Role of Flash Droughts in Defining a New Balance in Plant-Microbe Interactions

Abstract

This study investigated the effects of brief droughts on plant-microbe-soil continuum in Balochistan, Pakistan's temperate grassland ecosystem. The collection of soil and plant samples from three distinct locations under normal conditions, during sudden drought events, and after drought periods. In the controlled greenhouse experiment, using the same plant species and soil, we replicated field conditions by simulating drought by withholding water. Flash droughts decreased soil moisture from 38 to 8%, substantially increased soil temperature from 20°C to 30°C, and decreased total plant biomass from 700 to 370g, according to our findings. Photosynthetic rate and stomatal conductance decreased to 8 mol m-2s-1 and 0.08 mol m-2s-1, respectively, as the plant survival rate decreased from 95% to 65%. From -0.6 MPa to -1.9 MPa, leaf water potential also indicated a substantial increase in water stress. During drought conditions, bacterial abundance decreased from 12,000 CFU/g of soil to lower levels; similarly, the abundance of fungi, Arbuscular Mycorrhizal Fungi, and Nitrogen-fixing Bacteria decreased significantly. Although a partial recovery was observed in post-drought conditions, the majority of parameters did not revert to pre-drought levels, indicating that flash droughts have a lasting impact. This study highlights the importance of incorporating the dynamics of flash droughts into ecosystem models and advocates for strategies to mitigate their long-term effects.