The article discusses how plants absorb and use nitrogen, an essential nutrient for their growth. Researchers studied various aspects of nitrogen metabolism in plants, such as how they take up nitrate from the soil and transport it within the plant. They also looked at how different forms and concentrations of nitrogen affect plant growth. Key findings include the influence of root temperature on nitrogen uptake, the cycling of amino-nitrogen between shoots and roots, and the translocation of nitrogen in different plant species. Overall, the research sheds light on the complex processes involved in nitrogen metabolism in higher plants.