Efeito de coberturas poliméricas contendo compostos naturais sobre o crescimento da planta e o manejo do oídio em Hibiscus sabdariffa L.

Abstract

Edible coatings are formed from organic polymer matrices containing substances that do not cause damage to life or that promote improvements in your body. Organic matrices are biodegradable and have moderately formable features. In addition, natural antimicrobial compounds have a good outlook of use because of the lower impact on life and environment. However, they are easily degraded when applied in field. Therefore, the protection of these compounds is essential to be used in the field in the control of plant diseases. The edible coatings have been shown to be able to do this. However, its effect on the physiology and development of growing plants is still poorly understood, and may be indicated by the effects of antitranspirants, which are also fieldapplied polymer matrices to reduce plant transpiration and the effects of frost and saline stress on plants. In the first chapter, we review the application of this class of compounds and their effect on alternative management of diseases and plant development. In the second chapter, we prepared and tested edible coatings to control the powdery mildew in Hibiscus sabdariffa. We applied the following substances: 1) edible coating (EC) with starch and water (COB1), 2) EC with starch and Schinus terebinthifolius extract (EXT, 0.1 mg mL-1 of water) (COB2), 3) EC with starch, gelatin and EXT (COB3) and 4) EC with starch, gelatin, EXT, and S. molle oil (OIL, 0.3 mg mg-1 of starch) (COB 4), and 5) EXT and 6) water (control) in the periods of the crop cycle from 56 - 184 days after transplanting (DAT) or from 112 - 268 DAT. Our results do not indicate foliar warming effect by the coatings. They indicate that the EXT and OIL reduce the production of leaf of the plant, commercial product in certain regions of the world. The coatings did not affect fruit production and, inconsistently, reduced fruit diameter. However, the COB4 controlled up to 45% the powdery mildew in the leaves in relation to water, improving the quality of the commercialized product. Therefore, edible coatings are a promising tool in the management of plant diseases carrying antimicrobial compounds in the field.