The basis of seed vigour and vigour testing Alison A Powell University of Aberdeen United Kingdom
What links Aberdeen with Nagasaki? Battleships built in Aberdeen: Ryūjō (1864) and Hosho Maru: Japanese navy Kagoshima: for Satsuma clan Ship building company that became Mitsubishi Corporation of Japan Japan Brewery Company, later the Kirin Brewery Company Ltd Glover whisky 1 st Scottish-Japanese blend, 2015 Hanyu distillery in Japan Longmorn and Glen Garioch
Thomas Glover (1838 1911) The Scottish Samurai Order of the Rising Sun, 1908 Japan
Outline Background to vigour in the ISTA Rules What vigour differences mean In the field In transplant production In storage Summary of effects of vigour Requirements of a vigour test Types of vigour test Vigour tests in use What do vigour tests tell us? The aim of our presentations
Summary of the History of Vigour 1876: Friedrich Nobbe: Triebcraft, driving force 1950: ISTA President WJ Franck - ISTA Biochemical and Seedling Vigour Committee Many years discussion and debate! 2001: ISTA Ordinary Meeting accepted Seed Vigour Testing as Chapter 15 in the ISTA Rules
ISTA definition of vigour (2001) Seed vigour is the sum of those properties that determine the activity and performance of seed lots of acceptable germination in a wide range of environments Make comparisons of the performance of commercial seed lots with acceptable germination
Germination and field emergence of commercial seed lots Species No. of lots Range among lots in : Normal germination (%) Garden pea 80 >80 8-85 Green bean 90 75-100 34-93 Soybean 18 83-96 17-88 Maize 29 92-98 48-98 Oilseed rape 9 89-99 65-93 Onion 12 77-92 46-72 Lettuce 22 88-98 27-71 Cabbage 31 80-98 7-78 Cauliflower 12 85-96 10-64 Field emergence (%)
Emergence differences: Maize Low vigour High vigour High vigour Wide-spaced crop; Non-tillering Low emergence due to low vigour means yield penalty Photo courtesy E. Noli
Emergence differences: Phaseolus vulgaris Guerbiny Northern France Photo courtesy T. Loeffler
Emergence differences: chickpea (Cicer arietinum) High vigour Low vigour Photo courtesy C. Gallo
Emergence differences: Oilseed rape (Brassica napus ) High vigour Low vigour Photos courtesy S. Goertz
26 March 2012 9 April 2012 23 April 2012 Low vigour High vigour Oilseed rape Low vigour High vigour Yield differences: due to emergence and plant development? Low vigour High vigour
Field sown lettuce: Impact on marketable yield 60-90% of variation in head weight due to variation in timing of emergence Gray (1976) Annals of Applied Biology 82, 569 575
Photos courtesy H. Ilbi Tagetes
Transplant production Requires large uniform seedlings
Low vigour High vigour Cabbage
Low vigour High vigour Melon Photo courtesy of J. Marcos Filho
High vigour Lettuce Low vigour Photos courtesy of J. Marcos Filho
Species Transplant module emergence of Brassica species (50 modules per lot) Normal germination (%) Mean emergence time (days) Emergence (%) Plant height (mm) at first leaf stage Variation in plant height (CV) White cabbage 98 4.4 98 21.1 27.0 93 5.3 92 18.2 36.9 Cauliflower 98 4.4 92 26.7 21.5 91 6.2 88 19.8 25.9 Brussels sprouts 98 4.2 100 30.8 23.9 87 5.0 44 23.2 27.7 Red cabbage 97 4.6 98 25.6 22.1 85 5.7 100 16.8 32.5 Calabrese 93 4.1 92 21.1 20.5 88 4.6 91 21.0 25.6
Bell pepper Low vigour High vigour Photo courtesy I Demir
Pepper emergence in glasshouse conditions Normal germination (13 seed lots) 88 99% Low temperature sowing date (13 seed lots) (min / max temperature 11/ 23 o C) Emergence 71-96 % MET 16.9-22.1 days High temperature sowing date (13 seed lots) (min / max temperature 19/ 42 o C) Emergence 63 93 % MET 11.2 16.2 days Germination after storage (10 seed lots) at 8% MC 5 o C for 4 months 60 92% Başak et al. (2006) Seed Sci. & Technol, 24, 701-712
Initial lab germination (%) Storage potential Brassica oleracea var gemmifera, Brussels sprouts Ambient = ambient in UK DH = dehumidified and low temperature store Germination (%) after storage for 2 years Store 1 (ambient) Store 2 (ambient) Store 3 (DH) 84 28 33 56 97 84 88 91 93 54 63 73 91 17 21 39 Good storage potential Poor storage potential
Summary of aspects of performance associated with seed vigour Emergence ability of seeds particularly under unfavourable environmental conditions Rate and uniformity of seed germination and seedling growth Performance after storage particularly the ability to germinate
What vigour differences mean Vigour level High Low Mean rate of germination Spread of germination time Fast Narrow Slow Wide Mean seedling size Large, uniform Small, variable Emergence Good Poorer Storage potential Good Poorer
Requirements of a vigour test Simple to complete applicable in a wide range of seed testing environments more hi-tech options may also be available Results should correlate with a practical expression of seed vigour emergence in the field or glasshouse, or seedling size and uniformity, or seed longevity in store. Repeatable both within and between laboratories. results from different laboratories would be comparable trust in results of testing essential for ISTA accreditation / QA Preferably a quantitative method of assessment avoids subjective assessments standardization easier. Quick enables prompt reporting of results. The test should be economically practical. a critical aspect in the running of any seed testing laboratory,
Types of vigour tests Physiological assessments aspects of germination e.g. rate of germination, radicle emergence test stress tests e. g. cold test, cool germination test Biochemical assessments e.g. conductivity; tetrazolium Application of the ageing process accelerated ageing controlled deterioration
Vigour tests in use ISTA Validated tests Conductivity: grain legumes, radish * Accelerated ageing: soyabean* Controlled deterioration: Brassica * spp. Radicle emergence: * maize, oilseed rape, radish Tetrazolium staining: soyabean* K+ leakage Non-validated tests Single seed conductivity Accelerated ageing for other species * Saturated salt accelerated ageing: small seeded species * Stress tests: Cold test: maize * Saturated cold test: maize Cool test: cotton Seedling growth: range of species * Tetrazolium staining : species other than soyabean
What do vigour tests tell us? Information about: the planting value in a wide range of environments and/or storage potential of seed lots Additional information to the standard germination test differentiation between seed lots of acceptable germination Information that will help companies make marketing and storage decisions allow farmers to judge risks when sowing
Germination (%) Our aim: Basis of vigour, vigour tests and their use Two key concepts 100 80 60 40 20 F H I 0 0 24 48 72 96 120 144 Time from set to germinate (h) Seed survival curve Germination progress curve Our aim To illustrate how these two concepts help provide an integrated explanation for differences in vigour and vigour tests
Takashi Shinohara Tokyo University of Agriculture The use of vigour tests in Japan