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Changes in NMR relaxation times in soybean and wheat seeds equilibrated at different temperatures and relative
P Krishnan1, S Nagarajan, A V Moharir
1Division of Agricultural Physics, Indian Agricultural Research Institute, New Delhi 110 012.
Abstract:
The relationship between equilibration injury and equilibration dependence of the transverse relaxation time (T2) measurements was examined using NMR in two different seed species (sensitive-soybean and tolerant-wheat) differing in their sensitivity to seed equilibration conditions. The T2 values of both seed species declined with high temperature (45 degrees C) and low RH (5.5-1%) and, also with high temperature (45 degrees C) and high RH (74.5-100%) conditions. A comparison of injury based on electrolyte leakage, seed germination percentage and T2 indicated that membrane permeability increased both at high temperature (45 degrees C) and low RH (5.5-1%) and high temperature (45 degrees C) and high RH (74.5-100%) seed equilibration conditions. There was an increase in T2 until 11.5% and 5.5% RH in soybean and wheat species respectively, followed by a decline. Loss of seed viability during equilibration at very low RH (5.5-1%) at 45 degrees C, and similarly at high RH (74.5-100%) at 45 degrees C indicates that the changes in T2 are probably due to the loss of membrane injury.
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