WATER AND LIPIDS IN MAIZE SEED EMBRYOS - A PROTON NMR RELAXATION AND DIFFUSION STUDY

The proton NMR spin-spin relaxation time (T2) of water fractions in maize embryos was measured in seeds kept at six different relative humidities (0-65%), i.e. at relatively dry conditions. Three T2 components were found: T2a almost-equal-to 7 mus (macromolecules and closely bound water), T2b = 15-120 mus (water protons at different humidities) and T2c = 100-200 ms (triglycerides). Germination tests indicated that those water fractions with the shortest T2 values were essential for maintaining seed viability. Measurement of the self-diffusion coefficient D of oil in maize seed embryos using a pulsed gradient spin-echo (PGSE) NMR method revealed the effect of restricted diffusion of oil and indicated that triglycerides are mainly located within the oil bodies of embryos.