Browsing by Author "Bozo, Daniel"

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    Changes in leaf physiology for eucalyptus genotypes with increase in integral water stress and its consequence for initial growth in central Chile
    (2022) Goncalves de Oliveira, Thiago Wendling; Rubilar, Rafael; Sanquetta, Carlos Roberto; Dalla Corte, Ana Paula; Bozo, Daniel; Medina, Alex; Mardones, Oscar; Emhart, Veronica; Quiroga, Juan Jose; Valenzuela, Hector
    Limited information exists on how small changes in soil water affect the physiological responses of eucalyptus and their relationship with productivity. This experiment evaluated physiological traits during decreased soil water and compared them with growth and water stress integral (WSI) of 22 eucalyptus genotypes with 1.5 years old. The experiment was conducted in sandy soil with low water holding capacity in Chile. Selected genotypes were Eucalyptus globulus, E. nitens, and E. nitens x E. globulus hybrids (E. gloni). Seasonal predawn leaf water potential (psi(pd)) was evaluated under well-irrigated conditions and after 40 days without irrigation. Subsequently, two sampling instances were considered for analysis, well-irrigated conditions M-0 (470 days after planting) and 40 days without irrigation M-final (510 days after planting). During that period, we measured midday leaf water potential (psi(pd)), leaf area index (LAI), diurnal changes in photosynthesis (A(n)) and stomatal conductance (g(s)). The broad range of WSI among genotypes indicated contrasting levels of accumulated water stress during early development. In fact, E. globulus presented 30% more water stress than E. nitens, and genotypes with the highest WSI showed the lowest growth. Between M-0 and M-final, there was a reduction in A(n) and g(s) in the morning and midday with small changes in the afternoon, and consequently, values of the intrinsic water use efficiency (iWUE) increased. The psi(pd) showed small changes and we observed a large LAI increment for all genotypes. Changes in iWUE were more pronounced for genotypes with lower WSI, which suggested that these genotypes with lower accumulated water stress were more sensitive to changes in soil water, such as E. gloni genotypes allowing them to maintain high productivity.
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    Differences in rainfall interception among Eucalyptus genotypes
    (2023) Valverde, Juan Carlos; Rubilar, Rafael; Barrientos, Guillermo; Medina, Alex; Pincheira, Matias; Emhart, Veronica; Zapata, Alvaro; Bozo, Daniel; Espinoza, Yosselin; Campoe, Otavio C.
    Key messageHydrological indicators such as rainfall interception of Eucalyptus genotypes are essential to guarantee the water sustainability of forest plantations under climate change scenarios.Rainfall interception is a critical component of water balance in Eucalyptus plantations and may provide better water sustainability by reducing potential adverse effects under drought scenarios. This study evaluated rainfall interception of Eucalyptus globulus and E. nitens x globulus (high and low yield), E. nitens, E. badjensis, E. smithii, and E. camaldulensis x globulus. Rainfall, stemflow, throughfall, and interception (calculated as rainfall-stemflow-throughfall) were measured for 2 years (2020-2022) and correlated with plantation characteristics [diameter at breast height, total height, stem growth, and leaf area index (LAI)]. Our results showed an average rainfall of 1063.6 mm year(-1); only stemflow did not show differences among genotypes with an average value of 193.4 mm year(-1) (18.2% of annual rain). In contrast, throughfall and interception presented significant differences among genotypes, and both parameters showed a strong relationship with LAI. Therefore, three independent groups were obtained: E. badjensis and E. smithii showed the highest LAI (average 5.7 m(2) m(-2)) with 517.0 mm year(-1) of average interception and 427.6 mm year(-1) of average throughfall (48.6% and 40.2% respectively). For E. globulus (low-yield), E. nitens x globulus (low-yield), and E. nitens, that showed the lowest LAI (average 3.3 m(2) m(-2)), average throughfall reached 730.8 mm year(-1) (68.7%), and average interception reached 197.3 mm year(-1) (18.5%). Finally, E. globulus (high-yield), E. nitens x globulus (high-yield), and E. camaldulensis x globulus with an average LAI of 4.5 m(2) m(-2), average interception reached 345.2 mm year(-1) (32.5%), and average throughfall reached 602.7 mm year(-1) (56.7%). Our results suggest that understanding differences between taxas/genotypes may contribute to developing hydrological indicators that may improve estimates of plantation water sustainability under water scarcity climate change scenarios.
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    Morphological, physiological and carbon balance response of Eucalyptus genotypes under water stress
    (2024) Garcia, Luz Yeidy; Rubilar, Rafael; Valverde, Juan Carlos; Emhart, Veronica; Bascunan, Luisa; Medina, Alex; Bozo, Daniel
    Water stress is considered one of the main environmental factors that limit survival and productivity of Eucalyptus plantations. Identifying genotypes traits that provide evidence of tolerance to water stress may allow sustained productivity and secure better resilience of forest plantations under climate change in Mediterranean environments. Our study analyzed morphological, physiological, and carbon (C) balance responses of ten Eucalyptus genotypes under contrasting water regimes under nursery conditions. One-year-old cuttings of Eucalyptus nitens (En1 and En2), E. smithii (Es), E. badjensis (Eb), E. nitens x globulus (Eng1, Eng2, Eng3, and Eng4), E. globulus (Eg), and E. camaldulensis x globulus (Ecg) were evaluated under progressive drought from well-watered (soil water potential close to 0 MPa) to severe water stress (soil water potential close to - 2.5 MPa) conditions. Absolute growth rate (root collar diameter, height, shoot: root biomass ratio), net photosynthesis, stomatal conductance, transpiration, intrinsic water use efficiency (iWUE), predawn water potential (Psi(pd)) and C balance (flux and partitioning) were evaluated. As expected, water stress significantly reduced growth and physiological activity for all genotypes. Of all evaluated parameters iWUE and Psi(pd) were the key grouping physiological and growth response variables among genotypes. Genotypes En1, Eng3, and Eng4 were considered tolerant genotypes, with the smallest physiological change and larger morphological growth. Genotypes En2, Es, Eng1 and Eng2 were moderately tolerant showing intermediate responses compared to other groups. In contrast, Eg, Eb, and Ecg were considered highly sensitive, with major changes in morphology and physiological variables over time. Our results suggest that nursery stage physiological evaluation of genotypes may allow selection for sites with water resource availability risks and may allow to reduce mortality and early establishment productivity losses under drier climate change scenarios.
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    Rotation-age effects of subsoiling, fertilization, and weed control on radiata pine growth at sites with contrasting soil physical, nutrient, and water limitations
    (2023) Rubilar, Rafael; Bozo, Daniel; Albaugh, Timothy; Cook, Rachel; Campoe, Otavio; Carter, David; Allen, H. Lee; Alvarez, Jose; Pincheira, Matias; Zapata, Alvaro
    Although short- and medium-term responses to early silvicultural treatments have been documented, few studies show productivity gains or losses throughout a rotation across a range of soil types and resource availability. We evaluated the rotation length productivity responses of radiata pine to subsoiling, fertilization, and weed control in dry sand (DS), red clay (RC), and recent volcanic ash (RV) soils representing a gradient of physical, nutrient, and water limitations. Stands were planted in 2000 in a split-plot factorial design, with soil preparation (subsoiling vs. shovel planting) as the main plot and fertilization at planting (B only vs. NPKB) and weed control (none vs. 2-year banded application) as factorial randomized treatment plots within the main plots. Annual diameter at breast height, height, survival, and cumulative volume responses were measured. The rotation-age results for cumulative volume showed that early gains from weed control were maintained through at least 15 years of age. At rotation age, weed control increased the cumulative volume at the DS site (56 m3/ha, 20% gain), and the response over time was maintained at the RC site (28 m3/ha, 8% gain), whereas the volume was reduced at the RV site (-36 m3/ha, 7% loss). Fertilization resulted in the greatest response at the RC site (29 m3/ha, 8% gain); there were small responses at the DS site (5 m3/ha, 2% gain) and negative responses at the RV site (-18 m3/ ha, 4% loss). Interestingly, subsoiling resulted in null or negative responses at all sites, and negative effects increased over time, with volume responses ranging from -4 m3/ha (1% loss) and -27 m3/ha (7% loss) at the DS and RC sites, respectively, to -116 m3/ha (21% loss) at the RV site. Carrying capacity was reached at midrotation at the RV site and resulted in negative treatment effects at rotation age, suggesting the need for thinning or a younger harvest age at this site. Given the negative or null effects of soil preparation, a better understanding is needed for how this silvicultural treatment is affected by soil type and soil strength.
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    Taper and individual tree volume equations of Eucalyptus varieties under contrasting irrigation regimes
    (2022) Valverde, Juan Carlos; Rubilar, Rafael; Medina, Alex; Mardones, Oscar; Emhart, Veronica; Bozo, Daniel; Espinoza, Yosselin; Campoe, Otavio
    Background: Compatible taper and volume equations are key for traditional growth and yield and current process-based or hybrid models. However, most equations do not consider variables such as genotype, water regime and their interaction, limiting the development of general equations for species or regions. Our research investigated taper and individual tree volume equations for eight Eucalyptus genotypes (E. nitens, E. badjensis, E. smithii, E. camaldulensis x globulus and two varieties of low and high productivity of E. globulus and E. nitens x globulus), all materials are growing under summer irrigated vs. no irrigated conditions.