Vigor de sementes de Brachiaria brizantha cv. Marandu por análise de imagens

Abstract

Image analysis is a technique with potential of use in the evaluation of seed quality in the quality control programs of several crops, including forage grasses for optimization of time and reduction of human interference in obtaining the results. The objective in this research was to develop a fast and efficient methodology to evaluate the seed vigor of Brachiaria brizantha cv. Marandu by means of the seedlings images analysis. Nine lots of braquiária produced in the state of Mato Grosso, harvest of 2016/2017 were used. For the lots characterization, water content, germination, first germination count, tetrazolium, electrical conductivity, emergence, emergency speed index and average emergency time at 25 and 30 °C were determined. Experiments were carried out to verify the best substrate conditions, temperature and luminosity, for conducting the germination test in an attempt to adapt a methodology for the seedlings images analysis. It was established a protocol of normal seedlings analysis obtained in the germination test carried out between paper, in the alternating temperature condition 20-35 °C. The root length (RL), hypocotyl length (HL), seedling total length (STL) and root length ratio by hypocotyl length (RLR / HL) were obtained and analyzed using GroundEye® image analysis equipment, version S800. The lots were classified into two quality levels, in the initial characterization, by the electrical conductivity tests, first germination count and emergence average time, at constant temperature of 25 °C, highlighting lots 8 and 9 as the lower quality. It is possible the differentiation of seed lots Brachiaria brizantha cv. Marandu at seven days of sowing in substrate paper roll, in the light presence, which allow a better root orientation system and also seedlings aerial part. The seedlings images analysis of Brachiaria brizantha cv. Marandu by the root length evaluation, at seven days, allows the lots distinction of different physiological quality levels.