栽培温度がダイズの生育および感染ダイズ根粒菌の群集構造に及ぼす影響

We investigated the growth of soybean (Glycine max (L.) Merr.) under different cultivation temperature conditions, and the inoculation effect of useful bradyrhizobial strain and the community structure of infected soybean-nodulating bradyrhizobia to elucidate the effects of climate change on crop production due to global warming. “Orihime,” “Bonminori,” and “Fukuyutaka” were used as the test soybean cultivars, and Bradyrhizobium diazoefficiens USDA110T was used as the test strain. The soybean was grown in a temperature-gradient chamber with low-temperature zone, middle-temperature zone, and high-temperature zone. The results of cultivation test under different temperature conditions showed that inoculation with USDA110 significantly increased plant height, number of nodes, stem and leaf dry weight, the number of pods, pod dry weight, total plant dry weight, and number of nodules. However, all investigation items, except for the number of nodules were significantly reduced with increasing cultivation temperature. Correlation coefficients were significantly positive in many combinations, including the relationship between the number of nodules and stem and leaf dry weight. The occupancy of USDA110 was dominated by inoculated USDA110 in all cultivation temperature zones. However, the occupancy tended to decrease with an increase in cultivation temperature when comparing low- and middle-temperature zones and low- and high-temperature zones. These results suggest that the decreased number of nodules under high-temperature conditions inhibited soybean growth, reducing the growth and yield of soybean. However, the reduction of soybean productivity due to the increase in cultivation temperature may be reduced by ensuring the number of nodules and occupancy of B. diazoefficiens USDA110T．