C-4 Plants to Replace Wheat

Thursday, August 10, 2017
By Amanda Sudilovsky ’19 (2017 Cornell Botanic Gardens Intern)

This week in the Climate Change Garden we removed wheat from the project beds and replaced them with weeds common in gardens and agricultural settings. 

Why weeds?

The weeds we planted— Lamb’s Quarters (Chenopodium album) and Pigweed (Amaranthus)—are C4 plants. This name designates a plant’s photosynthetic pathway. C4 plants include sorghum, millet, corn, sugarcane, and other grasses, which make up about 3% of all vascular plants. We planted C4 plants to show how well they adapt to heat and drought.  All other plants in the Climate Change Garden are C3 plants. Under the climate conditions of 2050, it is expected that C4 plants will be more successful than C3 plants, which include beans, wheat, and trees.

Why are C4 plants expected to be more successful than C3 plants?

When temperatures increase, plants close their stomata (pores) to reduce water loss. Closing stomata prevents gas exchange from occurring, which is necessary for plants to produce energy in the form of sugar, or photosynthesis.  When this occurs, C3 plants are only able to fix oxygen stored in the plant instead of carbon dioxide, which prevents the plant from producing sugar. However, C4 plants are still able to perform photosynthesis when their stomata are closed because they store carbon dioxide in special cells in their leaves.

Why is this significant?

Because C4 plants are able to perform photosynthesis under warmer conditions than C3 plants, it is expected that C4 plants may grow larger and faster, yield more seed, and produce multiple generations per season. There is the potential for these weeds to crowd out C3 plants if they are more successful under the climate conditions of 2050, harming the balance of biodiversity.

Image above: Lamb’s Quarters (left) and Pigweed (right) are examples of C4 plants that we feature in the Climate Change Garden.