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close this bookSeeds and Plant Propagation. Agroforestry Technology Information Kit (IIRR, 1992, 105 p.)
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View the documentWorkshop to revise the agroforestry technology information kit (ATIK)
View the documentWorkshop to revise the agroforestry technology information kit (ATIK) - November 16-21, 1992 IIRR, Silang, Cavite
View the documentCurrent program thrusts in upland development
View the documentSeeds and plant propagation: An overview
View the documentTiming of seed collection
View the documentSeed processing
View the documentSeed quality testing
View the documentHastening seed germination
View the documentSeed treatement for better and faster germination
View the documentSeed storage and longevity
View the documentAgroforestry seed storage
View the documentTree nursery: Establishment and management
View the documentVegetative propagation
View the documentAsexual propagation methods for commonly used agroforestry species: Fruit crops
View the documentRooting of cuttings in homemade mist chambers

Seed storage and longevity

Seeds, even if adequately protected during storage, still undergo deterioration with time. Major factors affecting longevity (Iife-span) of mature, viable and healthy seeds are moisture, storage temperature and pests.

Most seeds are drying-tolerant (orthodox). Under ordinary room conditions (open storage), viability of these seeds is generally reduced by half within six months. Seeds with harder seed coats tend to live longer than those with thin coats. For improved storability, seed moisture and storage temperature must be kept low and controlled.

1. Store only new, mature, healthy and well-dried seeds, except for a few species which do not favor drying. Keep these in dry and cool environments for longer viability.

2. Seeds easily reabsorb moisture. To maintain dryness, place dried seeds in air-tight containers like tin cans or glass jars with tight-fitting lids and use some water-absorbing materials like sifted dry wood ash (white), dry charcoal, toasted rice (cooled), silica gel or pieces of newspaper (to occupy about a fourth of the container). Place a sheet of paper on top of these water absorbing materials if seeds are to be put directly into the container. Replace or redry these materials if containers are frequently opened. Fill the rest of the container with seeds. Plastic bags may be used to keep seeds dry if sealed by heat.

3. Label containers with the harvest and storage dates and place of harvest (or acquisition). If possible, also indicate the initial percentage viability or germination of seeds.

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4. Dry seeds may be protected from insects by using naphthalene bails (1 or 2 pieces per kg seed) or by mixing seeds in the containers with some materials like fine sand, dry wood ash, powdered seeds of black pepper or neem, plant oils from coconut, neem, peanut, castor, cotton, etc., (one teaspoon of oil per kg seed).

A few species have seeds which are sensitive to drying and, often, also to cold temperature (recalcitrant). They have storabilities of only several days to a few months under ordinary room conditions in contrast to the drying tolerant or orthodox species. Recalcitrant characteristics are commonly found in many fruit, plantation and forest species (such as lanzones, rambutan, durian, mangosteen, mango, jackfruit, avocado, rubber, cacao and Dipterocarpus spp.)

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For slightly longer storabilities, keep these seeds wellcleaned and moist (1 to 2 days of air-drying is generally sufficient to keep the seed coat slightly dry but still moist inside). Store them in small batches in a cool room in inflated plastic bags (half-filled with seeds and opened once a day to prevent fermentation) or in perforated plastic bags. Moist charcoal, peat moss, sawdust, sand or coirdust may also be placed inside the bags. Moist storage for more than a week requires that seeds be protected from molds and bacteria. This may mean soaking seeds in a sterilant like the commercial bleach, chlorox (1 part chemical to 5 parts water) or applying anti-mold substances like fungicides or some plant extracts (try extracts of garlic cloves, acapulco leaves, malunggay leaves or achuete seeds). A temperature of 15 C is often used to further prolong storabilities and, to some extent, reduce infection. Recalcitrant seeds also need special attention during transport. The life time of seeds can be extended if extraction is deferred until seeds arrive at the collection site at which time care must be taken to avoid heating and/or fermentation of fruits by aeration or cooling.