Scientists and famers can manipulate the growing conditions crops to produce the optimum quality and yield. In the Netherlands, massive greenhouses are used to grow peppers in constant light conditions, enabling farmers to reduce the growing season by four weeks. Carbon dioxide levels on Earth have in the past been much higher. Plants evolved the capacity to use higher levels of carbon dioxide, but under modern conditions, the rate of their photosynthesis is limited. Waste carbon dioxide can be directed into greenhouses growing tomatoes. This extra carbon dioxide enables the tomatoes to photosynthesise faster, which increases sugar production, improving flavour and yield.
Students can do practical work looking at the effect of changing light intensity or carbon dioxide concentration on the rate of photosynthesis. Students could also look into the impact of commercial plant cultivation on the environment. The balance between improving yield, the use of fossil fuels to generate light and the use of fertilisers could be discussed in terms of costs and benefits to people and the environment.