breeder seed production

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SEED PRODUCTION ANDPRESERVATION OF RICE

Dr. M Khairul Bashar


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INTRODUCTION

Seed is an important and basic input in

agriculture. Unlike other inputs, it is a livingthing subject to genetic and othertransformations anddeath. Therefore, seedproduction and preservation technology of

any crop must have given special attentioncompare to the normal crop production.


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After releasing a new variety there is achain of seed production from breederseed to the farmers seed. In Bangladesh,three categories of rice seed are generally

classified based on the stages of seedmultiplication. Those are:


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BreederSeed: Breeder seed or thevegetative propagating material produced

by the breederwho developed the particularvariety. It is produced by the institutewherethe variety was developed. Breeder seed isgenetically pure.

Foundation Seed: Foundation seedobtained from breeder seed by directincrease. Foundation seed is geneticallypure and is the source of certified seed.


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CertifiedSeed: Certified seed is producedfrom foundation. This group of seed isnamed as certified seed because it is

supposed

to be

ce

rtified

bySeed

CertificationAgency (SCA).

However according to the new seed rules in

Bangladesh BreederSeed and FoundationSeed are also certified regularly by SCA.


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Truthfully LabeledSeed (TLS): TLS seed isobtained from certified or foundation seed.The seed is must be maintained certain

prescribed standard of seed role. The purityshould be maintained at least 94%,germination should be 80% and seedmoisture must be 12%.


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The above classes of seed must have

followed certain standards in the field aswell as in the laboratory.

The important sources of rice seed supply

in Banglade

sh are

Farme

r saved

seed

,neighboring farmers; local market andBADC.

Out of total national demand, only 10% riceseed is supplied by BADC.So farmer saved seed is the major sourceof rice seed supply in Bangladesh.


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Most of the farmers in Bangladesh,

howe

ve

r,d

o not re

place

the

ir seed

and

as a result quality of the farmer's seeddeteriorates.

But it is expected that under on-farmsituations, the seed standard shouldbe maintained at par or at least veryclose to certified seed level.

As such there is a strong need toimprove the quality of this farmers'saved seed so that productivity mayincrease.


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TECHNIQUES & CRITERIAS FOR

SEED PRODUCTIONSelection of Land: The land used should beuniform as much as possible, to allow theevendevelopment of plants. It is vital that the plants

should not be subject to nutrient orwaterstress, which would prevent the fulldevelopment of the plants, nor should the soilbe too fertile, which would promote lushvegetative growth anddisease.

Selection of Variety: Selection of propervariety for appropriate season is necessary forsuccessful seed production.


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Land Preparation:Proper Land preparation is necessary forgood seed yield.

Ploughing:

The land should thoroughly be ploughed 3-4times followed by laddering to make the

land uniform level.


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Timing of SeedSowing:

Aus: April,T. Aman: Late June to Early July

Boro: Mid November to Early December.

Seedlings are transplanted usually at about 30days old in T.Aman, 40 days old in Boro and25 days old inAus.

Usually single

seed

ling pe

r hill or plant is used

for seed production.Correct timing is crucial for the plants todevelop properly so that their morphological

characters may fully beexpressed.

Sowing & transplanting


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Lay out ofSeedPlot for BreederSeed

Panicle to row system

Single seedling per hill or plantA gap between every six row

Isolation distance from other varieties


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Fertilizer:

The standard full dressing required is80/60/40 kg NPK/ha for Boro and T.Aman,and forAus is 60:40:40 kg NPK/ha. Gypsumand ZnS04 should be applied @ 100 kg and

10 kg pe

r ha.All the

P, K,S

and

Zn to be

appliedduring final land preparation.

Top dressing:

Nitrogen is splitted usually into threedressings: 7-12 days after transplanting,during maximum tillering time and 5-7 daysbefore panicle initiation stages, respectively.


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Irrigation:

T.Aman crops are normally rainfed but may needsupplementary irrigation.

Boro crops areentirely irrigated.

Irrigation water should be applied at 2-3cm depth3 days after transplanting.Too much water after transplanting will reduce thetillering ability of rice plants.

Waterdepth should be increasedduring latevegetative and reproductive stage and graduallywater should bewithdrawn 2 weeks beforeharvest.


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Weeding:

The crop is normally weeded 3-4 times,including after the top dressing hasbeen applied, to reduceweeds and

incorporate fertilizer.Pesticides:

Inse

cticide

s are

applied

if pe

stinfestation is high, but normally nofungicides are used. Plants seriouslyaffected by diseases are pulled out.


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Field Observations:Field observations should be made overthewhole growing season to monitor

the crop condition under field situation.Plants must be observed in a detailedand systematic way. Most frequentobservations are to be madeduring theperiod of panicleemergence to earlyseeddevelopment.


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Roguing:

Roguing is the removal of off-types, undesirableplants or mixtures.Roguing can bedone at any time of the cropstage.

Usually this operation should bedone fromvegetative to maturity stages to see that allpossible mixtures are removed before harvesting.

Varietal mixture should be removed on timebecause it will be very difficult when the rice plantslodged particularly in wet seasons. Off-typesshould be cut up to the root system. This is one ofthe most important operations in the production ofseeds to maintain varietal purity.


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Identifying characteristics of off-types:

Off-types can be identified by observing the

following characteristics of plants:Plant height:- Plants taller and shorter than mostof the plants in plot are off- types.

Colour of leaves, sheaths, and straws:- Plantsthat exhibit colours other than thedominant onesare off-types.

Panicleexertion:- Plants with earlier or later

panicleemergence are off-types.Angle of flag leaf- iferect flag leaf is dominantthen horizontal anddroopy leaves are off-types.


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Presence or absence of awns- if the majority ofthe plants arewith awns, and then thosewithoutawns are off-types. However, individual seeds inthe panicle should be carefully examinedbecause in some cases grains in a panicle couldbewith orwithout awns.

S

ize

, shape

, and

color of grains- if most of the

panicles have long grains, and then thosewithmedium grains are off-types. If slender grains aredominant, then bold grains are off-types. Somevarieties differ in the colour of grains (straw,brown, golden. etc.)


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Roguing should bedoneduring postemergence, vegetative growth, flowering, post

flowe

ring and

pre

-harve

st time

s.The best time for rouging is at flowering.

However, off-types should be rogued outimmediately, when those are identified.Besides, all weeds should be removed toensure that no weed seed is mixedwith the riceseeds.

Sources of off-types are volunteer plants fromprevious crop, natural out- crossing, mutation,minor genetic variation, developmental variation,and mechanical mixtures.


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Harvesting & threshing:

Harve

sting of seed

fie

ld

should

be

d

one

time

lyto prevent crop losses anddeterioration inseed quality.

The

optimum time

for harve

sting isw

he

n 80%grains are ripened.

Two methods are usually practicing forHarvesting ofRiceSeed

Individual plant selections

Selection of part of standing crop as seed


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Incase of individual plant selections theselected plants should be harvested firstand remove from the field and then therest of the field should be harvested.

Incase of selection of part of standing

crop as seed, the part of the field to beused as grain should be harvested firstand then the part to be used as seedshould be harvested.

The harvested plants/ produce should bedried properly to prevent deterioration.


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The selected plants / produce fromreserved area should be kept separately

to prevent mixing.The threshing floor should be cleanedthoroughly before threshing to avoid

mix

ture

s.The selected plants/ produce should bethreshed carefully to avoid mechanicald

amage

to seed

.The seeds should be cleaned properly toremove chaff, leaves, stones etc., as ameasure of preliminary cleaning.


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Drying:

Drying of seed immediately after threshing is amust in seed production.

One or two days seed storagewithout dryingmay spoil ordamage the seeds.

This may result in discolored seeds and possiblyaffect the viability and vigour of the seeds.

Drying can bedone by using artificial drier

particularly during the Boro/Aus season and alsoby sun drying during T.Aman.


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Seed Cleaning and Grading:

Dried seeds (less than12% moisture content)

should be cleaned by using blowers or seedcleaner to removeempty, light anddiseasedseeds, weed seeds, soil particles and other plantparts. The cleaned seeds are then temporallyplaced in clean sacks.

Seed preservation:

Seed is usually preserved or stored for the periodbetween seed harvest and planting of next crop.Seed usually deteriorates and loose generationand physical quality during storage. By providingproper storage condition and good management,the rate of loss of generation and physical quality

can be minimized.


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Factors influencing quality of seed instorage are moisture, temperature, andquality of seed at time of storage,storage fungi and insects, rodents andbirds.

Moisture and temperature are the twomost important factors affecting thequality of seed.

Seed

stored

at high moisture

are

more

likely to bedamaged from hightemperature, mechanical damage,storage fungi and insects.


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The following steps should be adopted for safestorage:

Storedried seed properly.Store healthy, undamaged, fully matured seedwith high generation. Store seed underdry andcool conditions.

Store seed in stores free from leak anddampness.

Clean the store properly before storage of seed.

Maintain cleanliness in and around seed store.Do not store seed bags on floor but on woodenplanks. Seed bags should not touch thewall.

Control insects and rats in store.


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Type of containers used for packing depends onQuantity of seed to be packed, cost of containers,

and availability of packing containers, storageconditions and moisture percentage of seed ofcontainer.

Commonly used containers aredrums and tins,gunny bags, gunny bags linedwith polyethylene,Plastic containers andearthen pots.

Seed may stored in controlled conditions ifpossiblewith low relative humidity and lowtemperature


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Precautions to be taken during storagePack only thoroughly dried seed in clean

containe

rs. Othe

rw

ise

,d

amage

to the

seed

w

illbe very fast.Biting test of seed is a commonly used andreliable method for checking thedrying of seed.

The seed moisture content should be below 12%for preservation.Close the containers properly after packing theseed.

Check stored seed often for insect attack duringstorage.Dry the seeds again before packing in containers.Open containers for checking only on a clean andsunny day.


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breeder seed production

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