MUHAMMED ASLAM 2014-12-127

Seed treatment refers to the application of fungicide , insecticide or both to the seeds to disinfect (deep seated ) and disinfest( over seed coat ) them from seed borne or soil borne pathogenic organisms and storage insects.

Benefits of seed treatment

1.Prevention of spread of plant diseases both systemic and non systemic

2.Protects seed from seed rot and seedling blights

3. Improves germination

4. Provides protection from storage insects and pests.

Dates back to 17th century when salt water was accidently discovered to control bunt and stinking smut of wheat seed.

In 1755, M.D Tillet, a french botonist recommented the use of lye and lime as a chemical treatment for wheat seed

Some 50 years later ,Prevost a Swiss botanist ,discovered the use of copper fungicides as seed treatment.

New concepts of treating seeds with Organomercurials like Ceresan and Semesan were introduced in 1920.

HISTORY

1.SYSTEMIC DISEASES

2.NON SYSTEMIC DISEASES

3.SEED ROT AND SEEDLING

BLIGHTS

4. STORAGE AND SOIL INSECTS

The major diseases and insect pests that can be controlled by seed treatment are

Stinking smut of wheat

1. SYSTEMIC DISEASES

Loose smut of wheat Helminthosporium stripe of barley

Loose and covered smut of oats

2. NON SYSTEMIC DISEASES

Helminthosporium spot of RICE and Wheat

3.SEED ROT AND SEEDLING BLIGHTS

4. STORAGE AND SOIL INSECTS

Wire worms

Seed corn maggots

METHODS OF SEED TREATMENTS

Hanson et al. [1] divided seed treatment methods into three groups

MECHANICAL METHODS

PHYSICAL METHODS

CHEMICAL METHODS

OTHER METHODS

1. MECHANICAL METHODS

These are designed to remove infectious materials mixed with seeds.

Seeds can be mechanically cleaned thoroughly before seeding to remove pathogenic organisms from the seed surfaces.

This often requires further treatment.

2. PHYSICAL METHODS

Physical methods include hot-water and water-soak treatments and ultraviolet, infrared, X-ray and other types of irradiation.

Do not protect seeds from soilborne organisms

3. CHEMICAL METHODS

Most commonly used method because of its effectiveness and ease of handling.

IDEAL CHEMICAL would be;

Highly effective in controlling the pathogenHarmless to the seed,animals and non toxic to peopleEconomic to useEasy to applyNon corrosive to machineryStable for long periods

A) Mercurial Compounds

1. Organo mercurials: Small grains , flax cotton and safflower

Eg: PMA (Phenyl Mercuric acetate), MEMC (Methoxy ethyl Mercury chloride), EMC (Ethyl mercuric chloride )

2.Inorganic mercurials: Mercuric chloride, mercurious chloride and mercuric oxide

Tuber and root crops , Garden and vegetable crops

Chemicals used for Seed treatment

B) Non Mercurials

1.Organic non mercurials Less effective than the organic mercurials Less damaging to the seeds Less damaging to the persons handling the seedsOver dose is not harmful and viability is not effected

Eg Thiram, Captan, Carbendazim, Metalaxyl

2. Inorganic Non Mercurials:Copper carbonate, Copper sulphate – Bunt disease in wheatCuprous oxide- seed decay and damping off in vegetables

I. Chemical treatments to improve germination and vigour potential

Soaking / treating the seeds with nutrients vitamins and micronutrients etc

1.Paddy: Seeds can be soaked in 1 % KCl solution for 12 hours to improve the germination and vigour potential.

2.Sorghum: Seeds could be soaked in NaCl2 (1 %) or KH2PO4 (1%) for 12 hours for improving the germination and vigour potential.

3.Pulses : Seeds can be soaked in ZnSO4, MgSO4 and MnSO4 100 ppm solution for 4 hours to improve the germination and vigour potential.

4. OTHER METHODS

ABCD specifically controls Fusarium, Alternaria, Drechslera, Aspergillus flavus

It was also very effective in controlling the major stored grain pests

ABCD was also found effective in reducing seedborne diseases

Siddiqui and Agarwal [2] brought to light a new material for seed treatment, ABCD (attapulgite - based clay dust), developed at the Indian Institute of Chemical Technology (CSIR, Hyderabad) for seed treatment and safe storage of seeds and food grains.

1.Seed disinfection: It refers to eradication of fungal spores present within the seed coat or more deep seated tissues

2.Seed disinfestations: It refers to the destruction of surface borne organisms that contaminated the seed surface but not infected the seed.

3.Seed protection: To protect the seed and young seedling from organisms in the soil which might otherwise cause delay of the seed before germination.

Seed Treatment Fungicides

Equipments for seed treatment

Slurry treater

Direct treaters

Drum mixer

Grain auger

Shovel

1 .Slurry treaters

A slurry is prepared by mixing the chemical with water.

The treatment material to be applied as slurry is accurately measured through a simple mechanism comprised of a slurry cup and seed dump pan.

The cup introduces a given amount of slurry with each dump of seed into a mixing chamber where the seeds are mixed thoroughly.

2.Direct treater

Panogen and Mist o matic treater

The "mist-o-matic" treater applies chemical as a mist directly to the seed.

The treater is equipped with a large treatment tank, a pump and a return that maintains the level in the small reservoir from which the seed is fed.

A simple mixer can be made by running a pipe through a drum at an angle.

The drum is then mounted onto a stand.

The seed and treatment are placed in the drum and it is rotated slowly until all the seeds are cornered with the chemicals.

3. Drum Mixer

Liquid materials can be dripped on the seed as they enter a grain auger or straw conveyer.

By the time seeds have left the auger the chemical is spread on the seeds.

4. Grain Auger

5. Shovel Seeds are spread on a clean dry surface 10-15 cm in depth.

The proper amount of chemical is diluted with water and sprinkled over the seed.

Mixing is done with shovel or sloop turning the seed at least 20 times.

SPECIAL SEED TREATMENTS

1. SEED COATING

Seed coating is the application of useful materials to the seed without changing its general size or shape.

Seed coating has been utilised to ameliorate environmental stresses such as drought and flooding

Seed coating with peroxide compounds provide oxygen to seeds under anoxic soil conditions

Hydrophilic polymers maintain a high water potential around germinating seeds

2. SEED PELLETING

Pelleting is enclosing of seed in a filler material using an adhesive with bioactive chemicals to ensure singling of seed and size increases for easy handling.

The binders for pelleting include gum arabic ,gelatin, starch and the commonly used fillers are Lime stone, gypsum, talc, vermiculite, peat etc.

The pellet may act as a physical barrier as well as mechanical barrier.

3. ENCAPSULATION OF SEEDS

Natural seeds also can be encapsulated using hydrogels

Redenbaugh et al.[3] mixed propagules with sodium alginate solutions and then transferred the coated propagules to a calcium salt to form a soft capsule.

This technology was developed to form capsules of somatic embryos by gelation to enhance their stability

4. FLUID DRILLING AND SEED PRIMING

It consist of germinating seeds in aerated water until radicle emergence

The seeds are then mixed in a viscous gel and sown with an appropriate drill.

The gel prevents seeding injury to the emerging radicle and maintains seed moisture

Seed priming allows for the regulation of the water content in the seed, either by soaking the seeds in water or in a solute; or, by exposing the seeds to water vapor.

Osmoticums such as PEG and inorganic salts have been used as a priming agentso Hydroprimingo Osmotic priming.o Solid matrix priming. o Drum priming

The seeds imbibe water for a time interval. After the time interval, the process is halted right before the first root, called the radicle, emerges from the seed.

With priming the germination process is activated so that seeds germinate more rapidly and emerge more uniformly

5. BIOLOGICAL SEED TREATMENTS

Seed treatment with beneficial microorganisms like Rhizobium spp. to treat leguminous seeds for nitrogen fixation and Azospirillum and other nitrogen –fixing bacteria has long been known.

Fathey [5] noted that an endophytic bacterium, Clavibacter xylii, when introduced into corn seeds is transformed to produce an insecticidal protien (§-endo toxin) from Bacillus thuringenesis which is active against the european corn borer

As a warning that the seeds have been treated .

The colour also indicate the uniformity of the chemical

coverage.Coloring of seeds prevents inadvertant use of treated seeds for food or feed purpose.

Coloring of seeds

Never used for animal or human consumption.

The treated seeds must be properly labelled.

Care must be taken to treat the seeds at correct dosage.

Do not treat the seed with concentrated liquid products.

The technique must be economical and practical for the specific crop, and above all the materials used should be environmentally safe

Precautions for seed treatment!!!

Name of Crop

Pest/Disease Seed Treatment

Sugarcane

Root rot, wilt Carbendazim (0.1%) 2 gm/kg seedTrichoderma spp. 4-6 gm/kg. seed

Rice Root rot disease other insects/pests

Bacterial shealth blight

Trichoderma 5-10 gm/kg. seed (before transplanting)Chloropyriphos 3gm/kg seed.

Pseudomonas flourescens0.5% W.P. 10 gm/kg.

Chillies Anthracnose spp.Damping off

Seed treatment withTrichoderma viride 4g/kg,

Carbandazim @ 1g/100 gm seed.

DOSAGES OF SEED TREATMENTS

Tomato Soil borne infection  of fungal diseaseEarly blight Damping offWilt

T. viride @ 2 gm/100gm seed.Captan 75 WS @ 1.5 to 2.0 gm a.i./litre for soil drenching.Pseudomonas fluorescens and V. clamydosporium @ 10gm/kg as seed dresser.

Cruciferous  vegetables(CabbageCauliflower, Broccoli, Knol-khol, radish)

Soil / Seed  borne  diseases (Damping off)Root knot nematode

Seed treatment with Trichoderma viridi  @ 2 g / 100 g  seeds Captan 75% WS @ 1.5 to 2.5 gm a.i./litre for soil drenching.Pseudomonas fluorescens and Verlicillium clamydosporium @ 10gm/kg seed as seed dresser

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