Avaliações morfofisiológicas em mudas de eucalipto resultantes da aplicação de ácido jasmônico e flexões caulinares

• Autor(a) principal: Lima, Paulo Ricardo
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do UNIOESTE
• Texto Completo: http://tede.unioeste.br/handle/tede/3259
• topic: Eucalyptus urophylla vs Eucalyptus grandis; Estímulo mecânico; Estímulo químico; Qualidade de mudas; CIÊNCIAS AGRÁRIAS:AGRONOMIA:SILVICULTURA

The objective of the present study was to evaluate the rustification of hybrids of Eucalyptus urophylla versus Eucalyptus grandis (clone 1528) with application of jasmonic acid (JA) and kaolin flexions stem and their subsequent field development. The experiment was conducted at the State University of Western Paraná, in the municipality of Marechal Cândido Rondon, PR. Three experiments were carried out to evaluate the responses of eucalyptus plants to the exogenous application of JA and flexions stem. In the first, a completely randomized experimental design with seven treatments (control, 2.0, 4.0, 6.0 and 8.0 μmol L-1 of JA, 20 and 40 stem flexions daily), with five replications of twenty seedlings, in the protected environment. After 4 weeks of application of the treatments were determined the increment in height, stem diameter, number of leaves, dry masses of roots and aerial part and relative index of chlorophyll (SPAD). At 90 days after planting (field), the increases in height and in the stem diameter and the height/diameter ratio of the seedlings were evaluated. In the second experiment in protected environment, using a completely randomized design with five replications of 20 seedlings, with the following treatments: T1: control, T2: 8.0 μmol L-1 of JA and T3: 40 stem flexions. They were measured the net assimilation rate of CO2 (A), stomatal conductance (gs), internal CO2 concentration (Ci), leaf transpiration rate (E), water use efficiency (WUE), intrinsic efficiency of use of Water (iWUE) and carboxylation efficiency (Fc). The third experiment in protected environment was a completely randomized design with seven treatments (T1: control: T2: 2.0 μmol L-1 of JA; T3: 4.0 μmol L-1 of JA; T4: 6.0 μmol L-1 of JA; T5: 8.0 μmol L-1 of JA; T6: 20 stem flexions; and T7: 40 stem flexions) with five replicates of twenty seedlings. After applied of the treatments were evaluated, the increment in height, diameter stem and lignin content of root and stem and flexural stiffness of the stem. The rustified seedlings were transplanted to the field and at 90 and 150 days the height and stem diameter increments were evaluated. The treatments with application of JA and control showed a greater increase in height and number of leaves during the rustification phase and obtained a greater increase in height and in the diameter of stem after field planting. The dose of JA applied in the seedlings was insufficient to alter the photosynthetic responses to the control. Mechanical stimuli promoted an increase in the maximum photosynthetic capacity and maximum assimilation of CO2, but reduction in the efficiency of water use, that is, lower photosynthetic efficiency when compared to other treatments. For flexural rigidity, seedlings submitted to mechanical stimuli presented greater curvature resistance. Applications of JA above 6.0 μmol L-1 and mechanical stimuli obtained an increase in the lignin content in the stem in eucalyptus seedlings. Minor doses of JA and imposition of 20 push-ups resulted in seedlings with increase in diameter stem increment. The track analysis showed that the increase in the lignin content promotes more rigid stems and these have a greater direct effect inversely proportional to the average increase in height and the diameter of the stem at the level of the ground. Therefore, the application of stem flexures and jasmonic acid were able to alter the lignin concentration in the stem, providing greater flexural stiffness in eucalyptus seedlings, but this smaller flexural stiffness was not reflected in higher seedling quality under the studied conditions.