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• Rice is the most important food crop of the world. • Seed treatment of rice is practiced to control pest

and diseases and to fix atmospheric nitrogen. • Seeds are either treated with wet or dry condition

with chemicals or bio-inoculants to get resistance from pest and diseases.

• Biological inoculants such as Azospirillum, phosphobacteria, Vesicular Arbuscular Mycorrhiza etc. are treated with seeds or seedlings.

• Seedlings of rice are raised in nurseries and transplanted to main fields.

• Nurseries are three types viz., wet-bed, dry-bed and Dapog method of nurseries.

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To learn the detailed seed treatment methods in rice

To know the nursery bed preparation methods for rice.

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• Rice is belonging to the family Poaceae or Graminae and propagation of plant is through seeds.

• Seeds are the most important inputs in rice cultivation decide major part of its production levels.

• Treating the seeds with certain organic or inorganic substances is practiced in rice since ancient days.

• The seed treatment is mainly carried out to reduce the pest and disease incidence, to enhance nitrogen fixation from the atmosphere and solubilizing phosphorus in soil, breaking dormancy and increase the storability and viability of seeds.

• After treatment, the rice seeds are sown in the main field in different methods.

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1. Pest and disease incidence

2. Bio-fertilizer treatment

3. Sowing methods of rice

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A. Dry seed treatment

• Fungicides such as captan or thiram or carbendazim @ 2g /kg of seed are mixed well in a seed treating drum or polythene-lined bag for 24 hours and the seeds are soaked in water for sprouting.

• The treated seeds can be stored for 30 days without any loss in viability.

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• The seeds are treated with carbendazim or pyroquilon or tricyclozole solution at 2 g/lit of water.

• The volume of water requirement is equivalent to the quantity (kg) of seeds required.

• Seeds are soaked in the solution at least for 2 hours.

• Solution is drained-off and the seeds are soaked overnight in water for sprouting and used for sowing.

• This wet seed treatment gives protection to the seedlings up to 40 days from seedling disease such as blast and this method is better than dry seed treatment.

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• Talc based formulation of Pseudomonas fluorescens @ 10g/kg of seed are required and soaking is made in water (1:1 of water: seeds) over night.

• Excess water is decanted and sprouting of the seeds is allowed for 24 hours and sowing is made.

• Bio-fertilizers and bio-control agents can be mixed together for seed soaking.

• Fungicides and bio-control agents are incompatible.

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A. Seed treatment with bio-fertilizers

• Rice seeds are treated with Azospirillum (600 g/ha) and phosphobacteria (600 g/ha) with sufficient water wherein the seeds are soaked overnight before sowing in the nursery bed (The bacterial suspension after decanting may be poured over the nursery area itself).

• P fluorescens can be mixed with bio-fertilizers, as it is not inhibitory.

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• Slurry with 5 packets (1000g) of Azospirillum inoculants is prepared with 40 lit of water and root portion of the seedlings are dipped for 15-30 minutes in bacterial suspension and transplanted.

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• Sowing methods of rice are of two kinds. 1. Sowing in main field under dry and semi-dry rice

cultivation areas and 2. Sowing in nursery beds (for raising nursery) under

transplanting in puddled lowland areas. a. Dry sowing• Three methods are commonly followed in sowing

dry and semi-dry rice cultivation.• They are Broadcasting, Drilling or Sowing in furrows behind plough and

dibbling.

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• This is the most common method of sowing. In this method, the field preparation is made and when the field is in good condition, sowing is done by broadcasting the seeds.

• The seeds are covered then by ploughing the land lightly with a country plough or with a cultivator and are left undisturbed with the miniature ridges and furrows formed in the process of covering the seeds.

• The small furrows act as small drainage channel to carry away the heavy rain water quickly but slowly without causing soil erosion and also conserve moisture during dry periods.

• This method is quick and simple; cost involved for sowing is less.

• The disadvantages of broadcast sowing are higher seed rate and un-uniform germination as all seeds don’t come in contact with moisture and there is possibility of bird damage.

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• This method enables to cover a larger area within a limited sowing period.

• The seeds are sown behind the country plough by manually or attaching the seed drill.

• Machineries such tractors are also put in to use in certain cases where, the seed drills are attached and covers large area.

• The advantages of this method are: Less seed requirement (compared to broadcasting).Uniform germination due to placement of seeds at

uniform depthBetter crop stand and better yield.

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Dibbling the seeds•In this method, seeds are dibbled in the furrows of the country plough at regular interval. •Dibbling has the same advantage as obtained by drilling.•But, this method is time consuming and labourious and not in practice currently.

Method of raising seedlings •Healthy and vigorous rice seedlings grow faster after transplanting and are important for getting high yields.•Good seedlings should be short, thick and heavy and free from pest and diseases.•There are three methods of raising seedlings, viz., dry seedbed, wet seedbed and dapog method.

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• Dry seedbed or dry nursery is invariably prepared in areas where sufficient supply of moisture is assured through rainfall and where soil is sufficiently friable to retain moisture.

• In this method, the field is ploughed repeatedly to a fine tilth and raised beds of 4 to 5 cm height, 1.0 to 1.5 m width and of convenient length (according to slope) are prepared keeping 30 cm wide channel in between.

• The seedlings raised on raised seed-beds come up much more vigorously than those grown on flat seed beds.

• Dry seeds are sown on the beds with required moisture establish themselves more quickly.

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• Wet seedbeds or wet nurseries are generally raised in areas with assured supply of irrigation.

• It is the best method for obtaining well grown seedlings within a short period.

• For wet nursery, land is first ploughed under dry or moist condition and then puddled by repeated puddling until attain a free flowing of mud.

• After this, beds are prepared at 1.0 to 1.5 m width and convenient length and sprouted seeds (the seeds are soaked in ordinary water for 24 hours, incubated for 12-24 hours in a warm shady place) are either broadcasted or sown in rows.

• While sowing, thin film (about 2 cm) water must be retained in the beds so that the seeds can slowly sail through water and settles in the soil and avoid deep sowing.

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• The water need to be drained for 18 to 24 hours after sowing.

• Germination will be affected in place where there is water stagnation.

• Saturated condition is to be maintained in the beds from the 3rd to 5th day.

•From the 5th day onwards, quantity of water is increased to a depth of 1.5 cm depending on the height of the seedlings.

•Afterwards, 2.5 cm depth of water is maintained.•In some areas, semi-dry nursery is also raised. In this method, seed-

bed is prepared to a fine tilth in hot weather and is wetted with water before sowing. Seedlings are then grown in moist soil.

•The comparative merits of seedlings obtained from dry and wet nursery have been studied at different places.

•Experimental results in India concluded that there was not much difference in the productive potential of the two kinds of seedlings.

•Available facilities of irrigation and other resources and convenience can determine the choice of seedbed.

•However, wet nurseries have been observed to give better seedlings when raised during December-January months in India, since the seeds take longer time for germination in the dry nurseries because of low temperatures.

•Dry nursery was superior to wet nursery in June-July sowing, because of better root development during the early stage of plant growth.

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• This method of raising rice seedling is commonly prevalent in Philippines and has been introduced in India.

• The essential features of this method are to have a very thick nursery seeding without any contact with the soil.

• Raised beds are prepared similar to wet nursery.

• The beds are covered with banana leaves (after removing mid-rib) or empty cement / fertilizer bags or polythene sheets to prevent the roots of seedlings from coming in contact with soil.

•A wall of 5-6 cm high is made of strips of banana sheaths on four sides of the bed to keep the seeds in place after they are sown.

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• Pre-germinated seeds @ 3 kg m-2 are sown uniformly on the beds.• Water is splashed on the germinating seeds and the seeds are

pressed down slightly by hand or light wooden plank. • This prevents exposure of roots to the air and helps germinated

seeds and with the ground. • For 3 to 4 days, the seedlings are kept moist by sprinkling water• Seedlings will be ready for transplanting within 14 days,

regardless of duration of the variety. • Fertilizer is not needed since the seedlings are nourished by food

in the seed. However, if the growth of the seedlings is not satisfactory, 1% urea solution may be applied.

• No plant protection measure is needed against pests and diseases.

• Concrete floor can be used as base for Dapog seedlings, but frequent watering is necessary on cemented base to avoid scorching effect on roots.

• The whole seedling mass with matted roots can be rolled and carried to the field where the seedlings are easily separated and transplanted. Seedlings raised on 40 m2 will be sufficient for planting 1 ha of land. Next Previous End

• The seedlings raised any of the three methods are pulled out carefully after attaining its required age (3-5 leaf stage) and transplanted to the main field @ 2-3 seedlings/hill for short duration and 2 seedlings/hill for medium and long duration varieties.

• Shallow planting (3 cm) ensures quick establishment and more tillers.

• Deeper planting (> 5cm) leads to delayed establishment and reduced tillers.

• Line planting permits rotary weeding and its associated benefits.

•A minimum row spacing of 20 cm is allowed to use rotary weeder.

(cont)..

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• Under System of rice intensification method, the seedlings are raised with modified mat nursery and pulled out at the age of 8-14 days.

• Seedlings are transplanted at 25 x 25 cm spacing using markers.

• Transplant within 30 minutes of pulling out of seedlings establishes without having transplanting shock.

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• The seed treatment in rice is mainly carried out to reduce the pest and disease incidence, to enhance nitrogen fixation from the atmosphere and solubilizing phosphorus in soil, breaking dormancy and increase the storability and viability of seeds.

• Captan, thiram, carbendazim, pyroquilon and Pseudomonas fluorescens are some of the chemicals and bio agents used for treating rice seeds to protect against diseases.

• Azospirillum and Phosphobacteria are generally used for seed treatment and sometimes, seedlings are dipped in the solution to fix atmospheric nitrogen and solubilize the phosphorus in the soil.

• Sowing methods of rice are of two kinds. 1. Sowing in main field under dry and semi-dry rice cultivation and 2. Sowing in nursery under transplanting in puddled lowland areas.

• Dry sowing methods comprise of broadcasting, drilling and dibbling the seeds and the first two are practiced widely.

• Method of raising seedlings under transplanted condition also has three methods, dry seedbed, wet seedbed and Dapog method. Of three, wet bed method is commonly followed. Next Previous End

• Fungicides must be treated prior to bio-agents in rice while making seed treatment (True/False)

• Bio-fertilizer treatment replaces fungicides treatment in seed treatment (True/False)

• Most common method of dry sowing areas of rice cultivation is broad casting (True/False)

• Dry-bed nursery is preferred over wet-bed in supply of water for transplanting is uncertain (True/False)

• Dapog method of nursery is common in Philippines(True/False)

 

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Chatterje, B.N. and S. Maiti. 1988. Principles and Practices of Rice Growing. Oxford and IBH Publishing Co. Pvt. Ltd., New Delhi.

CPG, 2005. Crop production Guide. Tamil Nadu Agricultural University, Coimbatore and Commissioner of Agriculture, Chennai, India.

Rajendra Prasad, 1999. A text book of Rice Agronomy. Jain Brothers, New Delhi.

Yellamanda Reddy, T. and Sankara Reddi, G.H. 1995. Principles of Agronomy. Kalyani Publisher, Ludhiana.

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