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Seed treatments.pptx
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- 2. Seed treatment • Refersto application of any treatment by chemical, physical or biological means • Purpose – To break the dormancy of seeds to alter / accelerate the germination To improve seedling growth to protect the seed from pest & disease during storage To tide over adverse conditions – seed hardening To improve storability of seeds
- 3. Types of seedtreatments • Different types on 4 basis – Objective basis Time basis Method basis Type basis
- 4. 1) Objective basis •Breaking dormancy • Augmenting germination • Improving seedling growth • Improving storability through decelerating senescence, discouraging pests & diseases by disinfection, disinfestation & protection, direct application of nutrients & protectants to seed, seed colouring
- 5. 2) Time basis 1)Presowing seed treatment – a) dormancy breaking treatments b) germination augmenting treatments c) seed coating treatments d) seed protection treatments 2) Prestorage seed treatments – a) Halogenation b) Antioxidant treatment c) seed sanitation – disinfection, disinfestation d) seed fumigation 3) Method basis – a) Mechanical b) Physical c) Chemical d) Biological 4) Type basis – a) Dry b)Wet
- 6. Dormancy breaking treatments 1)Mechanical Scarification 2) Acid scarification 3) Water soaking 4) Dry heat treatment 5) Warm stratification 6) Cold stratification 7) Biological methods 8) Seed treatment with growth regulators/chemicals 9) Others
- 7. Mechanical Scarification Used forlarge quantities of hard coated seeds Concrete mixer with sharp gravel or sand, sand paper, crushed glass etc Care should be taken to avoid over treatment Eg- Acacia nilotica Albizzia lebbek Cassia fistula Delonix regia Santalum album etc
- 8. Acid scarification Soaking in conc. Sulphuricacid (95%) Stir for few minutes to one hour depending on sps Wash them thoroughly in cool water for 5 -10 minutes Shade dry Eg. Prosopis juliflora
- 9. Dry heat treatment- Spread the light inflammable litter over the fruits & ignite it Adjusting heat of fire to achieve maximum effect on pericarp without embryo damage need experience Tectona grandis – 45 to 50 degree Celsius showed 50% germination Water soaking – To soften hard seeds & to leach out chemical inhibitors Soaking in cold water for few hours to several days – safe & simple treatment for most of the small seeds – 2 to 48 hours (depending on species) Eg. Acacia nilotica, Albizzia amara, Grevillea robusta etc Soaking in boiling water – leguminous seeds, oak & chestnut (1/2 minute)
- 10. Warm stratification Open the containers weekly& mix well & remoist if required Store at warm temp – 20-25˚C or 30˚C) Drain off water & mix the seeds with sand/vermiculite (3 -4 times their vol) Soak the seeds in cold water(3- 5˚C) for 48h - to overcome mechanical & morphological dormancy
- 11. Cold stratification Soak theseeds at 3-5˚C for 48 hrs Drain off the water Store the moist seeds in 3-5˚C for required period without medium Open the containers & mix if surfaces dry off - to overcome physiological dormancy Eg. Abeis sps, Eucalyptus delegatensis
- 12. Biological methods Attractive fruits Eaten by fruits Digestive tract Scarifyhard seed coat Improves germinability Examples – Azadirachta indica Syzygium cumini Ficus religiosa Santalum album Ficus benghalensis
- 13. Seed treatment withgrowth regulators/chemicals • Endogenous dormancy (due to the presence of inhibitors) - apply growth regulators at the low level to break dormancy • GA & Cytokinin and kinetin – Conc.100-1000 ppm used to break dormancy • KNO3 - 2% for breaking the dormancy of light requiring seeds. Eg. Oats, Barley and Tomato • Nitrogenous compounds like Thiourea, Hydroxylamine, Nitric acid, Nitrate can be used for breaking dormancy - Thiourea for breaking dormancy for both light and chilling treatment requiring seeds (e.g.) lettuce - thiourea @ 10-2 to 10-3 M is used • Ethrel can be used for breaking the dormancy of cotton seed (due to the presence of ABA in pericarp of seed) • Sulfhydryl compounds like 2 mercapto ethanol and 2,3 dimercapto ethanol can also be used • Plant products like strigol (root exudation from striga parasite host plant) can also be used for breaking the seed dormancy
- 14. Others Infra red radiationtreatment Infra red rays can be passed on to the seeds and dormancy can be released. Pressure treatment Dormant seeds can be kept in autoclave and required pressure can be employed for breaking dormancy. Magnetic seed treatment Seeds can be kept in the magnetic field for about 1 to 10 days for breaking dormancy
- 15. • Infusion ofbioactive chemicals into seed by soaking them in nutrient solutions • Soaking followed by shade drying Seed infusion/fortification • Infusion of bioactive chemicals into seed by soaking them in organic solvents containing dissolved nutrients • Organic solvents get rapidly evaporated at room temp Dry permeation • Involves 2-3 cycles of wetting – drying for specific durations to impart resistance to seeds against drought • Chemicals (drought resistance) are dissolved in water before soaking of seeds Seed hardening Germination augmenting treatments
- 16. • Hydrating theseeds in low water potential solution of organic / inorganic solutes for extended time period • Follows principle of imbibition Osmotic priming • Process of gradual increasing the seed moisture content • Seeds are placed in a sealed steel drum with circulating air at 20 ͦC & 100% RH in dark for 24hrs Humidification • Exposure of seeds to gamma rays • Increases the germination % & seedling growth Irradiation • Exposure of seeds to magnetic field • Increases the germination % & seedling growth Magnetic seed treatment
- 17. Seed coating treatments a)Seed pelleting – enclosing seed inside small quantity of inert material – to facilitate precision planting b) Seed coating – process of applying useful materials to form layer of thin coating over seed without altering shape c) Fluid drilling or gel seeding – germinating seed in aerated water until radicle emergence & then mix in viscous gel followed by sowing – prevents seedling injury & maintain seed moisture d) Seed colouring – colouring using natural / artificial dyes to prevent inadvertent use of treated seeds for food purposes e) Biological seed coating – treating seeds with beneficial micro organisms for sustained plant growth
- 18. Seed protection treatments Seeddressing • Application of pesticides to seeds before sowing • Eg: Thiram, Captan @2g/kg Heat treatment • Application of heat using hot water, hot air or solar heat • To eradicate viruses from seeds
- 19. Prestorage seed treatments a)Halogenation – halogens (Iodine, cl, Br) are applied as dry dust / vapour to seed before storage to prevent lipid peroxidation process b) Antioxidant treatment – antioxidants (vit A, C, E) provided as dry dusting/ through soaking to prevent free radical production c) Seed disinfection – removal of fungal spores within seed coat/ deep seated tissues through fungicide treatment d) Seed disinfestation – chemical dips, soaks, fungicides applied as dust, slurry to destruct the surface borne organisms that contaminated the seed surface e) Seed fumigation – exposing seeds to fumigants to control seed borne fungi & insects followed by placing seeds in aerated cloth bags for 21 weeks under room conditions. Eg- Ethylene oxide, Aluminium phosphide, Calcium cynide, Carbon tetrachloride etc
- 20. Method basis Mechanical • Aberratingthe hard seed coat by sand/ mechanical scarification to remove dormancy Physical • Hot & cold water soaking, dry heat treatments, UV, IR, X-Ray treatments Chemical • H2SO4,H2O2, KNO3, organic fungicides are used Biological • Usage of Rhizobium, Azospirillum, Trichoderma, Pythium etc
- 21. Seed treatment equipment's Seed pelletizer Seed coaters Seed treating drum Gustafson slurry treater Fumigation chamber
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