Final answer:
Water availability has not been observed to have an effect on cannabinoid content in hemp plants, while temperature, light intensity, and soil pH can impact cannabinoid content.
Step-by-step explanation:
The factor that has not been observed to have an effect on cannabinoid content in hemp plants is water availability.
Temperature can affect cannabinoid content in hemp plants. For example, lower temperatures can increase THC levels.
Light intensity can also affect cannabinoid content. Higher light intensity can lead to higher THC levels.
Soil pH is another factor that can impact cannabinoid content. For example, a more acidic soil pH can result in higher THC levels.