Course Content
Learn soil fertility, fertilizers and integrated nutrient management with Braimy- B.SC Agriculture
About Lesson
  • Rhizobium bacteria, basically form root nodules (stem nodules in Sesabania rostrata) in leguminous plants and fix atmospheric nitrogen in a symbiotic association.
  • These nodules act as mini-factory for fixation of atmospheric N.
  • The Rhizobium bacteria gives nitrogen to the plant and the plant gives protection to the
  • bacteria from oxygen damage by harboring it inside the root nodule.
  • The plant roots also supply essential minerals and newly synthesized substances to the bacteria.
  • Rhizobium inoculation is a well-known agronomic practice to ensure adequate N supply for legumes in place of N fertilizer.
  • Rhizobium gets entry into the legume root hairs and induces nodulation in plant roots.
  • There are two types of nodules effective and ineffective ones. Effective nodules are formed by effective strains of Rhizobium.
  • They are well developed, pink color due to the presence of pigment possess leghaemoglobin.
  • The bacteriod tissue is well developed and well organized with plenty of bacteriods.
  • On the contrary ineffective strains of Rhizobium form ineffective nodules which are generally small and contain poorly developed bacteriod tissue showing accumulation of glycogen.
  • The red pigment in the nodules acts as a biological value in regulating the supply of oxygen into the bacteriod tissue.


Rhizobium is

  • Host specific, can fix 50-100 Kg N/ha, 10-35% increase in yield
  • Also reduces seed rot, foot & root rot of leguminous and non-leguminous (okra, tomato) plants.
  • Need optimum P and Mo
  • Rhizobia also produce Phytohormones such as auxins, cytokinins, gibberllins and abscicic acid.
  • Also known to stimulate seed germination in a wide range of plant species.
Join the conversation
Scroll to Top