Morphological structure and water status in bulbs during their transition from dormancy to active growth: Visualization by NMR imaging Rina Kamenetsky Hanita Zemah Annette van der Toorn Haim D. Rabinowitch Henk van As Peter Bendel accepted by J. exp. Bot.

Tulip bulbs (Tulipa gesneriana L.) World wide use of tulip as ornamental plant Needs a cold period during dormancy to facilitate normal development and flowering Fundamental knowledge about bulb dormancy and growth is limited

Purpose of the project: To determine if significant differences in water status between bulbs stored at 4 o C and at 20 o C can be observed using MRI. Mainly using: Visible morphological changes in the images Proton density determination R 2 measurements (1/T 2 ) ADC measurements (reflecting proton mobility) R 1 measurements (1/T 1 )

scales bud basal plate 1 cm Morphological MR image of tulip bulb Resolution 350 x 350 x 700  m

e Single parameter images of the tulip bulb Amp of R1Amp of R2Amp of ADC R1 imageR2 imageADC image

o C4 o C 20 o C amplitude R2 start 2 weeks 4 weeks 8 weeks 12weeks Time- dependent change in amplitude for two bulbs Time- dependent change in R 2 for two bulbs

Planted bulbs (10 days after planting) 4 o C20 o C

Conclusions MR parameters such as R 2 and ADC can be used to observe differences between chilled and non-chilled bulbs MRI needs to be combined with histology to understand the observed changes in water status The majority of changes in water status take place between 2 and 8 weeks after storage