Digital image processing as a component to assess primary root emergence from soybean seeds

ABSTRACT Among the tests available for seed vigor assessment, the primary root emergence (RE) test has gained prominence as a provider of valuable information regarding the seed performance of different species on account of its efficiency, sensitivity and rapidity. Furthermore, the use of computational resources to identify the RE can be very useful for refining the information provided. This research study aimed to evaluate the efficiency of RE, compared to recommended tests assessing the seed vigor of soybean seeds, and verify whether specific parameters, as measured by the ImageJ® software to identify RE, are effective in estimating soybean seed vigor. Nine seed lots with similar germination but differences in vigor were used. Germination and vigor (germination first count, electrical conductivity, accelerated aging, tetrazolium, RE, and field seedling emergence tests were performed); RE was evaluated after germination under four temperature/period combinations. After the RE test, seedling images were captured and analyzed by ImageJ® software and data from the perimeter, area, circularity, aspect ratio, roundness, and solidity were obtained. Information provided by the RE test was similar to those from the accepted vigor tests, indicating the possibility of including this test in soybean seed quality control programs. Parameter circularity, aspect ratio, roundness and solidity provided consistent data for detecting the RE from soybean seeds germinated at 30 °C for 24 h, with a primary root length of at least 1.0 mm. These parameters provide a rapid and objective evaluation of soybean seed vigor.