Role of Microbiologically Rich Compost in Reducing Biotic and Abiotic Stresses

Abstract

Plant abiotic and biotic stress is related to unfavorable and environmental constraints. These stresses represent the principal cause of crop failure, decreasing average yields of major crops by more than 50%. Compost can be considered as a soil conditioner that contributes to soil fertility, structure, porosity, organic matter, water holding capacity and disease suppression. Composts suppress soil borne diseases and this suppression has been widely reported for Pythium spp., Phytophthora spp., Rhizoctonia spp. and Fusarium spp. Compost amendments also contribute to controlling foliar diseases, such as Puccinia spp., Alternaria solani and Pseudomonas syringae pv. syringae. Disease suppression by composts has been explained mainly by biotic mechanisms. The severity of soil-borne plant diseases is often reduced when microbiologically improved compost used as growth media. Wide variety of rhizosphere micro-organisms have been isolated and used as microbiological inoculants for improving plant growth and health. These include, arbuscular mycorrhizal fungi (AMF), plant growth promoting rhizobacteria (PGPR), nitrogen fixers and phosphorus solubilizing microorganisms (PSM). Utilization of compost with disease suppressive properties is a relatively new biological method of decreasing biotic stress in plant production. The main advantage of exploring the role of microbiologically rich compost in reducing biotic and abiotic stresses is that, it is a novel way to imitate the natural system occurring in ecosystems. Under saline conditions, compost was not completely efficient in correcting the detrimental effects of salt, but was able to mitigate them. Such an amendment may be used to enhance crop yield irrigated with saline waters or grown on saline soils. Compost amendments in soil are also efficient in combating the pH stress. The amendment of alkaline soils with composts has a positive effect on plant vigour. Molecular studies also showed a different profile of microorganisms in disease suppressive composts. This study shows a good approach to add-up value to compost, and make it more efficient in reducing biotic and abiotic stresses.