- 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.
- 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