Selective breeding of crops has been a tool of agriculture for thousands of years. Simply trying to breed plants to combine desired traits was and still is an important part of bringing about crops that yield more, stand better, or resist pests and disease more effectively. We farm many types of soils on our farm. Much of what we work with is good, dark soil or clay ground. But here in Indiana once we drive a few miles and get up to our rented ground North of US 24 soils change. Sandy soils enter the equation. When we select the corn or soybeans varieties we want to grow each year we may not choose the same seeds to grow at home in the black soil as we would in the sandy soils. On black ground I may want what farmers and seed sales people call a racehorse variety. This is a plant that will really pour on top end yield in good conditions. But that seed might falter in my sandy soils where it can't get all the nutrients it needs to push the limits. So on that soil I'm going to want a plant that has been bred over time to handle heat and drought stress it is sure to encounter on the sand hills. That racehorse will likely run out of steam in those conditions. The hardier plant might not have the high yield potential of the racehorse, but if it gets me a decent yield in tough conditions that is often better for my bottom line. There are many qualities plants can be bred for depending on the environment and location being farmed.
One of the most notable instances of selective breeding comes from Dr. Gibesa Ejeta of Purdue University. A native of Ethiopia, Dr. Ejeta won the World Food Prize in 2009 for his work with sorghum. He was able to create hybrid sorghum varieties to resist both drought and the parasitic weed striga which greatly affects the yield of a sorghum crop in his home country. These breeding advancements greatly increased food security in a part of the world where it was very much needed.