AGRONOMIC NEWS ITEMS
From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335
Fall 1997, No. 4
FEEDING THE GENETICALLY ENGINEERED CROP
The tools of genetic engineering and molecular biology are modifying the abilities of plants at a pace many times faster than with traditional plant breeding. As in the Human Genome Project, plant genome research is underway to construct a complete map of the DNA of wheat and rice, and soon will begin on corn. Genetic engineering is being put to use to produce a wide variety of new plant cultivars...
The market is witnessing the introduction of many new types of the old species of crops. In the first types, the changes are small, with resistance to a specific disease, pest or herbicide. Soon, we can expect cloned genes for yield, stress tolerance, and nutritional quality.
- An alfalfa line that produces a vaccine for a common swine virus.
- Canola with less glucosinolate and phytate, and more protein and oil.
- Corn, with genes from a soil bacterium, that produces a protein which kills the larvae of the corn borer insect pest.
- Herbicide tolerant soybean and canola.
- Papaya with a bacterial citrate synthase gene that confers tolerance to low pH soils with high aluminum.
- Tomato with four times the normal levels of beta-carotene and twice the levels of lycopene that could possibly help prevent heart disease and cancer.
- Transgenic wheat with herbicide resistance.
How will nutrient management for genetically altered plants differ from what we are practicing today? The answer will depend, of course, on the specific changes in crop cultivars. But there are a few unchanging principles to keep in mind.
1. Genetics controls a plant variety's potential, but the expression of that potential depends on many other factors, soil fertility being one of the important ones.
2. Genetic engineering will increase the range of uses for crop products and increase the total value of crops grown. The importance of attaining maximum economic yield of each crop will increase likewise.
3. Genetics, conventional or biotech, does not alter the laws of chemistry and physics. While genetics can be used to enhance the plant's ability to scavenge nutrients with limited soil availability, the yield potential will always be higher when plants are supplied with levels of nutrients that do not require them to expend excessive energy on nutrient acquisition.
4. Fertility management should complement the choice of genetics. For example, the use of Bt corn prevents stalk damage by insects, allowing later harvest at lower drying cost. Don't let stalk rot frustrate this strategy...supply sufficient potassium and chloride to strengthen the stalk and reduce disease. In one potassium response trial in Canada, a Bt hybrid has already shown more potassium deficiency symptoms than several other hybrids.
Sunlight, water and nutrients remain the major factors limiting crop yields. Genetic engineering will improve the ability of plants to utilize all three, for higher and more stable yields of better quality products. Transgenic crops will need as much nurturing as traditional ones, if not more.
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For more information, contact Dr. Tom W. Bruulsema, Director, Eastern Canada and Northeast U.S. PPI, 18 Maplewood Drive, Guelph, Ontario N1G 1L8, Canada. Phone (519) 821-5519. E-mail: firstname.lastname@example.org.
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