Abstract
Prosopis juliflora is a major invasive species in tropical and subtropical regions. This study explores the link between precipitation, soil moisture, and plant growth, focusing on the invasive P. juliflora in a simulated altered rainfall regime. The study was conducted simultaneously by using three rainout shelters, Normal Rainfall (NR, 1000 mm) (ii) High Rainfall (HR, 1400 mm) (iii) Low Rainfall (LR, 500 mm). Each rainout shelter was divided into three subplots measuring 2 × 2 m to establish P. juliflora by transplanting 20 seedlings per 4 m(2). After 1 years of establishments, plant growth, ecophysiological attributes and soil properties were recorded as per standard protocols. Increased rainfall led to higher soil moisture and promoted P. juliflora growth, biomass, and photosynthetic activity. Conversely, decreased rainfall triggered drought stress, impacting gas exchange and reducing growth. Statistical analysis showed significant (p < 0.05), SM, soil inorganic-N, N-mineralization, growth measurements, photosynthesis rate (A(area)), transpiration rate (E), height (H), diameter (D), root: shoot ratio, and biomass (AGB + BGB) exhibited the highest values in the HR plots during the rainy season and the lowest values in the LR plots during the summer season, following the trend HR > NR > LR. When different rainfall conditions were regressed against P. juliflora biomass, significantly positive linear relationships were observed. The findings suggest that P. juliflora adapts to changing rainfall regimes by allocating resources strategically. While it thrives under high precipitation, it exhibits surprising drought tolerance, potentially colonizing drier regions. Declining monsoon rainfall and increased precipitation intensity may boost P. juliflora's invasiveness.