Crescimento de espécies da Caatinga sob diferentes condições de estresses abióticos

Abstract

The Caatinga is the largest tropical dry forest in South America and encompasses enormous biodiversity, playing an essential role in ecosystem services. However, anthropogenic pressure has intensified the degradation of the Caatinga's native vegetation cover and soil salinization. The aim of this study was to evaluate the morphological responses of Handroanthus impetiginosus (Mart. ex DC.) Mattos and Handroanthus spongiosus (Rizzini) S. Grose seedling species to the use of natural resources when subjected to the combined stresses of salinity and water deficit. The work was carried out between July 10 and November 20, 2023, inside a nursery located in the Serra Talhada Academic Unit, in the municipality of Serra Talhada-PE. The seeds were sown in a tray and then transplanted into polyethylene bags with a capacity of 8 kg, which were filled with soil and sand in a 2:1 ratio. The plants were arranged in a completely randomized experimental design, with four replications. The species were subjected to three water regimes (RH) based on reference evapotranspiration (ETo): RH1 -50%, RH2- 75% and RH3-100% of ETo, and four salinity levels: N1 - mains water (0.27 dS/m), N2 - 2.52 dS/m, N3 - 6.35 dS/m and N4 - 7.38 dS/m. Biometric data was obtained at 15-day intervals: height (ALT), number of leaves (NF), collar diameter (DC). At the end of the experiments, information on total plant biomass and its partitioning was acquired. The results showed that H. impetiginosus was more tolerant to the conditions analyzed. The species showed greater sensitivity to salt stress, which negatively influenced growth and dry biomass accumulation by up to 98%. Increased water deficit reduced height, collar diameter, number of leaves, root biomass and total biomass. The best performing water table was 100% for both species.