Microbial Inoculants for Sustainable Plant Health

Healthy plants are the key for sustaining life on earth. Soil, being the largest microbial repository, has a major role to play in plant health. The microbes in the soil interact directly and indirectly with plants in diverse manners significantly contributing to their development and growth. They colonize either the rhizosphere or plant parts like roots, stems, or leaves as endophytes and possess an array of traits like plant growth promotion, nutrient mobilization (nitrogen, phosphorus, zinc, etc.), induction of systemic resistance, and antagonism to pests and pathogens either individually or in various combinations. Mostly they belong to viruses, actinomycetes, bacteria, fungi, or nematodes and are either endophytic or rhizosphere-dwelling in nature. In the quest to find sustainable means to manage pests and diseases of spices, intensified efforts were made for the past two decades to tap the biological potential of microorganisms endemic to spice ecosystems. The beneficial properties of many such microbes have been studied in detail and evaluated by conducting in vitro and in planta bioassays by several workers. Several of them are antagonistic to bacterial and fungal pathogens and also to nematode and insect pests of spices. The substantial progress achieved in the production, commercialization, and use of inoculants in the spice sector is reviewed in this chapter. These organisms need to be scaled up as biologicals for natural control of various pests and diseases of spices, which are currently managed by deploying chemical pesticides. For biological control to gain momentum in the spice sector, suitable formulations and delivery systems need to be urgently developed. A favorable policy environment is the need of the hour for successful commercialization of microbial technologies. Taking advantage of the technological advancements in the field of genomics, there is a need to elucidate the core microbiome of every spice crop to empower them to withstand biotic and abiotic stresses and the impact of climate change.