Influence of Imazethapyr on Rhizobium Growth and its Symbiosis with Pea (Pisum sativum)

• Published in: Weed science 1996-01, Vol.44 (1), p.31-37
• Main Authors: Gonzalez, A., Gonzalez-Murua, C., Royuela, M.
• Format: Article
• Language: English
• Subjects: CONTROL QUIMICO; DESHERBAGE; DOSE D'APPLICATION; DOSIS DE APLICACION; EFECTOS SECUNDARIOS; EFFET SECONDAIRE; ESCARDA; FIJACION DEL NITROGENO; FITOTOXICIDAD; FIXATION DE L'AZOTE; FORMATION DE NODOSITES; HERBICIDAS; HERBICIDE; Herbicides; INDICE DE CRECIMIENTO; Legumes; LUTTE CHIMIQUE; Microorganisms; NODOSITE RACINAIRE; NODULACION; Nodulation; Nodules; NUDOSIDADES RADICULARES; Peas; Physiology, Chemistry, and Biochemistry; PHYTOTOXICITE; PISUM SATIVUM; Plant growth; Plants; Rhizobium; RHIZOBIUM LEGUMINOSARUM; SIMBIOSIS; SYMBIOSE; Symbiosis; TAUX DE CROISSANCE
• ISSN: 0043-1745; 1550-2759
• DOI: 10.1017/S0043174500093516

Imazethapyr is a selective herbicide used to control a wide spectrum of weeds in several legume crops, including pea. The effect of imazethapyr on pea-Rhizobium symbiosis was studied through its effect on microorganism growth, microorganism nodulation ability and plant growth. Symbiotic plants were damaged by imazethapyr concentrations higher than 1.73 μM applied preemergence. The number of nodules per plant was affected more than nodule size, suggesting a direct imazethapyr effect on the nodule initiation rather than on nodule development. However, imazethapyr did not directly affect Rhizobium because doses higher than 0.34 mM were required to cause slight effects on Rhizobium growth in a defined medium. Also, nodulation ability of bacteria treated with imazethapyr was not affected. These results suggest that imazethapyr inhibits the growth of the symbiotic plant rather than having a direct effect on the bacteria. Accordingly, symbiotic plants were less affected than the corresponding nitrate-reducing pea plants.