INTERACTIONS BETWEEN BRADYRHIZOBIUM JAPONICUM, FORAGE AND ROUND-UP-READY SOYBEAN CULTIVARS.

Authors: HASHEM, FAWZY - UNIV. OF MD, E. SHORE; DADSON, R. - UNIV. OF MD, E. SHORE; GREEN, B. - UNIV. OF MD, E. SHORE; ALLEN, A. - UNIV. OF MD, E. SHORE; JOSHI, J. - UNIV. OF MD, E. SHORE; Devine, Thomas

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 11/2/2002
Publication Date: 11/10/2002
Citation: Hashem, F., Dadson, R.B., Green, B.M., Allen, A.L., Joshi, J., Devine, T.E. 2002. Interactions between Bradyrhizobium japonicum, forage and round-up-ready soybean cultivars [abstract]. American Society of Agronomy Abstracts. [CDROM] S03-Hashem175817-poster.

Interpretive Summary:

Technical Abstract: Soybean growth in the Delmarva region is often limited by the competitiveness of Bradyrhizobium japonicum inoculates to compete with the mediocre microbial strains present in the soil. Interactions between elite B. japonicum strains TA11NOD+, 532C, SEMIA 5039, NS-1, and SOY 212 and forage and Roundup Ready soybean genotypes were examined in field trials in the Delmarva region. Strain TA11NOD+ was the best microsymbiont with both the forage soybean cv. Tyrone and the Roundup Ready soybean cv. AG 4602, producing 309 and 303 nodules/plant, 104 and 3.34 umol C2H4/plant/ha and 2.2 and 3.8 t/ha, respectively. A combination of strains 532C, NS-1 and SOY 212 produced the highest nodule number, nodule mass and seed yield with cv. AG4902. To overcome the competition problem, selected rhizobiophages were used to reduce the competitive ability of ineffective native B. Japonicum strains in nodulating soybean. This resulted in decreased nodule occupancy by undesirable indigenous bacteria strains by 44% and increased nodule occupancy by introduced strains by 55%. This study shows that soybean growth was greatly influenced by bradyrhizobia strains under Delmarva climactic conditions.