By :Mohammad Safar NooriSr. M.Sc.

Seed production TechnologyOf Wheat

Introduction It is the most important human food grain and ranks second in total production as a

cereal crop behind maize and the third being rice. Wheat is the staple food for over ten billion people in as many as 43 countries of the

world. Wheat provides nourishment to 35% of world population. Wheat cultivation has traditionally been dominated by the northern region of India.

The northern states of Punjab and Haryana Plains in India have been prolific wheat producers.

Today, India is exporting sufficient quantities of all types of wheat and extensive research efforts are underway for improving its cereals and grain output in the years to come.

The major Wheat production State are Uttar Pradesh, Punjab, Haryana, Madhya Pradesh, Rajasthan, Bihar, Maharashtra, Gujarat, Karnataka, West Bengal, Uttaranchal, Himachal Pradesh and Jammu & Kashmir.

The share of wheat in total food grain production is around 35.5 % and share in area is about 21.8 % of the total area and their food grain (Rao, 2006).

Seed enterprises consider ‘wheat seed’ to be of secondary importance, since it is a self-pollinating crop and the grain can be used as seed, farmers tend to replant their own seed. In last ten years significant efforts have been made for commercial exploitation of hybrid wheat through the use of gametocide and CMS lines. Today France and Italy are at the verge of commercial release of such wheat hybrids for grain purposes.

Wheat Targets - 2030 AD 90.0 m tons of wheat to feed Indian population by the year 2030 A.D.

O R I G I N The exact place and date of the origin of wheat plant that we recognize today

is unknown. Hexaploid wheats, widely grown to day thought to have evolved before 7000 BC in an area from just south of the Caspian Sea in Northern Iran Eastward into Northern Afghanistan .

De Candolle believed – Valley of Euphrates and TigrisBut Vavilov

– Origin of Durum wheat probably Abyssinia– Soft wheat groups – In the region of Western Pakistan, SW Afghanistan,

and Some parts of mountainous Babshara

Major cultivated species of wheat

• Durum - (T. durum) The only tetraploid form of wheat widely used today, and the second most widely cultivated wheat today.

• Einkorn - (T. monococcum) A diploid species with wild and cultivated variants . One of the earliest cultivated, but rarely planted today.

• Common Wheat or Bread wheat - (T. aestivum) A hexaploid species that is the most widely cultivated in the world.

• Emmer - (T. dicocum) A tetraploid species, cultivated in ancient times but no longer in widespread use.

• Spelta - (T. spelta) Another hexaploid species cultivated in limited quantities.

Latest Release of wheat varietiesHD-2894 (2008) High yielding variety for NCR Delhi, with an average yield of 5.2

t/ha having a protein content of 12.9%, It is developed by IARI New Delhi

HD-4713 (durum) (2008) High yielding durum variety for NCR Delhi, with an average yield of 4.71 t/ha having a protein content of 5.15%. It is resistant to brown rust under both natural and artificial conditions

Pusa Gold (WR-544) (2005) for late sown, irrigated conditions of Delhi region, released by IARI New Delhi.

Pusa Visesh (HD-2851) (2005) & HD-4713(d) (2006)

timely sown, irrigated conditions of Delhi region, released by IARI New Delhi

Poorva (HD 2824) (2005) timely sown irrigated for NEPZ region, released by IARI New Delhi

HD-2888 (2006) timely sown, Rainfed conditions for NEPZ region, released by IARI New Delhi

Shresth (HD 2687)(2005),

Aditya (HD 2781)(2005)

timely sown, irrigated conditions of NWPZ region, released by IARI New Delhi

Floral biology • Main Culm flowers first & the tillers

bloom later in order of their formation .• Flowering starts at approximately 2/3

from the base and proceeds in both the directions.

• Blooming remains throughout the day & it takes 3-5 days for completion .

• Flower opening is usually during warmer part of the day i.e. , between 9 am to 2 pm and peak period between 10 am to 1 pm

• Anther dehiscence takes place simultaneously & hence the crop is highly self- pollinated ( < 1% cross pollination)

• Monocot species like wheat have caryopsis (cereal grains) as propagation units.

• Caryopses are single-seeded fruits in which the testa (seed coat) is fused with the thin pericarp (fruit coat).

• Cereal grains have highly developed embryos and in cereal grains the triploid endosperm consists of the starchy endosperm (dead storage tissue) and the aleurone layer (living cells).

• Organs of the cereal embryo are:• coleoptile (shoot sheath),• scutellum,• the radicula & • the coleorhizae (root sheath).

SEED

Seed development Stages in Wheat

Kernels at various stages during grain filling:a) kernel at watery ripeb) kernel at late milk c) kernel at soft doughd) kernel at hard dough showing loss of green color e) kernel ripe for harvest

Physiological maturity: When the kernels have attained maximum dry weight it is physically matured. Note the green color is gone from the peduncle and head parts.

Cultural Practices for Seed production of Wheat

Planning for wheat seed production

Land to be used for seed production of wheat should be: Free of volunteer plants. The field should be well drained, Free of weeds. The soil neither too acidic not too alkaline. Long interval of Crop rotation is desirable

Previous cropping The crop should be planted on a field with a known history

to avoid contamination from volunteer plants, noxious weeds and soil-borne diseases that are potentially seed transmitted.

A wheat seed crop should never immediately follow wheat, unless the wheat crop in the previous season was of the same variety and of the same or higher generation.

Two year rotation for flag smut and seed gall nematode is suggested where applicable.

Land requirement :

Isolation requirement Normally a self-pollinated crop(Clistogamous)• 1-4 % Cross pollination sometime occurs. • It is sufficient to isolate seed fields with a strip

of 3 meters all around which is planted with a non-cereal crop, or left uncroped.

• In cases where variety is susceptible to diseases caused by Ustilago spp. ( eg. loose smut) an isolation distance of 180 meters between seed field and other fields of wheat is recommended

• As per Indian minimum seed certification standards require only 150 m isolation from other wheat fields where in loose smut infection is in excess of 0.1% in the case of foundation seed production and 0.5 % in the case of certified seed production.

Cultural Practices

Time of Sowing:

Long duration varieties like C 306 should be sown during the first fortnight of November.

Short and medium duration varieties like Sonalika, HD 1982 should be sown during the second fortnight of November.

The optimum time of sowing for wheat is when the mean daily temperature is 23±3°C and for good tillering temperature should range between 16-20°C.

Preparation of Land • Deep ploughing with a soil turning

plough.• Running a harrow before the pre-

sowing irrigation.• Give a light shallow ploughing or

discing after pre-sowing irrigation. • Levelling is an important part of seed

bed preparation. • Keep the seed bed free of weeds.• Broadcast BHC, 10 per cent dust at 25

kg per hectare just before the last harrowing or ploughing. It may be added to the fertilizer and applied.This will prevent white ant and Gujhia attack.

Source of seed : Obtain nucleus/breeder's/foudation seed

from a source approved by the certification agency.

Seed Rate: The recommended seed rate for seed crop is 85-100 kg per ha. The seed should be treated with systemic fungicide to control loose smut. Spacing :The row distance for seed crop should be kept at 22 to 23 cm to facilitate roguing and inspection work. For late sown wheat reduce the line spacing to 15-18 cmCrop Rotation :Wheat is mainly grown in rotation with rice, sugarcane, arhar

(pigeon pea) and sorghum, cotton, pearl millet, cluster bean, sorghum, groundnut,

The seed crop is sown in rows with seed drill, or behind the plough in furrows.

The depth of seeding should be 5 cm. Seed drill should be thoroughly

cleaned and checked before use. Sowing of one variety should be

completed before taking up another variety, to avoid mixture.

If, for any reason, it has to be used for another variety, it should be thoroughly cleaned and checked so that not even a single seed of the previous variety is left.

Method of sowing

Fertilizer The recommended doses of fertilizers are:

80 to 120 kg/ha nitrogen, 50 to 60 kg/ha phosphorus 40 kg /ha potash 15 to 20 kg/ha zinc may be given at the

seeding time (in case of deficiency). Apply the whole of the phosphoric and

Potassic fertilizers and half of nitrogenous fertilizers while sowing, or just before sowing.

Apply the remaining half of nitrogenous fertilizer at first irrigation.

In rainfed conditions, all the fertilizer should be applied at the time of sowing as basal.

Field Inspection

The best time to access cultivar purity is after ear-emergence when seed has started to fill.

Latter inspection when glume and seed colour can be observed

Irrigation Depending on the soil, four to six

irrigations may suffice. The first irrigation should be given at

crown root initiation stage, about 30-35 days after sowing.

Other irrigations should be given at late tillering, late jointing, flowering, milk and dough stages.

Two to three extra irrigations may be needed on light soils.

In case of zero tillage, first irrigation should also be applied similar to conventional tillage.

Crown root initiation and heading stages are the most critical to moisture stress.

Interculture

Timely weeding and interculture are essential.

Weed control by Periodic hoeing and weeding.

For control of broad-leaved weeds spray 2-4 D at@ 0.5kg active ingredient per hectare in 750 liters of water after 25 to 30 days of sowing.

For control of Phalaris minor or wild oats make a pre-emergence application of Penda methalin (stomp) @ 1 kg per ha in 750 liters of water or spray Isproturon @ 1 kg per ha in 750 liters of water after 35 days of sowing.

Roguing

Two or three roguings may be necessary

First roguing : Just ahead of the flowering stage, or

during flowering to remove any off-type plants which are obvious at this state of growth.

Second roguing : Just after flowering is completed, and

before the crop starts to turn colour. Third roguing: should be done after the ear heads turn

colour and start to mature.

Wheat DiseasesFlag Smut (Urocystis agropyri) Masses of black teliospores are produced in narrow strips just

beneath the epidermis of leaves, leaf sheaths and occasionally the culms. The epidermis of older diseased plants tends to shred, releasing the teliospores

:generally it is not an economically important disease, but where present, yield losses can range from trace amounts to moderate levels.

Control: Seed treatment with Carboxin (75 WP @ 2.5 gm/kg seed) or Carbendazium (50 WP @ 2.5 gm/kg seed) or Tebuconazole (2DS @ 1.00 gm/kg seed) ,two days before sowing.

Loose Smut (Ustilago tritici) The entire inflorescence, except the rachis, is replaced by

masses of smut spores. The disease can occur wherever wheat is grown

Yield losses depend on the number of spikes affected by the disease; incidence is usually less than one percent and rarely exceeds thirty percent of the spikes in any given location.

Control: Seed treatment with carboxin (75 WP @ 2.5 gm/kg seed) or carbendazium (50 WP @ 2.5 gm/kg seed) Seed treatment with fungicide should be done one or two days before sowing.

………………………………………………………………………………………

Cover Smut (Tilletia tritici )Plants may be slightly shorter, and the heads are usually darker green than normal and remain green for a longer period. Bunt infections result in the complete replacement of the seed contents with a mass of smut spores. When crushed, the infected grain releases a fine black-brown powder with an odor like rotten fish. Bunt is potentially the most devastating smut disease.Control: seed treatment with Foliarflo-C , Maxiflo, Vitaflo C, or Vitavax Do not sow seed visibly infested with bunt (cover smut) Only sow disease free seed

……………………………………………………………………………………………………Stinking smut (Tilletia caries) When bunt balls are crushed, they give off a fetid or fishy

odor. Infected spikes tend to be bluish green in color (or darker), and the glumes tend to spread apart slightly; the bunt balls often become visible after the soft dough stage . A slight reduction in plant height is typical of common bunt.

Considerable yield losses can occur when susceptible cultivars are grown or chemical seed treatments are not used.

……………………………………………………………………………………………………..Septoria (Septoria tritici) Initial infection sites tend to be irregular in shape, oval to

elongated chlorotic spots or lesions. As these sites expand, the centers of the lesions become pale, straw colored, and slightly necrotic, often with numerous small black dots (pycnidia) .

The lesions of septoria tritici blotch tend to be linear and restricted laterally

Major losses can occur, through seed shrivelling and lower test weights, if these diseases reach severe levels prior to harvest.

Take-all (Gaeumannomyces graminis f. sp. tritici ) This fungus causes rotting of the roots and lower stems. Basal

stem and leaf sheath tissues, as well as roots, may turn a shiny black color.

When infection occurs early in the crop cycle, the number of tillers is often reduced and spikes are often sterile.

Take-all is widespread in monocropped areas and has been known to cause considerable yield losses in winter wheat and fall-sown spring wheat areas, especially where liming or minimum tillage is practiced.

Control: Later plantings are better,Use Ammonium Nitrate,Fertilize early, Use higher rates of fertilizer, Do not lime take-all infested soil, Rotate with other crops, corn may produce scab in wheat

Ergot (Claviceps purpurea)

……………………………………………………………………………………………..

At flowering, infected florets produce a yellowish, sticky, sweet exudate (containing conidia) that is visible on the glumes. As the spike matures, kernels of infected florets are replaced by brown to purplish black fungal structures (sclerotia or "ergot bodies") .

The disease is more prevalent in cool, humid climates. Yield losses tend to be small, but losses due to

discounted grain quality can be significant and occur worldwide

Common and Dwarf Bunt (Tilletia controversa ) Bunt balls of Dwarf bunt is nearly spherical. When bunt

balls are crushed, they give off a fetid or fishy odor. Infected spikes tend to be bluish green in color (or darker), and the glumes tend to spread apart slightly; the bunt balls often become visible after the soft dough stage.

Considerable yield losses can occur when susceptible cultivars are grown or chemical seed treatments are not used.

Stem Rust or Black Rust (Puccinia graminis f.sp. Tritici) Pustules (containing masses of urediospores) are dark

reddish brown, and may occur on both sides of the leaves, on the stems, and on the spikes .

If infection occurs during the early crop stages, the effects can be severe: reductions in tillering and losses in grain weight and quality. Under favorable conditions, complete crop loss can occur.

Control: Growing , varieties, like GW 322, HD 2781, HUW 510, NIAW 34, MACS 2846(D), Raj 4037, In Peninsular Zone

…………………………………………………………………………………CZ, PZ & SHZ

Powdery mildew on wheat (Erysiphe graminis f. sp. Tritici) the first visible symptoms of this disease are white to pale gray, fuzzy or

powdery colonies of mycelia, and conidia on the upper surfaces of leaves and leaf sheaths (especially on lower leaves),and sometimes on the spikes. Older fungal tissue is yellowish gray.

Powdery mildew can cause major yield losses if infection occurs early in the crop cycle and conditions remain favorable for development so that high infection levels are reached before heading.

Control: one spray of propiconazole (25 EC) @ 0.1 % at earhead emergence or appearance of disease (whichever is earlier) is recommended for the powdery mildew prone areas.

……………………………………………………………………………Strip Rust (Puccinia striiformis ) The pustules of stripe rust, which, contain

yellow to orange-yellow urediospores, usually form narrow stripes on the leaves . Pustules also can be found on leaf sheaths, necks, and glumes.

Severe infections can cause yield losses, mainly by reducing the number of kernels per spike,test weights, and kernel quality

…………………………………………………………………………………Leaf Rust (Puccinia recondita) Infection sites primarily are found on the upper

surfaces of leaves and leaf sheaths , and occasionally on the neck and awns.

Severe early infections can cause significant yield losses, mainly by reducing the number of kernels per spike, test weights, and kernel quality.

Control: Cultivation of recommended varieties like NW 1014, NW 2036, K 9107, HD 2733, MACS 6145, DBW 14, HD 2888 and HUW 468

All Zones

NWPZ &NHZ

Karnal Bunt (Partial Bunt) Tilletia indica (syn. Neovossia indica) Karnal bunt is not easily detected prior to harvest, since it is

usual for only a few kernels per spike to be affected by the disease. Following harvest, diseased kernels can be easily detected by visual inspection: a mass of black teliospores replaces a portion of the endosperm, and the pericarp may be intact or ruptured.

Diseased kernels give off a fetid or fishy odor when crushed.

Karnal bunt is a relatively minor disease. Actual losses in yield are minimal, but the disease is on the quarantine lists of many countries and therefore of importance in world grain trade.

Control: one spray of Propiconazole (25EC) @ 0.1 %

may be given (in seed crop only) at ear head emergence stage.

Wheat Spindle Streak Virus(WSSV)

Spread by the soil-borne Fungus Polymyxa graminis

Control Use resistant varieties. Damage is usually not

severe, especially when temperatures stay above65 F.

Plant Protection Measures

Replace with new resistant varieties for rust resistance

Spray the crop (susceptible varieties only) with Propiconazole 25 EC (Tilt 25 EC) @ 0.1% at yellow rust initiation. This spray will also help in control of powdery mildew and Karnal bunt diseases.

Seed treatment with Trichoderma viride @ 4 g / Kg seed in combination with Carboxin 75 WP (Vitavax 75 WP) @ 1.25 g / Kg seed or Tebuconazole 2 DS (Raxil 2 DS) @ 1.0 g / Kg seed.

For managing cereal cyst nematode (CCN) in dry belt of northern Rajasthan CCN resistant wheat variety - Raj MR-1

Wheat Insect Pests

AphidsRussian aphid (Diuraphis noxia) Russian wheat aphids damage small grains by injecting

toxic saliva into the leaves and by sucking sap from the leaves. Yield losses of 50 per cent or more have been attributed to Russian wheat aphids.

The feeding of Schizaphis graminin is especially damaging, resulting in the development of necrotic areas sometimes accompanied by purpling and rolling of the infested leaves. The feeding of Diuraphis noxis produces long white stripes on the leaves , leaf rolling, postrate growth habit, and sterile heads

Control :. foliar spray of Imidacloprid 200SL @20g a.i./ha on border rows at the start of the aphid colonization be given

Resistant varieties: Halt, Akron (Ankor), Lamar (Prowers99), TAM107 (Prairie Red) ,Yuma (Yumar) and Stanton.

Wheat midge

Damage : midge is a seed feeder and infests a wheat plant during heading through early flowering Crop injury is caused only by the larval stage. After hatching, wheat midge larvae crawl down to feed on the developing wheat kernel.Control:Early planting is the most useful cultural control method. This method is suitable only for hard red spring wheat.Crop rotation: . Planting crops that are not susceptible to wheat midge, such as soybean, sunflower, flax, pea, lentil, chickpea, oat or corn, will reduce the reproductive opportunities for wheat midgeUse of Resistant Varieties: A highly effective resistance trait called Sm1 which reduces survival of early instar wheat midge.Chemical: insecticides are not effective in controlling older wheat midge larvae, which are protected within the glumes as they feed on the developing kernels Organophosphate insecticides with the active ingredient chlorpyrifos can kill eggs.

Hessian Fly (Mayetiola destructor) Damage :Hard red spring wheat infested in the spring and early summer will take on a dark bluish-green color and becomedistinctly thickened and stunted.Control:Resistant variety : Guard released by South Dakota in 1983)Crop rotation: oat,corn,sunflowerTillage: Moldboard plowing in the fall after the first killing frost.Chemical: phorate 20% granules for both hard red spring wheat and winter wheat and disulfoton 15% granules for winter wheat only.

GrasshopperInsects with hind legs adapted for jumping. They include the longhorned grasshoppers, pygmy grasshoppers, and shorthorned grasshoppers, or locusts. They subsist on vegetation and are distributed worldwide wherever vegetation grows.Grasshoppers are 3 to 13 cm (1 to 5 in) long when fully grown. They develop by gradual metamorphosis: The nymph is initially wingless and gradually comes to resemble the adult as it grows through progressive molts. Only the adults can fly. Control:Deep plough during winter will kill eggs Malathion@4-5kg/ha , Sevin @ 1kg active ingredient /ha

Wheat Stem Sawfly

True Army worm…………………………………………………………………………………………………….

Sawfly damage is threefold. First, they cause 10 to 14 percent grain yield reduction by their tunneling activity in the infested stems. Additional loss occurs when sawfly-cut stems fall to the ground and become unharvestable.Control: Resistant varieties: Ernest, Glenman, Leader, Tioga, Fortuna, LancerCROP ROTATION: non-host crops should be considered in these areas.Tillage: shallow fall tillage will provide up to 90 percent sawfly controlCHEMICAL: No effective chemical treatment is available

Can be serious pest of wheat when populations reach large numbers. They sometimes start at one portion of the field and devour everything in their path. Treat wheat plant if 6-8 larvae per square foot are present

and wheat is still in the milk stage. Once past the milk stage, it can tolerate higher populations and treatment is not usually recommended unless larvae are cutting wheat heads.

Control :carbaryl (Sevin XLR Plus 4)@32 - 48 oz/ac, methyl parathion 4 (Methyl 4)@24oz/ac, spinosad (Tracer 4)@1.5-3oz/ac.

oz=0.0284 liter

Insect Pest Control Measures

Adopt recommended IPM methods Cultural Practices : - Fall deep plowing. - Crop rotation

Mechanical control

Biological control

Chemical control Using insecticides as last option

Determination of physiological maturity in dicoccum wheat (Uppar et al., 1999)

field experiments were conducted at the main research

station , UAS, dharwad during rabi 1997- 98 & 1998- 99 to determine the physiological maturity for getting high quality seed in dicoccum wheat varieties .

The results indicated that the dicoccum wheat varieties DDK-1001, DDK-1009, DDK-1013 and NP-200 attained physiological maturity at 35 DAA, 35DAA, 40DAA, 45DAA, respectively and at this stage, the seeds had higher dry matter accumulation with maximum germination, root length, shoot length and vigour indices.

Soon after maturity, the seed crop should be harvested to avoid shattering and losses due to uncertain weather.

Most suitable stage is grain moisture of 20-25%. Mechanical harvesting is a common practice for seed

production fields. Breeder and pre-basic seed are harvested by plot

combine and do not constitute many problems. foundation and certified seeds have to be harvested

with commercial combine harvesters. The most critical factors to be considered are : i)seed moisture content , ii)mechanical damage iii) cleanliness of equipment. For seed crops, dry weather during ripening and

harvesting is essential. Threshing or combine harvesting at 16 to 19

percent moisture content reduces mechanical damage (Thompson, 1979).

Harvesting and Threshing

Harvesting &Threshing

Harvesting may be done by sickle , Combine or reaper, and later the threshing with stationary thresher.

Threshing should be done promptly.

Threshing equipment should be cleaned after threshing other wheat varieties.

The threshing floor must be thoroughly cleaned to prevent mixtures.

Care must be exercised to ensure that laborers do not mix the harvested certified seed with other wheat on the farm.

Processing • After a seed crop has been harvested, the seed, if

necessary, has to be dried and cleaned.

• For wheat seed cleaning, mainly screens, indented cylinders and air screen cleaner are used

• Screens separate based on the width and thickness; a width (or diameter) separation is obtained by round screens, while for thickness separation oblong screens are used .

• Indented cylinders carry out length separation; the indents (cells or pockets) in the cylinder will, depending on their size, lift the seeds, which fit in the indents.

• Air separates seeds according to their behavior in an air stream (seed density) . The most important characteristic is the weight; light particles (dust, chaff, glumes or empty or partly filled seeds) will be lifted, whereas the heavier seed will fall down through the air stream.

Pre-cleaner It has one air channel to remove light material, one top scalping screen to remove large

particles and one bottom grading screen to remove small particles.

Dryer If wheat seed is above 11 to 12 percent moisture, it is dried before it goes into bulk storage

or processing.

Air-screen cleaner This is the basic cleaner, usually with two air channels and, preferably, four screens. The first air channel removes dust and light materials as the seed falls from the feed hopper. The second air channel removes light seed and materials after the seed passes through the

last screen. Screen configurations vary considerably, one or two top or scalping screens remove

particles larger than the good seed, and one or two bottom or grading screens remove particles smaller than the good seed.

Because the average size of wheat seed varies according to the growing conditions, standard screen sizes cannot be recommended..

In general size of Screen aperture for all wheat variety is :

Top screen 6.40 mm(R); Bottom screen 2.10 mm(S)

Length separator A length separator is almost always used to clean wheat seed. By using

the proper machine configuration, shorter or longer undesirable materials (such as broken grains, weed seeds, oat, barley, etc.) are removed. Broken grains and weed seeds, which are shorter than the good seed, are removed by using cylinders with smaller indents.

Larger impurities can be removed by using a cylinder with indents that lift all good seed, but contaminants (wild oats, oats or barley grains and unthreshed glumes) remain in the cylinder.

Gravity separator The gravity separator classifies a seed mixture mainly according to

density or specific gravity. It can be used to remove unthreshed glumes and soil particles, which have similar sizes to wheat but different weights.

Another application is the removal of weevil-infested grains from the seed lot and upgrading seed (in order to improve germination).

Further more, wild oats and some barley may be removed from the wheat seed lots.

Treater Wheat seed should, if necessary, be treated with the appropriate

fungicide to protect the seed and seedling after planting. Insecticides are sometimes applied to protect seed in storage and

in the soil. Treatments may be applied to protect the seedlings or adult

plants against pathogens carried on or in the seed.

Dryer In humid and hot climates, seeds may be sealed in vapour-

tight plastic bags to maintain viability over longer periods. In such cases, wheat seed moisture content must be below 9

percent, preferably not over 8.5 percent. Usually, a dehumidified, closed-circuit dryer is used after the seed treatment is applied.

Bagger-weigher• The final step is to weigh the proper amount of seed into the

proper kind of bag. • Wheat seed bags should be of a size that fits local farmer needs

(seed rates and field size).

Seed yield The average seed yield varies from 30 to 40 q/ha

Storage Seed should be harvested when it reaches harvest

maturity, dried to a safe moisture content (if necessary), stored under favourable conditions and protected from damage and pests until it can be planted.

Immature or damaged seed cannot survive long storage periods.

Mechanical injury to seed during harvest or handling makes it more susceptible to deterioration in storage.

seed should be properly dried before going into storage and protected from moisture and high relative humidity.

Fungi (Aspergillus and Penicillium) cause damage to stored seed if seed moisture is high.

High storage temperature has a damaging effect on seed. Stores should be designed so that low temperatures are maintained;

• In general, stored wheat seed should be kept at moisture content levels below 12 percent and relative humidity should not exceed 50 to 60 percent. The cleaned, bagged seed should be stored in a dry, insect and rodent proof warehouse.

• Effective rodent control (traps and poison) is essential in all seed stores.

• A complete programme of exclusion , sanitation and control should be used;

• Insects should be controlled by a combination of insecticides and fumigants. Use safest fumigants (e.g. Phostoxin ) because some fumigants (e.g. methyl bromide) will reduce germination.

Cont….

Wheat Storage pest

RedFlour beetle

Grain Borer

(Tribolium castaneum)

Granary Weevil Meal Moth

warehouse_moth

Lesser grain borer (Rhizopertha dominica)

Angoumois grain moth (Sitotroga cerealella)

(Oryzaephilus surinamensis)Sawtoothed Grain beetleRice weevil

(Sitophilus oryzae)

1. Preventive measures: Hygiene or sanitation. Disinfestation of store Legal method

2. Curative measuresNon Chemical control measure. Ecological control: Temperature : 140C retards reproduction, below 100C kills insectsSeed Moisture : seed stored at 10 % moisture content escape from insect.Availability of oxygen :Decrease in oxygen and increase in CO2 is lethal to insects.

Mechanical Control:Entoleters Probe trapsPitfall trapsPheromone traps

Chemical control: Malathione @ 2g/kg of seed.Fumigation : Aluminum phosphide @ 2 tablet of 3g / ton of seed, exposure period 5-7 days

Storage pest management

TNAU Probe Traps

PITFALL TRAP

TWO IN ONE MODEL

TNAU AUTOMATIC INSECT REMOVAL BIN25 kg 100 kg 500 kg

• Seed health is an important attribute of quality, and seed used for planting should be free from pests. Seed infection may lead to low germination, reduced field establishment, severe yield loss or a total crop failure

• In wheat, fungi (Fusarium spp., Tilletia spp., Drechslera spp., Septoria spp. and Ustilago spp.), bacteria (Corynebacterium, Pseudomonas and Xanthomonas) and nematodes (Anguina tritici) are the most important seed-borne diseases due to their worldwide distribution and losses they incur in crop production (Mamluk and van Leur, 1986; Diekmann, 1996a).

• Chemical seed treatment is one of the efficient and economic plant protection practices and can be used to control both external and internal seed infection.

• It protects young seedlings or adult plants against attack from seed-borne, soil-borne or airborne pests

• Meisner et al. (1994) indicated that Vitavax 200 (Carboxin [37.5 percent] and Thiram [37.5 percent]) is an effective broad spectrum seed treatment fungicide, both for externally and internally seed-borne diseases of wheat. Moreover, pre-harvest foliar application of chemicals can also reduce the internally seed-borne fungi and can be combined with seed treatment to produce healthy seed.

• Sinclair (1983) cited that foliar spraying of wheat with Benomyl, methyl benzimidazole carbamate or benomyl plus mancozeb reduced F. graminearum, whereas capatafol and mancozeb reduced Septori nodorum.

SEED TREATMENT

Stamina™ A New Fungicide It inhibits fungal respiration, depriving the pathogen of energy for growth and

development The labeled use rate for Stamina is 0.4 fl oz per 100 lbs of seed. It has shown to have activity against a broad spectrum of wheat and barley pathogens. Stamina in combination with Charter® Fungicide Seed Treatment provides protection

from a broad range of wheat and barley pathogens.

Charter (3.1) + Stamina (0.4)

BASF,2007

Seed Testing in Wheat

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Single–Kernel Characterization System (SKCS)Method1. A sample of wheat kernels (12 to 16 grams) is prepared by removing broken kernels, weed seeds, and other foreign material.2. The sample is poured into the access hopper of the single-kernel characterization system instrument.3. The SKCS instrument analyzes 300 kernels individually and records the results on a computer graph.

Results• Wheat kernel characteristics are analyzed for: kernelweight by load cell, kernel diameter and moisture content by electrical current, and kernel hardness by pressure force.• Averages and standard deviations of these parameters are reported as SKCS results in terms of values: kernel weight is expressed in milligrams (mg); kernel diameteris expressed in millimeters (mm); moisture content is expressed as a percentage; and kernel hardness is expressed as an index of –20 to 120.

Minimum Sample Weight for testing wheat Seeds

(ISTA, 2007)

Maximum weight of Seed lot

(Kg)Submitted Sample

(g)Working Sample

(g)Working Sample for Counting of other

Species (g)

30,000 1000 120 1000

Germination Test ( ISTA,2007 ) Objective: To obtain information with respect to the planting value of the seed and to provide results which could be used to compare the value of different seed lots.Procedure :Replications: Four replication of 100 seeds Substrata : TP, BP, STemperature: 200C RH : 95±1 First Count : at 4th dayFinal Count: at 8th dayDormancy breaking treatment: Preheating (30-350 C)

First Count

Final Count

Seed moisture content is one of the most important factor influencing seed quality and storability. Therefore, its estimation during seed quality determination is important. Seed moisture content can be expressed either on wet weight basis or on dry weight basis.

Procedure : Three Replication of 4 gram seed .Grinding : Course grinding Either LCT (1030C for 17h; or HCT (1300C) for 2h

Use desiccators : 30 – 45 min Calculate moisture content using following formula:

W2 – W3

Moisture content (%) = -------------- X 100 W2 – W1

Seed Moisture Test ISTA,1976

Wheat Varietal Identification

Phenol color reaction Extensively used for identification wheat

varieties It is easy, quick and reliable

test Pieper(1920) was first to use

this test

Procedure: Soak 50 seeds in water for 16 hrs Place seeds in Petri dishes on 2

layers of filter paper soaked in 1% phenol solution

Petri dishes are immediately covered. Observe after 2 hrs and finally at 4 hrs

The varieties could be grouped into : Nil, no reaction, Light brown Brown Dark brown Black

DETECTION METHODS OF PATHOGEN

Direct seed examination

Seed Health Testing

Germination test

Detection of Septoria nodorum on Wheat (Triticum aestivum)

• Treated Seed• This method has not been validated for the determination of Septoria

nodorum on treated seed.

• Materials• Reference Material: The use of reference cultures or other

appropriate material is recommended when ever possible.• Media : Malt Agar or Potato Dextrose Agar containing 100 ppm

streptomycin sulphate.• Sodium hypochlorite solution (1% available chlorine) for seed disinfection.• Petri dishes: When sowing density is given by a number of seeds per Petri

dish, a diameter of 90 mm is assumed.• Incubator: Capable of operating in the range 20 ± 2 ºC.

• Sample Preparation• The test is carried out on a working sample of 400 seeds as described in

Section 7.4.1 of the International Rules for Seed Testing.International Rules for Seed Testing ,2008

Method1. Pretreatment : 10 minutes in 1% (avilable chlorine) sodium

hypochlorite.

2.Agar method : Malt agar or Potato Dextrose Agar containing

100 ppm streptomycin sulphate.

3.Incubation : 7 days at 20 ºC in darkness.

4. Examination : After 7 days examine each seed by naked eye for

slow-growing circular colonies of dense white or cream mycelium that often covers infected seeds. The reverse of the colony is yellow/brown becoming darker with age.

Slow growing, finely tufted, white aerial mycelium of Septoria nodorum covering grain in an agar plate test

Detection of Karnal bunt of wheat, caused by Neovossia indica

Method: Sodium hydroxide ( NaOH) Seed soak. Procedure: a known quantity of wheat seeds are soaked in a flask/beaker

containing 500ml of 0.2 percent NaOH solution for 24 h at 20-300 C. After 24 h of soaking NaOH is decanted and seeds are thoroughly washed in

tap water. Seeds are spread over a blotter paper so to excess water on the surface of

seed is absorbed. Later seeds are transferred in to a petridish and examined visually aided with

light . The seeds exhibiting jet black shin appearance with hollow or without

hollowness are separated and individual seeds are ruptured on a slide in a drop of water and observed for the release of stream of fungal spores under compound microscope

The number of seeds releasing stream of fungal spores are counted and as infected seed and the result are reported in percentage.

Detection of Loose Smut of wheat, caused by Ustilago tritici

• Method: Embryo count method.• Procedure: Soak 2000 seeds in 5% NaOH and 0.02% trypan blue solution(one liter)

for 24 h at 25-300C.• Pass soaked seed material through 10 mm mesh sieve and retain material in 20 mesh

sieve along with showers of tap water.• Collect the extracted embryos in beaker and dehydrate embryos in rectified spirit for

5-10 min.• The hydrated embryos along with chaff etc are taken in a beaker containing 50 ml

lactophenol and add to above beaker 100 ml water, stir it well.• Allow to stand for 5 min to settle the chaff at bottom.• Collect the floating in beaker containing 25 ml fresh lactophenol and boil the above

material for 2 min.• Pour embryos in to glass dish and arrange in lines along with some lactophenol and

observe the embryos under steriobinacular microscope for the presence of mycelium. Mycelium appears as blue thread like knotted structure in the scutellum portion of the embryo.

• Total number of embryos and infected embryos are counted and the result are reported in percentage.

• Prescribed Seed standard for seed Certification(ISTA)

Seed Class Germination % Moisture

Pure seed (min)

Inert matter %

Other crop seed

(max)ODV (max)

Object-able Weed

Seed(max)

Foundation Seed 85 12.0 98 2 10 - 10

Certified Seed 85 12.0 98 2 20 - 20

Field Standards

Class of Seed Off-type Pollen shading Object-able plant

Plant head affected by designated

disease

Foundation Seed 0.050 - 0.010 0.10

Certified Seed 0.1 - 0.020 0.50

Conclusion Wheat is a high-volume, low-value crop and has been produced primarily by heavily

subsidized government seed programmes.

The private sector, however, may not focus on wheat seed due to its characteristics (self-pollinating, high-volume and low-profit).

To meet the demand for improved seeds of wheat, new improved varieties developed by National Agricultural Research Systems (NARSs) should be multiplied and made available to farmers in the shortest possible time. Appropriate seed production techniques coupled with strict quality control measures ensure that varietal purity and identity is maintained, which is the key foundation of the entire quality seed program.

Seed enterprises consider ‘wheat seed’ to be of secondary importance, since it is a self-pollinating crop and the grain can also be used as seed, farmers tend to re-plant their own seed.

In last ten years significant efforts have been made for commercial exploitation of hybrid wheat through the use of gametocide and CMS lines. Today France and Italy are at the verge of commercial release of such wheat hybrids for grain purposes.