Agriculture Reference
In-Depth Information
(Howarth and Stanwood, 1993a) using slant board approaches. The Seed Vigor Imaging System (SVIS)
is another example of computer imaging technology whereby seedling images are captured by scanners
and then analyzed by computers. The method has been successfully employed to measure the vigor of
many crops such as lettuce (Contreras and Barros, 2005), melon (Marcos-Filho et al., 2006), soybean
(Hoffmaster et al., 2005; Otoni and McDonald, 2005) and corn (Otoni and McDonald, 2005). The release of
seed exudates at predetermined intervals can be monitored by computers providing a more comprehensive
interpretation of conductivity test data (Furman et al., 1987). Perhaps the most exciting use of computers in
seed quality/vigor analyses has been in plug production of vegetable and loral bedding plants. Since bed-
ding plant producers are concerned with obtaining a uniform, marketable seedling in every cell in a plug
lat, empty cells must be manually illed - a costly and time consuming operation. This requirement places
stringent burdens on the production and marketing of only the highest quality seed. These needs have been
addressed with the aid of computer-assisted discrimination of the seedling canopy in a plug lat from the
background to identify and locate empty cells and calculate seedling leaf area in illed cells (Sase et al.,
1992; Fly et al., 1992; Hirvonen et al., 1992; Tai et al., 1994; Giacomelli et al., 1996; Ling and Ruzhitsky,
1996). These determinations are expressed as an index value by seed companies and are provided on the
seed label to the grower. Howarth and Stanwood (1993b) have also developed a software program to image
corn seed tetrazolium chloride staining patterns that are correlated with seed viability. There seems little
question that computers will increasingly be integrated into seed quality evaluation programs to provide
more precise, standardized information.
other Seed Vigor Tests
Seedling vigor classiication test.
The seedling vigor classiication test is attractive to seed analysts
because it utilizes materials and supplies already available in the laboratory. It is conducted according to
normal germination procedures prescribed in the testing rules and employs concepts, terms, and techniques
familiar to seed analysts. However, no irst count is made and, at the end of the prescribed germination time,
normal seedlings are placed into two categories based on vigor. Strong seedlings are those which are robust
and manifest no injury, while weak seedlings are those which have breaks, lesions, missing cotyledons, or
necrotic lesions (Fig. 8.12). Differentiation of normal seedlings into vigor categories can be subjective and
requires sound, intuitive judgment based on long experience of interpreting germination tests to provide
uniform test results.
Figure 8.12. Seedling vigor classiication test for cotton. Note strong, normal (left); weak, normal (middle);
and abnormal (right) seedlings.
