Differences between Korean and other Annual Lespedezas in Root Nodule Formation 1

In 1928 and 1929 examinations of roots of cultivated annual lespedezas showed that Korean plants (L. stipulacea) bore fewer root nodules than did common, Tennessee 76, and Kobe varieties (L. striata) growing in adjacent rows. This difference in nodulation behavior is of peculiar interest since all of these belong to the same genus and might be expected to utilize the same kind of bacteria in the nodulation process. Hence, experiments were undertaken on Norfolk sandy loam soil at Auburn, Ala., to determine differences in nodulation among the annual lespedezas mentioned above. At frequent intervals, counts were made of nodules on the roots of large numbers of plants that had been carefully dug from several locations in each plat. In one series of five experiments only 10% of Korean lespedeza plants had developed even one nodule per plant by the twelfth day after emergence, in contrast with 71% of nodule-bearing plants of the common lespedeza. The latter required only 13 days to reach a stage in which 85% of the seedlings bore one nodule or more against more than 52 days for Korean, common, Tennessee 76, and Kobe, all of which belong to the same species, formed root nodules at approximately the same rate.