Ontogenetic changes of the water status and accumulated soluble compounds in growing cherry fruits studied by NMR imaging

Ontogenetic changes of water status and accumulated soluble compounds in growing cherry fruits were examined by 1H NMR imaging, 1H NMR localized spectral imaging and 13C NMR spectroscopy. Water status was contradictory between the seed and pericarp of the fruit in relation to growth stages. There was a large amount of high-mobility water present in the seed, whereas only a small amount was present in the pericarp during the early growth stages. The diffusion coefficient of seed water was determined as 2.1×10-5 cm2 s-1 at the maximum, which corresponded to that of pure water (2.14×10-5 cm2 s-1 at 25±1°C). Water in the seed decreased in amount and mobility whereas that in the pericarp increased with maturation. The diffusion coefficient of pericarp water increased from 1.0×10-5 to 1.6×10-5 cm2 s-1 as the fruit ripened. Sugars accumulated in the pericarp with increasing water content, but disappeared with further ripening of the fruit. This suggests that over-maturation results in loss of sweetness and firmness. NMR imaging could probe changes in the physiological condition of the fruit with growth stages.