Abstract
In order to know whether the content of polyphenolic substances which were related to the tubers of Chinese yam were connected with respiration, the changes of respiration with the tuber development were observed. It was also observed how much the MH-spraying on the leaves effected on the respiration and the content of polyphenolic substances in tubers.
The results were summarized as follows:
1) The respiration in the top of tuber was markedly higher from middle July to middle August when the tubers were rapidly growing. After that, the period from late August to early September, the respiratory activity tended to down slowly. The content of polyphenolic substances changed in parallel with that in the respiratoryrate. This indicates that when the growth is in full swing, the respiratory rate is also in full swing, so that the polyphenol in the tuber may increase in content.
2) The foliar application with 0.1, 0.3 and 0.5% solution of MH (maleic hydrazide) resulted in the decrease the respirations of the tuber, and the content of polyphenolic substances in the tubers also decreased. Moreover, the increase of polyphenolic contents in the digged tuber was suppressed by the MH application. It was also observed that R. Q. in respiration of non-treated tubers decreased, to the contrary, the one on treated tuburs increased.
3) From the results above mentioned, it was considered that in the practical use on sand dune field, the MH application to the leaves of Chinese yam could suppress the browning, which was one of the most important deteriorations on Chinese yam.
