Abstract
To clarify physiological and ecological characteristics of red-kerneled rice, a comparative study was made with 25 cultivars on their low temperature adaptability, which was estimated with germinability, chlorosis and characteristics of seedlings under low temperatures. The results obtained are summarized as follows: Germinability of the red-kerneled type at low temperatures was higher than that of the white-kerneled type in japonica. In indica, a difference between red-kerneled and white-kerneled type was not detected (Fig. 1). The red-kerneled and the white-kerneled type showed a similar degree of low temperature-induced chlorosis. However, indica was more susceptible to the chlorosis than japonica (Fig. 2). Low temperature growth-ability in seedling height, root length, root number and fresh weight was obtained from the results of seedlings grown at 15 and 25°C. In both ecospecies a significant difference between the red-kerneled and the white-kerneled types was observed in seedling height, root number and fresh weight. The red-kerneled type tends to be higher in root length than the white-kerneled, although the difference was not significant. Growth inhibition caused by low temperatures was exhibited more strongly in seedling height than in root length and root number (Table 1). Low temperature germinability was not closely related to low temperature-induced chlorosis (Fig. 3). Moreover, the germinability was significantly correlated with low temperature growth-ability in seedling height, but not with that of other seedling characteristics (Fig. 4). These results suggested that higher adaptability under low temperatures was not peculiar to red-kerneled rice.
