Orthodox Seeds
These seeds can survive extreme freezing or drying conditions during ex-situ conservation. The sensitivity of different seeds to these extreme conditions are highly variable. Most of them can survive desiccation without any cell injury. Thus, they have a longer lifespan compared to other seeds. The ex-situ conservation of these seeds is easy.
Most food grains and legumes come under this category. Other examples include – Guava, Capsicum, Sapota, Dates, Cashews, Key lime, etc.
Recalcitrant Seeds
These seeds are just opposite to the orthodox seeds. They cannot thrive in freezing or drying conditions for a long duration. Thus, their ex-situ conservation is comparatively difficult. Desiccation of such seeds can lead to oxidative damage or deterioration of its cells. Recalcitrant includes large seeds, such as Mango, Avocado, Cocoa, Lychee, Jackfruit, etc.
Difference between Orthodox and Recalcitrant Seeds
Orthodox Seeds |
Recalcitrant Seeds |
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They can survive the freezing and drying that happen during ex-situ conservation. |
They cannot survive freezing and drying in ex-situ conservation. |
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They can dry their moisture content without cell damage. |
They can dry only up to a limit, and also cannot thrive for more than 3-4 days without cell injury. |
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They have a longer lifespan. |
They comparatively have a short lifespan. |
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They are desiccation-tolerant seeds that can be stored for a long time. |
They are not desiccation-tolerant, and hence cannot be stored for a long duration. |
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Most orthodox seeds are comparatively small. |
Most recalcitrant seeds are large. |
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This type of seed is seen in tropical pioneer species. |
This type of seed is seen in tropical climax species. |
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This includes most of the grains, guava, cashew, sapota, etc. |
This includes lychee, mango, avocado, etc. |
Frequently Asked Questions
What are intermediate seeds?
They are intermediate to orthodox and recalcitrant seeds. They can survive desiccation but not for a long duration like orthodox seeds. Examples – Coffee and Papaya.
What is ex-situ conservation?
It is a type of conservation method to protect an endangered animal or plant species outside its natural habitat. There is a lot of human management and control involved here. Cryopreservation and seed banking are some techniques in ex-situ conservation.
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