The advantages of planting high-quality seed may be apparent. Quality, however, is not gauged by visual examination, and seed lots must be tested. Fortunately, we have standardized testing protocols for most commercial crops, which have been established for almost one hundred years since ISTA (International Seed Testing Association) existed.
ISTA was founded in 1924 to develop and publish standard procedures in seed testing. ISTA is inextricably linked with the history of seed testing and member laboratories in over 80 countries/distinct economies worldwide. ISTA membership is truly a global network. Their mission statement is "ISTA members work together to achieve their vision of 'Uniformity in seed quality evaluation worldwide'. Our Association produces internationally agreed rules for seed sampling and testing, accredits laboratories, promotes research, provides international seed analysis certificates and training, and disseminates seed science and technology knowledge. This facilitates seed trading nationally and internationally and contributes to food security".
ISTA member testing laboratories worldwide follow the ISTA Rules to assess Standard Germination, the most commonly used quality measurement, also called "warm germination". This test evaluates the seed lot's maximum potential under favourable conditions and is the germination percentage included on the label of seed packages.
Growth conditions are, however, seldom perfect. Two seed lots with identical standard germination will often perform differently in the field. We are observing the difference in seed vigour between the two seed lots. Additional information about a seed lot beyond germination is needed to estimate seed performance under sub-optimal conditions.
Estimating seed vigour is essential, especially for high-value crops, and gives valuable information about field performance and storage potential. A vigour test must be susceptible to differences in physiological potential, an aspect not assessed in standard germination tests.
Measuring seed vigour, however, is more complicated than assessing germination. Seed vigour is not a single measurable property, like germination, but rather a concept describing several characteristics associated with various aspects of seed performance. Currently, there is no single, universally applicable vigour test.
Seed vigour is the result of several factors, such as species, environmental conditions during seed development, nutrition of the mother plant at critical times, maturity level at harvest, harvesting and conditioning methods, seed-lot age, and pathogens' presence. Testing, therefore, usually assesses vigour indirectly: for instance, a test can measure an attribute of vigour, such as the measurement of Radicle Emergence or First Counts of the germination test. Higher-vigour seed lots germinate faster than lower-vigour seed lots, and determining the number of seeds that have germinated at a given time indicates germination speed and vigour. Furthermore, a high-vigour seed lot has the potential to perform well under sub-optimal conditions.
Vigour tests can also expose the seed to stress factors and assess the impact on germination performance. The Cold Test is one of the most commonly used vigour stress tests, especially in the northern hemisphere, and it initially exposes the seed to cold temperatures and then measures germination under ideal conditions. This test is popularly referred to as "cold germination". Another popular vigour stress test is the Accelerated Ageing test, where seeds are exposed to very high temperatures (between 41°C and 45°C) and relative humidity (98%) for a crop-specific number of days, after which germination performance is measured. The Controlled Deterioration test is a variation of this test (used mostly for vegetable seeds). We can also measure the integrity of cell membranes, which is correlated with seed vigour, using the Electric Conductivity test - as seeds lose vigour, nutrients leak out across membranes, and so low-quality seeds leak electrolytes such as amino acids and organic acids while high-quality seeds manage to contain their nutrients within intact membranes. Seeds with higher conductivity measurements are therefore identified as being of lower quality.
It's essential to remember that vigour tests were not designed to predict the number of seedlings that will emerge in the field or a seedling tray or how long a seed lot will maintain quality while in storage. Test results must be properly and expertly interpreted to be correctly employed (i.e. if the best seed lots for a particular purpose are to be selected).
Furthermore, it is essential to sample correctly. Test results truly only reflect the quality of the sample under test. The examined sample must represent the seed lot to reflect the quality of the whole seed lot.
Seed vigour is essential to seed quality, and knowledge of the seed lot's vigour allows good decision-making.
SciCorp is registered with DALRRD (Department of Agriculture, Land Reform, and Rural Development) and holds SANAS ISO 17025 accreditation for GMO, microbiological, and molecular testing in food, feed, and seed methods. Our testing portfolio spans ISTA-accredited physical seed testing, molecular plant breeding support, authenticity verification, GMO detection, and comprehensive chemical and food safety analyses. Additionally, SciCorp offers a range of products for clients' in-house testing needs, including the Path-Chek® line for food pathogens, lateral flow sticks for allergens and mycotoxins, ELISA and LFS kits for GMO testing, and Anchor germination paper for seed testing.
The advantages of planting high-quality seed may be apparent. However, quality cannot be gauged by visual examination alone; seed lots must be tested. Established almost one hundred years ago, standardized testing protocols have been developed by the International Seed Testing Association (ISTA). Founded in 1924, ISTA aims to standardize procedures in seed testing, and it is now a global network with member laboratories in over 80 countries. Their mission is to achieve "Uniformity in seed quality evaluation worldwide." ISTA member testing laboratories worldwide follow the ISTA Rules to assess Standard Germination, the most commonly used quality measurement, also known as "warm germination". This test evaluates a seed lot's maximum potential under favorable conditions and is the germination percentage included on seed package labels.
However, growth conditions are seldom perfect. Two seed lots with identical standard germination may perform differently in the field, highlighting the difference in seed vigour. Seed vigour tests are essential, especially for high-value crops, providing valuable information about field performance and storage potential. Unlike germination, seed vigour is not a single measurable property but a concept involving several characteristics related to seed performance.
Seed vigour results from various factors, including species, environmental conditions during seed development, nutrition of the mother plant, maturity level at harvest, harvesting and conditioning methods, seed-lot age, and the presence of pathogens. Testing usually assesses vigour indirectly, such as through Radicle Emergence or First Counts of the germination test. Higher-vigour seed lots germinate faster than lower-vigour ones and perform well under sub-optimal conditions.
Vigour tests often expose seeds to stress factors to assess germination performance. The Cold Test, popular in the northern hemisphere, exposes seeds to cold temperatures before measuring germination under ideal conditions. Another test, the Accelerated Ageing test, subjects seeds to high temperatures (between 41°C and 45°C) and relative humidity (98%) for several days, followed by germination measurement. The Controlled Deterioration test is a variation used mostly for vegetable seeds.
The Electric Conductivity test measures the integrity of cell membranes correlated with seed vigour. Low-quality seeds leak electrolytes, while high-quality seeds contain nutrients within intact membranes, resulting in lower conductivity measurements.
It's essential to remember that vigour tests do not predict the exact number of seedlings that will emerge in the field or how long a seed lot will maintain quality in storage. Test results must be interpreted correctly by experts to select the best seed lots for specific purposes. Additionally, accurate sampling is crucial as test results only reflect the sample's quality under test.
Seed vigour is vital to seed quality, and knowledge of a seed lot's vigour enables informed decision-making. SciCorp is registered with DALRRD (Department of Agriculture, Land Reform, and Rural Development) and holds SANAS ISO 17025 accreditation for GMO, microbiological, and molecular testing in food, feed, and seed methods. Our testing portfolio includes ISTA-accredited physical seed testing, molecular plant breeding support, authenticity verification, GMO detection, and comprehensive chemical and food safety analyses. SciCorp also offers a range of products for in-house testing, including Path-Chek® for food pathogens, lateral flow sticks for allergens and mycotoxins, ELISA and LFS kits for GMO testing, and Anchor germination paper for seed testing.
