The number of trials conducted in an experiment can vary depending on a number of factors, such as the complexity of the experiment, the number of variables being tested, and the resources available.
In the case of an experiment on how the color of lights affects plant growth, it would be important to conduct multiple trials in order to increase the reliability and validity of the results. This is because a single trial may not provide a representative sample or may be subject to various sources of error or bias.
Conducting multiple trials allows you to average the results and account for any variability or outliers that may occur in a single trial. It also helps to increase the statistical power of the experiment, which is the ability to detect a significant difference between the treatment groups (in this case, the plants exposed to different colors of light).
To determine the appropriate number of trials for your experiment, you may need to consider factors such as the sample size, the statistical power of the test, and the resources available. You may also want to consult with a statistician or researcher experienced in conducting experiments to help determine the appropriate number of trials for your study.