Limited research exists on wood properties in E. nitens × E. globulus hybrid genotypes grown in water-limited conditions generated by the climate change influence in Mediterranean areas. The EUCAHYDRO project aimed to assess environmental stress impacts on eucalyptus genotypes, including responses to reduced water availability, and to evaluate wood density and resistance using the non-destructive drill resistance technique. This study focused on 10-year-old E. nitens × E. globulus hybrids and Eucalyptus badjensis Beuzev. & Welch, revealing that low irrigation led to a 13% (p < 0.05) decrease in diameter and a 6.5% (p > 0.05) increase in wood density for the hybrids. On the contrary, E. badjensis demonstrated a noteworthy 22% increase in wood density (p < 0.05), while showing a corresponding 0.6% growth increase (p > 0.05), as measured by the diameter at breast height. Drill resistance measurement results indicated that E. nitens × E. globulus’ amplitude ranged from 20.1% to 26.6%, while E. badjensis’ ranged from 20.8% to 27.2%. The study revealed a high correlation between resistance amplitude and wood density, with coefficients of 0.97 observed for E. nitens × E. globulus and 0.84 for E. badjensis (p < 0.05). These findings fall within the range reported in similar studies involving Eucalyptus spp. The primary focus of the research was to assess the growth potential and wood quality of novel Eucalyptus spp. under conditions of water limitation. The study also explored the utility of drill resistance as a predictive measure for evaluating wood density as an indicator of wood quality.

Water use, water use efficiency, and water use sustainability are challenging issues for the expansion of Eucalyptus plantations around the world nowadays. Fast-growing species’ effects on water resources are of concern to society, and the forest industry wonders about the effects on productivity and water sustainability under climate change. We evaluated growth, water use, and water use efficiency response at canopy closure (3 to 4 years of age) of eight selected E. globulus, E. nitens, and E. nitens × globulus (E. gloni) genotypes at four contrasting environments. Across sites and genotypes, the growth rate and water use ranged from 35–70-m³/ha/year and 350 to 900 mm ha⁻¹. Despite specific genotype cases, our results showed similar water use vs. productivity relationships for a single taxon (90 m³ of water per m³ of wood) but suggested large differences among taxa across sites. Our results suggest that hybrids may provide large productivity benefits but may need a more precise understanding of their physiological mechanisms. Interesting opportunities exist for matching genotypes to sites in order to reduce environmental concerns on water resource use for Eucalyptus plantations.

The selection of taxa/genotypes that have a rainfall interception that suits the conditions of each region is key to maintaining water stability and minimizing the effects of drought. This study evaluated rainfall interception on a seven-year-old plantation with the eight genotypes (Eucalyptus globulus and E. nitens x globulus (high and low productivity), E. nitens, E. badjensis, E. smithii, and E. camaldulensis x globulus) in Yumbel, Bio-Bio, Chile. In addition, diameter (DBH), total height (H), and Leaf Area Index (LAI) were considered and compared with stemflow (Sf), throughfall (Tf), and interception (INT). The results showed that DBH and H did not infer the rainfall interception parameters. In contrast, Tf and Int varied in each genotype; E. badjensis and E. smithii had a LAI > 5.1 m²m⁻² had the minimum Tf and maximum Int; in contrast, E. globulus and E. nitens x globulus with a LAI < 4.0 m²m⁻² showed low Int and high Tf. With Sf did not show differences between genotypes. These suggest the opportunity to select genotypes considering canopy interception to balance productivity and water resources under climate change scenarios.

Eucalyptus is a fast-growing genus widely used in the forestry industry; however, in the plant’s early stages, plantations are susceptible to drought conditions and it is common to find high mortality rates and loss of productivity. Therefore, this study analyzed the physiological response photosynthesis (An) and predawn leaf water potential (Ψ_PLWP) and the change in carbon balance (C) in ten Eucalyptus genotypes exposed to different water deficits, with the hypothesis that it is possible to identify and differentiate genotypes with a tolerance to drought. Therefore, ten one-year-old genotypes were placed in greenhouse conditions and soil matric power (Ψ_s) was regulated in four levels: −0.03 MPa (control), −0.7 Mpa (slight stress), −1.5 Mpa (moderate stress) and −2.5 Mpa (chronic stress); each level was determined from the automated monitoring of soil conditions. The example considered in the experiment was tree stress per genotype × Ψ_s. The measurements of An and Ψ_PLWP considered tree measurement per individual (n = 9 per genotype × Ψ_s); in contrast, the Gross primary productivity (GPP) was estimated with destructive sampling (n = 3 genotype × Ψ_s). We found a significant relationship between water deficit and physiological response (a major deficit produced a reduction of An and Ψ_PLWP). E. nitens clones had a minor physiological variation and GPP maintained the same trend and proportionality between aerial and underground production. In contrast, two hybrids of E. nitens × E. globulus showed an immediate physiological change and variation in GPP, with increased underground production and stagnant aerial production. These results suggest that it is possible to differentiate genotypes with a tolerance to water deficit early. This will allow genotype selection according to the climatic conditions of each site, minimizing mortality and optimizing the available water resources.

Tree volume equations for Eucalyptus plantations are essential to estimate productivity, generalize equations that consider different genotypes and low-bias water regimes, and simplify plantation management. Our study evaluated the possibility of a generalized tree volume equation for eight Eucalyptus genotypes under contrasting irrigation regimens. We evaluated a seven-year-old plantation with eight Eucalyptus genotypes in two contrasting irrigation regimens (summer-irrigated vs. non-irrigated conditions). Diameter (DBH) and total height (H) measurements were considered in the tree equations (Schumacher and Hall (1933), Honer (1967), and Clutter et al. (1983)). The equation with the best fit considered the coefficient of determination, mean square error, and AIC and BIC parameters. The results showed that it is possible to use a generalized tree volume equation; the genotype, irrigation regime, and their interaction were not statistically significant for all equations. The best tree volume equation was Schumacher and Hall (1933), which showed the best fit and minor bias, with a small trend of underestimating the total volume in trees with a DBH >18.3 cm. These results suggest that it is possible to use a generalized tree volume equation to simplify plantation productivity projections while maintaining a good fit and low bias.