Plant Breeding In The Home Garden

Perhaps the most satisfying of all gardening pursuits is the propagation of plants from seed and then growing them through to maturity. Imagine taking that a step further and creating a new plant that is worthy of replicating and planting in gardens all over the world. Professional plant breeders do this in a very systematic way but it can also be a fun project in the garden that may even lead to a new variety that has commercial potential.

Plant breeding is about creating genetic variability in a batch of seedlings with the hope that one or more of the resulting plants will be something spectacularly new and desirable. The trick lies in selecting the best parents to achieve your objectives. Those objectives may be traits such as larger flowers, more perfume, different flower colour and so on. The ideal result is to incorporate novel characteristics into a plant that is relatively easy to grow. The best way to do this is to include as one of the parents a plant that is already a good performer in the garden.

Cross pollination of two parent plants is the best way to generate a group of seedlings that are likely to give you what you want. It is best to stick to parents within the same genus, as this will generally give you plenty of seeds to play with. In other words stick to trying to cross a rose with a rose and so on. Crosses between different genera within the same family are sometimes possible (particularly with orchids), however, this idea is probably best left to the professionals.

Hand pollination ensures that you have exactly the parents you desire when cross-pollinating. It involves transferring pollen (a yellow or white powdery substance) from the anthers of the male parent onto the receptive stigma of the female parent.

The steps to a cross pollination are as follows:
• If you want to make absolutely sure of your cross it is a good idea to emasculate the flower by cutting off the anthers before pollen is shed. This step is only practical where the anthers are big enough to handle.
• Transfer pollen from the desired male parent to the stigma of the female parent. If the anthers are large enough to handle a whole anther can be removed and rubbed against the stigma. For smaller flowers it is sometimes easiest to take a whole flower and rub it against the stigma of the female parent you wish to pollinate For most species the female part of the flower that receives the pollen will be at its most receptive the second day after the flower opens and it will often be coated in a sticky mucus-like substance that will make it very obvious that it is ready to be pollinated.
• Enclose the flower by tying a piece of nylon stocking over it to protect it from chance pollination by insects or birds and also to ensure that the seed is not lost when the fruit ripens.
• A watchmaker’€™s tag (a small label that has a piece of string attached and available from your local newsagent) can be tied beneath each pollinated flower to enable you to keep track of your work. It is usual to write the name of the female parent first when you do your cross, followed by the male pollen donor plant.
• If the pollination is successful the ovary at the base of the flower will swell up and form into a seed pod.
•Watch carefully for the seed ripening, as immature seed will fail to germinate. Change of colour, the seed hardening, seed beginning to shed are some signs of maturity. The time can vary, some plants take months to ripen. Bagging the seed head with a paper bag can help to catch shedding seed.
• Sow the seed as you normally would when it is ready.
Generally it is best to hand pollinate from mid-morning onwards on a warm sunny day, as this is when pollen is released from flowers that have newly opened. If you brush one of the anthers lightly with your finger it will become coated with fluffy pollen.

The science of genetics is a fascinating subject that can be explored as little or as much as a breeder desires. You can just pollinate away within your chosen genus and let serendipity play a delicious role or be more systematic and try and unravel some of the patterns of inheritance. Look in your local library or on the Internet for more information on genetics and inheritance if you want to pursue a more scientific approach.

Plant breeding is sometimes described as a blend of art and science. Part of the fun of breeding is in assembling your collection from other enthusiasts (there may be a specialist society for your favourite plant), mail order catalogues and seed merchants. To get started, however, I suggest you choose your initial parents from plants that you have known and loved within your chosen genus, put them together and experience the thrill of watching your new hybrids coming up to flower for the very first time.