Effect of extracts from amphibian glandular secretions on asian rust (Phakopsora pachyrhizi) and biometry of soybean plants

Extracts from secretions of amphibians of the Bufonidae family were studied for their potential for direct control of phytopathogens, as well as for the activation of mechanism of defense against plant diseases. Thus, this study assessed the effects of glandular secretion extracts from Rhaebo guttatus and Rhinella marina against the fungi Phakopsora pachyrhizi and biometric responses on TMG 132 RR soybean cultivar. Thirty days after seeding, a spontaneously arise of the disease was noticed and, two days after the arise of the first pustules, plants were treated with glandular secretion extracts at the concentrations 0,1; 0,2; 0,3; 0,4 e 0,5 mg mL(-1), acibenzolar-S-methyl (500 L ha) and distilled water. None of the treatments resulted in statistical differences at the photosynthetic rates of the plants for chlorophyll a, chlorophyll b and total chlorophyll content. For the biometrical evaluations, glandular secretion extracts of R. guttatus resulted in statistical difference only for the variable plant height variable. Glandular secretion extracts from R. marina resulted in statistical difference only for number of root nodules but was not significant for the remaining variables. The results showed that glandular secretion extracts from R. guttatus and R. marina does not control Asian soybean rust; however glandular secretion extracts from R. guttatus at the concentrations 0,1mg mL(-1), 0,2 mg mL(-1) e 0,3 mg mL(-1) promotes greater plant height. The glandular secretion extracts from R. marina at the 0,1mg mL(-1), 0,2 mg mL(-1) e 0,4 mg mL(-1) negatively affects the number of plant nodules.

Automated summary

This study assessed the effects of glandular secretion extracts from Rhaebo guttatus and Rhinella marina on the control of the fungi Phakopsora pachyrhizi and the biometric responses of soybean plants. The results showed that the extracts did not effectively control the fungi, but certain concentrations of the extracts promoted plant growth, while other variables were not significantly affected.