Root Exudates, Rhizosphere Biodiversity and Plant Defense Mechanism-An Underrated Triangle of Rhizosphere in Agroforestry Ecosystem

Plants in general threaten by different biotic (caused by pathogen attack) and abiotic stresses. Although different chemical compound has been discovered so far which can manage this biotic threats but the chances of growing resistance, mutation in organism, environmental hazards and impact over non target organism are always there. To Tackle this issues finding of some sustainable method is the need of hour. In this condition biological control not only depends upon predatism and parasitism but also antibiosis, induced defense mechanism, competitive suppressiveness, production of defensive enzymes, phytolexin, toxins etc. Enhancement of the plant's innate immunity and strengthening of defense mechanism by acquired and induced way is becoming a new line of thought for researchers. In the rhizosphere specially in the complex agroforestry cultivation process the roots of many forest plant secret different complex compounds like phenols, propanoids, sugars, etc. in the root zone that harbors rhizosphere colonizer micro-organisms and turns the rhizosphere into an amazing place with the enriched microbe diversity and biomass. This microorganism are responsible for the production of plant defense modulator that enhance the innate capacity of the plant against pathogen attack.In this chapter, we will focus on the connection between these three components i.e. root exudates; rhizosphere biodiversity, and their effect on plant defense mechanisms. Their well-established interaction, mass effect, and the perspective of the trident will be discussed here in an elaborative manner.