Question

However, when experimentally raising CO2 concentrations to anticipated AD 2050 levels, while at the same time exposing plants to the increased drought conditions expected by mid-century due to climate change, Dr. Ainsworth is finding a sharp reduction in photosynthetic rate, resulting in reduced growth rate, and predicted loss of food production in crop plants as the climate and atmospheric CO2 concentrations continue to change. What is a likely explanation for this observation?

Answer 1

The reduced photosynthetic rate and growth rate in plants exposed to increased CO2 concentrations and drought conditions is likely due to stomatal closure, which limits carbon dioxide availability for photosynthesis. High concentrations of CO2 can also signal plants to reduce the number of stomata, further restricting carbon dioxide uptake. This combination of factors ultimately results in a decline in photosynthesis and growth in plants.

Step-by-step explanation:

A likely explanation for the observation of a reduced photosynthetic rate and growth rate in plants exposed to increased CO2 concentrations and drought conditions is the effect of stomatal closure. Stomata are tiny pores on the surface of leaves that allow gases, including carbon dioxide, to enter and exit the plant. In response to drought, plants generally close their stomata to reduce water loss, which also limits the amount of carbon dioxide available for photosynthesis. Additionally, high concentrations of CO2 can act as a signal to the plant to reduce the number of stomata, further restricting carbon dioxide uptake and photosynthetic activity. Therefore, the combination of increased CO2 and drought stress can lead to a reduction in photosynthesis and growth in plants.