Plasticidade fenotípica de plantas jovens de Handroanthus chrysotrichus (Mart. Ex DC.) Mattos (Bignoniaceae) em resposta a radiação solar

• Ano de defesa: 2012
• Autor(a) principal: Soares, Manuela Gonoring
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Biologia Vegetal; UFES; Programa de Pós-Graduação em Biologia Vegetal
• Palavras-chave em Português: Acclimation; Anatomy; Stem; Physiology; Leaf; Morphology; Caule; Ipê-amarelo; Morfologia; Plasticidade; Aclimatação (Plantas); Anatomia vegetal; Fisiologia vegetal; Agronomia; 57
• Link de acesso: http://repositorio.ufes.br/handle/10/5728

The ability of plants to show functional adaptive responses in relation to environmental conditions is known as plasticity and can be expressed by the acclimation process. In the forest environment, light is a major factor in the establishment and distribution of plant species. In this context, more plastic species have higher survival rates in relation to the variation of light availability. Adjustments can be physiological, morphological and anatomical and vary with the level of radiation exposure and the characteristics of plasticity of the individual. Thus, this study aimed to evaluate the plasticity of young plants of Handranthus chrysotrichus in response to different light intensities. For this purpose, plants were subjected to three treatments: full sun (100% of solar radiation), moderate shade (50% of solar radiation) and severe shading (5% of solar radiation). The plasticity was evaluated by analyzing changes in physiological characteristics levels, morphological and anatomical. Analyses of growth, photosynthetic pigments content, leaf soluble carbohydrates, antioxidant enzymes (catalase and ascorbate peroxidase), leaf anatomy (thick cuticle, epidermis, palisade parenchyma, paravenal mesophyll, spongy mesophyll and stomatal density) and stem anatomy (thickness of the periderm, secondary phloem, vascular cambium, secondary xylem, diameter, length and density of vessels), histochemical tests and plasticity index (PI) after 90 and 200 days of treatment. For leaves, were evaluated leaves pre-existing to the treatments and new leaves that emerged. Plants show responses commonly found in species adapted to sun and shade. Growth was stimulated in response to high irradiance by the greater accumulation of dry weight and leaf soluble carbohydrates. The content of photosynthetic pigments was higher in plants under severe shading. The catalase activity was lower in plants grown under full sun and the enzyme ascorbate peroxidase did not vary between treatments at the end of the experiment. In relation to leaf anatomy, there were variations in the thickness of the cuticle, of measured leaves tissues and stomatal density. The stem showed variation in the measured tissue thickness, diameter and density of vessels. The anatomic variables analyzed showed higher values in plants in full sun and moderate shade. Regarding the histochemical tests, differences were found in the deposition of starch grains in stem tissues, most in full sun. The analysis of IP demonstrated that the adjustments after 90 days of treatment were predominantly physiological. The content of photosynthetic pigments and the total dry mass were the most plastic characteristics. However, after 200 days of treatment, the settings were predominantly morphological (specific leaf mass, specific leaf area, leaf area ratio, as well as the production of total dry mass), leaf anatomical (thickness of the spongy parenchyma, stomatal density) and anatomical stem (thickness range of vascular cambia). The results indicate that young plants of H. chrysotrichus exhibit great plasticity to the variation of light availability, which makes this recommended species for reforestation and reclamation