Longitudinal NMR parameter measurements of Japanese pear fruit during the growing process using a mobile magnetic resonance imaging system.

Longitudinal nuclear magnetic resonance (NMR) parameter measurements of Japanese pear fruit (Pyrus pyrifolia Nakai, Kosui) were performed using an electrically mobile magnetic resonance imaging (MRI) system with a 0.2 T and 16 cm gap permanent magnet. To measure the relaxation times and apparent diffusion coefficients of the pear fruit in relation to their weight, seven pear fruits were harvested almost every week during the cell enlargement period and measured in a research orchard. To evaluate the in situ relaxation times, six pear fruits were longitudinally measured for about two months during the same period. The measurements for the harvested samples showed good agreement with the in situ measurements. From the measurements of the harvested samples, it is clear that the relaxation rates of the pear fruits linearly change with the inverse of the linear dimension of the fruits, demonstrating that the relaxation mechanism is a surface relaxation. We therefore conclude that the mobile MRI system is a useful device for measuring the NMR parameters of outdoor living plants.