Controlled conditions refer to a specific environment where variables are regulated to ensure consistent results in experiments or observations. This setup is crucial in scientific research, allowing researchers to isolate the effects of one variable while minimizing the influence of others. For example, in a laboratory, temperature, humidity, and light can be carefully adjusted to create a stable setting for testing. In agriculture, controlled conditions can be found in greenhouses, where factors like soil quality, water supply, and pest control are managed. This approach helps optimize plant growth and yield, making it easier to study the effects of different treatments or conditions on crops like tomatoes or lettuce.