caa a22 4500 477110703 CHVBK 20180405111608.0 cr unu---uuuuu 170330e19960901xx s 000 0 eng 10.1007/BF00035065 doi (NATIONALLICENCE)springer-10.1007/BF00035065 Enhanced competitiveness of a Bradyrhizobium japonicum mutant strain improved for nodulation and nitrogen fixation [Elektronische Daten] [L. Kuykendall, F. Hashem, W. Hunter] Bradyrhizobium japonicum strain TA-11NOD+, with altered indole biosynthesis, exhibited enhanced nodulation and nitrogen fixation on soybean in previous greenhouse studies. In this study, field experiments were conducted at Upper Marlboro, Maryland, in the summers of 1988 and 1993. In 1988, the site used was essentially free of soybean-nodulating bacteria and seed yield in plots inoculated with either I-110ARS or TA-11NOD+ was significantly higher by 12 or 20%, respectively, than that of the uninoculated controls. The 1993 site had an indigenous soil population (about 104 cells g-1) of symbiotically ineffective soybean-nodulating bacteria. Nevertheless, six-week-old ‘Morgan' soybean plants inoculated with strain TA-11NOD+ had 44% more nodules and exhibited 50% more nitrogen fixation by acetylene reduction when compared with plants that received the parental strain I-110ARS. Nodule occupancy, as determined using genetic markers for rifampicin and streptomycin resistance, was significantly higher for strain TA-11NOD+ than for strain I-110ARS. Overall, for the two years and the two soybean genotypes, the yield obtained with TA-11NOD+ was 6% higher than that obtained with I-110ARS. Competition experiments were conducted in the greenhouse and strain TA-11NOD+ was significantly more competitive than strain I-110ARS in competition with strains USDA 6 or USDA 438. Kluwer Academic Publishers, 1996 competitiveness nationallicence inoculant nationallicence nitrogen fixation nationallicence nodulation nationallicence soybean nationallicence yield nationallicence Kuykendall L. Soybean and Alfalfa Research Laboratory, USDA-ARS, 103000 Baltimore Avenue, 20705-2350, Beltsville, MD, USA aut Hashem F. Soybean and Alfalfa Research Laboratory, USDA-ARS, 103000 Baltimore Avenue, 20705-2350, Beltsville, MD, USA aut Hunter W. Soil-Plant Nutrient Research Unit, USDA-ARS, 1701 Center Avenue, 80526-2083, Fort Collins, CO, USA aut Plant and Soil Kluwer Academic Publishers; http://www.wkap.nl 186/1(1996-09-01), 121-125 0032-079X 186:1<121 1996 186 11104 https://doi.org/10.1007/BF00035065 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00035065 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kuykendall L. Soybean and Alfalfa Research Laboratory, USDA-ARS, 103000 Baltimore Avenue, 20705-2350, Beltsville, MD, USA aut NATIONALLICENCE 700 1- Hashem F. Soybean and Alfalfa Research Laboratory, USDA-ARS, 103000 Baltimore Avenue, 20705-2350, Beltsville, MD, USA aut NATIONALLICENCE 700 1- Hunter W. Soil-Plant Nutrient Research Unit, USDA-ARS, 1701 Center Avenue, 80526-2083, Fort Collins, CO, USA aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; http://www.wkap.nl/ 186/1(1996-09-01), 121-125 0032-079X 186:1<121 1996 186 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer