抄録
Experiments were carried out in order to determine maximum and optimum temperature as well as thermal death point for rhyzobia. Although the maximum temperature for most of rhizobia lies between 32°and 37℃., yet strains of alfalfa, Sesbania, and one of cowpea bacteria areable to grow at 39°to 42℃. The strains for which 32℃. is maximum are found in those from Indigofera, Styphnolobium, lupine-, soybean-, and cowpea-group, while the strains for which 37℃. is maximum are those from Mimosa, Leucoena, Dalea, and Vicia(nipponica), and some of pea-, clover-, and bean-group. The maximum temperature for fast-growers from pea-, clover-, and bean-group are somewhat higher than those for slow growers from lupine-, soybean-, and cowpea-group. The grouping of strains seems to be possible, depending upon maximum temperature, in each of Sesbania, alfalfa-, soybean-, and cowpea-group, respectively. The optimum temperature for alfalfa-, and Sesbania bacteria is about 34℃. The exposure for ten min. at 60℃ or thirty min. at 55℃ is necessary for the complete death of rhizobia, though there are many strains which are killed by the treatment for ten min. at 55°or thirty min. at 50℃.
