Overview – The six elements we know as macronutrients, N, P, K, S, Mg and Ca, are each indispensable for growth. Here we examine how macronutrients contribute to plant growth. Specifically, we look at (1) the availability of nutrients in the soil along with the effects of soil microbes and physical properties on their availability; (2) nutrient uptake from the external environment, across plasma membranes and into plant cells; (3) in some cases, the assimilation of the nutrient into organic molecules;
(4) the distribution and redistribution of nutrients throughout the plant; and (5) regulation of these processes. In parallel, we will examine the genetic basis of a plant’s nutrient-use efficiency (NUE), and evaluate strategies by which to replenish nutrients that growing plants extract from soil.
Study / exam questions (understanding and comprehension)
• In a plant, what are the functions of each of the macronutrients?
• A farmer’s wheat was growing slowly so she added NH4NO3. When this didn’t stimulate it to grow faster, she concluded that nutritional deficiency was not the problem. Was this a correct assumption? Why or why not?
• Name four organic molecules (each) that incorporate N, P and S.
• Diagram the global cycle of N, P or S. Indicate places where human activities impact the cycle.