This document discusses the classification of seeds based on their storage behavior. It begins by defining seed storage, deterioration, life span, and longevity. It then summarizes Ewart's 1908 classification of seeds into three categories (microbiotic, mesobiotic, macrobiotic) based on lifespan under optimal storage conditions. However, this classification is too rigid. The document goes on to describe the two major classes recognized today - orthodox and recalcitrant seeds. Orthodox seeds can be dried and stored at low temperatures, while recalcitrant seeds cannot survive drying or freezing. An intermediate category is also discussed. Various plant examples are provided for each classification. Factors that can help predict a seed's storage behavior are outlined.

1. Classification of Seeds on the basis of
Storage Behaviour
(SST 513)
Prof. Kumari Rajani
Department of Seed Science & Technology
Bihar Agricultural University, Sabour

2. Seed Storage
The preservation of seeds under controlled environmental
conditions which will prolong the viability of the seeds for
long periods
Seed Deterioration
Deteriorative changes occurring with time that increase the
seed’s vulnerability to external challenges and decrease the
Terminologies
seed’s vulnerability to external challenges and decrease the
ability of the seed to survive
Life Span
The average length of life of a kind of organism especially in
a particular environment or under specified circumstances
OR
The duration of existence of an individual
Prof. Kumari Rajani

3.  In seeds, it is the LENGTH OF TIME that they remain viable.
 The life span depends on the species and the environmental
conditions under which the seeds are stored.
Longevity or Life span of seed
 The duration is often qualified by the percentage of seed viability
at the end of the period because seedlots are populations in which
some seeds die sooner than others (e.g. 85% viability in order to
ensure that the majority of individuals in the seed population are
viable and in good condition at the end of this period).
Prof. Kumari Rajani

4. Ewart (1908) divided seeds into three biological classes according to
their LIFESPAN under the BEST POSSIBLE CONDITION OF STORAGE
in which they are capable of retaining viability:
1. Microbiotic (seed lifespan of less than 3 years)
2. Mesobiotic (seed life span of 3 to 15 years)
3. Macrobiotic (seed lifespan of 15 to over 100 years
Although Ewart's classes were useful in drawing attention to the
differences in natural longevity of seeds of different species, his
classification is too rigid to fit the variations between
individuals, provenances and seed years in a single species, or the
possible variations in storage conditions. Prof. Kumari Rajani

5. Today two major classes of seed are recognized (Roberts 1973):
1. Orthodox
Seeds which can be dried down to a low MC of around 5%
(wet basis) and successfully stored at low or sub-freezing
temperatures for long periods.
2. Recalcitrant
Seeds which cannot survive drying below a relatively high
moisture content (often in the range 20–50% wet basis) andmoisture content (often in the range 20–50% wet basis) and
which cannot be successfully stored for long periods.
3. Intermediate
Certain seeds do not conform fully either to ortho-dox or
recalcitrant category. Some of these seeds may have a
limited desiccation tolerance but are sensitive to freezing
temperatures. For these seeds, an intermediate category
has been suggested by Ellis (1991). Citrus and Coffee seeds
may fit this intermediate classification.
Prof. Kumari Rajani

6. Orthodox Seeds
• Long-lived seeds and can be
successfully dried to moisture
contents as low as 5% without injury
and are able to tolerate freezing.
• Desiccation tolerant seeds.
• The life span of orthodox seeds can be
prolonged with low moisture content
and freezing temperatures.
Recalcitrant Seeds
• Do not survive drying and freezing
for ex-situ conservation.
• Desiccation intolerant seed
• Cannot resist the effects of drying
below 30 % moisture content without
loosing viability or storage at
temperatures less than 10 °C.
• Cannot be stored for long periods
Classes of seed
and freezing temperatures.
• Ex-situ conservation of orthodox
seeds is therefore, not problematic.
• Exemplified by most annual and
biennial crops and Agroforestry
spe-cies.
• Relatively small-seeded.
• Ex:
Citrus aurantifolia, Capsicum
annum, Hamelia patens, Lantana camera,
guava (Psidium guajava), Cashew
(Anacardium occidentale) and most grains
and legume types.
• Cannot be stored for long periods
like orthodox seeds because they can
lose their viability in short period.
• Ex:
Avocado, mango, Jackfruit, mangosteen,
lychee, cocoa, rubber tree, some
horticultural trees, aquatic plants, such
as Nymphaea caerulea, and several
plants used in traditional medicine, such
as species of Virola and Pentaclethra.
Prof. Kumari Rajani

7. Intermediate seed storage behaviour
Seeds which exhibit the drying tolerance characteristic of the
orthodox seeds but are sensitive to low temperature storage like the
recalcitrant seeds.
Some of these seeds may have a limited desiccation tolerance but are
sensitive to freezing temperatures
Tolerate desiccation to relatively low moisture content (7 to 10Tolerate desiccation to relatively low moisture content (7 to 10
percent)
An intermediate category of seed and has been suggested by Ellis
(1991)
About 134 species: show intermediate seed storage behaviour. Many
of these species are trees of tropical origin, but a few are herbaceous
(Hong and others 1996).
Prof. Kumari Rajani

8. Examples:
1. Azadirachta indica (Neem)
2. Cinnamomum subaveniu
3. Citrus species
4. Coffea Arabica (Arabian coffee)
5. Coffea canephora (Robusta coffee)
6. Elaeis guineensis (Oil palm)6. Elaeis guineensis (Oil palm)
7. Khaya senegalensis (African mahogany)
8. Lindera megaphylla (Spicewood)
9. Neolitsea parvigemma
10.Swietenia Macrophylla (mahogany)
Prof. Kumari Rajani

9. In 1954, seeds of Arctic lupine were recovered
from a rodent burrow six meters below the frozen
silt in glacial sediments.
It was found in the Yukon Territory.
Arctic lupine (Lupinus arcticus)
Seed longevity in the natural environment
The seed was germinated in 1966.
Along with the seeds a collared lemming skull
was found in the burrow. Since this lemming
species disappeared from the region 10,000 years
ago it was proposed that the seeds were also of
this age.
Prof. Kumari Rajani

10. The oldest viable seeds in the world, dating from the Pleistocene
era, are not what we thought.
New dating techniques have revealed that the seeds, which have
been grown into live Arctic lupine plants, are not 10,000 years old as
believed.
Instead they are likely modern seeds (less than 10 years old) which
BUT...
Instead they are likely modern seeds (less than 10 years old) which
contaminating ancient rodent burrows.
Prof. Kumari Rajani

11. Silene stenophylla (narrow-leafed campion)
 An Arctic flower native to Siberia, Russia.
 The world’s oldest carbon-14-
dated seed that has grown into a viable
plant.
 The seeds were about 31,800 ± 300 years
old.
 In 2007, more than 600,000 frozen mature
 Three immature seeds
contained viable embryos
that were extracted and
grown in vitro (in test
tubes), which
grew, flowered and
created viable seeds of
Oldest Viable Seed
 In 2007, more than 600,000 frozen mature
and immature seeds were found buried in
70 squirrel hibernation burrows 38
metres (125 ft) below the permafrost near
the banks of the Kolyma River.
their own.
Prof. Kumari Rajani

12. Judean date palm
It is a date palm (Phoenix dactylifera) grown
in Judea (Israel).
The oldest mature seed that has grown into a
viable plant was a Judean date palm seed.
About 2,000 years old.
Recovered from excavations at Herod the
Great's palace on Masada in Israel.
It had been preserved in a cool, dry
place, not by freezing.
It was germinated in 2005 and the plant was
nicknamed "Methuselah" after the longest-
lived person listed in the Bible.
Prof. Kumari Rajani

13. A Japanese botanist found some viable lotus (waterlily) seeds in a layer of
peat under a layer of windblown soil in a dry lakebed in Manchuria
(Northeastern China).
A geologist classified the peat and loess layers of the lakebed as Pleistocene
deposits, but this geologic period the Ice Age in general came to an end 10
thousand to 15 thousand years ago.
Sacred Lotus or Indian Lotus (Nelumbo nucifera)
The ancient Manchurian seeds are the
size of small hazelnuts. They have thick,
horny seed coats. They closely
resemble the seeds of Nelumbo
nucifera (Sacred Lotus or Indian Lotus).
Preliminary tests on several whole
seeds by the residual carbon 14 isotope
method of dating organic carbon
residues indicated that the seeds were
between 830 and I250 years old.
Prof. Kumari Rajani

14. Prediction of Seed Storage Behavior
“No single criterion can provide a satisfactory estimation of likely
seed storage behavior, but combining information for at least four of
the six factors described below may be worthwhile”
(Hong and Ellis 1996)
1.PLANT ECOLOGY: From information on seed storage behavior1.PLANT ECOLOGY: From information on seed storage behavior
collated for almost 7,000 species from 251 families (Hong and others
1996), it is evident that species that show recalcitrant seed storage
behavior do not occur naturally in (i.e. originate from) arid
habitats, that is desert and savanna. In such environments, the
majority of plant species show orthodox seed storage behavior, while
a few may show intermediate seed storage behavior.
Prof. Kumari Rajani

15. 2. TAXONOMIC CLASSIFICATION: Orthodox seed storage behavior
can be found in all species within a few families (e.g.
Chenopodiaceae, Combretaceae, Compositae, Labiatae, Solanacea
e, Pinaceae), or almost all species in others with only a few
exceptional species (e.g.
Leguminosae, Graminae, Cucurbitaceae, Cruciferae and
Rosaceae). However, most families.
3. PLANT, FRUIT, OR SEED CHARACTERISTICS: Orthodox seed
storage behavior is shown by species that produce
achenes, many-seeded berries, many-seeded dehiscentachenes, many-seeded berries, many-seeded dehiscent
capsules, many dry-seeded pods (but not arillate), many dry-
seeded follicles, schizocarps, and utricles (Hong and others 1996).
4. SEED SIZE: Recalcitrant seeds often tend to be larger than
intermediate seeds, which in turn tend (on average) to be larger
than orthodox seeds. However, there is a very wide range of seed
weights or sizes over which seeds of different species show all
three types of seed storage behavior (Hong and Ellis 1996).
Prof. Kumari Rajani

16. 5. SEED MOISTURE CONTENT AT SHEDDING: Seed moisture
contents at maturity or shedding for species with
recalcitrant, intermediate, and orthodox seed storage behavior
overlap considerably.
6. SEED SHAPE: There appears to be a weak association between
seed shape and seed storage behavior. For example, recalcitrant
seeds are often spherical or oval (Chin 1988). Seeds that are thin
and flat, shapes that aid natural maturation drying, tend to show
orthodox seed storage behavior (Tompsett 1994). Flat seeds tendorthodox seed storage behavior (Tompsett 1994). Flat seeds tend
to show orthodox seed storage behavior in Acer spp. (Hong and
Ellis 1997b), but show both orthodox and intermediate seed
storage behavior in Meliaceae (Hong and Ellis 1998). The spherical
form is present in all three categories of seed storage behavior
(Hong and Ellis 1997b, 1998).
Prof. Kumari Rajani

17. Desiccation tolerance
Desiccation tolerance refers to the ability of an organism to withstand
or endure extreme dryness, or drought-like conditions.
It is the genetically and metabolically active stage associated with the
major loss of water.
Desiccation tolerance in certain living organisms provides one
Some Terminologies
Desiccation tolerance in certain living organisms provides one
mechanism of adaptation for survival
Tolerance to desiccation permits metabolic activity to be suspended
during periods of stress and occurs in a wide variety of organisms,
e.g. seeds, pollens, spores of Bryophyta and Pteridophyta, lichens,
resurrection plants, viruses, spores of bacteria and fungi, cysts of
several Protozoa, dry ova of several Ascaris spp. and dry larvae of
several nematodes and insects
Prof. Kumari Rajani

18. Imbibition Injury
If seeds are immersed (soaked) in water, the rapid uptake of water by
dry seeds can result in imbibitions injury
1. the lower initial moisture content of seed
2. the cool temperature at which they imbibe water
Most commonly found in Leguminosae and Malvaceae species
It can be avoided by conditioning (humidifying) the seeds in a moist
atmosphere (close to 100% RH) in order to raise seed moistureatmosphere (close to 100% RH) in order to raise seed moisture
contents to 16-18% before the seeds are set to germinate in contact
with liquid water.
This conditioning takes about 24 hours or more depending on initial
moisture content and species
It is suggested that seeds at 8% moisture content and below,
irrespective of species, should routinely be humidified before
germination tests
Prof. Kumari Rajani