Comparison of Water Absorption Patterns in Two Barley Cultivars,Using Magnetic Resonance Imaging

Two barley cultivars, Excel and Prisma (six-row and two-row types, respectively), were obtained from the 1993 harvest at Crookston, MN. Magnetic resonance imaging (MRI) was used to follow water imbibition in single, large seeds of Excel and Prisma barley. A comparison of moisture distribution on longitudinal sections of Prisma and Excel barley during early hours of steeping was then made. MRI analysis revealed that the majority of water initially entered the kernel through the kernel surfaces and into the endosperm tissues. Water was observed under the surface of the hull tissues and appeared to be migrating into the aleurone and endosperm tissues. Then water was detected moving from the embryo to the scutellum and then into the crushed cell layers. Aleurone and embryo tissue showed more rapid water uptake and distribution than did scutellar tissue. Some transient water distribution was observed in the scutellum, ventral furrow, and vascular tissues. This indicates that the hydration of surface tissues and crushed cell layers may be significant during the early hours of steeping. During the late hours of steeping, the crushed cell and endosperm cavity region appears to become remarkably active in water transport. Water was distributed throughout the endosperm tissue of the Prisma cultivar more efficiently than in that of the Excel cultivar, although Excel absorbed more water initially.