Storing pollen

[Wakinyan]

http://www.arghyagardens.com/?p=341


And another
http://www.shieldsgardens.com/DLPlace/pollen.html

And one more
http://hostalibrary.org/misc/pollen/

Many of you have different species or even different varieties of the same species that you may wish to breed together and find that either the flowers are not blooming at the same time and therefore the cross is missed or perhaps you don't have the other variety at all and wish to make a cross. Centrifuge tubes provide an easy means of storing pollen in the freezer for later use as well as shipping pollen across seas. I've successfully hybridized Brugmansia with pollen sent from the USA to Belgium and vice versa while I lived over in Belgium. I'm sharing this bit of information for those that might benefit from it. I will simply state that from my experience, you only need to dry the pollen for a few hours and then store in the freezer. Microcentrifuge tubes are nice, but also not needed. You can simply store pollen on fluffed up q-tips in old film canisters or pill bottles if you have the space. Hope this helps some of you.

[chiefbtflapflaps]

how about q tips and sandwich bags?   although i can see how one would really need to develop a system to keep organized as the numbers go up.   

[Stonehenge]

Pollen loses potency over time. I'm not sure how long it will last, probably longer in the freezer but no more than a couple weeks or so in room temps. It might last a long time in the freezer if its kept dry.

[chiefbtflapflaps]

I've been keeping it frozen.  Any idea how long frozen cactus pollen stays viable? 

[Wakinyan]

Pollen that normally stays viable for a day at room temp can last years if dried and frozen. Hybridizers take advantage of that fact. There are many articles on freezing pollen in scientific journals, plant groups such as daylily hybridizing groups, etc. The main thing you have to realize is that each time you open a batch of pollen and expose it to warm temperatures you are reducing its fertility and introducing contaminants, humidity, etc. Pollen needs to be air dried for a few hours and then frozen for later use. The general rule of thumb is not to refreeze pollen. Take what you need out and put the rest back. Replenish as pollen becomes available and get rid of the old pollen.
Mary Jane pollen can be stored for 7+ years if dried and frozen properly and not repeatedly warmed and introduced to moisture each time one wishes to pollinate. Many employ flour to dilute pollen, make it easier to apply, etc. The key to any storage of pollen however is always reducing the moisture and freezing that pollen. Use each batch only once if you wish to ensure maximum stability of that pollen and contamination issues. As for cacti pollen storage and usability.... I found this article that will help if you want more particulars.
http://hortsci.ashspublications.org/content/35/1/22.full.pdf

[Wakinyan]

http://hortsci.ashspublications.org/content/35/1/22.full.pdf
In the study above, cacti pollen lost its viability within one day of storage at room temperature or just a few days in the refrigerator. To me, this means shipping pollen is not going to work if kept at room temperature or above and no other means of preservation is done.  Oven drying of pollen at 70 degrees C for 30 minutes helped reduce moisture content to acceptable levels of moisture content regardless of initial moisture content of pollen. The stigma itself often produces enough moisture to rehydrate pollen. Increasing the humidity may be of benefit. Starch was found to increase germination rates and pollen tube growth. This is another reason why hybridizers frequently use flour or cornstarch to dilute pollen. Other reasons for diluting pollen are to simply make your pollen go further as many beginning hybridizers use far more pollen than is needed for fruit set.  Pollen dried and stored at subfreezing temperatures in this study gave 100% fruit set after more than 9 months storage. Dried pollen stored at normal refrigerator temps of 4 degrees C. yielded only 60% fruit set after the same period of time and smaller fruits and lower seed counts.
I've had good luck with simply air drying pollen for a few hours and placing pollen inside an airproof container with rice or salt. The bottom line of all of this is that the drier and colder you can store your pollen the better. Flour or cornstarch may help with pollen germination and growth as can increasing the humidity around your flower after pollination. Pollen properly dried is still viable for 9 months properly stored in the refrigerator this way, but seed set will be lower. Placing that same pollen in the home freezer and stored the same way increases seed set and acceptable levels of seed set are still seen 9 months later. Pollen stored in the refrigerator properly dried can still yield fruit 9 months later with a cacti pollen that is normally only viable for one day at room temperature. Anything you can do to increase the seed set such as removing from the refrigerator and placing in your home freezer should be done if your serious in your efforts to produce seed of a hybrid origin.

[chiefbtflapflaps]

I have been letting the q tip air dry, freezing it in a ziplock, then pulling it out when I need it.  I'm not doing any crosses yet just trying to get more seeds.  Every time I'm amazed at how fast the movements are.  so temp and humidity I see are the biggest factors. 

[Wakinyan]

Temperature and humidity are definitely the biggest factors to extending the life of your pollen. Remove the humidity by air drying and then freezing and your pollen will indeed be good for years. Q-tips are an old tried and true way of storing pollen. Most who store pollen on q-tips will fluff them up by rolling the head in their finger tips so as to partially unravel the cottony head. Then one simply gathers the pollen up on that fluffy cotton and one can then store those q-tips in a secondary container such as an old prescription bottle or an old plastic film container.