EFEITOS DO DÉFICIT HÍDRICO NO CULTIVO DE MUDAS DE EUCALIPTO     TÚLIO BARROSO QUEIROZ¹; SOFIA MARIA GONÇALVES ROCHA²; FRANCINE SOUZA ALVES DA FONSECA³; IVAN CALDEIRA ALMEIDA ALVARENGA⁴ E ERNANE RONIE MARTINS^{5   1}Programa de Pós-graduação em Ciência Florestal, Universidade Estadual Paulista “Júlio de Mesquita Filho”, UNESP, Botucatu, SP, CEP 18610-307. E-mail: tulio-bq@hotmail.com ²Programa de Pós-graduação em Ciência Florestal, Universidade Federal do Espirito, UFES, Jerônimo Monteiro, ES, CEP 29550-000. E-mail: sofiamaria.r@hotmail.com ³Instituto de Química, Universidade Estadual de Campinas, UNICAMP, Campinas, SP, CEP 13083-861. E-mail francinefonseca@yahoo.com.br ⁴Departamento de Agricultura, Universidade Federal de Lavras, UFLA, Lavras, MG, CEP 37200-000. E-mail: pytchouai@yahoo.com.br ⁵Laboratório de Plantas Medicinais e Aromáticas, Universidade Federal de Minas Gerais, UFMG, Montes Claros, MG, CEP 39404-547. E-mail: ernane.ufmg@gmail.com     1 RESUMO   O objetivo do estudo foi determinar a necessidade hídrica do Eucalyptus globulus submetidos a diferentes lâminas de irrigação na região Norte do Estado de Minas Gerais. Os tratamentos consistiram em 6 lâminas de irrigação (50%, 75%, 100%, 125%, 150% e 175% da Evapotranspiração de referência – ETo), com quatro repetições, em delineamento inteiramente casualizado. Os resultados observados indicam que as mudas de E. globulus cultivadas sob lâmina de irrigação correspondente a 75% da ETo (lâmina consumida de 377,66 mm) foi responsável por maior crescimento da parte aérea (63,75 cm), maior eficiência instantânea e de uso da água (0,14 µmol m^-2 s^-1 e 0,0419 g mm^-1, respectivamente). Além disso, as mudas sob esta lâmina de irrigação apresentaram maior índice de qualidade de Dickson (5,64) e alta capacidade de regulação osmótica com maior conteúdo de prolina foliar (124,94 µg g^-1). O coeficiente de cultivo (Kc) para as condições destacadas foi equivalente a 1,4. Palavras chave: evapotranspiração, irrigação, estresse hídrico, silvicultura     QUEIROZ, T. B.; ROCHA, S. M. G.; FONSECA, F. S. A da.; ALVARENGA, I. C. A. A.; MARTINS, E. R. EFFECTS OF WATER STRESS ON PRODUCTION OF EUCALYPT SEEDLINGS 2 ABSTRACT   The objective of this study was to determine the water requirement of Eucalyptus globulus under different irrigation levels in the North region of Minas Gerais. The treatments consisted of six irrigation levels (50%, 75%, 100%, 125%, 150% and 175% of the reference evapotranspiration - ETo) with four replications fully randomized. The results indicate that the seedlings of E. globulus grown under irrigation blade corresponding to 75% of ETo (blade consumed 377.66 mm) were responsible for shoot growth of plants (63.75 cm), higher instantaneous efficiency and water use (0.14 μmol m^-2 s^-1 and 0.0419 g mm^-1, respectively). In addition, the seedlings under this irrigation blade presented higher Dickson quality index (5.64) and higher capacity for osmotic regulation with higher leaf proline content (124.94 μg g^-1). The coefficient of cultivation (Kc) for the highlighted conditions was equivalent to 1.4.  Keywords: evapotranspiration, irrigation, water stress, forestry

Roots play a fundamental role in forest ecosystems, but obtaining samples from deep layers remains a challenging process due to the methodological and financial efforts required. In our quest to understand the dynamics of Eucalyptus roots, we raise three fundamental questions. First, we inquire about the average extent of the roots of two contrasting Eucalyptus genotypes. Next, we explore the factors that directly influence the growth and depth of these roots, addressing elements such as soil type, climate, and water availability. Lastly, we investigate how the variation in Eucalyptus species may impact root growth patterns, biomass, and carbon stock. In this study, we observed that the maximum root depth increased by an average of 20% when genotypes were grown on sites with higher water availability (wet site). E. urophylla stands had a higher biomass and carbon stock (5.7 Mg C ha⁻¹) of fine roots when cultivated on dry sites (annual rainfall~727 mm) than the wet sites (annual rainfall~1590 mm). In E. grandis × E. camaldulensis stands, no significant differences were observed in the stock of fine root biomass (3.2 Mg C ha⁻¹) between the studied environments. Our results demonstrated that genotypes with greater drought tolerance (E. grandis × E. camaldulensis) tend to maintain higher stocks of fine root biomass (3.2–6.3 Mg ha⁻¹) compared to those classified as plastic (E. urophylla), regardless of the edaphoclimatic conditions of the cultivation site. Finally, our research helps understand how Eucalyptus trees adapt to their environment, aiding sustainable forest management and climate change mitigation. We also provide a practical tool to estimate underground biomass, assisting forest managers and policymakers in ensuring long-term forest sustainability.

The establishment of forest stands after harvest requires an understanding of biomass and nutrient dynamics to support management decisions and ensure system productivity and sustainability. This study evaluated biomass and nutrient accumulation in Eucalyptus urophylla aged 2 to 5 years under planting and coppicing systems. A total of 1152 trees were assessed across eight treatments, combining four ages and two management systems. Aboveground biomass was estimated using 10 trees per treatment, while root biomass was assessed in 8 trees at ages 3 and 5. Nutrient concentrations were determined using three intermediate-diameter class trees per treatment. Biomass data were analyzed using Tukey’s test (5%), and biomass expansion factors (BEF) and the root-to-shoot ratio (R) were used to estimate root carbon. Total biomass was higher in the coppicing system (153 Mg ha⁻¹) compared to the planting system (119 Mg ha⁻¹), with greater root accumulation and carbon sequestration (≈17.2 t C ha⁻¹). The biological use coefficient (BUC) increased with age, except for Mn. Planted stands showed higher BUC for N and P, while coppiced stands were more efficient in Mg use. These results reinforce the need for distinct fertilization strategies for each system, aiming at productivity, nutrient efficiency, and carbon stock enhancement.

O objetivo deste estudo foi avaliar as condições ecogeográficas e edafoclimáticas dos ambientes de ocorrência da erva-baleeira (Varronia curassavica) nas mesorregiões Norte e Vale do Jequitinhonha de Minas Gerais. O estudo foi efetuado em 15 sítios de ocorrência dessa espécie, localizados em 14 municípios sob o bioma Cerrado e ocorreu nos tipos de vegetação Cerrado, Caatinga, restinga e floresta. Os sítios estão localizados predominantemente entre 495 e 895m de altitude, e as plantas localizam-se sempre na parte inferior da topossequência. A precipitação média anual variou de <1.000mm a 1.500mm e a temperatura média anual variou de <19 a 24°C. A espécie tolera solos fortemente ácidos e com alta saturação de alumínio, ocorrendo em diferentes níveis de fertilidade e classes de solo. Nas mesorregiões Norte e Vale Jequitinhonha de Minas Gerais, a erva-baleeira não apresentou condições ecogeográficas e edafoclimáticas específicas para a sua ocorrência

Varronia curassavica (Jacq.) is a shrub and perennial plant native to Brazil that has therapeutic, anti-inflammatory and cicatrizing properties. The objective of this work was to study the chemical diversity of the native populations of this species maintained in the in vivo germplasm bank from Montes Claros, Minas Gerais, Brazil. The essential oils of 10 accessions analyzed in triplicate were obtained by hydrodistillation. Fifty-five compounds were detected, 46 of which were identified by GC-MS analysis. Essential oil yield ranged from 0.1 (VC-9) to 1.22% (VC-3) among the studied accessions. Three groups were formed by cluster analysis. Group A presented lower relative abundance of the compounds α-humulene (1.4%) and β-caryophyllene (8.5%). Conversely, in Group B, the most abundant compound was α-humulene (31.6%). Group C, with the greatest number of accessions, presented values of up to 6.1 and 41.2% for α-humulene and β-caryophyllene, respectively. Only two accessions (VC-1 and VC-5) presented α-humulene content lower than that recommended for phytotherapeutic production. These results, along with consolidating breeding programs, contribute to the conservation of the species.