Presumptive diagnosis of dwarfed Japanese pear by using a mobile magnetic resonance imaging system

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This study was carried out to focus upon the water relation of branches of Japanese pear with the dwarfed symptom by using the novel mobile MRI (magnetic resonance imaging) system incorporated with the measurement of sap flow, water potential, root activity and so forth. As a marker of MRI, T1, T2, and proton density in the cross sections of the sound and diseased branches, show clearly the high density of mobile water protons around the xylem located close to the external surface ofthe branches. In the ADC maps, the diseased branch has no definite high ADC area while the sound branch clearly shows. This difference clearly shows that the water transport function is degraded or destroyed in the diseased branch. A diurnal change of ADC in the branch corresponds clearly the water transport in the pear tree branch which shown in the real sap flow pattern in a whole day. The sap flow shows remarkably lower value in the diseased branch from sprouting until leafing stage than sound branch, but comparable value over leafing stage. From these results, a mobile MRI system will be an available tool of the presumptive diagnosis for dwarf Japanese pear using non destructive measurement.