Abstract: Studies on the growth, nodulation, N-fixing and seed production of Sesbania rostrata-Azorhizobium caulinodans symbiosis in South China show that the symbiosis could grow and nodulate well in this area. The dry matter production and nitrogen yield of 65 days-old S. rostrata grown in Zhanjiang were 28752 and 681kg·hm^-2, while those of S.cannabina were 16520 and 352kg·hm^-2, respectively. Mixed inoculating A. caulinodans strians AR111 and AR56 to S. rostrata was available in South China, and a 100% appearance of stem nodule was observed. The average number and fresh weight of stem nodules per plant were 182 and 1.2g, respectively, and the biomass of stem nodules accounted for 70% of the total biomass of stem and root nodules. The biomass of root nodules was slightly higher than that of S.cannabina. S. rostrata could normally blossom and bear fruits in South China, and its seed production with a planting population of 4×10⁴ per hectare was 3200kg·hm^-2 .

Key words: Sesbania rostrata, Azorhizobium caulinodans, N-fixing symbiosis, South China, niche, fish, niche differentiation, interspecific association