Using H-1 magnetic resonance imaging and complementary analytical techniques to characterize developmental changes in the Zantedeschia Spreng. tuber

Nuclear magnetic resonance imaging (MRI) and complementary analytical techn iques were used to examine tissue structure and developmental changes occur ring during active growth in the root tuber of Zantedeschia Spreng, cv, Chi anti, a commercially significant cut flower. Plants were observed during th e period of leaf senescence and tuberization at the end of the first growth cycle of micropropagated plantlets and, following cool storage to break en dodormancy, during development occurring after the replanting of ecodormant tubers. MRI distinguished two distinct regions within the tuber, and the d ifferences in the binding state of water in the two regions were reflected in differences in tissue morphology and function. An abundance of free wate r was observed in tissue comprised of large parenchyma cells, at the base o f the tuber. This tissue appeared to be involved in maintaining the viabili ty of the plant during the period of dormancy, a function indicated primari ly by increased metabolic activity in this tissue during dormancy, and redu ced metabolic activity during periods of active growth, In contrast, water was more tightly bound in tissue comprised of small parenchyma cells. This tissue appeared to operate as a region for dynamic carbohydrate storage. Th e initial increase in the free water content of this tissue during the grow th phase was linked to the mobilization of starch during canopy development . The subsequent decrease in free water in the remainder of the growth peri od was linked to the reaccumulation of starch while the tuber functioned as a sink for photosynthate prior to canopy senescence.