The study looked at how different forms of nitrogen affect the uptake and distribution of nutrients in maize seedlings. They found that increasing nitrate concentration led to a decrease in uptake rate, while ammonium and glutamate increased the amount of nitrate needed for uptake. Nitrite and glutamate inhibited nitrate reductase activity in roots, while ammonium stimulated it. The researchers suggest that negative feedback effects on nitrate assimilation come from the shoot, not the roots. Overall, the results show that the uptake of nitrate in maize seedlings is influenced by the type of nitrogen present in the environment.