Initially, they studied the rice plants root growth in response to white light and total darkness. Over five days, one batch of excised rice stems was grown in a light environment and another was grown in a dark environment. At the end of the growth period, the stems that had grown in the dark had sprouted roots, while the stems grown in the light did not. The root angle of the dark grown stems stayed consistent throughout the time period at an average of 119°, and the roots grew at a consistent rate. This experiment showed that darkness is a stimulus for the plant to increase root penetration in order to find more nutrients, which is how the plants know when to grow adventitious roots underwater. When full plants were grown in light and dark while submerged, the plants grown in the light grew adventitious roots.
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