Nuclear magnetic resonance methodologies applied for seed evaluation

• Autor(a) principal: Marassi, Agide Gimenez
• Data de Publicação: 2021
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/76/76132/tde-08092021-104102/
• topic: Análise de imagem; Image analysis; Imagem por ressonância magnética; Magnetic resonance image; Seed technology; Tecnologia de sementes

Damages to seeds, whether due to the occurrence of mechanical injurie, attacks by insect pests, or by pathogens, cause effects that can be evidenced after their occurrence or during storage, resulting in losses of germination and vigor. The application of the X-Ray scanning has been recommended by different associations of seed analysis as a fast and non-destructive method for seed inspection, but this technique presents limitations when assessing the depth of damage in the internal tissues of the seeds or when the density variation of the tissues is small. However, the introduction of the Nuclear Magnetic Resonance (NMR) methodologies based on the nuclear density weighted can bring advances in the study of seed quality originated on internal anatomical changes. The objectives of this research were to evaluate soybean and corn seeds by comparing X-Ray and Magnetic Resonance Imaging (MRI) between healthy, immature seeds, and those attacked by pest insets, as well as evaluating soybean seeds of high and low vigor by NMR relaxometry. Soybean and corn seeds of the same cultivar with the problems described were selected and submitted to image analysis by X-Ray and MRI with the Fast Low-Angle Shot (FLASH) and Zero Echo Time (ZTE) sequences, respectively. On the other hand, soybean of the same cultivar but with high and low vigor were selected and submitted to the relaxometry T1-T2 correlation experiment. The NMR methodology allowed the identification of damage to internal seed tissues in a satisfactory way in the image, highlighting the full extent of the damage, as well as it was possible to evaluate high and low vigor seeds with this approach. Also, a new modification in the ZTE sequence was proposed. The results obtained corroborate the NMR technique as a powerful auxiliary tool in the evaluation of internal tissues and for the selection of high-quality seeds.