Jerusalem artichokes growth, development, and field storage. II. Carbon and nutrient element allocation and redistribution

Jerusalem artichokes store carbon predominately in the form of inulin, a functional food of increasing interest due to its dietary health benefits for humans and calorie replacement potential in processed foods. To better understand the developmental and agronomic requirements of this crop, the allocation of C and nutrient elements into individual plant parts (stems, leaves, stolons, tubers, 'seed' tuber, and roots) was monitored at 2-week intervals throughout the entire growth cycle of the cultivar 'Sunchoke' grown on a Cecil sandy clay loam. Accumulation patterns of C and nutrient elements in individual plant parts were generally in accordance to the pattern of dry matter accumulation, though concentration patterns differed. Overall, nutrient element levels in vegetative structures decreased with the onset of rapid tuber development. Leaves had the highest nutrient levels, except iron (Fe) and sodium (Na). The concentrations of nitrogen (N), phosphorus (P), potassium (K), sulfur (S), and copper (Cu) in tubers were greater than in stems. Total N, P, and K concentrations in the stolons were at lower levels and the total calcium (Ca), Fe, and manganese (Mn) at higher levels compared to the tubers. During rapid tuber growth, the concentration of individual phloem-mobile nutrient elements (e.g., N, P, and K) in the leaves and stems decreased progressively due in part to reallocation. In contrast, the concentration of less mobile nutrient elements (e.g., Ca and Mn) in the leaves and stems generally increased due to losses of C and other mobile materials. In the tubers, the concentration of C and most nutrient elements remained fairly constant through the final harvest, indicating carbohydrates and nutrient elements were accumulating at the same rate. Knowledge of C and nutrient element allocation/reallocation in the Jerusalem artichoke is of value for improving fertilization strategies and in identifying critical traits for the selection of new, high yielding cultivars.