Abstract
For the purpose of finding the role of roots on the aerial parts, tobacco plant of about ten varieties were water cultured. Respiratory rate and morphology of roots were investigated with reference to leaf weight. The results obtained were as follows. 1. A close positive correlation between leaf weight and root activity expressed by means of respiratory rate of whole roots was found to exist at the maximum growing stage. 2. The positive correlation between leaf weight and root number was indicated by both of the fine and thick roots at the maximum growing stage, the coefficient in the former, however, was higher than in the latter. At the flowering stage, the correlation between leaf weight and thick root number was insignificant. 3. Close relationship between the weight of leaves and roots was observed at the maximum growing stage. In this case, the correlation between the weight of leaves and fine roots was larger than that of thick ones. At the flowering stage, there could be found a significant relationship between the weight of leaves and those of the thick and fine roots. At the maturing stage, however, the correlation existed only between the weight of leaves and thick roots. From the results obtained, it can be concluded that the correlation between leaf weight and the physoilogical and morphological characteristics of tobacco roots is highest at the maximum growing stage.
