principles of crop production abt-320 (3 credit hours) lecture 17 determining seed quality seed...

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PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

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Page 1: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

PRINCIPLES OF CROP PRODUCTIONABT-320

(3 CREDIT HOURS)

LECTURE 17

DETERMINING SEED QUALITYSEED CLASSIFICATION

SEED TREATMENTSFACTORS AFFECTING SEED GERMINATION

Page 2: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

DETERMINING SEED QUALITY

Seeds of high quality should be: • true to its kind or variety --> these are varietal purity characteristics• contain a minimum of impurities --> these are seed lot characteristics• have high establishment rates in the field --> this is seed viability

So the 3 main criteria for describing seed quality are:

Page 3: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

1. VARIETAL PURITY CHARACTERISTICSVarietal purity is about the genetic purity or the purity of the cultivar. It can be described by its physical, chemical and crop characteristics.

• PHYSICAL CHARACTERISTICS Every variety has seeds with specific length and width, shape, size, color and aroma. These characteristics can be tested by calculating the 1000 grain weight, measuring color using the naked eye or a colorimeter and so on.

• CHEMICAL CHARACTERISTICSVarious chemical tests can also be used to see the difference between varieties. Amylase content, alkali digestion color, gel consistency and brown rice protein are all different between varieties.

• CROP CHARACTERISTICSMost of the time, a variety has always the same plant height, time to maturity, plant color and plant growth habit. (Small variations may occur especially in harsher environmental growing conditions.)

Page 4: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

2. SEED LOT CHARACTERISTICSA description of the seed lot includes the level of impurities, seed size, and damaged, deformed or diseased seed.

• IMPURITIES Impurities are weed seeds, seeds of other crops or species, and inert material such as stones, dirt or twigs. It is expressed on a percentage basis by weight.

• SEED SIZE Plumpness and/or fullness are usually good seed characteristics. They mean that the seed has the potential to produce vigorous seedlings under favorable conditions.

• DAMAGED, DEFORMED OR INFECTED SEED High quality seed should be free from seed-borne diseases, insects and other extraneous matter. They should also be free from various types of mechanical injury that reduce germination and seedling vigor.

Page 5: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

3. SEED VIABILITYThe viability of the seed in the field will depend mainly on its stored moisture level, germination potential and its vigor.

• MOISTURE CONTENT (MC)

Moisture content has a big influence on the life and vigor of the seed. The MC should be less than 14% and preferably less than 13% if stored for a long time.

• GERMINATION (IN %)This is the proportion of the total number of seeds that are alive. This is tested by counting the number of seeds that germinate. Many varieties have a dormancy period immediately after harvest. Stored under traditional open systems the germination rate of most rice seed begins to go down fast after 6 months.

Page 6: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

3. SEED VIABILITY• SEED VIGOR

Seed vigor gives a very good idea of the possible field performance, and subsequently, the field planting value. While the speed of germination varies slightly across varieties, seeds should absorb moisture and within 2 days produce a root and a first leaf in 4 days. Then the seed has germinated. How well the germinating seed continues to grow and survive determines crop establishment. Seed vigor is all these things that determine the level of activity and performance of the seed during germination and seedling emergence. Seed vigor is an important factor in seedling establishment.

• Seeds low in vigor produce weak seedlings that are susceptible (=vulnerable) to environmental stresses.

• A high level of vigor in seeds provide for early and uniform stands which give the growing seedlings good resistance against various environmental stresses.

Page 7: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

SEED CLASSIFICATIONA plant breeder develops a new variety – it is very good and every farmer wants the variety. The seed marketing companies want the seed to meet the high demand from the farmers. In this chain from plant breeder to farmer, there are a number of steps and, at each step the system must ensure that the original variety is truthfully produced.

Page 8: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

NUCLEUS STOCK• When a new variety is released there is very little seed. There may be only

a handful of seed selected by the breeder from individual plants. This seed is the basis of a variety and is known as the Nucleus Stock. This nucleus stock must be managed with great care so that all seed produced from it remains true to the new variety. This is a most important step and is the responsibility of the plant breeder who developed the variety.

• The nucleus stock seed is not available to farmers. The next step in the chain from plant breeder to farmer is that the plant breeder develops Breeder Seed.

Page 9: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

BREEDER SEED• Breeder seed is the seed of the highest purity of the new variety. It is

produced by the breeder and provided by the breeder’s institution to agencies for further multiplication. If you are from a non-governmental organization (NGO) seed business or a private company that is producing seed, you may need to purchase breeder seed from a research institution. Breeder seed is the most expensive seed to buy.

• As a private company or an NGO business you need breeder seed or foundation seed. Once again your interest is quality.

Page 10: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

FOUNDATION SEED• Foundation seed is the seed produced from growing breeder seed. It is

produced by trained officers of an agricultural station to national standards and handled to maintain the genetic purity of the variety. It may be produced by a government seed production farm or a private organization – this will depend on the regulations of the country. Foundation seed is less expensive than breeder seed.

• If your interest is to have quality seed to grow paddy, you will not be interested in buying breeder seed or foundation seed. You need registered seed or truthfully labeled seed.

Page 11: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

REGISTERED SEEDRegistered seed is produced from growing foundation seed. It is grown by selected farmers in a way that maintains genetic purity. Production has undergone field and seed inspections by Seed Inspectors to ensure conformity with standards.

Page 12: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

CERTIFIED SEEDCertified seed is produced from growing foundation, registered or certified seed. It is grown by selected farmers to maintain sufficient varietal purity. Production is subject to field and seed inspections prior to approval by the certifying agency. Harvest from this class is used for producing again.

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QUALITY DECLARED SEEDTruthfully labeled seed or Quality Declared Seed is produced from foundation, registered or certified seed. It is not subject to inspection by a certifying agency. As this seed is not inspected, its quality is dependent on the good reputation of the farmer who has grown the seed. His good name in the village is important.

Page 14: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

TODAY’S MODERN SEED TREATMENTS• Modern seed treatment products offer control of target pests and

diseases and ensure the establishment of healthy and vigorous plants. Their formulation and industrial application also contribute to improvement in growers’ and workers’ safety and stewardship of the environment.

• Today’s modern seed treatment products have to meet not only efficacy standards but also safety and environment standards. The newest active substances and formulations provide long-lasting, broad spectrum, control of pests and diseases (depending on the specific active ingredient).

• Modern formulated seed treatment products are precisely blended products consisting of several active ingredients, special wetting agents, colorants and sometimes bird repellents which are rigorously tested for their safety to the seed, the users and the environment.

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GOOD SEED TREATMENT PRACTICE• The seed industry and seed treatment applicators use an array of quality

management systems to optimize the application process. These quality systems define the treatment process, handling of treated seed, worker protection, environmental stewardship and provide the information required to facilitate the safe and legal treatment of seed and the disposal of treated seed.

• Seed treatment requires adequate standards and good application methods. These should be agreed upon between the involved parties on a case-by-case basis to insure producer, applicator, seed and environmental safety in the most cost efficient manner.

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SEED TREATMENTSeed treatments, in broad terms, are the application of biological, physical and chemical agents and techniques to seed that provide protection to seeds and plants and improve the establishment of healthy crops.

Page 17: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

THE ROLE OF SEED TREATMENT• Diseases and pests affecting crops can have devastating consequences in

agricultural and horticultural production if not properly managed.• Breeding is an excellent tool to build resistances against pests and

diseases in the plants. However, breeding alone does not address all of the agronomic challenges, therefore crop protection products are often needed and used for good crop management. These crop protection products can be applied during the growth of the crop but can also be added to the seed as a seed treatment. Seed treatments have played and are still playing a significant role in the history of mankind, in staving off hunger and starvation by improving the establishment of healthy crops.

Page 18: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

EVOLUTION OF SEED TREATMENTS• Some of the first recorded seed treatments are the use of sap from onion

(Allium spp) and extract of cypress in the Egyptian and Roman periods.• Salt water treatments have been used since the mid-1600s and the first

copper products were introduced in the mid-1700s. Other key milestones were the introduction of arsenic, used from 1740 until 1808 and the introduction of mercury, used from 1915 until 1982. Until the 1960s seed treatments had been only surface disinfectants and protectants. The first systemic fungicide product was launched in 1968. This systemic fungicide had not only seed surface activity but also moved into the plants protecting the young seedlings from airborne pathogens. Since the 1990s the crop protection and seed industries have developed and adopted new classes of fungicide, insecticide, and nematicide chemistry, expanding pest control while reducing user and environmental impact.

• The seed and seed treatments industries have a long history of partnership and dedication in providing growers with high quality seed. Today the seed must be as pest- and disease-free as possible and the treatment must provide protection against pests and diseases during germination, emergence and growth of the plant.

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SEED TREATMENT AND INTEGRATED PESTMANAGEMENT

• The FAO International Code of Conduct on the Distribution and Use of Pesticides (Revised version) adopted in 2002 defines Integrated Pest Management (IPM) as meaning “the careful consideration of all available pest control techniques and subsequent integration of appropriate measures that discourage the development of pest populations and keep pesticides and other interventions to levels that are economically justified and reduce or minimize risks to human health and the environment. IPM emphasizes the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms”.

• Seed treatments can be used as a primary tool in a successful Integrated Pest Management Program for sustainable agriculture since they target the pests and diseases with smaller amounts of active ingredients per hectare and are not introduced into the atmosphere. In many cases, without the use of seed treatment, growers would have great difficulty in controlling certain seed-borne and early season seedling pests and diseases and would have to resort to more expensive and less environment-friendly methods.

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HOW SEED TREATMENTS ARE APPLIED?

• Seed treatment is a term that describes both products and processes. Processes range from basic dressing to coating and pelleting. In all cases, the basis of good application techniques is to deliver the product to the seed at the correct dose and as uniformly as possible from seed to seed.

• Seed Dressing: The most common method of seed treatment. The seed is either dressed with a dry formulation or wet treated with a slurry or liquid formulation. Dressings are applied both on-farm or in specialized seed treatment facilities.

• Seed Coating: A special binder is used with a formulation to enhance adherence to the seed and begin to impact seed size and shape. Coatings require advanced treatment application technology.

• Seed Pelleting: The most sophisticated seed treatment technology, resulting in changing the physical shape of a seed to enhance plantability and handling. Pelleting requires specialized application machinery and techniques and is the most expensive of the applications.

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HOW SEED TREATMENTS ARE APPLIED

Depending on the type of desired treatment, various machines can be used. The more complex the treatment, the more cost is involved. Many modern treatment machines can deliver specific formulation and dosing by way of a direct injection process. The most sophisticated treatment machines can deliver the various formulations and additives as layers on the seed, which allows precise placement of the active ingredient.

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MEETING USERS’ EXPECTATIONS• Regulatory authorities, seed distributors and seed users have established

high standards for the seed and seed treatment industries regarding the quality of a seed treatment and its application to the seed. The expectations are that the treated seed will be easy to plant and that the seed treatment will be effective in the field, safe to the applicators, the growers and the environment.

• The industry recognizes that seed treatment must provide “added seed value” (e.g. better emergence, higher seedling establishment, improved crop health, higher yields and improved crop quality). It expects seed treatments to be easy to handle and apply to seeds, to complement and protect genetic improvements, to function as part of IPM (Integrated Pest Management), to be safe and cost effective in use and to reduce personal and environmental risks.

• Seed treatments, compared to conventional application of crop protection products, offer convenience to the grower, saving time and energy and reducing application efforts.

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ENVIRONMENTAL FACTORS ANDSEED GERMINATION

• Water• Temperature• Oxygen• Light

Page 24: PRINCIPLES OF CROP PRODUCTION ABT-320 (3 CREDIT HOURS) LECTURE 17 DETERMINING SEED QUALITY SEED CLASSIFICATION SEED TREATMENTS FACTORS AFFECTING SEED GERMINATION

SEED WATER UPTAKE

• Seed-soil contact varies with seed size, shape. • Small seeds and smooth coated seeds most efficient in H2O uptake.

• Increased soil contact; larger surface area/volume ratio.

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OXYGEN AVAILABILITY IN SOIL

• Found to vary from 19% to 21% in a wide range of conditions (time of year, tillage, soil depth, soil type)

• Exception may be when seeds are encased in soil particle aggregates, sealing them off from gas exchange with the soil environment

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OXYGEN SOLUBILITY IN WATER

• O2 solubility increases with decreasing temperatures (twice as much 02 available to seeds at 5oC than at 40oC)

• Literature on O2 role in seed dormancy is sometimes conflicting, inconclusive because of these solubility differences.

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EFFECTS OF LIGHT ON SEEDGERMINATION

• Light can promote or inhibit germination• Sensitivity to light is important to seed banks and other ecological

responses, providing a mechanism for optimal timing of seedling establishment

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SOWING TIME

PRIMARY SYMPTOMSExcessively high or low temperatures or moisture stress at heading indicate a possible problem of sowing date. Wheat is most sensitive to temperature and water stress during the flowering and heading stages.

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SOWING TIMESowing at the wrong time exposes the crop to temperature and moisture extremes.There is an optimum time for sowing for every location determined primarily by weather and availability of the field and irrigation water, but also by the variety that is being used and the likely timing of serious disease in the area. The best sowing time is that which gives the highest yield within the local limitations. It is usually decided on by working backwards from the date that is best for anthesis. Once the best sowing time has been determined, any delays in sowing at that date can reduce yield. Yield loss from delays will generally be greater in hotter regions.

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SOWING TIMEThe most suitable variety will be one that fits its growth stages into the available time. When deciding on variety and calculating your sowing date you should bear in mind the following risks:

• Frost from spike emergence through early grain filling should be avoided.• High temperature during anthesis and early grain filling is best avoided.• Avoid overcast and misty conditions during 2 weeks before to 1 week after

anthesis - solar radiation should be high for this period.• Irrigation water should be available from stem elongation through anthesis

to early grain filling.• Avoid varieties that run to head too quickly before producing tillers unless

the available season demands a very short duration crop.• Think not only of the current crop. Work out the best compromise planting

times for all sequential crops in the rotation so that annual production is optimized.

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THE END