Aging of soybean [Glycine max] seeds in relation to metabolism at different relative humidities
1995
Zhang, M. (Tohoku Univ., Sendai (Japan). Faculty of Science) | Yoshiyama, M. | Nagashima, T. | Nakagawa, Y. | Yoshioka, T. | Esashi, Y.
The present study was carried out to clarify the relationships between respiration, moisture content and the aging of dry soybean (Glycine max) seeds under different storage conditions. Ethanolic fermentation increased with increasing relative humidity (RH) during storage. However, at 75% RH which corresponded to a water content of 15.2% in seeds, the production of ethanol ceased after one month of storage. The ethanol that had accumulated within in container was re-absorbed by the seeds themselves and disappeared entirely within 3 months, unless the seeds were exposed to HCN gas. Similar changes were also found for methanol. The activity of mitochondria increased only in seeds stored at 75% RH, it reached a maximum after the third month of storage and then rapidly declined. The amounts of both CoA and acetyl CoA in seeds that had been stored for 4 months were far lower at 75% RH than at 53% RH, and the viability of soybean seeds started to decrease after the fourth month at 75% RH. Therefore, a major cause of the rapid deterioration of seeds at 75% RH at room temperature seems to be the rapid development of mitochondrial respiration, which is accompanied by the consumption of CoA and its acetyl derivatives. By contrast, the slow deterioration of seeds during long-term storage at 33% to 68% RH and/or at subzero temperatures seems to be due to the toxic action of acetaldehyde, an intermediate in ethanolic fermentation, which can slowly occur
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