Exploring the physiological adaptation and resilience of Leucaena Leucocephala to rainfall variability

Changes in rainfall patterns, induced by climate change, significantly affect the physiology and morphology of invasive plants in tropical ecosystems with broader ecological dynamics. In order to manage tropical ecosystems effectively and sustainably, it is crucial to evaluate how changes in rainfall impact the physiological and functional characteristics of invasive plants. In our investigation, we looked into eco-physiological and growth attribute responses of Leucaena leucocephala, an invasive plant, to varying rainfall conditions (OC, open control; LR, low rainfall; NR, normal rainfall; HR, high rainfall) under rainout sheltered and unsheltered plots over a two-year period. Following the randomised block design, three (2 m × 2 m) replication subplots were created for each sheltered and unsheltered plot. In each subplot, twenty Leucaena leucocephala seedlings were planted with 0.5 m spacing each plant. Plant sampling and analysis were performed at the peak of each season in 2021–2022, assessing various traits such as total biomass (B), height of plant (SH), relative growth rate (RGR), chlorophyll content, photosynthetic rate (Aarea), stomatal conductance, and transpiration rate (E). These metrics responded to changes in precipitation and increased by 65, 17, 19, 20, 19, 31, and 25% respectively, on rising the rainfall in HR, while decreased by 55, 29, 20, 16, 31, 31%, and 45% respectively, on lowering the rainfall in LR against the OC. However, root-shoot ratio (RSR), root Length (RL) and water use efficiency (WUE) showed an adverse response with rainfall. Our results indicate that rainfall variability has a substantial effect on the ecophysiology and functional aspects of Leucaena leucocephala. The species becomes a potential invader because of its significant morphological flexibility, which improves overall functioning under variations in rainfall. However, the adaptability and plasticity of L. leucocephala appear to maximum in the face of normal and high rainfall conditions, thus making the tropical ecosystem (extreme rain events) a favourable place for growth.