Wheat Viability at High Moisture Content under Hermetic and Aerobic Storage Conditions

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Abstract
Wheat seeds (Triticum durum) were stored under both hermetic and aerobic conditions at 25 °C with moisture contents from 15 to 33 per cent. Under hermetic storage, seeds lost viability more rapidly the higher the moisture content, whereas in aerobic storage, seed longevity was enhanced as the moisture content was increased from 24 to 31 per cent, and over this range of moisture content the seeds survived longer under aerobic than hermetic storage. On the contrary, an apparent reversal of this trend occurred when moisture content was increased above 31 per cent. The possibility that the changes in longevity occurring at higher moisture contents might be due to the activation of seed metabolism was supported by the enhanced incorporation of [3H]leucine into TCA insoluble material (indicating increased protein synthesis) and the reduced leakage of glucose (indicating increased membrane restitution) when seeds were allowed to achieve higher moisture contents during the prehydration period. The highest level of seed activation was found in seeds preconditioned to about 31 per cent moisture content. Moreover, these seeds, when subsequently stored under aerobic conditions, maintained a higher rate of protein synthesis and lower membrane permeability during the storage period than seeds at lower water contents. It is suggested that seeds stored at a sufficient hydration level in the presence of oxygen can sustain an effective metabolism during extended storage, thus permitting the repair of cellular damage. However, it might be possible that at about 33 per cent moisture content seed could suffer from an excessive advancement of metabolism.