Análise de imagens na determinação da viabilidade de sementes de milho pelo teste de tetrazólio

Abstract

Corn is one of the main agricultural crops in the world and an important source of starch, sugar, oil, and protein. Brazil is the third largest global producer of this crop, and the use of seeds with high physiological potential is essential to achieve the maximum productive potential of corn fields. Germination testing has been the method used to assess the viability of seed lots, but the tetrazolium test is a promising alternative technique as it can be conducted in a few hours and provides sufficient information about the physiological quality of seeds. Image analysis of seeds subjected to the tetrazolium test allows for precise and objective evaluation of seed quality, mitigating subjectivity and lack of accuracy in result interpretation. The objective of this study was to evaluate the physiological quality of corn seed lots harvested in the state of Alagoas by means of the tetrazolium test using image analysis resources and, at the same time, it was sought to optimize this test, establishing standards and techniques to aid in the interpretation of the results obtained. The evaluation of the physiological potential of the five corn seed lots was carried out using a completely randomized experimental design with four replicates of 50 seeds. The seeds were placed in moist germination paper, in the proportion of 2.5 times the amount of water in relation to the weight of the paper. Imbibition was performed for approximately 16 hours at a temperature of 30 oC. The corn seeds were sectioned longitudinally and medially through the embryo. After cutting, the half of each seed where the identification of the embryo parts was clearer was placed in disposable plastic cups, immediately submerged in a tetrazolium solution (0.075%), and placed in a chamber set at 40 oC. During the staining process, the seeds were kept in the dark. The staining time was 180 minutes. Once the embryos reached the ideal coloration, the solution was discarded, and the seeds were washed three times under running water for a total of 60 seconds and then kept immersed in water. Evaluation was performed under a 6x magnifying lens with lighting. To evaluate viability and vigor, the embryo was carefully examined and, according to the level of damage and deterioration, the seeds were classified into three classes. Class 1 included vigorous seeds, Class 2 included viable seeds with low vigor, and Class 3 included non-viable seeds. The image analysis method proved to be a valuable tool in determining the vigor and viability of corn seeds in a short period compared to conventional methods. The possibility of enlarging the images allows for precise analysis of the embryonic axis structures, which can contribute to the improvement in the selection of seed lots and consequently agricultural productivity.

Key words: agricultural productivity. vigor. Zea mays L.