Argilas silicatadas em Coffea arabica: intensidade da cercosporiose, características fisiológicas e mecanismos de defesa

Abstract

Cercospora coffeicola, the causal agent of brown eye spot, is widespread in all Brazilian coffee regions and the disease can lead to losses of up to 30% in production. The brown eye spot’s management is mainly carried out through chemical control. However, due to the reduced sensitivity of the pathogen to some active ingredients and concerns with the environment, studies of alternative components for the control of brown eye spot are necessary. Particle films, such as silicate clays, have shown promising results in the management of fungal diseases, both for physical protection and plant resistance induction. This study aims to evaluate the effects of different silicate clays on coffee physiology, on the incidence of brown eye spot and on the activity of defense enzymes of the phenylpropanoid pathway. The experiment was installed in a randomized block design, as silicate clays (Surround®WP, kaolinitic clay and ssl clay / 200) were sprayed on Coffea arabica seedlings under greenhouse and field conditions. Plant growth, chlorophyll a, chlorophyll b, carotenoids, total soluble phenolic compounds and soluble lignin were formulated. Based on the results obtained, the Surround® WP product was selected to conduct a new experiment in a greenhouse. The product application was carried out seven days before the inoculation of C. coffeicola and to correct the incidence of brown eye spot, they were carried out weekly after the appearance of the first symptoms. The activity of plant defense enzymes was also determined: phenylalanine ammonia-lyase (PAL), polyphenoloxidase (PPO) and peroxidase (POX) and leaves were collected at 0, 24, 36, 48 and 72 hours after the pathogen’s inoculation. The spraying of silicate clays did not influence coffee growth. Among the treatments produced, plants sprayed with the Surround® WP product stood out for presenting the highest levels of total chlorophyll and lignin in the greenhouse and total soluble phenolic compounds in the field. The application of Surround® WP reduced the incidence of brown eye spot in coffee and did not influence the activity of the enzymes PAL, PPO and POX. Surround® WP silicate clay can be a viable alternative in the integrated management of brown eye spot, reducing the environmental impacts.