Abstract
The responses of nodal rooting and partitioning of dry matter between shoot and roots were compared among nine species of summer cereals under waterlogging of short-term (seedling stage) and long-term (from seedling to heading) treatments. The crops used showed a general tendency to increase the number of roots from the main stem under both treatments. On the basis of rooting response to the long-term treatment, the crops were classified into three groups as follows; a crop which decreased the total root number (foxtail millet), crops which slightly decreased the total root number, but increased the root number per main stem (common millet, pearl millet), crops which increased the total root number (rice, finger millet, Job's tears, Japanese barnyard millet, sorghum, maize). The last group was further divided into two subgroups as follows ; crops with tillers (rice, finger millet, Job's tears, Japanese barnyard millet) and crops without tillers (sorghum, maize). The change of the nodal root number was generally associated with the relative changes of dry matter partitioning to roots under waterlogged conditions. The rooting responses to waterlogging of the summer cereals were discussed in relation to their waterlogging tolerances evaluated on the basis of the changes in dry matter production and transpiration coefficient under waterlogged conditions examined in the previous study8).
