masterThesis
Indução de resistência por agentes abióticos em soja à mosca-branca
Fecha
2017-08-28Registro en:
LOCATELI, Bruna Taiza. Indução de resistência por agentes abióticos em soja à mosca-branca. 2017. 65 f. Dissertação ( Mestrado em Agroecossistemas ) - Universidade Tecnológica Federal do Paraná, Dois Vizinhos, 2017.
Autor
Locateli, Bruna Taiza
Resumen
Soybean is one of the oldest and most practiced crops in the world,and its importance is due to its high protein content,its use in food for humans and animals, as well as being the main Brazilian export product. Despite the high national production, the crop has productivity losses due to attacks of insect pests, among them, the whitefly Bemisia tabaci Botype B (Hemiptera: Aleyrodidae). Its traditional control is carried out with
insecticides, but currently alternative methods are being evaluated considering the noncontamination of the environment and human health. The present work had as objective to evaluate the potential of resistance elicitors in the process of vegetal defense against the whitefly in soybean plants. Two experiments were carried out at the Federal University of Technology - Paraná, Campus Dois Vizinhos-PR, in 2017. Soybean seeds
of cultivar BRS 284 were sown in polyethylene pots with capacity of 10 liters, containing soil gathered from crops at UTFPR. Cultivation occurred in a greenhouse, and the vessels were placed on benches until the V6 phenological phase, when the elicitors were applied by microaspersion according to the treatments: ASM (0.005%), SA (2 Mm), foliar fertilizer composed of potassium phosphite (0.004%); chitosan (1%), silicon (0.25%) and control (distilled water). The first experiment aimed to evaluate the potential of the elicitors to activate plant defense mechanisms, considering the presence and absence of the whitefly. For this, the elicitors were applied, and for the condition of absence of insects, the vases remained in individual cages with anti-aphid screen, to avoid contact with the insect pest. Then, the plant material was collected at intervals of
0, 24, 48, 96 and 168 hours after the application of resistance elicitors. Total proteins, total and reducing sugars, phenolic compounds, tannins and the activity of the enzymes peroxidases, phenylalanine ammonia-lyase (FAL) and chitinase were evaluated. The second experiment sought to evaluate the oviposition preference due to the application of the elicitors. After 24 hours of application, 500 not sexed whitefly adults were
released in the center of the vases on the bench, having a choice among treatments. After 48 hours of the initial infestation, two leaflets of the median third of the plants were collected from each treatment. The leaflets were evaluated under stereomicroscope for the quantification of the number of eggs. The total leaf area of the leaflets was also calculated using Image J. The resistance elicitors have the capacity to activate the
primary metabolism through the synthesis of total proteins, as well as demonstrate the potential in the activation of defense mechanisms among them, the route of the phenylpropanoids with the activation of the enzyme FAL and the formation of phenolic compounds. They also activated pathogenic enzymes such as peroxidases and chitinase, such activations have specificity for the elicitor and the activation time. The use of
elicitors when challenged with insects demonstrated greater effectiveness of activation of the enzyme FAL, peroxidase and chitinase, these enzymes related to the process of plant defense against insects. ASM, silicon and chitosan elicitors have the potential to reduce oviposition of the whitefly, which may be related to the activation of plant defense mechanisms.