Contrasting Responses of a Native Palm and an Invasive Vine to Flooding Stress: Implications for Orchard Regeneration in Caatinga Ecosystems

The carnauba palm trees in the Caatinga ecosystem, in Northeast Brazil, have been impacted by invasive species, particularly in areas subject to flooding. This study aimed to evaluate morphological, physiological, and nutritional responses of <i>Copernicia prunifera</i> (native) and <i>Cryptostegia madagascariensis</i> (invasive) seedlings exposed to flooding stress. The experiment was conducted in a randomized complete block design, with a split-plot arrangement and five replicates. The treatments were formed by two species and five periods of flood stress (0, 8, 12, 16, and 20 days). Flooding significantly reduced shoot dry mass in both species; however, the reduction was more pronounced in the invasive species (27%) compared to the native palm (20%). The invasive species showed strong use of resources, with higher values for leaf mineral nutrient, net photosynthesis, growth rate, and leaf area, regardless of the water regime. Under flooding, the invasive species produced adventitious roots, and the net photosynthetic rate was less impacted, despite greater sodium accumulation in the leaves. The results indicate that the characteristics of <i>C. prunifera</i>, such as slow growth rate, low specific leaf area, and morphological adaptations of the root system, may ensure greater stability in net carbon assimilation in the whole plant under flooding. However, the rapid growth and high absorption of soil resources of <i>C. madagascariensis</i> pose a significant threat to the establishment of <i>C. prunifera</i> seedlings, directly jeopardizing the long-term renewal of carnauba palm groves in the Caatinga ecosystem.