that there were higher levels of total soluble phenols in plants treated with ASM and fungicide without pathogen inoculation and in all treatments except the control, with pathogen inoculation. The association of NEFID + copper phosphite + manganese phosphite, NEFID and manganese phosphite controlled the coffee rust of seedlings, increased activity of defense proteins, total soluble phenols and also by direct toxicity to the pathogen. The association of products with different modes of action, such as inductors of resistance and direct toxicity to pathogens, which are less toxic to humans and the environment has a promising future in sustainable agriculture.