Cultivation Of Eucalyptus Research Articles

Morphophysiological Responses in Eucalyptus Demonstrate the Potential of the Entomopathogenic Fungus Beauveria bassiana to Promote Resistance against the Galling Wasp Leptocybe invasa

The galling insect Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae) is a major limiting factor in the cultivation of drought-tolerant eucalyptus. The insect L. invasa is a major pest of eucalyptus plantations, and Beauveria bassiana (Bals.) Vuill (Ascomycota: Hypocreales) is being investigated as a potential biocontrol agent against this pest. The fungus B. bassiana can produce metabolites that affect insect biology and survival. Here, we investigated the ability of the entomopathogenic B. bassiana to endophytically develop and induce resistance to L. invasa in a drought-tolerant eucalyptus hybrid. In a greenhouse under semi-controlled conditions, a group of seedlings were sprayed with a solution containing the fungal spores of B. bassiana. The uninoculated seedlings and seedlings inoculated were infested with L. invasa, and their morphometric responses, gas exchange, and chlorophyll indexes were assessed. The number of leaves and height of the inoculated plants was higher than those of the uninoculated plants. The mean CO2 assimilation rate (A) and transpiration rate (E) were higher for inoculated plants. The inoculated plants showed higher chl a and chl b contents. Compared to the uninoculated plants, the inoculated plants developed much fewer galls, while some showed only scar formations where L. invasa deposited its eggs. These results indicated that inoculating Eucalyptus with B. bassiana promoted resistance to L. invasa. To the best of our knowledge, this is the first study showing that an entomopathogenic fungus can develop endophytically to promote resistance against a galling insect pest.

Short-term cultivation limiting soil aggregate stability and macronutrient accumulation associated with glomalin-related soil protein in Eucalyptus urophylla × Eucalyptus grandis plantations

The relationship between glomalin-related soil protein (GRSP) and soil aggregation has been a hot topic of research for its close link to soil stability and quality. However, the short-term cultivation of Eucalyptus poses serious threats to soil stability and nutrient stocks, and the effects of GRSP on soil aggregate stability and macronutrient accumulation remain unclear. The aim is to clarify the potential mechanisms affecting soil aggregate stability and macronutrient accumulation in short-term Eucalyptus plantations. Five Eucalyptus urophylla × Eucalyptus grandis plantations with different cultivation periods (1–5 years) in this study were investigated, and a native evergreen broadleaf forest (0 year) was selected as control. The mean weight diameter index increased in the first 3 years and then significantly decreased during 5 years cultivation of Eucalyptus. Soil organic carbon (SOC) and total nitrogen also decreased after planting Eucalyptus for 3 years, but variation in total phosphorus was not obvious. The relative abundance of Glomeraceae and Claroideoglomeraceae decreased in the 5-year-old Eucalyptus plantations and was positively correlated with GRSP content. In pathway modeling, nutrient-acquisition enzyme activities positively affected GRSP and macronutrient content. Total GRSP (T-GRSP) had higher total effects than easily extractable GRSP on soil aggregate stability, and positively correlated with SOC in macroaggregates. Both T-GRSP and SOC had positive and direct effects on soil aggregate stability. Variance partitioning analysis further explained the contribution of GRSP and SOC to aggregate stability, particularly in >2 and 2–0.25 mm macroaggregates. Our results suggested that GRSP was directly associated with SOC content and soil aggregate stability, and was a potential key factor affecting soil aggregate stability in Eucalyptus plantations. Improving T-GRSP and SOC are efficient approaches for preventing the gradual deterioration of soil aggregate stability. Short-term cultivation should be carefully used in Eucalyptus plantations, and a new cultivation period is needed.

Quality of eucalyptus seedlings of different clones produced at different times

Fast-growing economic forests are important, especially for the cultivation of eucalyptus, as they represent multiple uses associated with the preservation of native forests, generation of jobs, and income. In recent years, there has been significant growth in the number of nurseries that produce clonal eucalyptus seedlings throughout Brazil, and in Espírito Santo soil, most are concentrated in Sooretama, producing seedlings throughout Brazil and for export. However, information on the quality of these seedlings when produced throughout the different seasons is not available. This information can be important, from a practical point of view, for planting and management, and from an experimental point of view, to direct research involving newly produced seedlings. Thus, this work aims to qualify, through the characteristic of DQI, clonal eucalyptus seedlings of different clones and in different seasons, to study the presence of interaction between the clones, and the environments formed by the different seasons of the year. Statistical analyzes were performed from 6,400 eucalyptus seedlings of four clones produced at different times in Sooretama and Jaguaré in the state of Espirito Santo, applying joint evaluation methods to study the interaction between genotypes by environments and verification of adaptability and stability. In the analysis by Annicchiarico and Lin Binns, the G3 genotype showed general adaptability and also showed adaptability in unfavorable environments, and the G2 and G4 genotypes showed adaptability to favorable environments. Despite the specificities of adaptability, all four genotypes can be indicated for planting at any time of the year, as they have an DQI greater than 0.2.

Economics and Financial Feasibility of Major Pulpwood Trees Cultivation in Tamil Nadu

The main raw material for manufacture of paper is wood pulp which are mainly obtained from the pulpwood trees like Casuarina, Eucalyptus and Meliadubia. In Tamil Nadu, the cultivation of these pulpwood trees was promoted by two leading paper manufacturing industries viz., Tamil Nadu Newsprint and Paper Limited (TNPL) and Seshasayee Paper and Boards Limited (SPB).This study aims at estimating the cost, returns and financial feasibility of major pulpwood tree species cultivated in Tamil Nadu. The study found that the cost of cultivation of casuarina, eucalyptus and Meliadubia were Rs.1,76,939, Rs.1,60,593 and Rs.1,52,672 and the net income obtained from these trees were Rs.1,58,473, Rs.1,37,028 and Rs.1,33,831 respectively. Among these trees, Casuarina is more profitable and the results of the study concluded that the cultivation of these three major pulpwood trees are profitable and financially viable.

Carbon and nitrogen stocks and microbiological attributes of soil under eucalyptus cultivation in the Pampa biome of southern Brazil

In the south of Brazil, the intensification of eucalyptus planting can impact the local biome, characterized by grasslands that extends to Uruguay and Argentina. Thus, the objective of the study was to evaluate changes in soil carbon, nitrogen and their labile fractions and soil microbiological attributes due to the introduction of eucalyptus cultivation in the Pampa biome. The soils evaluated were Eutric Regosol (RG), Haplic Lixisol (LX), Dystric Leptosol (LP) and Pellic Vertisol (VR). For this, areas of homogeneous cultivation of Eucalyptus saligna (7 years old) and areas of grassland (native vegetation) were selected. Physical granulometric fractionation of soil organic matter (SOM) was performed in the 0–5, 5–10 and 10–15 cm soil layers, quantifying levels, stocks and distribution of total organic carbon (TOC) and total nitrogen (TN) in the labile and associated with minerals fractions, and the carbon management index (CMI) was calculated. In the 0–5 and 5–10 cm soil layers, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), basal soil respiration, metabolic coefficient, MBC / TOC, MBN / TN, MBC / MBN ratios were also evaluated. Eucalyptus cultivation increased the TOC and POC carbon stocks by 8.7 and 21.7%, respectively (0-15 cm) in compared to grassland. It was also observed that the cultivation of eucalyptus increased 6.7% and 26.0% the stocks of TN and PN, respectively, compared to grassland in the pampa biome. Carbon stocks associated with minerals were not affected by eucalyptus cultivation. The cultivation of eucalyptus increased the basal respiration and the microbial biomass carbon in relation to grassland and there is a reduction of microbial biomass nitrogen in the soil. Thus, the cultivation of eucalyptus in the Pampa biome in southern Brazil demonstrates that it is a forest crop that can contribute to the increase in total and labile carbon stocks and also the biomass and microbial activity of the soil, which are important indicators of assessment of soil quality.

Colonization by arbuscular mycorrhizal fungi improves salinity tolerance of eucalyptus (Eucalyptus camaldulensis) seedlings

Soil salinity affects soil quality and reduces plant performance. Arbuscular mycorrhizal fungi (AMF) can enhance the tolerance of plants under salinity stress. Cultivation of eucalyptus (Eucalyptus camaldulensis), which exhibits high water use efficiency, is possible in saline areas to produce raw materials for the pulp industry. We determined the effects of arbuscular mycorrhizal fungi (AMF) on the growth and survival of eucalyptus seedlings under saline conditions. Three different clones of eucalyptus seedlings were pre-inoculated with three salt-tolerant AMF species, namely Glomus sp.2, Gigaspora albida and G. decipiens, and without pre-inoculation. The seedlings were grown in a greenhouse for 45 days. They were then transferred to individual pots, filled with field soil and subsequently treated with NaCl solution until electro-conductivity (EC) reached 10, 15 and 20 dS m−1. They were watered for 90 days under nursery conditions. The results show that increased salinity levels reduced plant performance, fractional AMF root colonization, spore number, and eucalypt K/Na ratio. AMF significantly increased chlorophyll and decreased leaf proline concentrations by more than 50% and 20% respectively and increased the K/Na ratio three- to six-fold compared with non-inoculated plants. Pre-inoculation with AMF before outplanting also improved plant performance by more than 30% under salinity stress compared to non-inoculated plants. We conclude that AMF can alleviate the negative impacts of salinity on plant physiological and biochemical parameters.

O deserto verde cresce em Alagoas: uma análise crítica da expansão do eucalipto no estado

Na última década, a superfície cultivada com eucalipto em Alagoas cresceu exponencialmente. A territorialização do eucalipto em Alagoas ocupa extensas áreas da Mesorregião Leste e Agreste e tem o objetivo de fomentar o complexo de madeira-papel-celulose, apropriando-se de condições vantajosas para a reprodução ampliada do capital. Contraditoriamente, o aumento da superfície cultivada com eucalipto no estado coincide com a diminuição da oferta de um importante gênero, como o feijão, fragilizando a soberania alimentar. Ademais, a territorialização do eucalipto apresenta seus primeiros sinais de destruição social e ambiental, a exemplo da diminuição da oferta hídrica e contaminação de plantações e corpos d’agua de comunidades. Compreende-se que o advento do agronegócio do eucalipto, longe de representar uma alteração da realidade hegemônica do estado, atualiza suas contradições por meio do deserto verde.
 Palavras-chave: eucalipto, capital, agronegócio

Multifractal analysis of soil fauna diversity indexes

ABSTRACT The objective of this study was to determine the multifractality of diversity indexes of edaphic fauna in areas with natural vegetation and in agricultural systems. Biological sampling was carried out in seven treatments (millet, maize, soybean, eucalyptus, preserved cerrado, disturbed cerrado and pasture), containing 130 pitfall traps, distributed in transects with 3 m of spacing between sampling points, totaling 390 m. The multifractal analysis was determined based on the moment method, where estimates such as the capacity dimensions, entropy and the correlation of the diversity indexes were calculated. The soybean area had greater Shannon diversity (2.69), however it had smaller abundance of individuals. The partition functions were adjusted with coefficient of determination > 0.90. The difference between D-10-D10, ranged from 0.080 to 1,707 for Pielou equitability in soybean cultivation, for richness in the area under the cultivation of eucalyptus. The singularity spectra expressed graphs with different degrees of heterogeneity for the soil fauna indexes, and the richness expressed the best structure. The area cultivated with soybean had a monofractal tendency, due to the homogeneous distribution of individuals of the edaphic fauna along the transect. The fractal analysis provided the description of patterns of variability that are not detected by classical methods.

Effects of Eucalyptus Globulus on the Underground Water in Udigram, Swat, Pakistan

The plantation of Eucalyptus in hilly areas is not encouraging insight because it vanishes more than 50 litersof groundwater per day into the atmosphere and is gradually more dangerous to the water table and rock reservoirs. Therate of water evaporated by eucalyptus is higher than compared to the incoming showers in the area.This imbalance inthe water cycle caused changes in the water table as well as the flow of water from the springs.On the other hand, itswood is of poor quality and having low market demand as well as domestic use.The precipitation shows -2 inches (-25.8 millimeters) decline per year in the winter season between 1995 and 2014, while the ratio of increase is 1.24inches (31.5 millimeters) in the summer months. Generally,the major share of annual precipitation was from the winterseason before 1995, but onward, it is in summer and the area dropped from humid to sub-humid climate.This seasonalfluctuation of rainfall and dryness of rock reservoirs has not only decreased the water table, but also caused changes inthe flow of water from the springs and rivers. The dryness of the wells after reduction in precipitation, generally leadsto the digging and intensive use of tube wells in the area. The study reveals that the dryness in spring has an aftereffecttotally of cultivation of Eucalyptus on the Raja Gira hill slopes and required mitigation to overcome the issue of wateravailability for the locals.

Effects of Eucalyptus Globulus on the Underground Water in Udigram, Swat, Pakistan

The plantation of Eucalyptus in hilly areas is not encouraging insight because it vanishes more than 50 litersof groundwater per day into the atmosphere and is gradually more dangerous to the water table and rock reservoirs. Therate of water evaporated by eucalyptus is higher than compared to the incoming showers in the area.This imbalance inthe water cycle caused changes in the water table as well as the flow of water from the springs.On the other hand, itswood is of poor quality and having low market demand as well as domestic use.The precipitation shows -2 inches (-25.8 millimeters) decline per year in the winter season between 1995 and 2014, while the ratio of increase is 1.24inches (31.5 millimeters) in the summer months. Generally,the major share of annual precipitation was from the winterseason before 1995, but onward, it is in summer and the area dropped from humid to sub-humid climate.This seasonalfluctuation of rainfall and dryness of rock reservoirs has not only decreased the water table, but also caused changes inthe flow of water from the springs and rivers. The dryness of the wells after reduction in precipitation, generally leadsto the digging and intensive use of tube wells in the area. The study reveals that the dryness in spring has an aftereffecttotally of cultivation of Eucalyptus on the Raja Gira hill slopes and required mitigation to overcome the issue of wateravailability for the locals.

Soil Physical Attributes Under Eucalyptus stands With Non-living and Living Plants

The conservation of ecosystems has benefited from planted forests which provide reforested wood reducing the pressure on deforestation of natural forests. Soil physical attributes determine soil water storage capacity; therefore, they play an important role on plant roots’ development which may compromise plant’s survival. The study tested the influence of soil physical and water attributes on the survival of Eucalyptus spp. clones under dry tropical climate. Two areas were selected, including one with living plants and a second with non-living plants of Eucalyptus spp. clones. Moreover, five soil profiles were studied in each area and the parameters estimated were soil bulk density, total porosity, saturated hydraulic conductivity, soil water retention curve, pores size distribution, available water capacity, and S index. Soil physical and hydric attributes did not differ between the area with living plants and the one with non-living plants. The saturated hydraulic conductivity in the area surface layer was high for both the living plants and non-living palnts; 331 mm h-1 and 294 mm h-1, respectively. The S index (to give the value) indicated that the structure was suitable for the development of Eucalyptus trees. Furthermore, it was possible to affirm that soil physical and water attributes of the studied areas were promising for the cultivation of Eucalyptus spp. in the dry tropical climate.

Shifts in the bacterial community composition along deep soil profiles in monospecific and mixed stands of Eucalyptus grandis and Acacia mangium.

Our knowledge of the rhizosphere bacterial communities in deep soils and the role of Eucalyptus and Acacia on the structure of these communities remains very limited. In this study, we targeted the bacterial community along a depth profile (0 to 800 cm) and compared community structure in monospecific or mixed plantations of Acacia mangium and Eucalyptus grandis. We applied quantitative PCR (qPCR) and sequence the V6 region of the 16S rRNA gene to characterize composition of bacterial communities. We identified a decrease in bacterial abundance with soil depth, and differences in community patterns between monospecific and mixed cultivations. Sequence analysis indicated a prevalent effect of soil depth on bacterial communities in the mixed plant cultivation system, and a remarkable differentiation of bacterial communities in areas solely cultivated with Eucalyptus. The groups most influenced by soil depth were Proteobacteria and Acidobacteria (more frequent in samples between 0 and 300 cm). The predominant bacterial groups differentially displayed in the monospecific stands of Eucalyptus were Firmicutes and Proteobacteria. Our results suggest that the addition of an N2-fixing tree in a monospecific cultivation system modulates bacterial community composition even at a great depth. We conclude that co-cultivation systems may represent a key strategy to improve soil resources and to establish more sustainable cultivation of Eucalyptus in Brazil.

Composto de lodo de esgoto para o cultivo inicial de eucalipto

Neste trabalho, foi avaliada a viabilidade do uso de composto de lodo de esgoto, proveniente de estação de tratamento de esgoto, como fertilizante alternativo para o cultivo inicial de eucalipto. O experimento foi realizado em casa de vegetação no CCA - UFSCar, Araras, SP. Os cultivos ocorreram em vasos de 11 L durante 75 dias. O delineamento experimental foi inteiramente ao acaso, com cinco tratamentos e sete repetições. Os tratamentos adotados foram constituídos por uma testemunha, três tratamentos com composto de lodo de esgoto (25%, 50% e 75% do volume do vaso) e um tratamento com fertilizante mineral convencional, todos em solo arenoso. Ao final do experimento, a taxa de crescimento relativo (TCR) e a massa seca das plantas foram medidas e submetidas à análise de variância seguida pelo teste de Tukey a 5% de probabilidade. A TCR foi maior nos tratamentos com fertilização do que na testemunha, mas não diferiu entre a fertilização mineral e as doses de fertilização orgânica. A massa seca das plantas foi maior no tratamento com 50% do volume do vaso com fertilizante orgânico (p<0,01). Assim, o composto de lodo de esgoto se mostrou com potencial para substituir fertilizantes minerais convencionais no cultivo inicial de eucalipto.

Desierto (Desert)

Desierto, a performance piece, took place July 7th, 2015 in the Gallery Gabriela Mistral in Santiago de Chile.
 Desierto, Desert, was created for the Chilean context: it speaks of forms of oppression, abuse, racism and colonialism that hide behind the successful industry of pine that has invaded the Mapuche indigenous territory in that country, generating increased damage to the ecosystem. The work is not only about one site, however. In the artist’s words, "[t]he problem of land and indigenous peoples that have been violated and pillaged by wealthy families and the State is not a stranger to Guatemala context…during the war in my country, the scorched-earth strategy was a constant. Thousands of indigenous Maya were kept in their communities, were murdered and their lands expropriated. Many of these lands passed into the hands of the State, oligarchs, or foreigners. Many of these lands are currently exploited through mining, hydroelectric industries or areas of monoculture. In Guatemala there are no pine-forests, but there is another way to annihilate the Earth. In Guatemala, the African Palm has caused havoc. Recently the factory Xerxes (that produces Palm oil Olmec brand) contaminated the rivers’ waters and thousands of fish and other species have died in an ecocide without precedent".
 Speaking to this violence, in this work, the artist remains naked, buried in the sand dunes of sawdust created inside the Gallery. Sawdust refers to waste resulting after the over exploitation of the land and the ongoing desertification of large tracts of land, both in Guatemala with the cultivation of African Palm, as in Chile with the large scale cultivation of pine and eucalyptus. The desert is no longer the North but the South.
 Commissioned and produced for the Gabriela Mistral Gallery, Santiago de ChileCurated by Soledad Novoa DonosoPhotos by Rodrigo MaulenVideo by Andrés Lima, Sebastián Pando

LEVANTAMENTO DA ENTOMOFAUNA EM PLANTIOS DE <i>Eucalyptus</i> spp. POR MEIO DE ARMADILHA LUMINOSA EM SÃO FRANCISCO DE ASSIS - RS

A cultura do eucalipto tornou-se uma importante atividade econômica no Brasil, no entanto, com o aumento das áreas de plantio, os problemas entomológicos tendem a aumentar nas mesmas proporções. Neste sentido, torna-se necessário o constante monitoramento dos insetos associados a esses sistemas de plantio homogêneos, buscando o desenvolvimento de programas de manejo integrado de pragas. Assim, o objetivo deste trabalho foi o levantamento populacional da entomofauna associada a plantios de Eucalyptus spp., em São Francisco de Assis - RS. As coletas foram realizadas por meio de armadilhas luminosas no período de julho de 2008 a agosto de 2009, em talhões de três anos de idade, com as espécies: Eucalyptus dunnii, Eucalyptus grandis e Eucalyptus grandis x Eucalyptus urophylla. Os insetos coletados foram analisados através dos índices de frequência, abundância, constância e diversidade. Realizou-se ainda a correlação entre as espécies-praga identificadas e as variáveis meteorológicas do período. Foram coletados 3.623 indivíduos distribuídos em oito ordens (Blattodea, Coleoptera, Dermaptera, Hemiptera, Hymenoptera, Lepidoptera, Mantodea e Odonata), identificando-se três espécies e três gêneros de lepidópteros desfolhadores considerados de importância econômica: Automeris illustris, Eupseudosoma sp., Sabulodes sp., Sarsina sp., Thyrinteina arnobia e Agrotis ipsilon. e a coleobroca Phoracantha semipunctata. Pelos resultados obtidos, pode-se concluir que existem espécies-praga importantes da cultura de Eucalyptus já estabelecidas na região, necessitando, portanto, de monitoramento constante para que estas espécies não ocasionem danos aos plantios.

ABUNDÂNCIA NATURAL DE 15N E FORMAS DE NITROGÊNIO EM ARGISSOLO CULTIVADO COM EUCALIPTO E ACÁCIA

http://dx.doi.org/10.5902/1980509821121O nitrogênio e um dos nutrientes mais demandados pelas espécies vegetais, sua presença no solo, sob formas orgânicas ou minerais disponíveis para as plantas, está vinculada à qualidade e quantidade dos resíduos vegetais aportados ao solo. O estudo teve o objetivo de avaliar a influência do cultivo do eucalipto e da acácia na composição das formas orgânicas e inorgânicas de N e, na abundância natural de 15N em um Argissolo Amarelo. Para isso, foram coletadas amostras de solo e serapilheira em monocultivos do Eucalyptus urograndis (clone do Eucalyptus urophylla S. T. Blake x Eucalyptus grandis W. Hill ex Spreng) de ciclo curto (sete anos), sistemas de cultivo de rotação de acácia (Acacia mangium Willd.) após monocultivo de eucalipto, monocultivo de eucalipto de ciclo longo (24 anos) e mata nativa (Mata Atlântica) como condição original de solo do litoral Norte do Espírito do Santo. Foram avaliados os teores de C orgânico total, N total, N-NH4+, N-NO3-, relação C/N, fracionamento do N orgânico e abundância natural de 15N no solo e serapilheira. Das formas de N-orgânico hidrolisado, o N- amino foi a fração que apresentou maior contribuição (39%), seguida pela fração de N- não identificado (27%), da fração N-amida (18%) e N-hexosamina (15%). O povoamento de acácia promoveu menor abundância natural de 15N e maiores teores de N total e C orgânico no solo e aumentou as formas orgânicas de N-hidrolisado, quando comparado àqueles de eucalipto de ciclo curto. Isto indica o aumento de formas lábeis de N orgânico no solo para as plantas e redução da humificação da matéria orgânica do solo (MOS) de acácia. Neste sentido, a rotação de cultivos florestais com acácia após eucalipto de ciclo curto contribuiu para o aumento de formas orgânicas no solo, importantes para a nutrição de plantas, por serem potenciais fontes de nutrientes às plantas em curto período de tempo.

Labile and Non-Labile Fractions of Phosphorus and Its Transformations in Soil under Eucalyptus Plantations, Brazil

Phosphorus (P) is the main limiting nutritional factor in the cultivation of Eucalyptus in Brazil. Despite this, little is known about the P fractions and dynamics in Eucalyptus soils in tropical regions. The aims of this study were (1) to evaluate the distribution of labile and non-labile fractions of P in soil in 10 sites of Eucalyptus in the state of São Paulo, Brazil and (2) to determine the interactions among the P fractions and to identify which fractions act as sinks or sources for the available P fraction. The P fractions were separated using the Hedley sequential extraction method, and the P transformation processes were evaluated via structural equation modeling. The labile P (resin-Pi + Pi and Po in NaHCO3) varied between 6% and 16%, the moderately labile P (Pi + Po in NaOH) varied between 28% and 40%, the occluded P (Pi + Po in Sonicate + NaOH) varied between 6% and 19%, the P associated with Ca (HCl-Pi) varied between 0.4% and 3% and the residual-P varied between 35% and 47%. The hypothetical structural model of soil P cycle was composed of four P pools (latent variables): the organic pool, occluded pool, inorganic pool, and available pool. The structural model was adequate to identify functional pools of P in soil, and to identify transformation processes of P based on the source-sink relationships. The available P pool was highly dependent on inorganic and occluded pools and the organic pool acted predominantly as a sink of P on available and inorganic pools. The results reinforce the high level of recalcitrance of the organic pool and the fact that Eucalyptus plants must access pools of limited-availability P to meet their nutritional demands.

Rentabilidade Econômica do Arrendamento de Terra para Cultivo de Eucalipto em São Paulo

RESUMOO presente estudo teve como objetivo analisar o arrendamento de terra para o cultivo de eucalipto no Vale do Paraíba, São Paulo. Utilizaram-se informações de dez propriedades, sendo oito proprietários da terra, uma empresa de papel e celulose e um investidor em ativos florestais. As ferramentas econômicas utilizadas foram VPL, TIR e VET. Com uma TMA de 8,75% a.a., o cultivo de eucalipto com investimento em terra na região estudada mostrou ser viável economicamente em cinco propriedades. Com a garantia de produtividade estabelecida em contrato, o investimento apresentou viabilidade econômica para o arrendamento de terra, porém inviável para o investidor. A garantia de produtividade mostrou ser importante para manter a rentabilidade para o investidor e para o arrendado pois, sem a mesma, apenas três propriedades apresentaram viabilidade econômica para arrendamento.

Doses of N, P and K in the cultivation of eucalyptus in soil originally under Cerrado vegetation

Many eucalyptus plantations in Brazil are in areas of soil with low fertility, with little phosphorous (P) and potassium (K) availability and with low organic matter (OM) content, resulting in a low supply of nutrients to plants, directly reflected in reduced yield. Thus, our objective was to evaluate the effects of nitrogen (N), P and K fertilization on the growth of eucalyptus plants, with the aim of achieving nutritional balance and high yield. The experiment was conducted on Renascenca Farm, an agricultural property administered by Cargill Agricola S.A., located in the city of Tres Lagoas, Mato Grosso do Sul state, Brazil. The experimental design consisted of randomized blocks with ten treatments and five replicates. The treatments were composed of doses of N (0, 70, 105 and 140 kg ha-1), doses of P (0,40, 70 and 100 kg ha-1 of P2O5) and doses of K (0, 90, 135 and 180 kg ha-1 of K2O). The doses of N and K were applied at planting and as top dressing, and the doses of P were applied only at planting. The diameter at breast height (DBH), plant height and timber volume with bark were assessed, and the concentrations of macronutrients in the leaves were determined. DBH and volume were positively affected by N fertilization, and eucalyptus growth in DBH, height and volume increased with P and K fertilization. The maximum yield of eucalyptus at 21 months of age was obtained with the application of 71 kg ha-1 of N, 100 kg ha-1 of P2O5 and 125 kg ha-1 of K2O. The concentrations of macronutrients were adequate even in the absence of the application of N, P and K. With increasing doses of K, there was na increase in leaf concentrations of K and a decrease in those of calcium and magnesium.

Physiological changes in eucalyptus hybrids under different irrigation regimes

With the expansion of the cultivation of eucalyptus into areas with limited water resources, recommending genotypes which are tolerant to low water availability is important in order to maximize productivity under such conditions. The aim of this work therefore was to evaluate five hybrids of Eucalyptus grandis x E. urophylla (H1 to H5) subjected to four irrigation regimes in the greenhouse: daily (IR1), every two days (IR2), every four days (IR4) and every six days (IR6). The following characteristics were evaluated: photosynthetic rate (A), transpiration (E), stomatal conductance (gs), leaf water potential (Ψw), leaf relative water content, photochemical efficiency and chlorophyll content index. Evaluations of A, gs and E were carried out on two occasions: 1 - under stress, at the end of the interval between irrigations for each treatment; and 2 - in recovery, 48 h after irrigation for all plants in the experiment. On average, there was reduction of 25 and 40% in A values, 40 and 55% in gs, 15 and 22% in E, and 96 and 103% in Ψw respectively in those plants under regimes IR4 and IR6, compared to under IR1. Stomatal conductance had only partially recovered 48 h after irrigation, and due to being more sensitive, its changes are a good indication of water stress. Hybrid H3 is the most tolerant and H5 the most sensitive to a reduction in water availability in soil.