Efeito e detecção de reguladores de crescimento no lenho de Eucalipto

Abstract

Plant hormones are organic substances that perform important functions for growth regulation and plant development. Auxin (IAA) and gibberellin (GA) are the main hormones involved in the process of xilogenesis. Many studies in the exogenous application of GA and IAA, separately and jointly, were conducted in order to elucidate its actions in the plant. The joint application of GA and IAA has constantly promoted greater growth and plant development, which promoted its use as regulators for agriculturally int eresting plants. Currently, the exogenous application of plant hormones is a common practice in many agricultural cultures, occurring in many configurations, which are used for various ends. However, in the forestry sector, with the exception of in vitro tissue propagation and stake rooting, the hormones are not yet used as a silvicultural practice for increasing productivity and wood quality. In order for the exogenous application of IAA and GA to become a silvicultural practice, it is necessary to determine the ideal concentrations and relations of these hormones by means of a dose-response experiment, according to the reported in chapter 2 of this dissertation. In addition to its practical use, by means of the exogenous application, it is of great importance to understand the form of action of the plant hormones. Priority must be given to IAA, since many studies have shown IAA as the main regulation organizer of the cellular dimensions and spatial standardization of the development of vascular tissue by means of its longitudinal and radial concentration gradients, respectively. The development of a unifying concept for the roe of IAA in the plant depends, among other things, on the detailed knowledge of its final distribution, which can be achieved by using techniques highly sensitive to IAA quantification from micro-samples of the plant. The 3 rd chapter of this dissertation reports a promising technique using the high performance liquid chromatography system coupled to sequence mass spectrometry (LC-MS/MS) equipped with electrospray ionization interface (ESI).