Saving seeds through gardener curators
THE consciousness today about genetic resources and their importance to humankind is at an all-time high. Discussion has focused specially on the loss of traditional varieties, or "genetic erosion" and the control of germplasm by vested groups or companies. Varieties are being lost as they cease to be cultivated. There is a call to search out and retrieve these vanishing resources - if not for any other reason than for preservation, the same way a curator in the museum preserves heirloom cutlery. Finally, traditional varieties are sources of useful genes concerning special qualities such as resistance to diseases or drought. Such genes are invaluable in breeding new cultivars.
Tomorrow is Late
Unfortunately, conferences and workshops, do not save seeds. Despite the many meetings and papers on the topic of genetic erosion, action efforts to save seeds are sadly lacking in quality and impact. Historically, the best conservers of seeds have been small farmers and backyard gardeners, but programs to conserve seeds at their level are sadly lacking. Meanwhile, every day, the seed heritage slowly but steadily diminishes.
The Gardener or Small Farmer as Curator
Nongovernment organizations and others interested in saving seeds in situ (as opposed to storing them in laboratories) need to address this issue with a sense of urgency and through field-level and farmer-or gardener-involved interventions.
The concept of a farmer/gardener curator is valid because the seeds used by the majority of today's farmers in developing countries have been handed down by generation of farmers. When planted out every year, these varieties continue to evolve and adapt to the changing environment. These same seeds, stored in conventional low-temperature seed storage facilities, just remain dormant, and their characteristics remain unchanged - they do not evolve any further. In fact, varieties stored this way, if planted many years later in the field, may not be able to withstand the changed environment in the place they were originally collected.
Many traditional varieties do not meet the criteria and standards of today's consumers and so are not planted commercially even if they have superior nutritional, taste or storage qualities. One example is the bitter gourd. A favorite of Filipinos, improved varieties of this crop are superior in production and of larger individual size but are dependent on chemicals. Other varieties do not have synchronous harvests and so are getting lost. An example is the araw-araw ("daily") eggplant, so called because it provides a few eggplants every day compared with the improved varieties that come to harvest at a peak time and so are preferred for marketing.
Many traditional vegetable cultivars have multiple uses. A good example is the winged bean which produces a tasty and nutritious pod and has edible flowers and tubers. Unfortunately, many of the tuber-producing cultivars are rare and can only be found in remote areas such as Papua New Guinea.
The potato yam is another crop which is steadily getting lost. Even though it produces both aerial and ground tubers on the same plant, this is not enough to ensure its survival for the next generation of farmers.
The list of cultivars that have special qualities is long: cherry-sized tomatoes which can be grown in the rainy season with no fungal problems (as many as 1000 fruits can be harvested in the life of this cultivar), the mung bean with hairy leaf surfaces that keep most insects away and the deep-rooted leafy amaranths that can go for as long as six weeks i!, summer with no water and no wilt symptoms.
These qualities do not often make a difference to the consumers of marketed vegetables, who look for good size more than anything else. The bigger the better is the norm! In fact, most farm produce in exhibitions and competitions use size as a major criterion in crop judging. Is it not ironic when miniature vegetables in the West fetch the highest prices, but developing countries prefer the longest, heaviest, largest products? Why this obsession, when we know that eventually these are going to get cut down into small pieces to be eaten?
The emphasis on producing seedless products is another example of how preferences have changed over the years. The seedless grape and the papaya with just a few seeds in each fruit are examples.
But, finally, the most important factor is how our technicians and extension workers perceive the growers of such indigenous cultivars. If they treat farmers as primitive or outdated in their thinking and choice of varieties, then the farmers will have a poor self-perception and image. Unless an effort is made to give these traditional cultivars a new image, they will gradually be neglected by the farmers themselves. When that happens, all is lost for the cause of seed conservation.
The greatest opportunity for conserving such varieties is by reintroducing them for use in gardening programs'- in backyards of farm households, in urban gardens or in school areas. These gardens are raised primarily for family use and nutrition for school children. The special qualities of traditional cultivars, their hardy nature, prolific seed production, high nutritional value, well distributed fruiting periods (as opposed to peak production), shade tolerance, etc., all make them especially useful for these programs. What is also important to realize is that their yields do not have to be low because, if combined with improved crop husbandry techniques such as the big-intensive technologies, their output per unit area could compare favorably with the output, using conventional technologies and chemicals. Such gardens can consist of a great diversity of crops: a typical big-intensive garden area of 200 sq m can contain as many as 30 selections. Isn't that biodiversity also? While biodiversity often refers to natural forest ecosystem, we can create this in garden spaces and backyards as a conservation strategy. Of course, they will not have the looks of a neat garden with distinct rows and clean space between rows.
How Does One Get Started if There Are No Traditional Varieties in the Area?
Most developing countries still have a vast selection of materials to collect, if one knows where to look for them and what to look for. Where modern agriculture has been aggressively promoted, these genetic resources will still be around but often growing only in remote areas in backyards or in intercropping systems, or often as weeds. However, the way to ensure success is to focus the seed retrieval and collection missions in areas away from the beaten tracks and asphalt roads. It is less likely that seed merchants will have reached these places. Ethnic groups in most countries are especially important communities from whom to collect seeds. Often, these groups continue to grow old cultivars because they have not been exposed to extension agents or for cultural reasons (in defense of their cultures) have been resistant to change. The most diverse collection of planting materials can be found in the remotest areas.
One has to time one's visit to ensure that seeds are ready for collection. Usually, the three to four months immediately preceding the summer season are ideal times for legumes and other vegetables. The end of summer is the best time to select droughttolerant vegetables: just look for unirrigated areas where the crops have survived through the summer season. Market days are excellent opportunities for seed collection, especially in those parts of the world where small quantities of seeds are traditionally sold by fanners in the weekly market. If seeds are not available, these market days are good for acquiring produce from which seeds can be extracted. In the case of legumes, these can be bought from traders dealing with dried legumes - though germination is inevitably a problem with this method of acquiring seeds.
One of the most efficient ways to collect the greatest diversity of seeds is to get in touch with local schools in remote areas and through the authorities, launch an effort for seed retrieval through children. Finally, a consortia of NGOs in a country can be used for seed retrieval and subsequent exchange. NGOs working with farmer organizations can use their infrastructure to collect planting materials and seeds.
Common Problems Faced by Seed Collectors
The amateur seed conservationist will find the seed-saving idea a lot more complicated than when he or she anticipates. The problems of categorization, outplanting, characterization, storage and quality control are all essential to a systematic effort; yet, they are theeconsuming and, unfortunately, require financial resources.
The NGO or amateur conservationist will first have to limit the collection based on priorities, e.g., vegetables, cover crops, trees, fruits or rice. It is a common mistake to try to collect everything because it soon becomes overwhelming, difficult to manage and expensive. With cooperation, it is conceivable mat each NGO could focus on one crop and then exchange the collected and tested materials with other partner NGOs.
The planting-out of collected seeds is another important step - probably the most expensive. Human labor is needed for this, as long as the crops are in the field. Seeds must be planted and observed for two to three seasons to ensure that the characteristics (e.g., planting season, flowering habits, pest susceptibility, etc.) can be recorded. Here we are not talking of sophisticated data but very simple but essential information without which the gardener or farmer receiving the seeds could get the wrong conclusion, i.e., indigenous varieties are not good. Many traditional varieties are season-bound and, if planted in the wrong season, give very poor results. Others do badly if fertilized and do well only under low fertility conditions.
The collection of seeds is labor-intensive and time-consuming. The next step, that of drying and then depodding or cleaning, is also labor-intensive. However, all activities mentioned so far can be easily learned and require systematic effort rather than expertise.
The storage of seeds and maintenance of viability is probably where the most problems will occur and where guidance from a seed technologist in the design of a technical strategy is important. Seeds can be dried too much or not enough. They can get infested with fungus while in storage, affecting their viability, or the seedlings can be damaged soon after germination. The seed moisture content in storage is the single most important factor. But the storage temperature and humidity often critical determinants of how successful the seed production effort has been.
The importance of labeling seed packets with information on the place of origin, local name and the date of collection cannot be over emphasized. Any observations from the gardener or farmer will be very helpful in future characterization of accessions, e.g., some cultivars store better than others, an important characteristic of old cultivars of beans and a trait lost in the new varieties. If this information is not recorded one might not know it by observing plants in the field. Another attribute of traditional legumes that farmers know well and use to describe their collections is the versatility, for instance, some legumes can be sold as green vegetables but are also equally good as dried legumes. This knowledge is best collected from the original growers themselves.
An institutional effort to conduct seed collection missions is justified (as opposed to farmers collecting the seeds from their own area for in sin' conservation) if seeds are rare and must be brought from other parts of the country and exchanged in order to reinstate the original diversity and variability. But such efforts are only useful and relevant if the seeds collected, tested and multiplied are returned to the communities for them to plant, try out and conserve. The sooner the materials are moved out, the better. The ideal approach is to give farmers a diversity from within each crop, e.g., six kinds of mungbeans, so they can choose from a range. Some retain what others will not. So somewhere in every village the materials will get preserved.
Unless the program is backed up with an elaborate conscientization strategy, one should not expect fanners to understand the philosophical or aesthetic dimensions of genetic resources conservation program. Their agenda may be different from that of the organization: they conserve the varieties for a host of reasons, the last of which may be conservation for conservation's sake. So, the idea of getting growers to continue to raise seeds only for purpose of saving them, as is being done in some Western countries, is a bit unrealistic. There is need to focus on seed accessions whose attributes will in themselves result in their being conserved. The genetic resources agenda then become a hidden one and need to be integrated with other activities, such as family food production though improved agricultural technologies for farms and gardens, or health and nutrition interventions.
It seems clear that conservation will not result from workshops on the topic of genetic erosion, even as we admit these are important at certain stages of the campaign. Nor will it result only from storing seeds in national or international germplasm banks, because of the need for these plants to continue their process of evolution and adaptation. Seed conservation is everybody's concern and not an activity limited to geneticists and breeders.
We still have time to do something about this ... only if we start today.
Why producing your own vegetable seeds is important?
1. High-quality seeds can be easily produced and at a low cost, thus, reducing the costs of
gardening.
2. When the seeds you want are not available in the market, you can produce your own seeds.
3. When you produce your own seeds, you can sell them for income and/or share them with neighbors and friends.
4. By producing your own seeds, you can select seeds suited to your environment. If you want fruits that are big and are not attacked by pests in your garden, you can choose seeds of the plants that are grown in your garden with these specific traits.
5. Saving your own seeds is fun. It is also challenging to save seeds since you can experiment with different seed-saving techniques.
6. Seed self-reliance can be achieved by producing your own seeds.
7. Valuable traditional or indigenous seed varieties of vegetables can be preserved for future generations.
Definition of a Seed
A seed is an undeveloped and dormant plant, usually with a reserve food supply and protected by a seedcoat. It is also defined as a miniature plant in an arrested state of development.
Botanically, the seed is a mature ovule enclosed within the ovary or fruit Seeds of different species vary greatly in appearance, shape, location and structure of the embryo and the presence of storage tissues.
A seed has three basic parts:
(1) embryo; (2) food storage tissues or endosperm; and, (3) seed covering or seedcoat.
Definition of a Seed
Traditional or indigenous seeds
Traditional or indigenous seeds are those produced, growing or living naturally in a particular country or climate. They are seeds that have been selected and managed by local people in the local growing environment.
Traditional or Indigenous seeds
Characteristics of Traditional Seeds
1. Adapted to the conditions of the area where they are grown.
2. Multiple uses (examples: food, medicine, fuel, fiber, fertilizer, craft materials, feed for animals, religious articrafts).
3. Most are resistant to pests, diseases and environmental conditions, such as drought.
4. High nutritional value.
5. They do not have a peak season harvest. The fruits do not mature at the same time, so harvesting is staggered. Hence, they can provide a daily source of food for the family.
6. They provide plant breeders with valuable traits needed for crop improvement.
Choosing Good Plants for Seeds (Plant Selection)
The selection criteria for seeds depend on the selector's needs or use (example: food, fodder). Below is a list of characteristics which can help the selector find good plants for seeds:
1. vigor and health of the plant2. resistance to pests and diseases3. resistance to adverse environmental conditions, like drought, heat, flood4. time of fruit bearing5. yield6. characteristics of fruit and seed like color, size, shape, texture, etc.7. cooking and eating quality (if the fruit or seed is meant for eating)8. storage life of fruit and seed9. other characteristics depending on the use (example: medicine, crafts, religious articrafts)
Based on the above criteria, select the plant to be used for seeds. Put a tag or mark the plant so that it is not harvested by accident and so that special care can be given to it.
Seed production
Seeds come from flowers. Plants have to be pollinated in order to produce seeds. The pollen, the fertilizing powder which comes from the male part of the flower or anther, is brought to the female part of the flower - the stigma or pistil.
Seeds come from flowers
In cross-pollination, the pollen that will fertilize the plant will come from another plant. The plant cannot produce seeds if only one plant is planted because there will be no source of pollen. Examples of cross-pollinated plants are watermelon, melon, cucumber, squash, bottle gourd, sponge gourd, bitter gourd, pechay, mustard, radish, onion, carrot.
In cross-pollination
Plants may either be self-pollinated or cross-pollinated. In self-pollination, the plant can produce seeds without another plant. The pollen comes from the same flower or from another flower from the same plant. Examples of self-pollinated plants are tomato, hyacinth bean, soybean, lima bean, mungbean, Baguio bean, pea, winged bean, yardlong bean, cowpea, water hyacinth, lettuce.
Plants may either be self-pollinated or cross-pollinated
Sometimes mixed-pollination occurs. A single plant may either self-pollinate or cross-pollinate, depending on the environmental conditions. Examples of mixed-pollinated plants are eggplant, bell pepper, chili, pigeon pea, cauliflower, amaranth, ladyfinger.
Site selection and timing of seed production
Seed comes from the flower. The flowering and seeding are affected by the health of the plant and its surroundings or environment. Seed quality is also affected by the parent plant.
I. Environmental Factors that Affect Seed Production
A. Photoperiodism
Photoperiodism refers to the flowering response of a plant to the length of day, or more precisely, the length of the light and dark periods.
1. Short-day plants flower and bear fruit juring the months where the nights are long and the days are short. In the Philippines, short-day periods occur during the months of. September to February.
Example: most soybean varieties, winged bean, hyacinth bean, lima bean, pigeon pea
2. Long-day plants flower and bear fruit during the months wherein the nights are short and the days are long. In the Philippines, long-day periods occur during the months of March to August.
Example: onion, sunflower
3. Day-neutral plants flower and bear fruit all year round.
Example: yardlong bean, ladyfinger, cowpea
Depending on the variety, some plants, like soybean, can either be short-day, long-day or dayneutral.
Photoperiodism
B. Temperature
Temperature has a direct effect on flowering and seed production.
1. Tropical plants - These are plants that flower and produce seeds in hot or tropical areas. Most of these plants flower and produce seeds in the Philippines.
Example: tomato, pepper, cowpea, ladyfinger
2. Temperate plants - These are plants that flower and produce seeds in cold or temperate areas. Most of these plants flower and produce seeds in cold areas in the Philippines, like Baguio and Tagaytay.
Example: pea, cabbage, pechay, radish, onion, carrot, cauliflower
Temperature
In areas where the temperature is not cold, temperate plants can be induced to flower and produce seeds if they are placed in cool conditions before planting. This method is called vernalization. Vernalization is done by soaking the seeds in water and placing them (after the radicle or rudimentary root has protruded) or their plant parts (example: onion bulb, tuber of carrot) in a cold (but not freezing) place like a refrigerator.
Example:
No. of days inside the refrigerator
| |
onion bulb
|
30 - 90
|
onion seed
|
15
|
garlic bulb
|
40 - 50
|
tuber of carrot
|
14 - 56
|
radish seed
|
5- 7
|
pechay seed
|
4 - 8
|
cabbage seed
|
5 - 7
|
mustard seed
|
5 - 7
|
C. Water/Rain
The right amount of water is needed for the growth of the plant. Hard and continuous rain is not good for seed production since:
1. pollen is not transferred;2. seeds do not develop from flowers;3. the vegetative stage of the plant or the maturity of the fruit/seed is prolonged;4. seeds germinate even if it is still not harvested from the plant;5. harvesting becomes more laborious;6. pests attack or infest the plants; and,7. seed yield decreases.
To prevent seed production during the rainy periods, plants can be spaced at wider or longer distances so that all the plants can have enough sunlight.
On the other hand, lack of rain or water is not good for the plant since it will prevent the normal growth of the plant and the plant may not produce flowers and seeds. Even if flowering occurs, the quality of the seeds is not good and the the seed yield is low.
D. Wind
The strength and direction of the wind affect the pollination of flowers.
E. Soil
To produce good seeds, the soil must be healthy and fertile. The right pH (acidity of the soil) for a specific plant should also be obtained.
Water, rain, wind and soil
II. Cultural Practices
A. Timing of Planting
Plant seeds when the weather is good. Usually, seeds are planted during the rainy season in order to have continuous amount of water. It is good to transplant early in the morning or late in the afternoon.
B. Planting Distance and Rate of Planting
The distance between plants used for seed production is wider compared to that of plants used for other purposes (example: vegetable production, fodder production). More seeds need to be planted if the broadcast or sowing method is done. The distance of planting is also wider if the soil is not fertile and in the rainy season. Widening the distance will enable plants to receive enough sunlight.
C. Hastening Seed Germination
1. Seed Cleaning or Seed Washing - Soak the seeds in a container of water and remove the seeds that float. Seeds which float have poor quality.
2. Use of Inoculants - Some microorganisms help in good growth of seeds. Rhizobium (a kind of bacteria) gets nitrogen from air and gives the nitrogen to the plant and soil. This is usually used for legumes. Mychorrhiza (a kind of fungus) helps the root absorb elements like phosphorus from parts of the soil that cannot be reached by the root. This has been found effective in corn and different vegetables. The two inoculants can be used to Minimize the use of fertilizer.
3. Seed Scarification - This method is appropriate to seeds (example: winged bean, bitter gourd, sponge gourd) that are hard and difficult for water and air to penetrate. This is done by (1) nicking off the seed coat with a knife or nailcutter, (2) puncturing the seed coat with a needle; and, (3) rubbing the seeds in sandpaper, file or any rough material. Care should be done so as not to injure the internal portion of the seeds, especially the radicle.
4. Hot Water Treatment - Pour hot water (boiled and then cooled for about 10 - 15 minutes) into a container with seed (10 parts water to 1 part seed). Let stand for 3 -10 minutes or until water cools off. Seeds may be left soaking overnight. Old seeds are soaked for a shorter time than new seeds.
5. Soaking Seeds in Ordinary Water Overnight - Soak seeds in tap water for 1248 hours (depending on the species). This method is not recommended for all seeds, especially seeds that quickly absorb water like most legumes.
Cultural Practices
D. Maintaining Seed Purity
The following methods are important to prevent contaminating other plant varieties from the variety that is being grown.
1. Planting distance - The plant being grown should be kept at a distance from other varieties and also from plants that are of the same family. Varieties of cross-pollinated plants should be planted at greater distances from each other than self-pollinated plants. For self-pollinated plants, the planting distance should not be less than 10 meters. For cross-pollinated plants, the planting distance should not be less than 100 meters.
2. Planting timing - Avoid planting at the same time plants from the same family or of different varieties of the same species. This ensures that they will not flower at the same time.
3. Use of Windbreaks -Choose an area where there are tall plants in between plants of the same family or species.
4. Border Rows - Rows of plants of the same variety as the plants being used for seed production, planted on the edges of the plot. Seeds from the plants in the border rows are not used for planting.
5. Roguing - Roguing is done by pulling out plants that are: (1) off-types (plants with different color, shape, etc.); (2) diseased or insect-damaged; and, (3) of different varieties. Failure to remove off-types results in poor quality seeds since off-types might cross-pollinate with good plants.
6. Bagging and Caging - This prevents pollination of plants that are of different species and variety.
E. Nutrition
Proper care and the right nutrition should be given to the plant to have good and high seed-yield. Organic fertilizers are recommended
F. Irrigation/Watering
The amount and frequency of watering should be adjusted for good seed-yield. Plants need less water after flowering than during the vegetative stage.
G. Pest and Disease Management
Pests and diseases affect the quality and quantity of seed yield. To prevent infestation of pests and diseases, cultural practices like intercropping, mixed or multiple cropping and crop rotation are recommended.
Botanical pesticides can also be used to prevent infestation of pests and diseases. If some plants already have disease, pull them out and burn or bury them underground to prevent contaminating other plants.
Use of good quality seeds (seeds with good germination percentage and without seedborne pests and diseases) can also prevent pest and disease infestation.
Another way of controlling pest and disease infestation is to use traditional seeds.
Seed harvesting and seed extraction
Seeds should be carefully harvested to ensure high quality. The seeds should possess the qualities of the variety that was planted. For example if a long purple eggplant was planted the harvested fruit should possess these qualities. Seeds from more plants should he harvested when the plant is cross -pollinated.
Seed harvesting and seed extraction
Seeds should also be harvested when they are already mature. Seeds that are overmature are not recommended since they might have already been infected with pests and diseases. Secondly they are already weak because they are old. Seeds that are undermature will not produce good seedlings and usually do not germinate. Usually for fruits that have lots of seeds (example: bottle gourd sponge gourd bitter gourd eggplant) the seeds that will be used for planting are collected or extracted from the middle portion of the fruit where the maturity of the seeds is just right and the seeds are the same age. If earliness or lateness of fruiting is not one of your selection criteria it is recommended to get fruits that ripen in the middle of the fruiting season.
To allow for losses during storage germination and early growth' about 50% more seeds than needed for planting should be harvested. It is very important that the seeds are labelled after harvesting to avoid mixing up the seeds.
How To Determine if the Seeds are Already Mature
1. The fruit has a hollow sound.
Example: squash watermelon melon
2. Color size and shape of the fruit.
Example: tomato and chili (red); cowpea and other legumes (yellow to brown); eggplant (yellow)
3. Shattering of pods.
Example: legumes
4. Fruit is disconnected from the branch.
Example: squash watermelon melon
5. Number of days - This depends on the familiarity of the farmer for the type of plant.
How To Determine if the Seeds are Already Mature
After-ripening
Some seeds improve their germination if they are allowed to stay inside the fruit for several weeks.
Example: squash bottle gourd sponge gourd
Seed Extraction/Cleaning
The extraction of seeds from the fruit depends on the condition of the fruit and seeds that will be harvested:
1. Wet seeds from fleshy fruits -The fruit and the seeds are both wet. Usually, the flesh is attached firmly to the seeds. Seeds are extracted using the hands or a knife. The fermentation process is sometimes done to remove the seeds. Soak the fruit in water for one to two days. After soaking, separate the seeds from the flesh, and throw away the flesh together with the seeds that float (except when the seeds naturally float). Sunken seeds are then washed and dried.
Example; eggplant, cucumber, tomato, bitter gourd, squash, sponge gourd, bottle gourd
2. Dry seeds - These are obtained or extracted from a dried fruit or pod. These are extracted by hand or pounded collectively while inside a sack or net bag. Pounding the seeds inside the bag is necessary to prevent them from scattering.
Example: cabbage, cauliflower, mustard, pechay. lettuce, pea, lima bean, cowpea, hyacinth bean, yardlong bean, pigeon pea, munghean, onion
If possible, do not harvest these seeds when it is raining or in early morning when there is still dew. Also, do not harvest at midday since the pods will break or shatter, allowing the seeds to come in contact with the soil and with microorganisms that lower seed quality.
3. Dry seeds from fleshy fruits -The ripe fruit is dried before extracting the seeds.
Example: chili, ladyfinger
For all kinds of seeds, winnowing or removal of contaminants after drying and before storage is recommended to maintain good quality. Contaminants include weed seeds, seeds of other crops or of different variety of the crop, chaff, dust and other inert materials like rocks, dirt, twigs and leaves.
Seed Extraction/Cleaning
Seed drying
It is necessary to dry moist seeds before processing and storing. Seeds with high moisture content are more susceptible to physical damage during processing. This reduces viability and encourages the formation of molds.
In addition, the germination of moist seeds that are stored can be severely reduced. In this condition, the respiration of the seeds and of the microorganisms present in and on the seeds may produce enough heat to kill the seed. Excess moisture favors infestation of insect pests. It also increases the respiration of the seeds, consuming the stored food of the seeds and resulting in weak seedlings. Seeds which are not welldried have high respiration rates, causing them to rot. Usually, the moisture content of seeds after harvesting is high, especially when they are cleaned by washing.
If the air is humid, dry seeds absorb the water from air. If the air is dry, it absorbs water from wet seeds. This is why air-drying can dry wet seeds. This is also the reason seeds are stored in air-tight containers after they have been properly dried.
Things to Remember in Drying Seeds
1. Do not allow the seeds to come in contact with the soil or ground. This will prevent the seeds from getting in contact with soil microorganisms that will lower the quality of the seeds. Use a wedge so that the seeds can be dried above the ground.
2. Use a drying material with holes (example: sack, winnowing basket, mat) to allow air to pass through, giving fast, even drying.
Do not allow the seeds to come in contact with the soil or ground
3. Do not dry the seeds rapidly because it will lower seed germination. Rapid drying can also harden the seed coat, making the seed impermeable to water when planted. If the initial moisture content of the seeds is high, air-dry the seeds in a shady area for one to two days before sun-drying. Do not dry seeds under the sun from 11:00 a.m. to 2 p.m. when the heat of the sun is intense because it will kill the seeds.
Do not dry the seeds rapidly
4. Spread the seeds thinly and stir and turn them occasionally (at least 4 to 5 times a day) to make drying fast and even.
5. Before it rains or gets dark, cover the seeds and take them indoors to prevent their moisture content from increasing.
How to Determine if Seeds are Well-dried
1. Seeds that were harvested dry have enough moisture content when they are dried under the sun for 2-3 days. If seeds were harvested wet or were washed before drying, 3-5 days sun-drying is enough after they have been air-dried for 1-2 days.
2. Seeds have distinct sounds when their moisture content is already low enough for storage.
a. Large, thin seeds will break with a "snapping" sound when twisted between the fingers.
Example: squash, bottle gourd
Will break with a "snapping" sound
b. Large, thick seeds will break with a "cracking" sound when bitten between the front teeth. Do not do this for very hard seeds because it might damage your teeth. Also, avoid this if the source of the seeds is unknown since they might have been applied with chemicals.
Example: ladyfinger, cowpea
c. Small seeds will break with a "cracking" sound when squeezed between the fingernails.
Example: mustard, pechay, amaranth
3. Seeds 'have a distinct tinkle when they are well-dried.
4. If possible, use an oven which can reach a temperature of 100°C or higher. Weigh the seed sample before placing it inside the oven. Weigh the seeds again after drying for 17-20 hours inside the oven. The lost weight indicates how much water was lost after the seeds have been dried. From these, the percent moisture content of the seeds can be computed. The seeds are dried enough for storage when they reach a moisture content of or less than 10%.
Example: Before oven drying - weight of seeds is 10 grams After oven drying - weight of seeds is 9 grams
Lost water 1 gram
% Moisture Content of the Seeds = 1 / 10 × 100= 10%
% Moisture Content of the Seeds = 1 / 10 × 100= 10%
However, it is not easy to obtain an oven to determine the moisture content of the seeds so the practical methods above are recommended.
How to Determine if Seeds are Well-dried
Seed storage
The length of time that seeds can be stored depends on: (1) the seed type; (2) its quality; and, (3) the storage conditions.
Factors that Affect the Longevity of Seeds During Storage:
1. Moisture Content of the Seed - Even if seeds are thoroughly dried, improper storage can still enable them to absorb water. To avoid damage caused by excessive moisture content, (1) store seeds in air-tight containers (bottle with tightly closed metal cover, tin can, sealed thick plastic); (2) keep seeds dry by including desiccants or materials that absorb moisture (example: dry charcoal, dry ash, toasted white rice, lime, silica gel) inside the storage container, and, (3) replace desiccants, such as dry charcoal, dry ash and toasted white rice, each time the container is opened. The moisture content of the seeds can also be kept low if the seeds are sun-dried from time to time.
2. Temperature - The life of vegetable seeds during storage is prolonged when the storage temperature is low or cold (but not freezing). If a refrigerator or airconditioner is not available, choose a cold place (example: near the river, under trees, underground, inside a clay jar). Ensure that the seeds will not get wet.
As a general rule:
The life of seeds doubles when the moisture content is lowered by 1% or when the storage temperature is lowered by 5°C.
Example:
If the storage life of a seed with 14% moisture content is two years, its storage life can be prolonged to four years if the moisture content of the seed is lowered to 13%.If the expected life of a seed is three years in a storage room with a temperature of 15°C, its life can be prolonged to six years if the storage temperature is lowered to 10°C.If both the moisture content of the seed and storage temperature are lowered, the increase in the life of the seed is greater.
Example
Condition Result
Moisture Content
|
Temperature
|
Storage Life
|
% Germination
|
13%
|
30°C
|
½ year
|
50%
|
12%
|
30°C
|
1 year
|
50%
|
13%
|
25°C
|
1 year
|
50%
|
12%
|
25°C
|
2 years
|
50%
|
11%
|
25°C
|
4 years
|
50%
|
10%
|
30°C
|
4 years
|
50%
|
3. Pests - Storage weevils, fungi and bacteria shorten the life of seeds during storage. Storage weevils begin to multiply when the moisture content is 10%. Fungi infestation becomes a problem when the moisture content is 13%. Bacteria become a problem when the moisture content is above 20%. To prevent pest infestation, choose only pest-free seeds during storage. Pest problems can also be prevented if the seeds are maintained dry. Materials that prevent or stop the growth and multiplication of pests can also be used. These are:
a. Dry ash and charcoal - They absorb water inside the storage container. Ash prevents the growth and increase of weevils. Use one-half kilo of ash for every one kilo of seed. Use ash which has been cooled for at least 12 hours to prevent the seeds from burning.
b. Sand - Mix the sand with the seeds and make sure that the storage container is full so that the weevils cannot move around.
c. Cooking Oil - Some seeds can be mixed with cooking oil to prevent increase of weevil. The recommended rate is one teaspoon oil for every one kilo of seeds.
d. Lime - In addition to absorbing moisture, lime can also prevent an increase in the number of weevils. Mix 15 teaspoons (about 50 grams) of lime for every kilo of seeds.
e. Dried and powdered leaves or seeds of different aromatic plants - Weevils are sensitive to odorous plants which prevent their multiplication and cause their death The effect of the plants depends on their preparation, the amount applied and the type of seed and weevils. Some of these plants can affect the seed so it is important to test what is appropriate for a certain kind of seed. Also, make sure that the right amount is applied.
Examples of Aromatic Plants
Neem - Dry the leaves or seeds under the sun and grind them to a powder. Mix 3-4 teaspoons (15-20 grams) of powdered seeds (double the amount if powdered leaves are used) for every one kilo of seeds.
Hot pepper or chili - Dried and powdered fruits are better than dried whole fruits. Mix 46 teaspoons (20-30 grams) of dried and powdered chili for every one kilo of seeds.
Black pepper - Mix 6 teaspoons (30 grams) of powdered black pepper (double the amount if powdered leaves are used) for every kilo of seeds.
Other plants which can be tried:
Powdered rhizome of turmeric - Mix 4 teaspoons (20 grams) for every kilo of seeds.
Powdered leaves of mint - Mix 14 teaspoons (5-20 grams) for every kilo of seeds.
Powdered seeds of yambean -Mix 1-2 teaspoons (5-10 grams) for every kilo of seeds.
Powdered leaves of lagundi, mango and tobacco - Mix 14 teaspoons (5-20 grams) for every kilo of seeds.
4. Other factors - The storage life of seeds can become shorter if the seeds are overmature, if they came from plants that have been attacked by pests and diseases or if the seeds were damaged during seed processing.
Labeling
Place labels inside and outside the storage container, especially when lots of different types of seeds will be stored.
The following should be included in the label:
(1) name of seed;
(2) date harvested;
(3) date stored;
(4) date germination test was conducted; and,
(5) percentage germination. If necessary, the characteristics of the plant and the seed should also be included.
Testing seed quality
Seed quality should be determined when buying seeds, selling seeds, giving or sharing seeds, storing seeds and sowing or planting seeds.
A. Seed Vigor
The strength or vigor of seeds, especially after exposing these to conditions of the storage room and planting area, needs to be determined. Weak seeds planted in poor field conditions will die, or the resulting plants will be susceptible to pests and diseases. Yields will, therefore, be low. Weak seeds will also not survive long during storage. In addition, even if a number of seeds have germinated, their rate or timing of germination and growth will be slow and not uniform. Determine seed vigor at the same time as measuring the percentage germination, in which seed vigor is the speed and uniformity of germination of the seeds. Compare the number, speed and uniformity of germination of the seeds being tested to those of good quality seeds.
Seed vigor can also be determined by soaking the seeds in water. Usually, the seeds which float are weak.
Seed Vigor
B. Seed Health
Healthy seeds are free of pests and diseases which can kill or damage. They will not infect other plants and spread a disease. If a microscope is not available, examine the seeds carefully. Look for blemishes or stains in the seedcoat, molds, holes caused by insects or eggs of insects. These seeds might cause an epidemic or will introduce a new pest or disease and are, therefore, unfit for planting. Clean the seeds and remove diseased or infected seeds.
Sometimes, a disease can be seen only after the seeds have been planted. Check if germinating seeds have fungi or bacteria (symptoms of infection: seeds are watery, shiny and have bad smell). It will also be helpful to know the place and the plant where the seeds were collected, especially for purposes of determining seed-borne diseases.
Many fungi and bacteria which can be killed by soaking the seeds in hot water (50°C) for 30 minutes. However, some pests and diseases cannot be killed by this method. Some tests on seed health are better conducted in the laboratory. If you think that your seeds have pests and diseases, have them tested in appropriate offices or agencies (example: Bureau of Plant Industry).
C. Seed Purity
Make sure the seeds you procure are the right ones or the ones as stated in the label. This can only be determined by knowing the characteristics of the seeds well. Also, determine whether there are contaminants in the seeds, such as dirt, stones, leaves or seeds of other plants, broken seeds and pests and diseases. The contaminants lower seed quality. If possible clean the seeds before storing or giving to others.
Seed Purity
D. Moisture Content of the Seeds
The standard moisture content is 14% for seeds that are not oily (like ladyfinger and pechay) and 12% for seeds that are oily (like soybean, peanut, yardlong bean and mungbean). High moisture content decreases the viability of seeds.
E. Percentage Germination
Obtaining percentage germination gives an idea on whether the seeds should still be stored, planted or thrown away. This will also indicate the number of seeds to be planted to get the desired number of plants. You need a material which can absorb water. For large seeds, use river sand or clean soil (usually boiling water is poured on the soil before using to kill germs) as a germination medium. For small seeds, paper (example: filter paper, tissue paper) or cloth (example: cheese cloth) can be used as a germination medium. Arrange the seeds (not dose together) in the germination medium and roll the medium like a mat, or cover with another layer of the medium. Water the seeds, but do not flood them. Place the medium with the seeds in a box or plastic bag which allows air to penetrate, or stand it in a container with enough water to be absorbed upwards. Do not place the medium in the sun or where it can be reached by rats or ants.
After several days, count the number of normal seedlings (the ones which have the ability to continue growing normally and those which have normal leaves and roots).
Calculate the percentage germination.
Example:
The more seeds tested for percentage germination, the more accurate the percentage germination will be. If possible, replicate testing and use 50 or more seeds. You can then find the number of seeds to plant:
Example:
Abnormal Seeds
Do not store or plant seeds if their percentage germination is lower than 50%. These seeds will usually produce weak seedlings and will deteriorate rapidly, if stored.
There are instances when seeds do not germinate at once, not because they are dead, but because they are dormant or fail to absorb water (example: mungbean, winged bean). In addition, some temperate seeds (example: pechay, carrot, cabbage) absorb water but do not readily germinate, especially when they are new or fresh. Hard-coated seeds need methods that will open the seedcoat (example: rubbing in sandpaper, use of nailcutter or chipping with a knife). Take extra care in preventing embryo damage. You can also soak the seeds in hot water for 3-10 minutes (l part seed for every 10 parts water) or in boiling water for 1-10 seconds. The duration of soaking depends on the type of seed and the age of the seed. Seeds which are old, hard and easily absorb water should be soaked for a shorter length of time compared to seeds which are young, soft and do not easily absorb water. Seeds usually grown in cold areas can be placed in the cold for several days while In the germination medium before transferring them to a planting area.
References:
Chapman, S. and L. Carter. 1976. Crop Production - Principles and Practices. W.H. Freeman and Co., USA: 566 p.
Cleveland, D. and D. Soleri. 1991. Food from Dryland Gardens: An Ecological, Nutritional and Social Approach to Small-scale Household Food Production. USA: pp. 285 - 306.
Fernandez, P., E. Masilungan, E. Corcolon, B. Garcia, M. Petalcorin, C. Ramirez and M. Tolentino. 1992. Pagpaparami at Pangangalaga ng Binhi. Philippines. 33 p.
Janick, J. 1963. Horticultural Science. 2nd Edition. W.H. Freeman and Co., USA. 586 p.
McCollum, W. 1968. Producing Vegetable Crops. The Interstate Printers and Publishers, Inc., USA: 588 p.
Nursery techniques for seedlings
Direct seeding is the most common method of sowing vegetable seeds. However, some vegetable seeds perform better if they are sown in containers or seedbeds initially and are later transplanted. Here are some basic steps in starting plants by this method:
1. Select suitable container. Planting in a seedbed is cheaper than using a container. However, using a container allows the gardener to choose the right medium for growing the seedlings. Any container deep enough to allow seedlings to root and wide enough to prevent their becoming cramped will do. Containers may be:
Seed flats
Clay seed-pans
Plant bands/paper box
Rag doll
2. Prepare container for planting. Containers should be cleaned properly to ensure they harbor no fungus spores or insect pests. Adequate drainage should also be provided to avoid damping-off (soil-borne disease that destroys seedlings).
Cleaning containers
Providing drainage
3. Prepare the soil medium. The soil medium should be free of weed seeds, fungus spores and garden pests. It should be sufficiently porous to allow the delicate rootless to penetrate and to admit air and moisture. Usually, a mixture of equal parts of sand, soil and compost is recommended, though a modified mixture can be made to produce a soil mixture that is more favorable for the growth of seedlings.
Sterilizing soil
Filling flat or pan
Watering
4. Sow the seeds. The manner in which seeds are placed in the soil depends largely on their size.
Fine seeds are usually broadcast together with sand.
Medium-sized seeds are often sown in drills.
Large seeds can be poked in slightly with a finger.
5. Cover the seeds. Cover the seeds by sifting soil medium through a fine sieve held above the seed bed. Large seeds are covered to a depth equal to twice their width.
Cover the seeds
Fine seeds are not covered but are merely pressed gently into the soil with a flat, level piece of wood.
Fine seeds are not covered
6. Care for Germinating Seeds. Seedlings should be protected from temperature fluctuations. Enough moisture and air circulation must be provided.
Dry soil can stop germination, but overwatering can encourage damping off. When watering is necessary, soak by immersion if possible.
It is advisable to set the seedbox in the open. If it is covered or is indoors, the seedlings may suffer from lack of moving air.
The seedlings should continue to get some protection until the first true leaves emerge. When one or two sets of true leaves become visible, the seedlings are ready for transplanting.
The seedlings should continue to get some protection
7. Pricking/thinning is the process of transplanting seedlings from the seedbox to another seedbox. This step gives the seedlings a chance to start development of root and leaf systems before the plants are left to fend for themselves in the garden. Seedlings should be pricked out as soon as they have two sets of leaves
Pricking/thinning is the process of transplanting seedlings
Use a sharp tool to help remove the plants so as not to injure them.
If seedlings come up with their roots entangled, they can be separated by soaking the root ball in water.
If seedlings come up with their roots entangled
Transplant the Seedlings. Punch holes in the seedbed with a dibble at two inches apart. Working quickly, insert the roots of the individual seedlings in the holes and firm them in with either the dibble or with forefinger and middle finger.
Transplant the Seedlings
If roots of a seedling are lengthy, they should be cut with shears or sharp knife.
They should be cut
When the seedbox is filled, it should be watered with a fine spray from a hand syringe to settle the soil around the roots and to freshen wilted stems and leaves.
Should be watered with a fine spray
If plants are particularly soft and subject to wilting, cover the box with a sheet of newspaper or another box fumed upside down.
Cover the box with a sheet of newspaper
In about four or five weeks, the young plants will be ready to go out into the open ground. A week before transplanting, the plants should be hardened by gradually increasing exposure to sun and air. Before finally setting in the garden, the plants should be given several days of full sunlight; and if they are going into a sunny position, watering is also held back gradually before transplanting..
Reference:
Sunset Western Garden Book. 1959. Lane Publishing Co., Menlo Park, California, USA. 384 pp.
Reference Source: International Institute of Rural Reconstruction
Reference Source: International Institute of Rural Reconstruction
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