Carbon dioxide quantified by the infrared in respiratory activity evaluation in corn seeds

The respiratory activity is one of the first biological manifestations of vigor loss and detecting it can help the monitoring and quality control of seed production by seed industries. This research aimed to develop and validate the methodology of the carbon dioxide concentration in the evaluation of physiological quality of Zea mays (L.) seeds. The proposed method is grounded on the measurement of the CO2 content by infrared through a drag system and exhaustion of the gas released by the seed maintained in a closed system up to the detection chamber of the gas meter. Samples of 15, 20 and 25 seeds of 6 lots of cultivar CD 384 Hx were incubated at temperatures of 15, 25 and 40 °C. The CO2 content released after 1, 3, 6, 9, 12 and 24 h of incubation were quantified. In parallel, the percentage of normal seedlings emerged in the field were evaluated. The simple correlation coefficients among tests were calculated. After determining the reading conditions, the accuracy and precision of the proposed method were evaluated, using 15 seed lots. For the evaluation of the respiratory activity in Z. mays seeds, we recommend a sample of 25 seeds, incubated at 15 °C for a maximum of 12 h, which allows to classify lots with different levels of vigor and predict the establishment of seedlings in the field, being the appropriate method for measuring CO2 as it externalizes precision between successive measurements and agreement to the reference method.