Characterizing chilling responses for tulip bulbs by ¹H-NMR imaging in relation to metabolic activity

The physical state of water and metabolic activity in tulip bulbs held at low temperatures were observed using ¹H-NMR imaging and TNBT staining. A strong water signal was observed in cortex parenchyma for bulb scales held at 15°C for 3 weeks, followed by storage at 5°C for 8 weeks, while a weak water signal was recorded in non-chilled bulb scales. Signal intensity and NMR longitudinal relaxation time (T1) for tulip bulbs reflected differences in the degree of water binding and metabolic activity between chilled and non-chilled bulbs.