JARS v37n4 - A Pollen Bank Update

A Pollen Bank Update
Marthaann Mayer, Huntington, N.Y.

It has been some time since an article about the ARS Pollen Bank has appeared in the Quarterly. As there have been a number of requests for information about this service it seems that an update is in order.

I started the Pollen Bank in 1975 as a New York Chapter project in an effort to assist the hybridizers who were supplying much of the seed for our chapter seed exchange. I was seed chairman at the time and felt that since they did so much for the seed exchange I wanted to do something for them in return. It soon become apparent that members of other chapters wanted to participate and that the Pollen Bank would be much more useful to everyone as a national function; so, at the request of August Kehr, who was then president of the American Rhododendron Society, our chapter pollen bank became the ARS Pollen Bank.

There is a national committee consisting of Kendall Gambrill, Dick Murcott, George Miller, Jim Todd, Carl Deul, and myself. In addition to these "regional consultants" each chapter has been asked to appoint a member to serve as a liaison between interested chapter members and the Pollen Bank. These liaisons serve in an educational capacity and encourage contributions of pollen from members of their chapters.

The Pollen Bank has been growing slowly but surely. The supply of pollen is keeping pace with the demand for it with the exception of some very choice things which nearly everybody wants and which are in short supply. Collecting, storing and distributing pollen is a time consuming process so we have been concentrating mainly on working with the hybridizers in the society. All ARS members, however, are invited to participate in the program. The regulations for participating have been changed and should be noted. In the past all ARS members were permitted to receive unlimited amounts of pollen. This is no longer possible. As of the beginning of this year any member who has not previously received pollen may order pollen once. After that a donation will be required before obtaining additional pollen. This will, in effect, create a pollen bank membership system. A donation will allow a member to receive pollen (as available) for two years. After that time membership will expire and another donation will be required. Members will have priority in the distribution of pollen from lists to which they have contributed. Each year the list of available pollen will automatically be sent to all members who have contributed pollen to that year's list.

The general response to the pollen lists has been very favorable. The variety and quality of the pollen contributed has been commended and some people have mentioned that their contributions to the ARS Seed Exchange were the result of crosses made with pollen obtained from the bank.

Pollen contributions fall into three main categories: a) species - selected or named forms; b) named or registered hybrids; and c) new or unregistered hybrids (including those still in the working stages but considered to have good potential as parents). A brief description of the plant and an estimate of hardiness would be appropriate with pollen from the last group. Good choices for contributions would be pollen from plants that have recently been registered or those recently mentioned in the ARS Quarterly because they frequently have a limited distribution and are highly in demand. Other good choices for contributions are some of the more tender varieties grown only on the West Coast, late blooming varieties, and pollen collected during travel abroad. Any surplus pollen from your travels, even one capsule of a variety, will be gladly received.

Pollen for the Pollen Bank should be prepared using the following techniques:

1. Collect pollen from healthy, well-grown plants, preferably on a dry day, from flowers that are just about to open. This will prevent contamination by foreign pollen brought in by insects. Take anthers only, NOT the whole stamen. It is important to dip forceps (tweezers) in 50% alcohol (vodka, undiluted, may be substituted) to avoid contamination between varieties.

2. Pollen should be placed in labeled capsules. Don't fill capsules more than half full. If capsules are not available use tissue paper (gift wrap type) to make small packets or other paper NOT plastic envelopes.

3. Pollen should be dried by placing the capsules in a closed jar containing a desiccant such as calcium chloride, silica gel or powdered milk covered by a loose layer of cotton. The jar may be kept at room temperature several hours or overnight until the pollen starts to dry and then transferred to the refrigerator. NEVER put damp pollen directly into the freezer as this may cause the pollen grains to burst and render them useless.

4. When the pollen is thoroughly desiccated it should be stored in the freezer compartment of the refrigerator. Keep it in a sealed glass jar containing a desiccant. A layer of cotton or tissue should be placed between the desiccant and the capsules.

5. Pollen should be sent to me as soon as it is dried. DO NOT send damp pollen. It rots in the mail and is not usable. If you have kept the pollen in your freezer please be sure that all moisture which may develop when you remove the pollen from the freezer has evaporated before you package the pollen for mailing. This moisture may damage the pollen during shipment. Please use a crush-proof container and some packing material, such as cotton, to prevent the capsules from rattling around and opening, thus spilling their contents. If you include desiccating material in your package please be sure that this material is separated from the capsules by cotton or tissue. A list of the enclosed pollen should be included.

6. To use the stored pollen simply remove the jar from the freezer and allow it to defrost at room temperature.

If you are sending a large quantity of pollen you may send it in bulk packets or large capsules and I will package and label it for individual use.

It is probably best to use fresh healthy pollen whenever it is available for seed production. There are, however, several valid reasons for using frozen pollen, among them, differences in blooming dates of the prospective parent plants, as when the seed parent blooms in April and the pollen parent plant blooms in May; or the desire to use pollen from a plant that is impossible to grow in your climate or from a plant that is in limited supply. Frozen pollen keeps for at least three years in the home freezer (and probably indefinitely at much lower temperatures). The pollen available through the Pollen Bank is kept for only one year. We start each year with fresh pollen and the first part of each number denotes the year we received the pollen. For instance, "82-1 " means that the pollen was collected in the spring of 1982.

While some characteristics (particularly with hybrids) may be affected by freezing the pollen there has not been sufficient data collected at this time to indicate any undesirable influences from this type of storage. Animal studies have shown that fewer birth defects occur when frozen sperm is used for artificial insemination than would be expected to occur from natural insemination. It would appear that some of the weaker sperm cells are destroyed during the freezer process. This may also possibly occur with plant pollen so we should be aware that there may be subtle differences between seeds produced using pollen which has been frozen and seeds produced with the use of fresh pollen One should note, however, that many hybridizers have been using frozen pollen for some time now with excellent results.

I want to thank the many people who have supported our efforts in the past and hope that they will continue to do so. I hope, also, that we will have many new contributors next spring.