Assimilates stem storage

Timing during the development cycle is also a critical factor. For example, during the first half of the developmental cycle, photosynthate is partitioned predominantly into stem storage sites (Incoll and Neales, 1970 McLaurin et al., 1999). However, with the onset of tuber bulking, allocation within the plant shifts dramatically. Now a major portion of new assimilate preferentially moves into the rapidly developing tubers, and assimilate previously stored in the stems begins to be recycled to the tubers. 

During initial development, structural growth generally has a higher priority in the hierarchical scheme of photosynthate distribution than stem and tuber storage sites. The relative importance of structural development is illustrated by the fact that after severe defoliation, the stem and leaves have the highest priority for assimilates as the plant reestablishes its carbon fixation intrastructure (Swanton and Cavers, 1989). 

A model of crop growth, development, and yield formation was used to compare Jerusalem artichoke and chicory — the two main agricultural sources of inulin (Meijer et al., 1993). The pattern of assimilation in the two crops was very different. Chicory is a biennial, with only vegetative growth in the first season and dry matter distributed to the storage roots during the second season. A greater fraction of total production is diverted to structural stem matter in Jerusalem artichoke. Most dry matter is allocated to the stem until the reproductive phase of Jerusalem artichoke, mainly in the form of structural stem material, but also as stored carbohydrates. 

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