Why is hybrid plant breeding beneficial and when is it used over traditional methods?
Submitted by: jakia
Expert response from Kent Bradford
Director, Seed Biotechnology Center, UC Davis
Friday, 06/19/2015 14:25
In general, hybrid varieties will be better for almost all situations. They have more uniform growth and higher yields due to hybrid vigor (or heterosis), which means they are also often more broadly adapted to diverse environments. In developed countries, hybrids are dominant in all crops where the seed can be produced economically. Since hybrid seeds must be produced by the controlled crossing of two inbred parents, the pollination mechanism of the species must be adaptable to this. In maize, for example, the male (tassels) and female (ears) flowers are distinct on the plant and it is easy to remove the tassels from female plants to ensure that the pollen comes only from the male plants and the resulting hybrid seed is harvested only from the female plants. In other crops, such as tomato or peppers, the hybrids are made by hand-pollination, as the value of the seeds can justify that investment in labor. In other crops that normally self-pollinate (e.g., wheat, beans), it is difficult to accomplish large-scale crossing, and the low seed yield per cross makes hand-crossing uneconomical, so hybrid varieties are not available in those species.
The only situations where nonhybrid (or open-pollinated) seeds would be more desirable would be where it is intended for farmers to save seed for replanting. As the hybrids are first-generation crosses, in the next generation, the traits of the two parents will segregate, the next generation will not be uniform and much of the benefit will be lost. Hybrid seed production requires special methods, and thus farmers must buy seed each year, the cost of which the higher yields more than compensate for. Another situation where open-pollinated varieties might be preferred is when uniform maturation is not an advantage, as when a small farmer would want to harvest over a period of time to extend the marketing period. However, this requires that the farmer walk the entire field each time to select the fruits that are ripe at a particular time, an inefficient process. So, even here, it would be better to plant a smaller area with hybrid seeds each week and then harvest those more uniform plots sequentially, rather than rely on the lack of uniformity of open-pollinated varieties to spread out the harvest period.
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