The aims of the Vigour Committee are:
1 - to develop and validate vigour tests for introduction to the ISTA Rules
2 - to encourage the use of vigour tests
3 - to ensure that these are carried out to achieve repeatability between and reproducibility within laboratories.
Since the introduction of the Vigour chapter (Chapter 15) to the ISTA Rules in 2001, two further vigour tests have been added to those already validated in 2001 (accelerated ageing test and conductivity test), 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.
Background to the initial development and validation of the CD test can be found in Seed Testing International STI 129 (pag. 21-24). More recent work has provided an alternative procedure for raising seed moisture content during the test. In addition the assessment of the electrical conductivity of seed leachates can be used as an alternative to the germination test after deterioration (see Vigour Committee reports 2014, 2016 and ISTA Rules 2017).
The Radicle Emergence (RE) test, originally introduced for Zea mays in 2012, is now also in the ISTA Rules for Brassica napus (oilseed rape Argentine canola) and radish (Raphanus sativus). Research within the committee has provided evidence that RE provides an assessment of rate of germination and vigour for a wide range of species (see references in the Vigour Committee Activity report 2010, STI 142, 44-48 and list of publications). We are currently developing the test for wheat, alfalfa, oats, Elymus nutans, onion, soyabean, tomato and sweet pepper, with plans within 2016-2019 to extend our work to sunflower, barley and faba bean. This test provides an opportunity for the development of an automated vigour test, as described in STI 142, 44-48 and in the article by Wagner et al. (STI 142, 49-51). Indeed automation of the RE test has already been adopted by large seed companies (D Johnston, 2016, ISTA Congress Discussion Forum). The RE test can be developed for additional species by individual researchers and guidelines for this are included in the documents section.
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 (Kabuli type) as well as garden pea (Pisum sativum). 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 radish (Raphanus sativus) (Mavi et al, 2014, Seed Science and Technology, 42, 76-86), As a result of subsequent collaborative tests, radish is now also a species in the Rules to which the EC test can be applied. This work suggests that the EC test may be applicable to other dicotyledon species.
The development of new 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, Seed Science Research, 22, S69-S73; Powell and Matthews, 2012, Seed Technology, 34, 15-25). 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.