The development of new vigour tests by the Vigour Committee is soundly based on the physiological nature of differences in seed quality, namely seed ageing/deterioration and the metabolic repair of deterioration, which is achieved during the early stages of germination (Matthews et al., 2012; Powell & Matthews, 2012). This basis in science, and the establishment of a clear link between test results and a practical outcome of vigour, e.g. emergence (rate and final), seedling uniformity and storage potential, is a major emphasis of the work of the Committee.
- To develop and validate vigour tests for introduction to the ISTA International Rules for Seed Testing.
- To encourage the use of vigour tests by seed laboratories.
- To provide information and training to ensure that vigour tests are carried out to achieve repeatability between, and reproducibility within, laboratories.
Chapter 15 on Vigour was introduced to the ISTA Rules in 2001, including the accelerated ageing test and the conductivity test. Two further vigour tests have been added to those already validated, namely the controlled deterioration (CD) test for Brassica (added to the Rules in 2010) and the radicle emergence (RE) test (2012). In addition, there are now more species to which the conductivity test can be applied.
Controlled deterioration test
Background to the initial development and validation of the CD test can be found in Seed Testing International (STI 129). More recent work has resulted in an alternative procedure being provided in the ISTA Rules for raising seed moisture content during the CD test. In addition the assessment of the electrical conductivity of seed leachates can be used as an alternative to the germination test after deterioration (Activity report 2014, 2016; ISTA Rules 2017).
Radicle emergence test
The Radicle Emergence test was originally introduced for Zea mays in 2012 and is now also in the ISTA Rules for Brassica napus (oilseed rape, Argentine canola) and Raphanus sativus (radish). Research within the Committee has provided evidence that RE provides an assessment of rate of germination and vigour for a wide range of species (Activity report 2010; STI 142). The test is currently being developed for wheat, alfalfa, oats, Elymus nutans, onion, soyabean, tomato and sweet pepper, with plans to extend our work to sunflower, barley and faba bean. The RE test provides an opportunity for the development of an automated vigour test (STI 142, 49-51). Automation of the RE test has already been adopted by large seed companies (Johnston, 2016). The RE test can be developed for additional species by individual researchers and guidelines for this are included under Documents.
Electrical conductivity test
New species have also been added to the well-known and established electrical conductivity (EC) test, which can now be applied to Glycine max, Phaseolus vulgaris and Cicer arietinum (Electrical conductivity testNew species have also been added to the well-known and established electrical conductivity (EC) test, which can now be applied to Glycine max, Phaseolus vulgaris and Cicer arietinum, as well as Pisum sativum (garden pea). Until recently the EC test has only been considered for grain legume species. However, recent research has shown that differences in leakage and EC can also predict the field emergence and storage potential of Raphanus sativus (radish) (Mavi et al., 2014), As a result of subsequent collaborative tests, radish is now also a species in the ISTA Rules to which the EC test can be applied. This work suggests that the EC test may be applicable to other dicotyledon species.
Johnston, D. (2016). ISTA method development needs: a large scale industry perspective. Presentation at the ISTA Congress, Tallinn, 2017.
Matthews, S., Noli, E., Demir, I., Khajeh Hosseini, M. and Wagner, M.-H. (2012). Evaluation of seed quality: from physiology to international standardisation. Seed Science Research, 22, 69–73. http://dx.doi:10.1017/S0960258511000365
Mavi, K., Mavi, F., Demir, I. and Matthews, S. (2014). Electrical conductivity of seed soak water predicts seedling emergence and seed storage potential in commercial seed lots of radish. Seed Science and Technology, 42, 76–86. http://dx.doi.org/10.15258/sst.2014.42.1.08
Powell, A.A. and Matthews, S. (2005). Towards the validation of the controlled deterioration vigour test for small-seeded vegetables. Seed Testing International, 129, 21–24.
Powell, A.A. and Matthews, S. (2011). Towards automated single counts of radicle emergence to predict seed and seedling vigour, 142, 44–48.
Powell, A.A. and Matthews, S. (2012). Seed ageing/repair hypothesis leads to new testing methods. Seed Technology, 34, 15–25.
Wagner, M.-H., Demilly, D., Ducournau, S., Durr, C. and Lechappe, J. (2011). Computer vision for monitoring seed germination from dry state to young seedlings. Seed Testing International, 142, 49–31.