Sexually or vegetatively propagated planting materials which are used
for seeding and planting and as such should be free from any infection
(pests and diseases) and should give a good crop stand by good seeding.
The ovule after fertilization develops into the seed with its coats
completely fused together with the developing ovary wall or pericarp.
The rice grain has the following structures.
The Pericarp or Fruit Coat
The pericarp is made up of distinct layers of quadrangular cells which
forms the epicarp. These cells have slight thickening and are followed
by cells which are much compressed and form the mesocarp consisting
of two to three layers.
The endocarp is single layer of tube cells. The colour in the rice
grain is found in the pericarp layer in the mature stage.
The Seed Coats
Due to the pressure brought out by the developing seed on the pericarp,
the testa and tegmen become much pressed down and out of shape. A few
layers of such cells below the pericarp can be diagnosed as the integuments
of seed coats.
Aleurone Layer
A prominent layer of rectangular cells which contain protein lies
next to the seed cents. This layer is known as the aleurone layer. This
layer in rice is not coloured unlike in the case of maize.
It has been observed that in coloured varieties of rice, the aleurone
layer is thicker than in the white rice varieties. The coarse rice generally
have a larger aleurone layer than the finer rice. It has also been found
that in poor soils, the aleurone layer is thin and improves in thickness
with the fertility of the soil and manure.
The Endosperm
The entire mass of tissue below the aleurone layer is made up of cells
which contain plenty of starch grains and these form the endosperm.
The Embryo
The scutellum has an upper free part which has a flesh projection
known as ventral scale. Below this upper ventral scale and almost at
the middle of the free part there is another out growth which can be
called as the 'inner ventral scale' and this inner ventral scale is
peculiar to rice embryos only.
On the surface of the embryo this out growth along with the epiblast
forms a continuous covering around the plumule. The structure between
the scutellum and the plumule is the mesocotyl.
Local varieties are nothing but traditional varieties but which are
susceptible to diseases and pests and are having long duration for maturity.
In case of rice - Krishnakatukalu, Basangulu.
High Yielding Varieties
High yielding varieties are dwarf varieties and having short duration
with resistant to pests and diseases with maximum yield potential.
Eg: I.R -64, I.R - 36, I.R - 50.
Hybrids
A systematic and extensive evaluation of the experimental hybrids,
across the country, at the twelve research net work centers has been
taken up. About eight hundred experimental hybrids have been evaluated
so far. During the wet season ( Kharif), the experimental hybrids are
being evaluated at 12 centers, where as during dry season ( rabi ) the
experimental hybrids are evaluated in seven centers, located in southern,
western and eastern India. Very useful information on performance of
hybrids and data on yield and yield components and other auxiliary characters
of hybrids across the locations and seasons has been collected over
the years.
As a result of concerted, goal oriented, time bound and co-ordinated
efforts for the first time in the country, four rice hybrids were released
for commercial cultivation during 1994, by the state variety release
committee. These are APHR-1 and APHR- 2 for the Telangana and Rayalaseema
regions of Andhra pradesh, MGR-1 for the Tamilnadu state and KRH-1 for
Karnataka state. Subsequently two more hybrids, viz., CHRH -3 and DRRH-1
were released recently.
Genetically Engineered Seeds
One of the major concerns of cultivating hybrid varieties is that
farmers can not use seed from the harvest for their next crop and thus
have to buy new seed for each crop. More-over, the cost of hybrid seed
is 5-20 times more than that of seeds of inbred varieties. Possibilities
for true -to- type multiplication of hybrid rice are being explored
through two approaches.
Production of artificial seeds through somatic embryogenesis and
Development of apomictic hybrid rice through wide hybridization and
genetic engineering techniques.
Production of Artificial Seeds And Mass Propagation of True-
Breeding Hybrids
Artificial seeds, consisting of somatic embryos, enclosed in a protective
coating, are being proposed as low-cost, high-volume propagation system.
The objective is to produce clonal seeds at a cost comparable with that
of producing hybrid seed by conventional methods. Artificial seeds can
be produced through somatic embryogenesis. This is the process by which
somatic cells develop through the stages of embryogeny to give whole
plants without gametic fusion. Somatic embryogenesis has been reported
in more than 150 plant species. Somatic embryos have been induced from
a variety of plant tissues, such as germinating seedlings shoot meristems,
young inflorescence, nucellus, leaf, anther, root and others.
Artificial seed technology involves various steps for the production
of somatic embryos and their utilization as commercial propagules.
Optimization of somatic embryogenesis system from cultured cells
Optimization of embryo maturation.
Automation of embryo production.
Production of mature synchronized embryos.
Encapsulation of embryos with necessary adjuvants.
Coating of encapsulated embryos.
Optimization of green house and field conditions for conversion of
embryos into plants. And
Delivery system for artificial seeds.
Tissue Culture
"It is the process of growing tissue or cells which are exercised
from healthy plants. These tissues are grown on nutrient medium under
aseptic conditions."
It is also called as micro propagation. Tissue culture involves
several techniques which are
Anther culture
Embryo rescue or ovary culture or Embryo culture.
Protoplast culture and protoplast fusion.
Somatic embryogenesis.
To develop a straight variety or true to type variety in crop plants,
pure line selection method is adopted. In this method the seeds of pure
lines are selected from homogeneous population of a particular crop
and multiplied in the next season. This multiplication process is conducted
in different co-ordinated centers and performance of the pure lines
is tested. If the performance is good then the state varietal release
committee or central varietal release committee releases the variety
of that particular crop.
The seed supplied from Agricultural Research Stations, Department
of Agriculture, or A.P. State seed corporation is not adequate to meet
the requirements of the farmers. So the private seed producers are actively
engaged in multiplication and supply of seed to the farmers. But the
cost of seed is some times high and the quality also is not maintained.
Hence, the farmers are motivated to develop their own seed in respect
to varieties.
A seed village concept was introduced and the farmers were encouraged
to develop their own seed. In this process the farmer is supplied with
limited quantity of foundation seed or certified seed by Research stations
or A.P State seed corporation. The farmer will grow variety with the
seed supplied in a limited area with good management practices of both
plant husbandry and plant protection.
He is also provided with information of the characters of the variety
like duration, grain type, the time of panicle initiation etc. He observes
the crop from time to time, and the off-types will be removed as and
when noticed. He maintained a homogenous type of plants having the varietal
characters . while harvesting he eliminates 1 meter crop from all sides
of the field to avoid contamination from other varieties grown in neighbor
hood and threshed, separately with all the care to prevent admixture
of other varieties in threshing floor.
Like wise care will be taken during storage to maintain purity. Such
seed will be used continuously year after year for the period of 3 to
4 years. Such seed can also be spread to the co-farmers interested in
that specific Variety. After 4 years the farmer can again secure foundation
seed or certified seed from the Research station. If it is practiced
by atleast 25% of the farmers there will not be any scarcity for pure
good seed.
Breeder seed is seed or vegetative propagating material produced by
or under the direct control of the sponsoring plant breeder. It is the
basis of the first and recurring increase of foundation seed.
Foundation Seed
It is obtained from breeder seed by direct increase and is the source
of registered and or certified seed. Foundation seed is produced on
experimental stations of Agricultural Universities and Government forms.
Certified Seeds
Certified seed is produced from foundation or registered seed. It
is so known because it is certified by a seed certifying agency.
The certified seed is annually produced by progressive farmers according
to standard seed production practices. Certified seed is available for
general distribution to farmers for commercial crop production.
Public Hybrid
The hybrids developed by Govt. agencies or Govt. Institutions and
Agricultural Universities are called public hybrids.
F1 Hybrid
The resultant seed obtained from crossing of two genetically dissimilar
parents is called F1 Hybrids.
Seed viability is defined as " The capability of a seed to show living
properties like germination and growth". Or
It is represented by germination percentage which expresses the number
of seedlings that can be produced by a given number of seeds.
The duration of seed viability of rice varieties depends mainly on
the following aspects.
Seed moisture % at the time of storage ( 10 to 12% is desirable).
Storage conditions.
Weather conditions ( relative humidity, rainfall)
Seed Moisture
The formation of germination inhibitors was accelerated under reduced
oxygen tension and thereby the water content of the seed is increased
which deteriorates viability.
Storage
The embryos and endosperm of seeds of different ages were found to
respire, the rate being higher in fresh seeds then in older ones. Thus,
the old seeds are living but failed to germinate.
The germination and viability of the rice seed are related to the
formation of inhibitors during storage.
Weather Conditions
Higher relative humidity and rainfall during the storage periods will
deteriorate the seed viability .
The paddy seed viability depends on the weather conditions. The seed
viability deteriorate very fast during monsoon season.
Due to this, the seed harvested during rabi season do not retain
its viability upto the next rabi season, because it passes through the
monsoon weather conditions i.e., from June to October months, where
as the kharif harvested seed retains its viability till the next kharif
season.
Seed dormancy refers to the resting stage of embryo with low germinability
of viable and freshly harvested grains. It is also defined as inability
or failure of perfectly matured seed to germinate even when placed under
conditions favourable for germination.
Seed dormancy is an important varietal trait in tropical rice where
rain fall and high humidity are of frequent occurance during the maturity
and harvest periods. Without dormancy, seed would germinate on the standing
crop.
Classification of Dormancy
Seed Dormancy at Maturity Stage
Strong seed dormancy at maturity of the crop is a most desirable trait
for all the kharif varieties. Some of the rice varieties ( Masuri, I.R
-50) have little or no seed dormancy and in periods of wet weather at
harvest time, the seed may germinate on the panicle itself.
Duration or Length of Dormancy
This refers to the period from harvest time to the time when the seeds
have broken their dormancy.
Intensity of Dormancy
This refers to the level of breaking dormancy by artificial means,
i.e., based on the germination percentage after heat treatment for four
days at 50 degrees centigrade, and the rice varieties classified based
on germination percentage as follows
Strongly Dormant
Varieties in which 50% of dormancy is broken after 4 days of heat
treatment.
Moderately Dormant
Varieties in which 50 to 79% of dormancy is broken after 4 days of
heat treatment.
Weakly Dormant
Varieties in which above 80% of dormancy is broken after 4 days of
heat treatment.
Factors Influencing Dormancy Period
Climatic Conditions
Temperature
Rice produced during the cloudy wet season ( kharif) has a strong
dormancy and longer duration of dormancy than that of produced during
the summer dry season ( rabi).
This is mainly due to the temperature differences ( higher temperatures
in rabi) during the ripening stage of the crop.
Relative Humidity
Higher R.H in atmosphere at maturity stage also increase the degree
of dormancy.
Age of Seeds
A wide variation in maturity of seeds can be observed within a hill,
i.e., between the mother tiller to tertiary tillers. Similarly there
is about 7 to 10 days difference in the maturity of individual seeds
within the same panicle.
The seeds in the upper portion of the panicle have earlier maturity
than the lower portion of the panicle. So the duration, the dormancy
of the individual seed varies with in the hill and also within the panicle.
Genetics of Dormancy
Genetically dormancy is dominant over non-dormancy. Dormancy is inherited
independently and can combine with early maturity, photo sensitivity
and also with a range of grain types.
Mechanism of Dormancy
Dormancy is the resultant of the slowing down effect of the metabolic
process during seed maturation and also by the slow oxidation of the
hormone IAA ( Indole Acetic Acid).
Hence, it is essential that any treatment aimed at breaking seed dormancy
should hasten the rate of oxidation. Respiration is a strong competitor
for the oxygen available for the dormancy breaking reaction.
Breaking Seed Dormancy
Among the several methods available the most suitable method to break
seed dormancy at farmers level is nitric acid treatment. - Soaking the
seed in o.1 N nitric acid i.e., 6.3 ml per lit. of water for 12 to 24
hours effectively breaks the seed dormancy, where as the varieties like
MTU-1001 which is having 8 weeks and above dormancy duration should
be treated with higher nitric acid concentration i.e., 10ml per lit.
of water.
The seeds can be utilized for sowing immediately after the treatment
or they can be dried thoroughly and can be utilized later for sowing.
Seed treatment refers to the application of fungicide, insecticide
or a combination of both to seeds, such as to disinfect and disinfest
them from seed-borne or soil-borne pathogenic organisms and crop pests
both in field and in storage. It also refers to the subjecting of seeds
to solar energy exposure, immersion in conditioned water etc.
Benefits of Seed Treatment
Prevention of spread of plant diseases.
Seed treatment protects seed from seed rot and seedling blight.
Improves germination.
Provides protection from insect pests.
Controlling soil insects.
Seed Treatment for Breaking Dormancy (Physiological Dormancy)
Dry Storage
For species where dormancy is naturally of short duration, it is often
sufficient to store the samples in a dry place for a short period.
Pre-Chilling
The replicates for germination are placed in contact with the moist
substratum and kept at low temperature for an initial period. Agricultural
and vegetable seeds are kept at a temperature between 5 and 10 degrees
Centigrade for an initial period of upto 7 days. In some cases it may
be necessary to extend the pre-chilling period or to re-chilling.
Pre-Heating
The replicates for germination should be heated at a temperature not
exceeding 40 degree C, with free air circulation, for a period of upto
7 days before they are placed under the prescribed germination conditions.
Light
The test should be illuminated during atleast 8 hours in every twenty
four hours cycle and during the high temperature period when the seeds
are germinated at alternating temperatures. The light intensity should
be approximately 750 - 1250 lux from cool white lamps. Illumination
is recommended especially for certain tropical and sub-tropical grasses.
Eg. Chloris gayana, Cynodon
Potassium Nitrate ( KNo3)
The germination substratum may be maintained with 0.2% solution of
KNo3. It effectively break the seed dormancy.
Gibberellic Acid( GA3)
This GA3 method is recommended for wheat, oat etc.
Sealed Polythene Envelops
When a high proportion of fresh un-germinated seeds are found at the
end of the standard test, then re-test in a sealed polythene envelop
of sufficient size will usually induce these seeds to germinate.
In case of rice among the several methods for breaking dormancy are
available the most suitable method at farmers level is nitric acid treatment.
Soaking the seed in 0.1 N nitric acid i.e., 6.3 ml per lit. of water
for 12 to 24 hours effectively break the seed dormancy, where as the
varieties like MTU-1001 which is having 8 weeks and above dormancy duration
should be treated with higher nitric acid concentration i.e., 10ml per
lit. of water.
The seed can be utilized for sowing immediately after the treatment
or they can be dried thoroughly and can be utilized later for sowing.
Seed Treatment for Protection Against Pests and Diseases
Several insecticides and fungicides are used in seed treatment to
protect the seeds from pests and diseases. These may be merchandized
in combination or individual. In case of paddy the seed is treated with
carbendism @ 1 gm / Kg of seed to protect against plant diseases.
The seedling dip in chlorpyriphos 2.5 EC solution @ 1ml /lit of water
was suggested to protect against insect pests like rice stem borer,
BPH etc.,
Seed germination is the resumption of growth by the embryo and development
of young plant from the seed.
Germination, in a laboratory test, is the emergence and development
from the seed embryo of those essential structures which, for the kind
of being tested, indicate the ability to develop into a normal plant
under favourable conditions in the soil.
Treatments for Promoting Germination
For reasons such as physiological dormancy, hard seededness, inhibitory
substances a considerable number of hard or fresh seeds may remain at
the end of the germination test.
When a proportion of fresh or dormant seeds remain at the end of the
test period, complete germination can often be obtained by re-testing
after a period of dry storage. The following methods may also be used
to induce germination.
The purpose of seed storage is to maintain the seed in good physical
and physiological condition from the time they are harvested until the
time they are planted.
Stages of Seed Storage
The seeds are considered to be in storage from the moment they reach
physiological maturity until they germinate or until they are thrown
away because they are dead or otherwise worthless.
The entire storage period can be conveniently divided into following
stages.
Storage on plants ( physiological maturity until harvest).
Harvest, until processed and stored in a warehouse.
In - storage ( warehouses)
In transit ( Railway wagons, trucks, carts, railway sheds etc.).
Nucleus Seed- From Breeder of Hybrid /Variety of Proprietor Breeder
Breeder Seed - From Breeder of Hybrid /Variety of Proprietor Breeder
Foundation Seed-From Breeder Seed
Certified/Truthful Seed- From Foundation Seed
Nucleus Seed /Breeder Seed à Foundation Seed Stage I/Stage-II –
Certified/Truthful Seed– Commercial grain for farmer’s consumption
Seed Production Planning
MOTTO: Plan every thing before starting
Requirements for Quality seed production facilities
Good source of BS and F/S- Process start three years in advance before the actual seed production for marketing
Trusted Seed Growers
Qualified dedicated seed production team
Good Seed Processing plant Machinery capable to process the full planned marketing quantity.
Storage facilities including cold storage provision for off season storage, B/S and F/S
Seed Health Laboratory with/without finger printing facilities
Grow Out Farm (GOT)
Reliable, quick and economic transportation facilities
Knowledge of statuary Seed laws
Foundation Seed Production
MOTTO: Purity of Foundation will ensure minimum efforts in field for production of high quality seed
High purity of breeder seed.
For in-house hybrids Inspection of Breeder Seed plot by team of other breeders to produce best quality breeder seed.
For in-house foundation seed of proprietary hybrids involvement of concerned Breeder with F/S production official.
High Quality foundation seed minimizes the efforts for quality seed production.
Plan the production of foundation Seed three years in advance before the actual marketing of Seed.
Inspection of F/S plots by concern Breeders to ensure best quality
Seed Production
MOTTO: Dedicated Team work with Quality consciousness
Selection of reliable growers before start of season
Growers should be knowledgeable,financially sound and willing to take extra efforts to take up seed production operations
Seed production meeting before start of season for allocation of area to different production areas
Development of new production areas
Regular field inspections by seed production team at different stages of crop growth to advise growers on different operations
Random Field inspections by Seed Quality Field Team to monitor the various seed production operations
Midseason review of seed production to go for alternate area if falling short of targets.
Group and mass Seed Field inspections by seed production team at critical stages of crop growth in crucial highly cross pollinated crops like Pearl millet, maize sunflower and Jowar
Harvesting and threshing instructions to growers to avoid admixtures.
Other important operations / instructions as per crop growth
Seed Processing Plant Operations
MOTTO: Quality of processed seed should reflect on Market
Most important function after seed production
Overhauling and servicing of plant Machinery before start of season. Replace worn-out parts. Keep spares for emergencies. Extra Important implements to be kept in godown.
Trained operators of plant machinery
Separate godown for incoming, processed, sales return and ruminant seed.
Co-ordination with seed health team for sampling, dispatches and movement of Seed
Proper up storage and placement of screens,
Proper records of processed, remnant and processing losses to build full faith of seed grower in company
Record of seed arrival, dispatch and sales returns
Seed Health Laboratory
MOTTO: To ensure that only and only quality seed reaches the growers .
All facilities for testing of seed produced
To ensure that every lot of seed is tested for all the quality parameters of seed health before the dispatch of seed.
Trained qualified officicial for sampling of seed during processing of seed lots
Testing of all seed lots for germination, seed vigor, infestations and purity etc
Confidentiality of seed sampling and testing process
Seed health laboratory person to be trained in such a way that he catches the problems of seed even visually and to be very careful while testing these suspected lots for seed health.
Grow out tests (GOT)
MOTTO: To Test the Genetic purity of each and every seed lot
Allocation of area before the season to create all the facility required.
As no. of lots are known before the arrival of samples hence infra structure should be kept ready before testing season (maximum Kharif)
Highly technical qualified staff for the Grow out Tests.
Regular institutional Training of staff to update their knowledge
All seed lots of hybrids, parental lines and in-house varieties are to be tested through grow out tests.(GOT)
To strictly adhere to the plant characters of hybrids and varieties/lines
while taking the plant purity observations.
In high value crop seeds like sunflower and vegetable hybrids the Finger Printing technology to be used to check the Genetic purity of seed.
In case of crops where the time gap between seed arrival and dispatch is very less the finger printing has to be adopted to avoid any problem in field.
Do not look at short term gains while dispatching of seed at the times of Urgency of seed to market.
Handling of Seed complaints
Motto: Find the root cause of problem and rectify it immediately.
Mechanism to check the authenticity of seed complaints
Special cell to deal with seed complaints through marketing network.
To keep records of history of all seed lots to be kept to trace the reasons for complaints.
Find the reason for the complaints
If the faults found in production/processing/Grow out tests, mechanism to address those problems
Handling of Seed Seed law Enforcement Agencies
Motto: Hassle free marketing of seeds To Deal with Seed law Enforcement agencies (Agric. Department and Court cases seed failures and consumers forum cases):
Separate person to deal with court cases
To keep the records ofall seed lots.
Knowledge of seed laws to ensure there no convictions.
Collection of judgments by various courts in country
Court cases can be handled easily with experience of system.
Not to accept faults in courts in seed failures but to fight it out
Seed Logistics
Motto: Placement of seed at market in time, safely with least costs in minimum time
Selection of good reliable transporters through tendering process
required for bringing the raw seed from field and dispatch of packed
seed in bulk.
For the small packings dispatches selection of transporters with maximum
reach to destinations
Emphasis on cost reduction through proper planning of dispatches.
Safe movement of material by sending through quality vehicles with
full protection
Use of railways instead of road transport for bulk transportation
and small important seeds to far off locations
Monitoring of movement of seed till it reaches the destination
