Agriculture Reference
In-Depth Information
detailed system for pedigree veriication. Seed certiication has done much to make farmers aware of the
importance of varietal purity when purchasing seeds.
The Plant Variety Protection Act
The U. S. Plant Variety Protection Act, passed in 1970, had an immediate impact on the seed industry. Its
purpose is “to encourage the development of novel varieties of sexually reproduced plants and to make
them available to the public while providing protection available to those who breed, develop, or discover
them, and thereby promoting progress in agriculture in the public interest” (Otto, 1985). The Act encour-
aged private seed companies to initiate their own breeding programs, a role at one time illed largely by
public experiment stations. It enables private seed companies as well as public agencies to protect and
control seed sales of a new cultivar for 17 years.
The Act applies only to nonhybrid varieties and has been responsible for the rapid development of a
large number of new varieties available to the American farmer.
Why Test Seed for Varietal Purity?
Seed production of new crop varieties may involve the multiplication of literally a handful of seeds through
several generations of seed increase to enhance seed availability to multiple seed buyers. In the process,
many factors can modify the genetic integrity of the seed. Thus, seed samples are usually subjected to vari-
etal testing for ive principal reasons (Cooke, 1998):
1. Identiication in the strict sense - What is the variety?
2. Conirmation/veriication of identity - Is this sample variety “X”?
3. Distinctness testing - Is this variety different from all others?
4. Genetic purity - Does this sample contain more than one variety (and, if so, at what level)?
5. Genetic characterization - What is the description of the variety?
Criteria for a Variety Identification Test
The ideal variety identiication test must meet four criteria (Payne, 1986). First, results must be easy to
reproduce, not only within a laboratory, but also among different laboratories. Second, it should be techni-
cally uncomplicated so analysts may be successfully trained to conduct the test in a minimal amount of
time. Third, it should require only a short time to complete. Finally, it should be inexpensive to conduct.
The basic objective of varietal identiication is to test for the occurrence of traits that help identify a
particular variety when grown in different environmental conditions and generations. Thus, it is assumed
that these characteristics are environmentally stable and will not change from one generation to another.
Following are reviews of various genetic and varietal purity tests that are used to distinguish among
cultivars which differ in one or more speciic characteristics. The tests will be divided into two main parts
according to their functions: Part one includes DNA and protein tests used to determine the genetic purity
of genetically modiied cultivars as well as traditional cultivars developed by conventional plant breeding
techniques. Part two includes cultivar purity identiication tests that use morphological, chemical, growth
habits, and other characteristics to differentiate among cultivars.
