Agriculture Reference
In-Depth Information
and seedling emergence.” In an attempt to more precisely quantify the components of seed vigor, AOSA,
in 1983, deined seed vigor as “...those seed properties which determine the potential for rapid, uniform
emergence, and development of normal seedlings under a wide range of ield conditions.” This deinition
utilized measurable parameters such as rapid and uniform emergence which could be assessed numerically.
The development of “normal seedlings” was a criterion with which seed analysts were very familiar. The
deinition also emphasized the ability of the seed to emerge not only in the ield, but also under a wide range
of ield conditions to include both stress and optimum conditions. These deinitions clearly differentiated
seed vigor from seed germination.
Finally, the deinition of seed vigor can be understood by showing its relationship with germination
(viability) with increasing deterioration (Figure 8.1). The graph clearly shows that as seed deterioration pro-
ceeds, the loss in vigor precedes the loss in viability. Thus, it is in the area of early loss in vigor that vigor
testing of seed lots is useful. Although this relationship was irst shown by Delouche and Caldwell (1960),
it is still useful for helping understand seed vigor.
Figure 8.1. The relationship between the relative speed in loss of vigor vs. viability as seed ages (Delouche
and Caldwell, 1960).
AoSA Progress in Vigor Testing
After the 1950 ISTA Congress, less attention was given in the United States to discrepancies in germination
test results, which were viewed primarily as an European concern. It was not until the publication of two
articles on seed vigor testing (Isely, 1957; Delouche and Caldwell, 1960) that the key stimulus was provided
