The researchers studied how different levels of fertilizer affected the way young Eucalyptus grandis leaves take in carbon dioxide and release oxygen. They found that higher fertilizer levels increased the leaf's ability to photosynthesize and grow, as well as its water use efficiency. The leaves showed the best photosynthesis rates at 2:00 PM, without a midday slump. The amount of chlorophyll in the leaves also increased with higher fertilizer levels. The temperature, humidity, and sunlight all played a role in how well the leaves could photosynthesize and release water. Overall, adding fertilizer helped the Eucalyptus grandis trees grow better and use water more efficiently.