Authors: Ravi kumawat, Madhu Choudhary, Kana Ram Kumawat
Improvement in shelf life of the seed, protection of seed during germination, seedling establishment and improvement in the vigour of seedling and plant with chemical or physical treatment.
Merits of seed treatment
- Wide spectrum it controls both systematic and non-systematic pathogens
- Prevent spread of both systematic and non-systematic pathogens
- Protects seed from seed borne and soil borne pathogens.
- It improves field emergence by enhancing vigour.
- It improves germination through control of surface moulds.
- Enhance shelf life of seed.
- Facilitate infected seed to form a healthy seedling.
- Easy to apply cost effective.
- Optimum plant population with reduced seed rate.
- Assured plant population in naturally infested soil.
Types of seed treatment:
Seed disinfectant: It eradicates pathogens present deep in the seed for effective control disinfectant should penetrate into the different parts of the seed.
Seed disinfestant: it is effective on the pathogen present n the surface of the seed i.e. contaminated the seed surface but not infected the seed.
Seed protectant: it is effective to protect the germinating seed and young seedling fro soil borne pathogen that may decay the seed before germination or seedling before or during emergence.
Agents for seed treatment
Fungicides: for dressing, seed dried to low moisture content are thoroughly mixed with required quantities of fungicides e.g. thiram or carboxin @ 2 g/ kg of seeds as powder or slurry. For dry application fungicides is moistened with water at the rate of 5 ml/ kg of seed.
Insecticide: it is applied to seed to control damage of insects such as wire worms and seed corn maggots at the time seedling establishment and to check dispersal of seed by ant e.g. sesame.
Bioagents: seed are treated with pre identified beneficial bioagents to protect the seed and supplement the nutrient. Use of bioagents for seed treatment is ecologically sound, biologically sustainable. It is an essentially of organic farming.
Fungi Trichoderma spp., Aspergillus flavus,
Bacteria Pseudomonas, Bacillus subtilis,
Botanicals leaf powder of Azadirachta indica,
Vitex negund, Prosopis, Acasia,
Nutrient supplementation Rhizobium and Azospirillum
Methods of seed treatment
A. Seed dressing:
seed dressing is a chemical, typically antimicrobial or fungicidal treatment with which seeds are treated dressed prior to planting.
B. Slurry treater:
Large quantity of seed in the seed processing plant is treated by slurry treater. Slurry is prepared by mixing the chemical with water. The required quantity of chemical is automatically mixed with the specified quantity of the seed before bagging. In seed processing plant is done by rotary seed dryer.
Seed seeping in botanicals:
Soaking of loose smut infected wheat seed in 3 per cent onion 4 per cent garlic extract at 30 C for 29 hours bring down the infection.
Rotary seed dresser: small quantity of the seed is treated by rotary seed dresser. In this dresser the seed and treatment are placed in the drum and it is rotated slowly until all the seeds are corned with the chemical.
Vacuum infiltration: Soaking of seed in captafol or benomyl (1 g active ingradient / 1 water) solution for 7 days with change of solution every day. Keeping the seed in a vacuum pump has been reported most effective for controlling deep seated Fusarium oxysporum fsp. Elacidies in Oil palm.
Osmotic priming: aqueous solution of polyethylene glycol (PEG) provides an osmotic environment. Immersion of seed in PEG solution followed by drying and storage does not impair germination and the method is called osmotic priming. e.g. immersion of rice seed in 20 per cent containing 0.1 percent carboxin reduce seedborne infection of Drechslara oryzae.
Solid matrix priming: pre sown hydration in a solid based media is called matrix priming. it increases the efficiency of the fungicides in control of seed borne infection.
Seed dip method: it involves the dipping of seed or propagating material in a chemical solution for a specified period prior to sowing. e.g. seed soaking in Dithan M-45 ( for late blight of potato), streptomycin sulphate ( for cabbage, cauliflower, mustard bacterial and fungal diseases) have been found superior.
Seed treatment involving physical factors
Hot water treatment: the seed are dipped for specified period of time in hot water to a particular temperature safe to the seed embryos and deleterious to the associated pathogen. The method is effective for internally associated fungi and bacteria pathogens. e.g. hot water (52 C) treatment for minutes ensure effective control of back leg of cabbage and black rot of cabbage and cauliflower.
Seed dip in water: Soaking of seed in plain water at 20 C for 41 hours reduce the loose smut infection without damage to wheat seed.
Solar energy treatment: The seeds are soaked in water for 6 to 8 hours there by activating the dormant mycelium present in the embryos and subsequently exposing the seed lot to solar heat. As a result of the solar heat the activated mycelium is destroyed without damaging the seed. The method is used for control of loose smut of wheat.
Hot air treatment: The seed material is exposed to the hot air stream for a specified period, which is safe for viability of the seed. The method is more effective for pathogens present on surface of the seed coat. e.g. effective control of smut pathogen associated with sugarcane set.
Seed seeping: seed seeping in 20 per cent commercial salt effectively eliminate the lighter, chaffy, kernel bunt infected seeds and nematode galls from wheat seed and seed of Cichorium intybus from Egyptian clover. This method is partially used to separate the ergot of pearl millet, sorghum.
Grain auger: seed is treated by spraying of chemical of required concentration on seed in an auger or straw conveyer. Individual seed is coated properly with a film of the chemical.
Bio- priming: treatment with biological agents is known as bio-priming.
Crop seed | Biological | Remarks
A. Brassica seed | Gilcoladium roseum and Trichoderma harzianum | reduce infection of alternaria , brassicola increase, Seedling emergence
B. Chickpea Seed | Pseudomanas fluresecens | seed and soil borne pathogen
About Author / Additional Info:
I am pursuing Ph. D from MPUAT, Udaipur