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Phosphorus (P) is one of the most limiting nutrients for plant species and its intensive use can exhaust world reserves. In general, forest production is unviable without the availability of P. The objective of the study was to determine the effect of phosphate fertilization on plant growth of four families of lemon eucalyptus (Corymbia citriodora). Plants produced from seeds of four seed trees were used, which were subjected to seven doses of phosphorus: 0, 25, 50, 75, 100, 125 and 150 mg P dm-3. The experiment was carried out in a 7 × 4 factorial arrangement, with four replicates and using containers with 5 dm3 of a Red Eutropheric Latosol type soil. The response variables measured were monthly plant height, plant collar diameter at 90 d, dry biomass weight of leaves, roots, stems and branches, and phosphorus use efficiency of leaves. The variations of the characteristics evaluated as a function of phosphorus concentration were analysed by means of polynomial regression equations. Phosphate fertilization is necessary for the growth and development of C. citriodora plants. Plants of the four C. citriodora seed trees from different provenances responded differentially to phosphorus doses. It was found that the optimum amount of phosphorus ranges between 30 and 100 mg dm-3 according to the characteristics evaluated and the seed tree.

The accelerated aging test is efficient for evaluating the seed vigor of many species, but there are few studies on forest tree species. The aim of this study was to determine the adequate exposure time of Piptadenia moniliformis Benth. seeds to the accelerated aging test in order to evaluate the vigor of seeds classified by color and size. Ten sub-lots were obtained by separating the seeds into two tegument colors (light and dark) and five size classes (11, 12, 13, 14, and 15), using round wire sieves. Before the accelerated aging (AA) test, the seeds were treated with concentrated sulfuric acid for 20 minutes to overcome dormancy. Next, the sub-lot seeds underwent different aging times (0, 24, 48, 72, 96 and 120 hours) at 45 ºC. The AA test, conducted at 45 ºC for 72 hours, is adequate to evaluate the quality of P. moniliformis seeds, in terms of color and size.

Made available in DSpace on 2021-06-25T10:20:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 The survival, initial productivity, and the genetic parameters of Corymbia citriodora subsp. citriodora (CCC), Corymbia citriodora subsp. variegata (CCV), and Corymbia torelliana (CT) were used to develop a breeding strategy for the Corymbia species. Survival, height, and diameter at breast height (DBH) data were assessed 24 and 36 months after planting, and the mean annual volume increment was estimated in three trials. Longitudinal DBH data analysis was applied individually to each trial to identify the best and the poorest families at both ages. The mortality ranged from 5% in CT to 27% in CCC, and the mean annual increment varied from 17.8 to 20 m3·ha 1·year 1 at 36 months after planting. The 36-month narrow-sense heritability (h2a) was high for CCV (0.69 6 0.17), moderate for CCC (0.41 6 0.11), and low for CT (0.21 6 0.09). The genetic parameters indicated the need for different breeding strategies for each species. Selecting the best families while roguing the poor families allowed forward selection of CCC and CCV. It was possible to select good CT trees for hybrid breeding; however, improving the species population requires focusing on increasing the effective size and expanding the genetic variability in the CT population. São Paulo State University (Unesp) School of Agricultural and Veterinary Sciences, Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane, Km 5 Forest Industries Research Centre University of the Sunshine Coast, Maroochydore DC Midwestern State University (UNICENTRO) Sector of Agricultural and Environmental Sciences (SEAA/I), Rua Professora Maria Roza Zanon de Almeida Engenheiro-Gutierrez Forest Science and Research Institute (IPEF), Via Comendador Pedro Morganti, 3500 Bairro Monte Alegre São Paulo State University (Unesp) School of Agricultural and Veterinary Sciences, Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane, Km 5

Made available in DSpace on 2021-06-26T08:03:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-15 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) In general, genetic improvement programs for Eucalyptus seek to increase productivity. Diallelic methods are commonly used in crossbreeding designs, but few studies use this methodology to assess competitive ability. The aim of this study was to estimate the competitive capacity and effects of intra- and inter-genotypic in Eucalyptus spp. clones and identify combinations that support increased productivity. To do this, 12 commercial clones were evaluated in a competitive trial located in Tres Lagoas, Mato Grosso do Sul State, Brazil, established in a randomized block design, with three replicates and five plants per plot. Data for the mean annual increment (MAI) obtained at five years of age were assessed using two statistical approaches. Groups were classified according to specific (ability of the two clones to compete each other) and general competitive ability (average ability of a clone to compete with others). There were differences in the genotypes' ability to suffer or exercise competition. The results obtained showed the best combinations resulted in up to 10% increase in productivity. That combined use of diallelic analysis with the statistical approach which allows for the assessment of the effects of intraand inter-clonal competition, may be useful for Eucalyptus spp. improvement programs, especially in terms of identifying the best combinations for planting when the objective is to obtain gains in crop productivity. Sao Paulo State Univ UNESP, Sch Nat Sci & Engn, Brasil Ave 56, BR-15385000 Ilha Solteira, SP, Brazil Suzano Papel & Celulose, Antonio Trajano Santos 100, BR-79601901 Tres Lagoas, MS, Brazil ArborGen, Dr Emilio Ribas 174, BR-13025140 Campinas, SP, Brazil Sao Paulo State Univ UNESP, Sch Agr & Veterinarian Sci, Prof Paulo Donato Castellane S-N, BR-14884900 Jaboticabal, SP, Brazil Sao Paulo State Univ UNESP, Sch Nat Sci & Engn, Brasil Ave 56, BR-15385000 Ilha Solteira, SP, Brazil Sao Paulo State Univ UNESP, Sch Agr & Veterinarian Sci, Prof Paulo Donato Castellane S-N, BR-14884900 Jaboticabal, SP, Brazil CAPES: 001

Made available in DSpace on 2019-10-05T21:44:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01. Added 1 bitstream(s) on 2019-10-09T18:34:39Z : No. of bitstreams: 1 S1984-70332019000100047.pdf: 423506 bytes, checksum: ea72b5912d886934c29aaf349518ea52 (MD5) The objective was to select productive and stable E. grandis families across contrasting sites in Brazil and Uruguay. Survival and growth of 130 open pollinated families were evaluated three years after planting. Survival ranged from 28 to 89% and mean annual increment from 20.5 to 48.4 m(3)ha(-)y(-1). Low productivity in one site was attributed to unusually low rainfall and in the other, because of Cylindrodadium leaf disease. Heritability among families and the correlation family by environment were intermediate. Genetic pairwise correlations ranged from 0.03 to 0.81 across sites. The lowest genetic correlation between sites was observed where Cylindrocladium leaf disease occurs. Selection of top families across sites allowed selecting the best ones in each site. However, the effect of genotype-environment interactions was observed where climatic conditions are not adequate to the E. grandis, favoring the occurrence of Cylindrocladium disease. Inst Pesquisas & Estudos Florestais, BR-13415000 Piracicaba, SP, Brazil Univ Estadual Paulista, BR-18603970 Botucatu, SP, Brazil Estn Expt Agr Concordia, CC 34,E3200AQK, Concordia, Entre Rios, Argentina Univ Sunshine Coast, Forest Ind Res Ctr, Maroochydore DC 4558, Sippy Downs, Qld, Australia Univ Estadual Paulista, BR-15385000 Ilha Solteira, SP, Brazil Univ Estadual Paulista, BR-14884900 Jaboticabal, SP, Brazil Univ Estadual Paulista, BR-18603970 Botucatu, SP, Brazil Univ Estadual Paulista, BR-15385000 Ilha Solteira, SP, Brazil Univ Estadual Paulista, BR-14884900 Jaboticabal, SP, Brazil

Seed germination and seedling development are strongly influenced by water availability and temperature, therefore, knowledge of the tolerance limits against these factors can generate subsidies to improve the multiplication and conservation strategies of native tree species. This study evaluates the effects of water stress on the germination of Tabebuia roseoalba, Handroanthus chrysotrichus, and H. impetiginosus seeds at two temperatures. Germination was performed on paper rolls moistened with polyethylene glycol (PEG 6000) solutions for the osmotic potentials of 0 (water);-0.05;-0.10;-0.15;-0.20;-0.30;-0.40;-0.60;-0.80 and-1.00 MPa. Germination tests were conducted at 25 and 30 °C, under 8 h photoperiod. Statistical analyses for each studied species followed a randomized complete block design, in a 2 × 10 split-plot scheme (plots - two temperatures and subplots - ten water potentials). The percentage of germination and normal seedlings, as well as the germination speed and synchronization indexes, were evaluated. The germination of T. roseoalba, H. chrysotrichus, and H. impetiginosus seeds decreased with increasing water deficit and at higher rates when associated with higher temperatures. The results demonstrate that the species sensitivity to water deficits induced by PEG 6000, increases with rising temperatures. T. roseoalba and H. chrysotrichus exhibited a germination tolerance range between-0.80 and-1.00 MPa. Furthermore, H. impetiginosus is more sensitive and displayed a tolerance range between-0.60 and-0.80 MPa. RESUMO A água e a temperatura influenciam na germinação de sementes e no desenvolvimento de plântulas. O conhecimento dos limites de tolerância frente a estes fatores, pode gerar subsídios para melhorar as estratégias de multiplicação e conservação das espécies arbóreas nativas. Objetivou-se avaliar os efeitos do estresse hídrico na germinação de sementes de Tabebuia roseoalba, Handroanthus chrysotrichus e H. impetiginosus sob duas temperaturas. A germinação foi realizada em rolos de papel, umedecidos com soluções aquosas de polietilenoglicol (PEG 6000) nos potenciais hídricos de 0 (água);-0,05;-0,10;-0,15;-0,20;-0,30;-0,40;-0,60;-0,80 e-1,00 MPa. Os testes de germinação foram conduzidos a 25 e 30 °C, sob fotoperíodo de 8 h. As análises estatísticas foram realizadas separadamente por espécie, segundo o delineamento experimental de blocos casualizados, em esquema de parcelas subdivididas 2 × 10 (duas temperaturas nas parcelas e dez potenciais hídricos nas subparcelas). Avaliou-se a porcentagem de germinação e de plântulas normais, e os índices de velocidade e de sincronização da germinação. A germinação de sementes de T. roseoalba, H. chrysotrichus e H. impetiginosus diminui com o aumento do déficit hídrico e em maior proporção, quando esse está associado a temperaturas mais elevadas, demonstrando que a sensibilidade das espécies frente ao estresse hídrico induzido por PEG 6000, aumenta com a elevação da temperatura. A faixa limite de tolerância para a germinação de sementes de T. roseoalba e H. chrysotrichus se situa entre-0,80 e-1,00 MPa; H. impetiginosus é mais sensível, com limite de tolerância entre-0,60 e-0,80 MPa.

Made available in DSpace on 2022-04-28T19:44:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-10-01 For continuous genetic gains over time, a balance between genetic gain and maintaining the genetic base must be a constant concern of forest breeders. This study aims at determining the best thinning strategies for a population of Eucalyptus dunnii, by incorporating the effects of environmental heterogeneity and competition in the analysis, as well as the best growth trait regarding precision and accuracy. The population studied consisted of 160 open-pollinated families. The survival and growth (height, HT; diameter at breast height, DBH; and volume, VOL) were evaluated 4 years after planting. The growth rate data were analyzed and compared by four mixed models. Selection and thinning strategies were simulated by varying the number of families, individuals within families, and selected individuals, considering the estimated genetic gains and the effective size. The species showed good survival (89.7%) and productive performance (mean annual increment = 42 m3 ha−1 y−1). The Spatial+Competition Model provided the best fit for DBH and VOL. The strategies that allow a balance between improvement (genetic gains) and genetic conservation (effective size) consist of keeping 36 to 50% of the individuals in the test (370 to 510 trees ha−1), by reducing more intensively the number of individuals from the worst-performing families. The selection of 100 individuals with a restriction of at most one individual per family generates the largest number of effective size (Ne), with more than double the Ne obtained without restricting the individuals per family, with a small drop in genetic gain. IPEF – Instituto de Pesquisas e Estudos Florestais, Via Comendador Pedro Morganti, 3500 Bairro Monte Alegre Faculdade de Ciências Agrarias e Veterinárias (FCAV) Universidade Estadual de São Paulo Julio de Mesquita Filho (Unesp) Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane, Km 5 Universidade Federal do Tocantins UFT- Campus de Gurupi Laboratório de Silvicultura e Melhoramento Florestal Palmasola S/A Madeiras e Agricultura Av. Claudino Crestani, 515 - Centro Escola Superior de Agriculutra Luiiz de Queiroz Universidade de São Paulo, Av. Pádua Dias 11 Universidade Estadual de São Paulo (UNESP/Botucatu), Rua José Barbosa de Barros, 1780, CP 237 Faculdade de Ciências Agrarias e Veterinárias (FCAV) Universidade Estadual de São Paulo Julio de Mesquita Filho (Unesp) Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane, Km 5 Universidade Estadual de São Paulo (UNESP/Botucatu), Rua José Barbosa de Barros, 1780, CP 237

The electrical conductivity test (EC) used to evaluate seed vigor is directly related to the integrity of cell membranes, but its use in forest species is still restricted. Thus, the objective of this study is to analyze the efficiency of the EC test to evaluate physiological parameters regarding seed quality and the genetic variability among Handroanthus serratifolius mother trees. Seeds from 15 mother trees were evaluated for germination (G%) and germination speed index (GSI). In the EC test, the seeds were imbibed in two water volumes (75 and 100 mL) at 20 and 25 °C, and the electrical conductivity was measured after five imbibition periods (24, 48, 72, 96, and 120 h). The germination test data were submitted to a randomized block design (RBD) analysis of variance and means were compared by the Scott-Knott test. The EC test was conducted as an RBD in a split-split plot scheme, with interaction unfolding by polynomial regression analysis. The mother trees were divided into four groups regarding G% and SGI. The EC test separated the mother trees into a larger number of groups, regardless of temperature, volume, and imbibition period. In conclusion, the EC test consisting of imbibition 25 seeds in 75 mL of deionized water at 20 °C for 48 h is suitable for evaluating the physiological quality of seeds and the variability among mother trees of Handroanthus serratifolius (Vahl) S. O. Grose. RESUMO - O teste de condutividade elétrica (CE) na avaliação do vigor das sementes relaciona-se diretamente com a integridade das membranas celulares e seu uso em espécies florestais é, ainda, restrito. Assim, objetivou-se analisar a eficiência desse teste na avaliação da qualidade fisiológica de sementes e da variabilidade entre árvores matrizes de Handroanthus serratifolius. Sementes de 15 matrizes foram avaliadas quanto à germinação (G%) e ao índice de velocidade de germinação (IVG). No teste de CE foram estudados dois volumes de água (75 e 100 mL) e cinco períodos de embebição (24, 48, 72, 96 e 120 h) das sementes, a 20 e 25 °C. Os dados do teste de germinação foram submetidos à análise de variância em delineamento de blocos casualizados (DBC), seguido de comparação de médias pelo teste de Scott-Knott, e os do teste de CE foram analisados em DBC em esquema de parcelas sub-subdivididas, com desdobramento da interação por análise de regressão polinomial. As matrizes foram divididas em quatro grupos quanto a G% e IVG. O teste de condutividade elétrica separou as matrizes em maior número de grupos, independentemente da temperatura, volume e período de embebição. O teste de CE conduzido a 20 °C, com 25 sementes embebidas em 75 mL de água desionizada por 48 h é adequado para a avaliação da qualidade fisiológica de sementes e da variabilidade entre matrizes de Handroanthus serratifolius (Vahl) S. O. Grose.

Made available in DSpace on 2020-12-12T01:33:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-11-01 Understanding the mechanisms governing drought tolerance in highly productive clonal Eucalyptus plantations in Brazil will become increasingly important with climate change driven increases in temperature and drought events. We quantified how leaf water potential, hydraulic safety margin (mid-day – pre-dawn leaf water potential, Ψδ) and the physiological parameters obtained from standard pressure–volume curves differed between four contrasting Eucalyptus genotypes across a temperature and water availability gradient in Brazil. We hypothesized that genotypes developed in dry areas were more drought tolerant and would exhibit lower mid-day leaf water potentials and turgor loss points than clones developed in wetter regions. Recognizing that standard pressure volume curves are time consuming and may not be a suitable screening tool for forest managers, we also tested if a key physiological parameter from the pressure–volume curve (turgor loss point, πtlp) could be accurately estimated from an osmometer as has been found in other species. We found no support for our first hypothesis; physiological parameters determined (including turgor loss point) from the pressure volume curves were not associated with the supposed drought tolerance of any of the clones. Similarly, mid-day leaf water potentials were not directly correlated with drought tolerance. The lack of support for our hypothesis may be because our measurements were taken during periods of minimum water stress. However, we did find that, overall, turgor loss point tended to be lower at the dry compared to wetter sites we studied suggesting that it may be a useful tool for assessing drought tolerance of Eucalyptus plantations in the future. We also found that estimates of osmotic potential at full turgor were similar between the pressure volume curve and osmometer techniques and that turgor loss point can be accurately estimated with an osmometer in highly productive Eucalyptus genotypes (R2 = 0.79). São Paulo State University (Unesp) College of Agricultural Sciences Federal Rural University of Pernambuco – UFRPE USDA Forest Service Rocky Mountain Research Station São Paulo State University (Unesp) College of Agricultural Sciences

Made available in DSpace on 2020-12-12T02:29:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-09-01 Recently, pest occurrence in forest plantations has been increasing influenced by genotypes and environmental conditions such as climate change, thus impacting production negatively. In 2008, the exotic pest Leptocybe invasa (Hym: Eulophidae), known as the blue gum chalcid, was introduced in Brazil causing damage to eucalypt plantations in many regions of the country. To this end, this study evaluated the susceptibility of Eucalyptus camaldulensis (one seedlot), E. grandis (four seedlots), E. urophylla (four seedlots), and the “E. urograndis” hybrid (E. urophylla × E. grandis) (three seedlots) exposed to a natural infestation by L. invasa in two seasons (winter and summer). The attack on seedlings was classified in terms of severity as healthy (no pest attack), oviposition (only oviposition signs) and gall formation. The results show a significant higher pest incidence in summer compared to winter. Further, Eucalyptus urophylla was the least attacked and 90% of the seedlings were healthy whereas E. grandis showed the highest number of seedlings with galls. The E. urograndis hybrid showed intermediate results between the two species. Differences in susceptibility were observed between seedlots within species. Eucalyptus camaldulensis, which was expected to have the highest incidence of galls, had a high oviposition incidence (60%) and low gall incidence (< 10%), probably due to its provenance. The susceptibility of the different eucalypt families varied significantly with respect to L. invasa infestation, and family heritability ranged from 0.27 to 0.68. The genetic control of L. invasa is possible through the selection of tolerant and resistant material, considering the species, provenance, and family. Forest Science and Research Institute (IPEF), Via Comendador Pedro Morganti, 3500 - Bairro Monte Alegre School of Agriculture São Paulo State University (Unesp), Rua José Barbosa de Barros, nº 1780, C. P. 237 Escola Superior de Agricultura “Luiz de Queiroz”/Universidade de São Paulo, Avenida Pádua Dias 11, Caixa Postal 9 School of Agricultural and Veterinarian Sciences São Paulo State University (Unesp), Via de Acesso Prof. Paulo Donato Castellane, km 5 School of Engineering São Paulo State University (Unesp), Av. Brasil Centro, 56, C. P. 31 School of Agriculture São Paulo State University (Unesp), Rua José Barbosa de Barros, nº 1780, C. P. 237 School of Agricultural and Veterinarian Sciences São Paulo State University (Unesp), Via de Acesso Prof. Paulo Donato Castellane, km 5 School of Engineering São Paulo State University (Unesp), Av. Brasil Centro, 56, C. P. 31

Made available in DSpace on 2018-12-11T16:54:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-05-01. Added 1 bitstream(s) on 2019-10-09T18:29:49Z : No. of bitstreams: 1 S0100-204X2018000500611.pdf: 789670 bytes, checksum: 0030acbf3f4f5d4a690887652ffe3235 (MD5) The objective of this work was to evaluate the genotype x environment (GxE) interaction in openpollinated Eucalyptus saligna progenies for simultaneous selection for greater stability and adaptability for wood volume, as well as to compare the selection strategies through combined and individual analyses in three environments. Three experiments were conducted in a randomized complete block design, with four replicates and six plants per plot, with 102 to 122 progenies. Three years after planting, survival rate and wood volume were evaluated. The genetic parameters were estimated by the maximum restricted likelihood and best linear unbiased prediction (REML/Blup) methods, and the stability and adaptability analysis was conducted using the harmonic mean of the relative performance of genetic values (HMRPGV). The highest survival rate (82%) was observed in Sabinópolis and the highest volume (120 m3 ha-1) in Lençóis Paulista. The mean heritability of progenies for the two analyzed variables was considered high, and the genetic correlations between survival rate and volume were weak for all sites. The G×E interaction was significant and of the complex type, with genotype correlation between sites of 47%, indicating that the ranking of the best progenies differed in each studied environment. The analysis of stability and adaptability indicated the possibility of selecting progenies with good performance in the three environments; however, to improve the quality of the evaluated characteristics, it is necessary to select specific progenies for each environment. O objetivo deste trabalho foi avaliar a interação genótipo x ambiente (GxA) em progênies de polinização aberta de Eucalyptus saligna, para seleção simultânea para maior estabilidade e adaptabilidade para volume de madeira, bem como comparar as estratégias de seleção por análises conjunta e individuais em três ambientes. Foram instalados três experimentos, em delineamento de blocos ao acaso, com quatro repetições e parcelas de seis plantas, com 102 a 122 progênies. Três anos após o plantio, foram avaliados a taxa de sobrevivência e o volume de madeira. Os parâmetros genéticos foram estimados pelos métodos da máxima verossimilhança restrita e melhor predição linear não viciada (REML/Blup), e a análise de estabilidade e adaptabilidade foi realizada pela média harmônica do desempenho relativo dos valores genéticos (MHPRVG). A maior taxa de sobrevivência (82%) foi observada em Sabinópolis e o maior volume (120 m3 ha-1) em Lençóis Paulista. As herdabilidades médias das progênies para as duas variáveis avaliadas foram consideradas altas, e as correlações genéticas entre taxa de sobrevivência e volume foram baixas para todos os locais. A interação GxA foi significativa e do tipo complexa, com correlação genotípica entre ambientes de 47%, o que indica que o ordenamento das melhores progênies foi diferente para cada local estudado. A análise de estabilidade e adaptabilidade indicou a possibilidade de selecionar progênies com comportamento plástico nos três ambientes; contudo, para melhoria da qualidade das características avaliadas, é necessária a seleção de progênies específicas para cada ambiente. Universidade Federal do Paraná Departamento de Ciências Florestais, Avenida Prefeito Lothário Meissner, no 900 Universidade Estadual Paulista (Unesp) Faculdade de Ciências Agrárias e Veterinárias Campus Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane, s/no Universidade Estadual Paulista (Unesp) Faculdade de Engenharia Campus de Ilha Solteira, Avenida Brasil Sul, no 56, Centro Suzano Papel e Celulose, Avenida Dr. José Lembo, no 2.215, Jardim Bela Vista Suzano Papel e Celulose Unidade Mucuri, BR 101, Km 945,5, Caixa Postal 63 Instituto de Pesquisa e Estudos Florestais, Via Comendador Pedro Morganti, no 3.500 Universidade Estadual Paulista (Unesp) Faculdade de Ciências Agrárias e Veterinárias Campus Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane, s/no Universidade Estadual Paulista (Unesp) Faculdade de Engenharia Campus de Ilha Solteira, Avenida Brasil Sul, no 56, Centro

Made available in DSpace on 2018-12-11T17:17:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 Eucalyptus plants are sensitive to abiotic stresses in their initial growth, and nutritional deficiency is one of the most recurrent among them. Trinexapac-ethyl, which is a plant growth regulator, can positively affect eucalyptus, a response known as hormesis, possibly providing plants with greater tolerance to stress. The objective of this study was to evaluate the effect of trinexapac-ethyl at two application times, before planting (BP) or after planting (AP), in Eucalyptus urophylla under conditions of nutritional deficiency (NPK). Two experiments (one for each application time) were conducted simultaneously during 81 days after planting of eucalyptus in 15 L pots. The treatments consisted of three doses of trinexapac-ethyl (0, 30, and 60 g a.i.·ha−1) and four variations of nutrient supply: complete solution (NPK) and solutions without nitrogen (−N), without phosphorus (−P), and without potassium (−K). The variables of gas exchange, growth, and dry matter were evaluated. For both application times, trinexapac-ethyl had a positive effect on the root–shoot ratio of plants grown in −N and also positively affected some eucalyptus photosynthetic characteristics. In the AP application, the compound provided gains in height and dry matter, regardless of the nutrient supply. Under phosphorus deficiency, trinexapac-ethyl provided gains in total dry matter (BP) and leaf area (AP). Sao Paulo State University UNESP/FCAV Department of Biology Applied to Agriculture, Via de Acesso Prof. Paulo Donato Castellane, s/n Sao Paulo State University UNESP/FCAV Department of Plant Production, Via de Acesso Prof. Paulo Donato Castellane, s/n Bairro Rural Sao Paulo State University UNESP/FCAV Department of Biology Applied to Agriculture, Via de Acesso Prof. Paulo Donato Castellane, s/n Sao Paulo State University UNESP/FCAV Department of Plant Production, Via de Acesso Prof. Paulo Donato Castellane, s/n Bairro Rural

Made available in DSpace on 2022-04-30T03:18:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-01-01 Weeds play a strong pressure on the eucalyptus early growth, leading to a delay in their development. Therefore, many studies have tried to identify eucalyptus clones that are more tolerant to weed competition to supply information to producers, genetic improvement programs and the scientific community. The objective of this study was evaluate the interference of signal grass (Urochloa decumbens) and guinea grass (Panicum maximum) in the early growth of six clones of Eucalyptus urograndis, as well as the reciprocal effect. The experiment was conducted in an open and semi-controlled area in 8-L pots using a completely randomized experimental design with a 3 x 6 factorial scheme (U. decumbens, P. maximum and weed-free control and six eucalyptus clones). After ninety days of planting, the following variables were measured: eucalyptus stem diameter, height, total chlorophyll concentration, chlorophyll fluorescence (Fv/Fm), net assimilation rate and eucalyptus and weed dry biomass. In coexistence with Guinea grass (Panicum maximum), clone 3 (ms 709 H) exhibited a 78.2% reduction in dry biomass compared to clone 4 (C 219 H), which obtained the highest dry biomass. In coexistence with signal grass (Urochloa decumbens), clone 6 (ms 686 H) was the most negatively affected by weed competition, with an 80.7% lower dry biomass than clone 4. In general, clones 1 (ms 710 H), 2 (H 1069) and 4 were more resistant, and clones 3 and 6 were more sensitive to weed interference. Both weeds were affected by eucalyptus, but Guinea grass was more sensitive than signal grass. Universidade de São Paulo Escola Superior de Agricultura Luiz de Queiroz, Avenida Pádua Dias, 11 Universidade Estadual Paulista Júlio de Mesquita Filho Departamento de Biologia Aplicada à Agropecuária, Via de Acesso Prof. Paulo Donato Castellane, s/n Rural Universidade Estadual Paulista Júlio de Mesquita Filho Departamento de Produção Vegetal, Via de Acesso Prof. Paulo Donato Castellane, s/n Rural Universidade Estadual Paulista Júlio de Mesquita Filho Departamento de Biologia Aplicada à Agropecuária, Via de Acesso Prof. Paulo Donato Castellane, s/n Rural Universidade Estadual Paulista Júlio de Mesquita Filho Departamento de Produção Vegetal, Via de Acesso Prof. Paulo Donato Castellane, s/n Rural

Handroanthus heptaphyllus (lapacho negro) es una especie arbórea de alto valor económico, principalmente por la calidad de su madera; además tiene uso medicinal y en proyectos paisajísticos para arborización urbana. El presente trabajo tuvo como objetivos determinar la variabilidad genética entre árboles de H. heptaphyllus a partir de caracteres de calidad fisiológica de semillas, evaluados en ensayos de germinación y vigor; e identificar las variables más influyentes para la diversidad genética entre árboles. Las semillas fueron recolectadas de 25 árboles madre, localizados en la ciudad de Jaboticabal, San Paulo, Brasil. Se evaluaron 11 caracteres de calidad fisiológica de semillas, mediante ensayos de germinación, conductividad eléctrica, envejecimiento acelerado e inmersión. Se utilizaron cinco repeticiones de 20 semillas por cada árbol madre. La diversidad genética se evaluó utilizando el método jerárquico de Ward y la dispersión por componentes principales, a partir de la distancia euclidiana calculada entre los pares de accesos. La variabilidad genética entre los árboles resultó expresiva. El valor pico y la conductividad eléctrica fueron las características más efectivas para la diferenciación de los árboles. El análisis de componentes principales detectó semejanzas y diferencias entre los árboles, basadas en las características evaluadas, y se mostró coherente con los agrupamientos del método de Ward. El valor pico de la germinación, el índice de sincronización del proceso germinativo y la longitud de las plántulas fueron las que presentan mayor diversidad. Estos resultados permiten identificar árboles para la recolección de semillas, dando soporte a programas de conservación y mejoramiento genético de la especie.

Made available in DSpace on 2020-12-10T19:36:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-09-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The efficiency of methods in adequately interpreting the nutritional status of Eucalyptus spp. rooted cuttings remains unknown. The aim was to evaluate the quality of diagnoses obtained using the critical level (CL), diagnosis and recommendation integrated system (DRIS) and compositional nutrient diagnosis (CND) methods to assess the nutritional status of Eucalyptus spp. rooted cuttings, based on two different yield indicators. The data were obtained from commercial nursery and calibration experiments, using seven nutrients as treatments (N, P, K, Mg, Ca, B and Fe) and four concentrations per nutrient, arranged in randomized blocks, with four repetitions. The Eucalyptus spp. clone used in the experiments was AEC 0144. A total of 222 rooted cuttings were obtained from the experimental area and commercial nurseries and the following were determined: leaf nutrient content, whole plant dry matter (DM) content and the Dickson quality index (DQI). Diagnostic accuracy in the experimental plots was ascertained by comparing the diagnosis with plant response as a function of adding the corresponding nutrient. Five measures of accuracy were used to test the efficiency of the diagnostic methods: total accuracy, accuracy for deficiency and sufficiency, deficiency ratio, efficiency ratio, and the net increase in in DM and DQI. The performance of diagnostic methods varied between CL, DRIS and CND, and among the nutrients studied. Given that the seedling production system is largely more controlled, where environmental variations are minimal, and considering that the different diagnostic methods exhibited distinct performance in terms of assessing the true nutritional status of eucalyptus rooted cuttings, the CL method is the most indicated for this situation, due to its better performance in evaluating the nutritional status of most nutrients and easy implementation. Sao Paulo State Univ Julio de Mesquita Filho, Dept Soils & Fertilizers, BR-14884900 Jaboticabal, Brazil Embrapa Rondonia, BR-76815800 Porto Velho, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Plant Prod, BR-14884900 Jaboticabal, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Soils & Fertilizers, BR-14884900 Jaboticabal, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Plant Prod, BR-14884900 Jaboticabal, Brazil

Made available in DSpace on 2019-10-06T15:29:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Universidade de São Paulo To identify stable and productive Eucalyptus urophylla S.T. Blake families across diverse climate zones in Brazil, we evaluated growth and survival of 322 open-pollinated families derived from 13 genetically improved seed sources in 10 trials across the country. Survival and growth data were analyzed using linear mixed models and REML/BLUP. Survival ranged from 51% to 92%, and the mean annual increment varied from 19 to 46 m 3 ·ha −1 ·year −1 . Although planted in suitable climatic zones, some trials had low survival and (or) productivity. Conversely, the highest productivity was recorded in a zone considered to be of low suitability. These results show the importance of assessing the climatic requirements of eucalypts beyond those determined from analyses of their natural distribution, especially when testing already improved seed sources. A number of productive and stable families were identified based on analysis of the interaction between genotype and environment, and from these, 144 individuals were selected and had their genetic diversity estimated using 19 microsatellite DNA markers. The genetic diversity of these selected trees was equivalent to that observed in previous studies of natural populations of E. urophylla, indicating that breeding programs of E. urophylla in Brazil still retain high levels of diversity for sustainable genetic gains. Instituto de Pesquisa e Estudo Florestais (IPEF) Via Comendador Pedro Morganti, 3500 – Bairro Monte Alegre, CEP School of Agriculture São Paulo State University (Unesp) Botucatu Rua José Barbosa de Barros, n° 1780, C.P. 237, CEP Escola Superior de Agricultura “Luiz de Queiroz”/Universidade de São Paulo Avenida Pádua Dias 11, Caixa Postal 9, CEP APSD – Ghana, Plot 27, Block 27 Escola Superior de Agricultura “Luiz de Queiroz”/Universidade de São Paulo, Avenida Pádua Dias 11, Caixa Postal 9, CEP School of Engineering São Paulo State University (Unesp) Ilha Solteira, Av. Brasil Centro, 56, C.P. 31, CEP Plant Genetics Laboratory EMBRAPA Genetic Resources and Biotechnology, CEP Graduate Program in Genomic Sciences and Biotechnology Universidade Católica de Brasília, SGAN Qd 916, CEP School of Agricultural and Veterinarian Sciences São Paulo State University (Unesp) Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane, km 5, CEP School of Agriculture São Paulo State University (Unesp) Botucatu Rua José Barbosa de Barros, n° 1780, C.P. 237, CEP School of Engineering São Paulo State University (Unesp) Ilha Solteira, Av. Brasil Centro, 56, C.P. 31, CEP School of Agricultural and Veterinarian Sciences São Paulo State University (Unesp) Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane, km 5, CEP FAPESP: 15/15651-2

Eucalyptus plants are sensitive to stress during their initial development, and water deficit is the most important one. Thus, the hormetic effect caused by the application of chemical products may be a factor that allows plants to tolerate such stresses. The objective of this study was to evaluate the effects of trinexapac-ethyl on the initial growth of Eucalyptus urophylla (Clone I-144), under water deficiency, at two application timings (before planting - BP; and after planting - AP). Two experiments were conducted simultaneously in a greenhouse for 74 days after planting (DAP) eucalyptus in 15 L pots. Treatments consisted of three trinexapac-ethyl doses (0.0, 30, and 60 g a.i. ha-1) and two water conditions (with and without water deficit). A complete randomized block design was used, in a 3 x 2 factorial arrangement, with five replications. At the BP application timing, trinexapac-ethyl was sprayed at 0 DAP, and at the AP timing, at 24 DAP. In both experiments, plant height, diameter, leaf area, dry matter, total relative chlorophyll content and gas-exchange were evaluated. There was a positive effect for the net CO2 assimilation rate at 27 and 40 DAP, for AP and BP, respectively. Eucalyptus plants, without water deficit, presented higher growth, regardless of the application timing. In conclusion, the application of trinexapac-ethyl before planting caused a positive effect on the height and diameter of eucalyptus; and the application timing influenced, in different ways, the evaluated characteristics, not having harmful effects on any of them. RESUMO: Plantas de eucalipto são sensíveis a estresses durante o desenvolvimento inicial, sendo a deficiência hídrica o mais importante entre eles. Assim, o efeito hormético ocasionado pela aplicação de produtos químicos pode ser um fator que proporcione às plantas tolerar esses estresses. Objetivou-se neste estudo avaliar o efeito de trinexapac-ethyl no crescimento inicial de Eucalyptus urophylla (Clone I-144) sob deficiência hídrica, em duas épocas de aplicação (antes do plantio - AP; e depois do plantio - DP). Dois experimentos foram conduzidos simultaneamente em casa de vegetação, durante 74 dias após o plantio (DAP) do eucalipto, em vasos de 15 L. Os tratamentos consistiram de três doses de trinexapac-ethyl (0,0, 30 e 60 g i.a. ha-1) e duas condições hídricas (com e sem deficiência hídrica). Foi utilizado delineamento casualizado em blocos, em esquema fatorial 3x2, com cinco repetições. Na época de aplicação AP, a pulverização de trinexapac-ethyl ocorreu aos 0 DAP, e na época DP, aos 24 DAP. Foram avaliados: altura das plantas, diâmetro, área foliar, massa seca, teor relativo de clorofila total e trocas gasosas. Houve efeito positivo para a taxa de assimilação líquida de CO2 aos 27 e 40 DAP, para as épocas DP e AP, respectivamente. As plantas de eucalipto na ausência de deficiência hídrica apresentaram maior crescimento, independentemente da época de aplicação. Conclui-se que a aplicação de trinexapac-ethyl antes do plantio proporcionou efeito positivo para a altura e o diâmetro do eucalipto. As épocas de aplicação influenciaram de formas distintas as características avaliadas, não havendo efeito prejudicial em nenhuma delas.

Made available in DSpace on 2019-10-06T15:51:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01. Added 1 bitstream(s) on 2019-10-09T18:34:58Z : No. of bitstreams: 1 S1984-70332019000200176.pdf: 345602 bytes, checksum: b44287ef7d6751c1c8ec98f34db0afae (MD5) Plantations made up of clones carry genetic uniformity that can compromise production. The use of multiclonal plantations is a possible solution. The objective of this study was to identify effects of competition on silvicultural performance of Eucalyptus spp. commercial clones. The experiment was carried out in a randomized block design with 12 eucalyptus clones, three replicates, and five plants per plot. Clones were evaluated for two competition types, intra-and intergenotypic, at 3 and 5 years of age. Competition parameters were estimated based on the analyses performed. Differences were found between the types of competition at both ages for mean annual increment and wood volume. Clones 8 and 9 stood out from the others in both intra-and intergenotypic competition. At 5 years of age, intergenotypic competition produced productivity gains of 13% in clones 8 and 9 and 4% overall considering wood volume and mean annual increment. São Paulo State University (UNESP) School of Engineering São Paulo State University (UNESP) School of Agricultural and Veterinarian Sciences Suzano SA ArborGen, Cambuí, 13.025-140 São Paulo State University (UNESP) School of Engineering São Paulo State University (UNESP) School of Agricultural and Veterinarian Sciences

Nitrogen deficiency and toxicity, primarily in its ammonium form (NH4+), can suppress plant growth and development. The use of silicon (Si) or salicylic acid (SA) may be an alternative to minimize the harmful effects of nutrient imbalances caused by NH4+, thereby improving the photosynthetic efficiency of plants. The aim of the present study was to assess the action of fertigation-applied Si and SA foliar spraying in mitigating NH4+ toxicity and deficiency in eucalyptus clonal seedlings. Two experiments were performed with eucalyptus clonal seedlings (Eucalyptus urophylla x Eucalyptus grandis), in a greenhouse. Both were carried out using a 4x2 factorial design and four concentrations of NH4+ (5, 15, 30 and 60 mmol L-1), in the absence and presence of Si (2 mmol L-1), in experiment I; or with and without SA foliar application (10−2 mmol L-1), in experiment II, with six repetitions. Nitrogen content rose as a result of increasing N-NH4+ concentration in the nutrient solution, and Si supplied via the nutrient solution was efficient in increasing the Si content in eucalyptus seedlings. The rise in N-NH4+ concentration favored the maintenance of the photosynthetic apparatus, but high N-NH4+ concentration increased energy loss through fluorescence and decreased the efficiency of photosystem II. The addition of Si to the nutrient solution proved to be beneficial to the photosynthetic apparatus by decreasing F0 at 15 and 30 mmol L-1 of NH4+; and Fm at all NH4+ concentrations studied. In addition, the beneficial element also increases Fv/Fm at all NH4+ concentrations studied. SA foliar application was also efficient in reducing photosynthetic energy losses by decreasing F0 and Fm at all NH4+ concentrations studied. However, SA only increased the Fv/Fm at the high concentrations studied (30 and 60 mmol L-1 of NH4+). Nitrogen disorder by deficiency or N-NH4+ toxicity reduced shoot dry mass production. The addition of Si to the nutrient solution and SA foliar application increased shoot dry mass production at all N-NH4+ concentrations studied, and benefitted the photosynthetic apparatus by decreasing fluorescence and improving the quantum efficiency of photosystem II as well as dry mass production.

Among the most widely used tests for evaluating seed vigor, electrical conductivity (EC) stands out as one of the most promising due to its speed and simplicity. This study aimed to verify if the EC test could be used to evaluate the physiological quality of seed lots of Piptadenia moniliformis Benth. A seed lot, which was classified by seed tegument color and size, was used based on seed retention in round-hole screens, sizes 11 and 15, constituting 10 sub-lots. Prior to germination and the EC test, the seeds were immersed in concentrated sulfuric acid for 20 minutes in order to overcome tegument dormancy. During the EC test, we soaked seeds in 75 mL of water at 25 ºC and tested eight soaking periods (2, 4, 6, 24, 48, 72, 96, and 120 h) and two seed quantities (25 and 50) per replicate. The EC test, regardless of the number of seeds or soaking period, was not adequate for evaluating the physiological quality of color- or size-classified seed lots from P. moniliformis Benth. . RESUMO Entre os testes mais utilizados para a avaliação do vigor de sementes, o de condutividade elétrica (CE) se destaca como um dos mais promissores, pela sua rapidez e simplicidade. O presente trabalho teve por objetivo verificar a aplicabilidade do teste de CE na avaliação da qualidade fisiológica de lotes de sementes de Piptadenia moniliformis Benth. Foi usado um lote de sementes classificado quanto à coloração do tegumento e tamanho das sementes, com base na retenção das mesmas em peneiras de furos redondos de tamanhos 11 a 15, constituindo, assim, 10 sub-lotes. Antes da realização do teste de germinação e de CE, as sementes foram imersas em ácido sulfúrico concentrado por 20 minutos, visando superar a dormência tegumentar. No teste de CE, testaram-se oito períodos de embebição (2, 4, 6, 24, 48, 72, 96 e 120 h) e duas quantidades de sementes (25 e 50) por repetição, embebidas em 75 mL de água a 25 ºC. O teste de condutividade elétrica, independentemente do número de sementes e período de embebição não foi adequado para a avaliação da qualidade fisiológica de lotes de sementes de P. moniliformis Benth. classificados pela coloração e, ou tamanho das sementes.

http://dx.doi.org/10.5902/1980509821119O presente trabalho avaliou características dendrométricas, químicas e a densidade básica da madeira de cinco híbridos de Eucalyptus grandis x Eucalyptus urophylla, com 2,25 anos de idade. O experimento foi implantando no espaçamento 3,5 x 2 m, com 35 repetições e parcelas de uma planta. Quatro repetições do experimento foram cortadas avaliando-se o diâmetro a altura do peito (DAP, a 1,3 m do solo), altura total e comercial, biomassa seca de folhas, galhos, madeira e casca, volume com e sem casca e volume de casca. Das árvores abatidas foram retirados discos de 5 cm de espessura no DAP e a 0 (base), 25, 50, 75 e 100% da altura comercial, para determinação da densidade básica e caracterização química da madeira. Os dados foram submetidos à análise de variância e comparação de médias pelo teste de Tukey a 5% de probabilidade. Os clones de Eucalyptus grandis x Eucalyptus urophylla diferiram quanto ao volume e biomassa com destaque para o C5 com valores superiores aos demais clones. A densidade básica da madeira foi maior na base da árvore; nas demais posições de amostragem, os valores de densidade foram semelhantes entre si; dentre os clones, o C5 apresentou densidade básica da madeira superior ao C3 e ao C4, assim como o C2 superou o C3. As características químicas da madeira foram semelhantes entre os clones e, apesar da avaliação ter sido realizada em plantas jovens, os clones demonstraram bom potencial em Jaboticabal - SP.

The aim of this work was to evaluate nutrient use efficiency in interspecific hybrids of eucalypt, as an aid in the development of forest breeding programs for areas with limited nutrients. To do this, five clones were evaluated at 2.25 years of age from hybrids resulting from crosses of Eucalyptus grandis x E. urophylla (C1, C2, C3, C4 and C5). The experimental design was of randomised blocks, with single-tree plots and 35 replications. For the study, four trees of average performance were cut down (replications) from each treatment (clone); the biomass, and content and efficiency of use of N, P, K, Ca and Mg were determined in the wood, bark, leaves and branches. The data were submitted to analysis of variance and the F-test, and the means compared by Tukey's test at 5% probability. It was found that the average for biomass allocation was greater (66.2%) for the wood, followed by the branches (13.2%), leaves (11.0%) and bark (9.6%). The C2 and C5 clones stood out as the most efficient in the use of P, Ca and Mg in the wood. The use of genotypes which are efficient in the use of nutrients is essential to the sustainability of forest ecosystems, reducing nutrient export in proportion to the biomass produced. Also, the recommendation of genotypes which are efficient in the use of nutrients for sites of poor soil fertility can optimise productivity in these locations.

Made available in DSpace on 2020-12-12T00:56:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-12-15 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The genetic gains from eucalypt breeding programs have decreased compared to previous decades while productivity reduced in recent years. This decrease is mainly attributed to climate change that, according to studies, has been limiting productivity and changing the adaptation of forest species. But other aspects can be listed, as pests and diseases and decreasing gains with the advance of breeding programs. The objective of this work is to investigate the genotype × site × age interaction in a multi-environment trial with eucalypt clones to verify the adaptability and stability of the genotypes and, finally, to identify mega-environments over time, as well as the influence of climate variables on the genotype performances. The trait diameter at breast height (DBH) of 11 Eucalyptus commercial clones at 11 sites (range from −0.84 to −24.23 latitude and from −39.60 to −52.59 longitude) and three evaluated ages (Age 1 – ranging from 13 to 17 months after planting; Age 2 – from 31 to 34 months; Age 3 – from 48 to 53 months old) was measured and analyzed by factor analytic multiplicative mixed (FAMM) model associated with the GGE biplot and multivariate regression tree using climate variables. A significant G × E interaction and genotypes with different performance across environments and ages were observed. There are clones with high adaptability to specific sites while others show good stability. The results clustered the sites into three mega-environments according to a latitude gradient, over time. The performance of Eucalyptus clones over time indicate precisely either roughly similar or extremely contrasting environments. Temperature affected the most the clustering of the studied sites followed by the latitudinal gradient, impacting productivity negatively, regardless of age. These results may help future studies on the development of selection strategies in tropical regions to address climate change and assist forest breeding programs to deal with the effect of climate change on eucalypt productivity. São Paulo State University (Unesp) School of Agricultural and Veterinarian Sciences Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane, Km 5, Zip Code: 14.884-900 Department of Forestry Science Federal University of Lavras, Campus Box 3037, Zip Code: 37.200-000 Forest Science and Research Institute (IPEF), Via Comendador Pedro Morganti, 3500 – Bairro Monte Alegre, Zip Code: 13415-000 São Paulo State University (Unesp) School of Agricultural and Veterinarian Sciences Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane, Km 5, Zip Code: 14.884-900

Unesp - Universidade Estadual Paulista Julio de Mesquita Filho Faculdade de Ciencias Agrarias e Veterinarias de Jaboticabal, Via de Acesso Prof. Paulo Donato Castellane, s/n

Made available in DSpace on 2018-12-11T16:52:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-03-31 In silvopasture system, the coexistence of eucalyptus seedlings with other species may result in growth reduction, especially during eucalyptus early development. Therefore, studies elucidating how forage species affect the eucalyptus growth can provide important information for their rational management aiming to obtain the maximum gain of the system. The aim of this work was to evaluate the effect of increasing densities of Urochloa brizantha cv. Marandu in the early development of Eucalyptus urograndis. An experiment was conducted in 20 L pots, in an open and semi-controlled area, during 90 days after planting of eucalyptus. A completely randomized design with four replications was used, in a 6 × 7 factorial system, meaning six evaluation periods and seven densities of U. brizantha: 0 (control), 22, 33, 44, 67, 89 and 111 plants m−2. Fortnightly, eucalyptus height, stem diameter and chlorophyll fluorescence (Fv/Fm) were evaluated. At the end of experimental period, the net assimilation rate, stomatal conductance and transpiration rate of eucalyptus plants were determined, in addition to the dry matter of eucalyptus (leaves and stem) and U. brizantha (leaves). In coexistence with 111 plants m−2, eucalyptus had reduction of 63.9% on total dry matter and 72.7% on leaf area, compared to the control. From the density of 22 plants m−2, U. brizantha negatively interfere significantly the growth of E. urograndis. Up to 8 plants m−2 there are no reductions greater than 5% in eucalyptus height and stem diameter. University of Sao Paulo – USP/ESALQ, Avenida Pádua Dias 11 Sao Paulo State University – UNESP/FCAV, Via de Acesso Prof. Paulo Donato Castellane s/n Sao Paulo State University – UNESP/FCAV, Via de Acesso Prof. Paulo Donato Castellane s/n