Efeitos do evento sobre características estruturais, fisiológicas e bioquímica de mudas de Theobroma cacao L. (Malvaceae) e uso do silício como amenizador do estresse

• Autor(a) principal: Fantinato, Dayana Effgen
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/10736
• topic: Cocoa farming; Enzymes; Abiotic stress; Lignin; Morphoanatomy; Gas exchange; Estresse abiótico em plantas; Trocas gasosas; Morfoanatomia; Agronomia; Cacaueiro x Cultivo; Enzimas; Lignina; Anatomia vegetal; 57

The cacao tree (Theobroma cacao) is a perennial species, of arboreal origin originating in the Upper Amazon region. The economic importance of this species is mainly related to its seeds, which are used for the manufacture of chocolate. Within the national scenario, Espírito Santo occupies the 3th position as the largest producer, and most of this production is in the municipality of Linhares. In Espírito Santo, the cultivation of cacao began to be full sun. In this condition, the plants are more exposed to the action of winds. It is known that wind is characterized as an environmental variable that interferes with plant growth, however, little is known about its effects on the anatomical, physiological and biochemical characteristics of cacao. In an attempt to ameliorate abiotic stresses, silicate fertilization has shown promise with positive effects on growth, gas exchange and biochemical defenses. In this context, the objective of the present work was to evaluate the influence of the wind through the analysis of gas exchange, the morphoanatomic characteristics, the contents of structural carbohydrates and lignin on cocoa seedlings. From the results, the effects of a possible action of the silicon in the improvement of the behavior of the cacao tree in the face of the stress caused by wind were evaluated. For this, in a first experiment, seedlings grafted with the genotype PS-1319 of T. cacao were used in two areas, one being open, more exposed to the wind and another one consorted with banana trees, with lower wind incidence. Monthly growth analyzes were performed on these plants for 12 months and at the end of this period, leaf anatomy, gas exchange and the content of structural carbohydrates and lignin were evaluated. In the second experiment, seedlings of the same genotype were grown in nurseries and submitted to silicon treatments, applied to the leaf and soil, at concentrations of 2 mM and 1 mM, respectively. Later, the seedlings were submitted to a wind source with an average velocity of 2.25 m / s, from 11 am to 6 pm, for 28 days. At the end of the experiment, growth analysis, foliar anatomy, foliar and lignin carbohydrate content, gas exchange and biochemical analysis were performed. The results showed that the plants of the open area had higher density, stomatal conductance and greater photosynthesis. Anatomically, the leaves were thicker, presenting larger palisade and spongy parenchyma, greater abaxial and adaxial epidermis, besides a larger central vein and hemicellulose and lignin contents. However, there was a reduction in growth. The evaluation of the effects of silicon on the plants subjected to the wind showed that the silicate fertilization had a positive effect, promoting greater robustness, higher values of area and stem diameter, stomatal density and leaf thickness with increase of the vein, adaxial epidermis and palisade parenchyma, improving the intrinsic efficiency of water use and lower transpiration, and having made the enzymatic activity efficient, providing energy savings