Rhizobium and Mycorrhiza — Definition
Definition
Imagine plants needing specific nutrients to grow strong and healthy, much like we need a balanced diet. While plants can absorb some nutrients directly from the soil, certain essential elements, like nitrogen and phosphorus, are often locked in forms they can't easily use.
This is where 'biofertilisers' come into play – living microorganisms that enrich the nutrient quality of the soil. Among the most important biofertilisers are Rhizobium bacteria and Mycorrhizal fungi, both forming incredible partnerships with plant roots.
Rhizobium are tiny bacteria that live freely in the soil but become truly remarkable when they meet the roots of specific plants, primarily legumes like peas, beans, and lentils. These plants send out chemical signals, inviting Rhizobium to colonize their roots.
In response, the bacteria induce the formation of special structures called 'root nodules' on the plant roots. Inside these nodules, the Rhizobium bacteria transform atmospheric nitrogen gas (N), which plants cannot use directly, into ammonia (NH), a form of nitrogen that plants can readily absorb and use to build proteins and DNA.
In return, the plant provides the bacteria with sugars produced during photosynthesis. It's a classic win-win situation: the bacteria get food, and the plant gets essential nitrogen, allowing it to thrive even in nitrogen-poor soils.
This process is called 'nitrogen fixation' and is crucial for natural ecosystems and agriculture.
Mycorrhiza (plural: mycorrhizae) refers to a symbiotic association between a fungus and the roots of almost all vascular plants. Think of the fungus as an extension of the plant's root system, but far more efficient at scavenging nutrients.
The fungal threads, called 'hyphae,' are much finer and can spread further into the soil than plant roots, accessing water and nutrients, particularly phosphorus, that would otherwise be unavailable to the plant.
The fungus absorbs these nutrients and transports them directly to the plant root cells. In exchange, the plant supplies the fungus with carbohydrates (sugars) produced through photosynthesis. There are different types of mycorrhizae, but they all share this fundamental mutualistic exchange.
This partnership significantly boosts the plant's ability to absorb water and minerals, enhances its resistance to diseases and drought, and helps it grow stronger. Both Rhizobium and Mycorrhiza are natural, eco-friendly ways to improve plant health and soil fertility, making them invaluable tools in sustainable farming.