Teste do etanol: desenvolvimento de equipamento para determinação do vigor em sementes de soja

Abstract

In tests for assessing vigor in seeds, they must be fast, efficient, and standardized, including tests that allow precise differentiation between lots. Among these tests, the ethanol one appears as an alternative that provides desirable characteristics to be applied in the internal quality control programs of seed-producing companies because it is practical and fast. However, the test is performed with adapted equipment, requiring its equipment, using high-precision sensors, which will guarantee the reliability of the results. Thus, to develop equipment capable of quantifying the presence of ethanol produced by soybean seeds when subjected to hypoxia for different soaking times, to compare the results obtained by the new equipment with other standard vigor tests and evaluate the metabolism fermentation during the ethanol test. The work was divided into two chapters, and both used a completely randomized experimental design, with treatments consisting of 10 lots of soybean seeds. Chapter I was divided into two experiments, the first corresponding to the development of equipment for measuring ethanol with the MQ-3 sensor and its components and the second related to the sensor stabilization time (3; 6; 9; 12; 15; 18; 21; 24; 27 and 30 seconds) in soybean seeds submitted to the anaerobic process. Chapter II initially evaluated the initial quality of the lots by testing water content, germination, seedling emergence, accelerated aging, tetrazolium test, electrical conductivity, and seed respiration. For the ethanol test, 25 seeds without physical damage were used and placed in 150 mL flasks containing 40 mL of deionized water. Subsequently, the seeds remained soaked for 30, 60, 90, and 120 minutes at a temperature of 41 °C in BOD. After this period, the flasks were attached to the equipment developed, and ethanol released by the seeds was measured. The equipment and the MQ-3 sensor had a satisfactory performance, showing the stability of average measurement after 16 seconds. This time is recommended for the use of the breathalyzer in soybean seeds. Through this same MQ-3 sensor, it is possible to efficiently detect ethanol present in the air released by soy seeds during the anaerobic process. The application of the ethanol test in soybean seeds is efficient in ranking the lots at different vigor levels when the soaking time of 30 minutes is used, showing a moderate association between the electrical conductivity test and seed respiration. The activity of the enzymes LDH, PDC and ADH proves that there was the production of ethanol during the soaking process of soybean seeds.