Biofertilizers as an eco-friendly approach to combat drought stress in plants

Drought is a severe abiotic stress adversely affecting agricultural activity worldwide. Biofertilizers have emerged as an environmentally-safe tool to combat drought adverse effects in plants. Biofertilizers like endophytic fungi (EF), arbuscular mycorrhizal fungi (AMF), plant growth-promoting bacteria (PGPB) and natural compounds have enormous potential to mitigate drought negative effects in plants. Microbials like PGPB and AMF improve physical, chemical and biological features of soils by promoting nutrient uptake and water flow. However, natural compounds provide drought stress tolerance by inducing morphological and structure changes, water status adjustment, stomatal regulation, osmotic regulation, ion balance and pH regulation, reactive oxygen metabolism, antioxidant defense system, photosynthetic system, plant hormones, signal transduction, and gene expression regulation. This review provides valuable background knowledge on various biofertilizers that have proven effective against drought and serves as theoretical basis for conducting future research under field conditions to validate their practical use.