Weeds are plants that compete with the soya bean crop for essential resources such as light, water, and mineral ions from the soil. This competition reduces the growth of the soya beans, leading to a lower yield.
Normally, if a farmer sprays a field with a broad-spectrum herbicide like glyphosate, it would kill both the weeds and the crop plants.
However, the GM soya bean plants have been modified to be resistant to glyphosate. This means the farmer can spray the entire field with glyphosate. The herbicide will kill the competing weeds, but the GM soya bean plants will be unaffected and survive.
By eliminating the competition from weeds, the GM soya bean plants have access to more light, water, and mineral ions. This allows them to grow larger and healthier, resulting in a significantly increased yield of soya beans.
This question requires an explanation of the agricultural advantages of using genetically modified, herbicide-resistant crops.
1. **The Problem of Weeds:** In any agricultural field, crop plants (soya beans) must compete with weeds for limited resources. This includes competition for sunlight (for photosynthesis), water (for photosynthesis and transport), and mineral ions (for making proteins, DNA, etc.). This competition stresses the crop plants, limits their growth, and ultimately reduces the final yield.
2. **The Role of Herbicide:** Herbicides (weedkillers) like glyphosate are designed to kill plants. A standard, non-selective herbicide would kill all plants it contacts, including the soya bean crop, making it useless for weed control in a growing field.
3. **The GM Solution:** Scientists have genetically modified the soya bean plants by inserting a gene that makes them resistant to glyphosate. This means the herbicide does not affect the GM soya bean's metabolism and it can survive being sprayed.
4. **Application and Outcome:** The farmer can plant the GM soya bean seeds and then, once the crop and weeds are growing, spray the entire field with glyphosate. The glyphosate kills the weeds, but the resistant GM soya beans are unharmed.
5. **Increased Yield:** By eliminating the weeds, competition for light, water, and minerals is removed. The GM soya bean plants can therefore absorb the maximum available resources, allowing them to grow more vigorously and produce a higher yield of beans.
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