Agriculture Reference
In-Depth Information
VIGor TESTS - PrInCIPLES And ProCEdurES
The cold, accelerated aging and conductivity vigor tests are recommended vigor tests for corn, soybean and
garden pea, respectively. This does not mean that they are the best vigor tests with respect to determining
seed vigor. Rather it implies that these tests have results that correlate with seed vigor and have been the
easiest to standardize.
Accelerated Aging Test
The accelerated aging (AA) test is one of the most popular seed vigor tests due to its simplicity, ease of
standardization (TeKrony, 1995) and applicability to a wide range of crops (McDonald, 1995). The test
subjects seeds to a high temperature (usually 41°C) and high relative humidity (usually 100% RH) stress for
short durations (generally 72 h) followed by a standard germination test (AOSA 2009). Low quality seeds
deteriorate more rapidly than high quality seeds under these conditions. The AA test is considered standard-
ized and correlates with ield emergence under a variety of seedbed conditions (Egli and TeKrony, 1996).
The value of the accelerated aging test is well known. It is the second most popular seed vigor test
in the United States, surpassed only by the cold test (Ferguson-Spears, 1995; Baalbaki and Fiedler, 2008;
Tables 8.3, 8.4). This importance has led to considerable research focusing on improvements in standardiza-
tion. Among these were the utilization of individual inner trays with seeds suspended in a monolayer above
the water to enhance uniform moisture uptake (Fig. 8.2; McDonald and Phaneendranath, 1978) and stable
temperature incubators such as water-jacketed chambers (Fig. 8.2) to achieve a uniform ± 0.3°C acceler-
ated aging environment (Tomes et al., 1988). These and other accelerated aging considerations to enhance
standardization have been summarized by TeKrony (1995).
Figure 8.2. On the left, the “tray” used in an accelerated aging test. These are placed in a water-jacketed
chamber (right) used in the conduct of an accelerated aging test.
One of the advantages of this test is that temperature and duration of aging are easy to manipulate to
obtain the best AA conditions for speciic crops. As a result, research continues to further deine the ideal
test conditions for various crops. Many of these are listed in the AOSA Seed Vigor Testing Handbook
(2009) and some of these recommendations continue to be reined. For example, an AA regime of 43°C
