Storing cacti seeds

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mmcavall
Posts: 1436
Joined: Tue May 17, 2016 11:54 pm
Location: São Carlos - SP, Southeast Brazil, Cerrado Region

Storing cacti seeds

Post by mmcavall »

Hi all,
In another thread, JFabiao recommended me to store my seeds in the fridge. While it could be a good idea, I wasn’t sure about the scientific rationale, and whether this applies to all species or only to those that naturally get some cold in winter.

In search for information, I’ve personally “interviewed” a PhD in seeds conservation. Here is the information I get from him, which corroborates JFabiao suggestion:

- All live tissues (including seeds) breathes;
- The more hot and humid is the atmosphere, the more the tissue will breathe;
- Breathing leads to ageing of any tissue;
- So, it is a good idea to reduce breathing, and this can be done by reducing temperature and humidity;
- Seeds can lose or acquire humidity from the atmosphere; if the air is dry, seeds will dry (until a certain point) without losing its germination properties;
- Losing 1% of its humidity to the dry air will make the seed double its lifespan;
- Also, for each decrease of 5°C in temperature, the lifespan of the seed will also double;
- The stated above is valid to any orthodox seed (see definition below), even to seeds from tropical climates that are hot and wet;
- Orthodox seeds are usually stored in dry chambers at 10°C and 20% humidity;
- Fridges are dryer than the atmospheric air (in many places); temperatures ranges from 6°C to 10°C (but you may want to check it)
- For all said, it is a good idea to keep your seeds in the fridge!
- IMPORTANT NOTE: take the seeds out of the fridge about 48 hours before sowing. This is important to let the seed slowly acquire humidity from atmosphere. Otherwise, it will quickly suck the water from the substrate and it may lead to fissures, hampering germination.

The information above was told me by the professor. Now back to cacti:

Cacti seeds are probably orthodox, because they are released in arid environments. This review (http://www.sciencedirect.com/science/ar ... 6399905827) says that there most cactus seeds have an orthodox storage behavior. Also here: http://opuntiads.com/oblog/cactus-seeds-are-orthodox/).

So, in my opinion, storing cacti seeds in the fridge is a good thing to do. Does anyone has different information/points of view?


Definitions (according to Wikipedia):
Orthodox seeds are seeds which will survive drying and/or freezing during ex-situ conservation. According to information from the U.S. Department of Agriculture, there is variation in the ability of orthodox seeds to withstand drying and storage, with some seeds being more sensitive than others. Thus some seeds are considered intermediate in their storage capability while others are fully orthodox. One notable example of a long-lived orthodox seed which survived accidental storage followed by controlled germination is the case of the 2,000-year-old Judean date palm (cultivar of Phoenix dactylifera) seed which successfully sprouted in 2005.This particular seed is reputed to be the oldest viable seed, but the upper survival time limit of properly stored seeds remains unknown.

Recalcitrant seeds (subsequently known as unorthodox seeds) are seeds that do not survive drying and freezing during ex-situ conservation and vice versa. By and large, these seeds cannot resist the effects of drying or temperatures less than 10 °C; thus, they cannot be stored for long periods like orthodox seeds because they can lose their viability. Plants that produce recalcitrant seeds include avocado, mango, mangosteen, lychee, cocoa, rubber tree, some horticultural trees, and several plants used in traditional medicine, such as species of Virola and Pentaclethra. Generally speaking, most tropical pioneer species have orthodox seeds but many climax species have recalcitrant or intermediate seeds.
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Gustavo Augusto Rosa
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Joined: Sat Mar 03, 2018 3:10 am
Location: Brazil
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Re: Storing cacti seeds

Post by Gustavo Augusto Rosa »

Very nice post! has u used this process!?
DaveW
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Joined: Thu Dec 20, 2012 2:36 pm
Location: Nottingham, England/UK

Re: Storing cacti seeds

Post by DaveW »

Interesting and very useful for cactus seed storage.

Regarding recalcitrant or unorthodox seed. I did once read where Kew Gardens could not get the conventionally cleaned seed of a certain tropical plant to germinate whatever they did. Somebody then had the bright idea of asking that the seed be sent in the rotting remains of the fruit and warned the British Customs not to throw away the stinking mass thinking it was useless.

When Kew received it they just set it in the wet fruit remains and the seed germinated freely. Evidently it was one of those exceptional seeds that should never be cleaned and allowed to dry out from the fruit before setting, or it's viability drops rapidly.

I also read of some where the seed is so hard it only germinates if it has passed through an Elephants gut and been subject to it's stomach acids for a certain period.
keith
Posts: 1860
Joined: Wed Jun 12, 2013 3:50 am
Location: S. CA USA

Re: Storing cacti seeds

Post by keith »

I store seeds in used medicine containres which are airtight so I poke small holes in the lid. they seem to last a few years. I often wash them with water then dry them then store them.
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