Visualization of morphological structure and water status during storage of Allium aflatunense bulbs by NMR imaging

The effect of cold storage on the developmental morphology and water status in bulb tissues of Allium aflatunense B. Fedtsch. was studied using scanni ng electron microscopy (SEM) and magnetic resonance imaging (MRI). Morpholo gical MR images were produced by a T-1-weighted spin echo pulse sequence. W ater status was assessed according to the ratio between two images acquired at two different echo times (4 and 25 ms) from which an apparent T-2 value was calculated. A significant decrease in T-2 in both vernalized and non-v ernalized bulbs was observed after 4 months in storage. This effect may be associated with a reduction in water mobility in stored bulbs. At the end o f the storage period, the apparent T-2 values in the basal plate were signi ficantly lower in vernalized than non-vernalized bulbs. Intrabulb floral de velopment was similar in both vernalized and non-vernalized bulbs, but scap e elongation and actual bloom occurred only in the vernalized plants. Chang es in intrabulb development and water status during storage cannot by thems elves provide a valid explanation for the significant differences between v ernalized and non-vernalized bulbs during the growth stage. The possible ro le of the basal plate is discussed. (C) 1999 Published by Elsevier Science Ireland Ltd. All rights reserved.