Plant breeding is the process of developing a new variety, or cultivar, of a crop plant that better satisfy our needs. At the dawn of agriculture, improvement of plants was obtained by simply selecting better types from “wild” plant populations
Plant breeding is the process of developing a new variety, or cultivar, of a crop plant that better satisfy our needs. At the dawn of agriculture, improvement of plants was obtained by simply selecting better types from “wild” plant populations that grew in the area.
The objectives were simple: select plants that provide increased food value.
This can be related to larger seeds or fruits, or it might have been grain that did not fall from the seed spike making collection of a hand full of grain more efficient, or just tasted better.
As a reference on how long this improvement has been going on, agriculture or the deliberate cultivation of plants and animals is thought to have begun more than 10,000 ago. During this time, humans have consistently improved the plants they grew to better serve their needs.
Since the 20th century, plant breeding also has been an area of scientific investigation, where careful studies on the inheritance of particular genetic characteristics made it possible to predict the appearance of the character. It also led to the explanation of why certain characteristics appeared in one generation and not the next, only to appear in the following generation.
The study of inheritance made it possible to deliberately track individual characteristics such as flower color or disease resistance. It also made possible the efficient combining of several desirable characteristics into a single plant.
A backyard breeding program or project should begin with the setting of objectives. This should simply state what you want to accomplish. The objectives can be as simple as wanting yellow fruit versus red, large versus small, or much more involved such as combining this characteristic and that characteristic within a single new cultivar.
Your objective(s) also should be practical and achievable. You should not expect yellow flesh tomatoes if all of the plants you are working with are red. Unless natural mutations occur, new characteristics do not just appear.
The simplest method of plant breeding is the selection of better plants from a population you are growing.
In any population of crop plants, variability exists where selection can create a more uniform and/or better adapted variety.
For example, growing pumpkins from seeds someone gave you, you find different flesh color, shapes and sizes of fruit from the many plants growing in the garden. Those you find desirable are the ones about 7-8 inches in diameter, have thick dark orange flesh, and a flatten sphere fruit shape with slight ribbing.
Therefore, you select seeds from fruits that have those desirable characteristics and replant them in your garden. Again, select those that have the desired characteristics.
After a number of generations, you will start to see that many of the pumpkin fruits will be of the type you desire. It is in this fashion the many of the heirloom varieties we know and grow today arose.
In many cases, the desire of would-be backyard plant breeders is to combine the desirable characteristics from this variety with the desirable characteristics of another, creating a new variety that is better or best.
In plant breeding or gardening in general, what is best is a transient goal, which is highly dependent on what needs it needs to satisfy. Should a new pest or disease arrive in your area, the need for host plant resistance increases.
Hybridizing two plants will combing the desired characteristics into a single line. The plant breeding task is to stabilize the characteristics into a single non-segregating line by a series of selection.
Once the characteristics are stabilized in to a true breeding population, a new variety has been created. In this way, cultivars become the accumulation of many desirable characteristic that are represented in many of the modern varieties we grow today.
As you can see, plant breeding is a long term commitment that can extend into many years, depending on the generational time for each generation. A seed to seed generation in bush beans would be 80–100 days, while crops such as carrots could be 18 months or more.
While most of us consider the time to the crop’s harvest maturity, in plant breeding you also must take into consider the time it will take to flower and bear seeds.
And remember, once you develop your new variety — the one that only you have — you need to develop a plan to maintain this precious creation.
Share it with your friends to grow and store. See if they like it. If you maintain all of the seeds in one refrigerator or at one location, it all can be lost by a single catastrophic event and your creation will be lost forever.
Unless you practice good seed production protocols, your variety can be susceptible to genetic drift, which is the change in average value for all characteristics within your variety. The largest contributor to genetic drift is small plant population size when growing out your seeds generation after generation.
Think about the pumpkin example, how did we create that new variety? But on the other hand, this also is how one variety can become many new varieties with time.
For more information about this and other gardening topics, please visit the CTAHR electronic publication website at http://www.ctahr.hawaii.edu/Site/Info.aspx or visit any of the local Cooperative Extension Service offices around the island. I can be reached at russelln@hawaii.edu.
