LOSS OF WATERCORE FROM FUJI APPLE OBSERVED BY MAGNETIC-RESONANCE-IMAGING

Watercore is a physiological disorder affecting apples in which interc ellular spaces are filled with liquid. Proton magnetic resonance imagi ng (H-1-MRT) was used to investigate its postharvest amelioration in ' Fuji' apple (Mabs domestica Borkh.)-a cultivar where spatial distribut ion of affected tissue is manifest in two distinct forms (block and ra dial watercore), and curing leads to fruit of normal appearance and ta ste. Badly-affected fruit were identified by imaging after harvest in each of two seasons, and in one season, the two forms were compared. A semi-quantitative analysis of the curing dynamics, and a description of the spatial clearing in parenchyma tissue was obtained based upon s erial analysis of 2-dimensional multi-slice images (echo time (T-E) = 40 ms; repetition time (T-R) = 1000 ms) and volume rendering of 3-dime nsional (3D) data arrays acquired from individual fruit during storage (20 weeks, 0 degrees C). Results indicated that the proportion of wat ercore-affected tissue decreased linearly with time, irrespective of d isorder pattern. However, the length of time taken for symptoms to dis appear depended on the severity of the disorder at harvest. Percent wa ter-soaked tissue was greatest in central image slices and least in sl ices nearest the surface in both transverse and longitudinal sections. The distribution of affected tissue between basal and distal hemisphe res of the fruit was season-dependent. A basic spin-echo pulse sequenc e was sufficient to exploit relaxation differences between tissues in 3D data arrays. Differentiating between saturated tissue as opposed to unaffected tissue (T-E = 20 ms; T-R = 200 ms), or saturated vs. vascu lar tissue (T-E = 5 ms; T-R = 150 ms) was achieved by altering T-E and T-R. By reconstructing images with equivalent fields-of-view from wit hin these arrays it was possible to explore relationships between vasc ular tissue and watercore-affected areas in 3D space. (C) 1998 Elsevie r Science B.V.