Methodology Proposal for Evaluation of Vigor in Soybean Seeds by Respiratory Activity

The respiratory activity is one of the first biological manifestations of vigor loss in seeds. Detecting loss of seed vigor can help to monitor and control seed production by the seed industry. This research aimed to develop and validate a novel method using carbon dioxide concentration to evaluate vigor of Glycine max [(L.) Merrill] seeds. The proposed method measures CO2 released by seeds with infrared through a carrier and exhaustion system in a closed system. Samples of 25 seeds of six seed lots of cultivar CD 2737 RR were incubated at temperatures of 15, 25 and 40 °C. The CO2 released after 1, 3, 6, 9, 12 and 24 h of seed incubation was quantified as well as the percentage of normal seedlings emerged in the field. We calculated the simple correlation coefficients between the two tests. We evaluated the precision and accuracy of the proposed method using 15 seed lots. For the evaluation of the respiratory activity in G. max seeds, we recommend a sample of 25 seeds, incubated at 15 °C for a minimum of 9 h. The method allows to classify seed lots with different levels of vigor and predict the establishment of seedlings in the field. The tested method is appropriated for measuring CO2 as it externalizes precision between successive measurements and agrees with a reference method.