Seed Vigor Testing of Tomato

Two cultivars of tomato seeds from Known-You Seed Company were subjected to seed treatments aiming to evaluate the vigor of each seed. 'Tropical Ruby' and 'Farmers 301' were selected as seed materials. For priming, both seed varieties were exposed in a saturated solution of 6.5 g PEG (polyethylene glycol) 600 and 100 ml of water for 48 hours. Accelerated ageing was done by subjecting seeds at 42 °C and 100% relative humidity (RH) for 72 hours. The treated seeds were evaluated by measuring germination percentage, seedling emergence, seed electrical conductivity and respiration rate at optimal (25°C), low (15°C) and high temperature (35°C) . Accelerated ageing significantly deteriorated seed vigor by the following results: reduced the germination rate of 'Farmers 301' from 50-43% at 35°C, a delay of emergence of 'Farmers 301' seeds from 9.8 to 14.3 days at 15°C. Ageing also significantly hastened the seed deterioration of seeds imbibed at 35°C for both 'Tropical Ruby' and 'Farmers 301'. Priming resulted to an enhanced seed germination (64-74 %) of 'Tropical Ruby' seed when exposed to 35°C and 60-78% on 'Farmers 301' seeds at 15°C. Emergence of 'Farmers 301' was significanly hastened from 7.2 to 4.7 days at 35 °C. Respiration rate was significantly enhanced from 39.0 to 50.1 ml CO2/g/hr at 25°C . It also significantly reduced the electrical conductvity of both seed varieties imbibed at 15°C. The study found out that effect of both priming (enhance seed vigor) and ageing (deteriorate seed vigor) on 'Tropical Ruby' and 'Farmers 301' but the degree of significance was dependent to temperature.TABLE OF CONTENTS Abstract……………………………………..……………………………………………….…….i Table of contents…………………………………………………………………………………..ii Contents of figures ….….…….…..…………...……………………………………………….... iv Chapter I Introduction……………………………...…………………………………………...1 Objectives………………………………………………………………………………................2 Chapter II Literature Review……….……….……………….………………………................3 2.1 Characteristics and Seed Germination of Tomato....................................................................3 2.2 Seed Vigor Testing……………………………………………………………………………4 2.2.1 Physical Tests………………………………………..……………………………………4 2.2.2 Physiological Tests…………………………………….………………………………….5 2.2.2.1 Accelerated Ageing Test (AAT)........................................................................................5 2.2.3 Biochemical Tests…………………………………………..…….………………………5 2.3.1Tetrazolium (TZ) test...............................................................................................................5 2.3.2 Electrical Conductivity........................................................................................................5 2.3.3 Respiratory Activity.............................................................................................................6 2.3.4Potassium leakage....................................................................................................................7 2.4 Seedling Evaluation Test.........................................................................................................8 2.5 Seed Enhancements.................................................................................................................8 2.6 Prehydration.............................................................................................................................8 2.7 Priming.....................................................................................................................................9 Chapter III Materials and methods...........................................................................................11 2.1 Seed Materials.......................................................................................................................................11 2.2 Seed Treatments....................................................................................................................................11 2.3 Priming.................................................................................................................................................11 2.4 Accelerated Ageing .................................................................................................................11 2.5 Germination ..........................................................................................................................................11 2.6 Emergence Test........................................................................................................................12 2.7 Electrical Conductivity Test....................................................................................................12 2.8 Respiration Rate.......................................................................................................................13 2.9 Data Analysis...........................................................................................................................13 Chapter IV Results......................................................................................................................14 3.1 Germination of aged tomato seeds...........................................................................................14 3.2 Emergence of aged tomato seeds ............................................................................................14 3.3 Electrical conductivity of aged tomato seds............................................................................15 3.4 Respiration rates of aged tomato seeds ...................................................................................15 3.5 Germination of primed tomato seeds......................................................................................16 3.6 Emergence of aged tomato seeds ............................................................................................16 3.7 Electrical conductivity of aged tomato seds............................................................................17 3.8 Respiration rates of aged tomato seeds ...................................................................................17 Chapter V Discussion..................................................................................................................30 References.....................................................................................................................................33   Contents of Figures Figure 1. Germination percentage of aged and untreated 'Farmers 301' under different temperatures...................................................................................................................................18 Figure 2. Germination percentages of aged and untreated 'Tropical Ruby' under different temperatures. .................................................................................................................................18 Figure 3. Mean day of germination of aged and untreated 'Farmers 301' under different temperatures...................................................................................................................................19 Figure 4. Mean day of germination of aged and untreated 'Tropical Ruby' under different temperatures...................................................................................................................................19 Figure 5. Emergence percentage of aged and untreated 'Farmers 301' seeds under different temperatures...................................................................................................................................20 Figure 6. Emergence percentage of aged and untreated 'Tropical Ruby' seeds under different temperatures...................................................................................................................................20 Figure 7. Mean day of emergence of aged and untreated 'Tropical Ruby' seeds under different temperatures...................................................................................................................................21 Figure 8. Mean day of emergence of aged and untreated 'Farmers 301' seeds under different temperatures...................................................................................................................................21 Figure 9. Electrical Conductivity of aged and untreated 'Farmers 301' seeds at different temperatures. .................................................................................................................................22 Figure10 . Electrical Conductivity of aged and untreated 'Tropical Ruby' seeds at different temperatures...................................................................................................................................22 Figure 11. Respiration rates of aged and untreated 'Tropical Ruby' seeds under different temperatures. .................................................................................................................................23 Figure 12. Respiration rates of aged and untreated 'Farmers 301' seeds under different temperatures. .................................................................................................................................23 Figure 13. Germination percentage of primed and untreated 'Farmers 301' under different temperatures...................................................................................................................................24 Figure 14. Germination percentages of primed and untreated 'Tropical Ruby' under different temperatures. .................................................................................................................................24 Figure 15. Mean day of germination of primed and untreated 'Farmers 301' under different temperatures...................................................................................................................................25 Figure 16. Mean day of germination of primed and untreated 'Tropical Ruby' under different temperatures...................................................................................................................................25 Figure 17. Emergence percentage of primed and untreated 'Farmers 301' seeds under different temperatures...................................................................................................................................26 Figure 18. Emergence percentage of primed and untreated 'Tropical Ruby' seeds under different temperatures...................................................................................................................................26 Figure 19. Mean days of emergence of primed and untreated 'Tropical Ruby' seeds under different temperatures....................................................................................................................27 Figure 20. Mean days of emergence of primed and untreated 'Farmers 301' seeds under different temperatures...................................................................................................................................27 Figure 21. Electrical conductivity of primed and untreated 'Farmers 301' seeds at different temperatures. .................................................................................................................................28 Figure 22. Electrical Conductivity of primed and untreated 'Tropical Ruby' seeds at different temperatures...................................................................................................................................28 Figure 23. Respiration rates of primed and untreated 'Farmers 301' seeds under different temperatures ..................................................................................................................................29 Figure 24.Respiration rates of primed and untreated 'Tropical Ruby' seeds under different temperatures ..................................................................................................................................2