Morimasa Yamasaki

On the Changes in the Resistance to Potassium Chlorate and Reducing Matters Content during the Process of Vernalization in Wheat

The resistances to KClO3 toxicity of slightly germinated wheat seeds were tested after being vernalized at 0°C for 7, 12, 28, 45 and 60 days respectively, comparing with control (nonvernalized ones). Almost always, the resistance increased evidently by vernalization. In spring type and intermediate one, the increments were slight after the short period treatments, though after 28 or more days treatments they became remarkable. In winter type, however, the resistance increased markedly all over the periods of vernalization. Moreover, the increments of the resistances appeared to be greater in winter wheat than in the spring one. The correlations between the resistances and the winter nature intensities in the employed 6 varieties, in which highly negative correlations were observed between those two characters when they were not vernalized, decreased by vernalization, no correlation being recognized for 60 days period which seems to be long enough for vernalizing winter wheat. From these results, the increased resistances are probably related to the flower initiating process by vernalization, as well as to the direct effect of low temperature. Sugars and ascorbic acid contents increased by vernalization. When the vernalized seeds had been transferred to high temperature (15°C), reducing sugar content became less in the vernalized seeds than in the control, sucrose and ascorbic acid content, however, showed no such relation. Reducing sugar and ascorbic acid have been thought to be, related closely to KClO3 resistance, that is, the more those matters a plant contained, the less the resistance. the plant shows. In this study, the reducing sugar showed the above-mentioned relation with KClO3 resistance, but in ascorbic acid content this relation was hardly recognized.