Electrical conductivity (EC) stands out among vigor tests because of its capability of detecting damage in seeds in the initial stage, since EC is related to disorganization of the cell membrane. The aim of this paper was to study use of the EC test as an alternative for vigor evaluation in soybean seeds, verifying its relationship to different vigor tests and thus suggesting values and the range of values of electrical conductivity that indicate the performance potential of a seed lot in the field. Eleven seed lots from each of four soybean cultivars were used for this study. The moisture level was determined and the following tests were performed: electrical conductivity, germination, tetrazolium, accelerated aging, first germination count, seedling vigor classification and emergence of seedlings in the field and in sand. The EC test had a significant and negative correlation (p < 0.01) with all the tests performed. Linear regression analysis allowed separation of the seed lots into classifications of very high vigor (EC ≤ 70 μS.cm-1.g-1), high vigor (EC from 71 to 90 μS.cm-1.g-1), medium vigor (EC from 91 to 110 μS.cm-1.g-1) and low vigor (EC ≥ 111 μS.cm-1.g-1).

The success of soybean cultivation depends on several factors, one which is the use of high-quality seeds, which can guarantee growth of the desired plant population. The objective of this study was to monitor possible failures during the seed production process, and to determine the association between germination and tetrazolium tests through tools of Statistical Process Control (CEP). The experimental design was based on premises of the CEP, using percentage of germination, seed viability, mechanical damage, bed bug, and moisture as indicators of quality. It is possible to detect flaws in the soybean production process through control charts, as well as through germination and tetrazolium tests; results indicated that germination failures are largely caused by mechanical damage and bed bug attacks.