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Made available in DSpace on 2021-06-25T10:32:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Fertilization is commonly used to increase growth in forest plantations, but it may also affect tree water relations and responses to drought. Here, we measured changes in biomass, transpiration, sapwood-to-leaf area ratio (As:Al) and sap flow driving force (ΔΨ) during the 6-year rotation of tropical plantations of Eucalyptus grandis under controlled conditions for throughfall and potassium (K) fertilization. K fertilization increased final tree height by 8 m. Throughfall exclusion scarcely affected tree functioning because of deep soil water uptake. Tree growth increased in K-supplied plots and remained stable in K-depleted plots as tree height increased, while growth per unit leaf area increased in all plots. Stand transpiration and hydraulic conductance standardized per leaf area increased with height in K-depleted plots, but remained stable or decreased in K-supplied plots. Greater Al in K-supplied plots increased the hydraulic constraints on water use. This involved a direct mechanism through halved As:Al in K-supplied plots relative to K-depleted plots, and an indirect mechanism through deteriorated water status in K-supplied plots, which prevented the increase in ΔΨ with tree height. K fertilization in tropical plantations reduces the hydraulic compensation to growth, which could increase the risk of drought-induced dieback under climate change. CIRAD UMR Eco&Sols Eco&Sols Univ Montpellier CIRAD INRAe IRD Montpellier SupAgro Department of Forest Sciences Universidade de São Paulo “Luiz de Queiroz” College of Agriculture (USP-ESALQ) Center of Nuclear Energy in Agriculture Universidade de São Paulo (USP-CENA) Edafotec SL NIPE UNICAMP Bordeaux Sciences Agro UMR INRAe-ISPA 1391 Nicholas School of the Environment Duke University Ecologie Systématique Evolution Univ. Paris-Sud CNRS AgroParisTech Université Paris-Saclay School of Agricultural Sciences UNESP—São Paulo State University School of Agricultural Sciences UNESP—São Paulo State University

Climate change is expected to increase the frequency of droughts in most tropical regions in the coming decades. A passive phenomenon called hydraulic redistribution (HR) allows some plant species to take up water from deep and wet soil layers and redistribute it in the upper dry layers where other plants and soil biota can benefit from it. In addition, soil fertilization, particularly potassium (K), may also affect drought-adaptive mechanisms and increase water use efficiency (WUE) on poor and acidic tropical soils. The present study aimed at quantifying the role of HR and K fertilization on both wood productivity and WUE for stemwood production (WUEp) of Eucalyptus grandis plantations in Brazil under ambient and reduced (−37%) throughfall conditions. Tree transpiration was measured using trunk sap flow sensors over 21 months, and HR was estimated from the reverse sap flow (RF) observed in shallow roots over 18 months. Tree biomass, hydraulic conductance, soil water storage from surface to the water table (down to 17 m), and leaf photosynthetic capacity were also assessed. Significant HR was detected over the whole year, even during the rainy seasons. Neither potassium fertilization nor throughfall exclusion affected the velocity of water transported by HR, probably because most trees reached water table. Nonetheless, some photosynthetic capacity parameters, including the maximum photosynthetic rate (Amax), increased in treatments with K addition. This higher Amax combined with an increased sapwood area index, was associated with an increase in water uptake by 30 %–50 % and WUEp by 300 % relative to K-deficient trees. We postulate that the increase in WUEp promoted by potassium fertilization was partly driven by an increase in biomass allocation to wood, at the expense of foraging organs (leaves and roots), because K addition alleviated constraints on light and water use. Our results indicate that fertilizing E. grandis plantations with K is beneficial to both wood biomass production and WUEp.

El déficit hídrico tiene un impacto negativo en el crecimiento y desarrollo de las plantas a través de alteraciones morfo-fisiológicas. Esta investigación se centró en la dinámica de los rasgos ecofisiológicos y arquitectura de dosel en dos cultivares de café, RUBI-MG1192 (Rubi) y IAPAR59 (I59), sensible y tolerante a la sequía, respectivamente. Los ensayos fueron durante dos años con tres tratamientos de riego, seis muestreos y 7-10 plantas por tratamiento. I59 retuvo sus hojas durante la sequía y demostró ser más isohidríco y plástico para rasgos de funcionamiento hídrico, con un ajuste precoz a la sequía. En contraste, Rubi tuvo desprendimiento de hojas y fue más anisohídrico y plástico para rasgos tardíos a la sequía. Se concluye que la aptitud de las plantas de café sometidas a eventos climáticos depende del ajuste entre las características morfo-fisiológicas y órgano-morfológicas. Estos rasgos deberán ser considerados en los programas de mejoramiento de café.

Made available in DSpace on 2018-11-26T16:27:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-03-15 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) CIRAD USP-COFECUB AGREENIUM (Plantrotem project) SOERE F-ORE-T Agence Nationale de la Recherche Adaptive strategies to improve tree water-use efficiency (WUE) are required to meet the global demand for wood in a future drier climate. A large-scale throughfall exclusion experiment was set up in Brazil to study the interaction between water status and potassium (K) or sodium (Na) availability on the ecophysiology of Eucalyptus grandis trees. This experiment focused primarily on the changes in aboveground net primary production, stand water use, phloem sap and leaf delta C-13, net CO2 assimilation and stomatal conductance. The correlations between these response variables were determined to gain insight into the factors controlling water-use efficiency in tropical eucalypt plantations. The intrinsic WUE in individual leaves (the ratio of net CO2 assimilation to stomatal conductance) was estimated at a very short time scale from the leaf gas exchange. Sap flow measurements were carried out to assess the WUE for stem wood production (the ratio of wood biomass increment to stand water use). Averaged over the two water supply regimes, the stemwood biomass 3 years after planting was 173% higher in trees fertilized with K and 79% higher in trees fertilized with Na than in trees with no K and Na addition. Excluding 37% of the throughfall reduced stemwood production only for trees fertilized with K. Total canopy transpiration between 1 and 3 years after planting increased from about 750 to 1300 mm y(-1) in response to K fertilization with a low influence of the water supply regime. K fertilization increased WUE for stemwood production by approx. 60% with or without throughfall exclusion. There was a strong positive correlation between phloem sap delta C-13 and short-term leaf-level intrinsic WUE. Whatever the water and nutrient supply regime, the gas exchange WUE estimates were not correlated with WUE for stemwood production. Phloem sap delta C-13 and leaf delta C-13 were therefore not valuable proxies of WUE for stemwood production. The allocation pattern in response to nutrient and water supply appeared to be a major driver of WUE for stemwood production. In areas with very deep tropical soils and annual rainfall

Made available in DSpace on 2018-11-26T17:51:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-06-01 Universidade de Sao Paulo Centre de cooperation Internationale en Recherche Agronomique pour le Developpement (CIRAD) Agence Nationale de la Recherche (MACACC) Agropolis Foundation Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Although large amounts of potassium (K) are applied in tropical crops and planted forests, little is known about the interaction between K nutrition and water supply regimes on water resources in tropical regions. This interaction is a major issue because climate change is expected to increase the length of drought periods in many tropical regions and soil water availability in deep soil layers is likely to have a major influence on tree growth during dry periods in tropical planted forests. A process-based model (MAESPA) was parameterized in a throughfall exclusion experiment in Brazil to gain insight into the combined effects of K deficiency and rainfall reduction (37% throughfall exclusion) on the water used by the trees, soil water storage and water table fluctuations over the first 4.5 years after planting Eucalyptus grandis trees. A comparison of canopy transpiration in each plot with the values predicted for the same soil with the water content maintained at field capacity, made it possible to calculate a soil-driven tree water stress index for each treatment. Compared to K-fertilized trees with undisturbed rainfall (+K+W), canopy transpiration was 40% lower for K deficiency (-K+W), 20% lower for W deficit (+K - W) and 36% lower for combined K deficiency and W deficit (- K - W) on average. Water was withdrawn in deeper soil layers for -W than for + W, particularly over dry seasons. Under contrasted K availability, water withdrawal was more superficial for -K than for +K. Mean soil water content down to 18 m below surface (mbs) was 24% higher for - K+ W than for +K+W from 2 years after planting (after canopy closure), while it was 24% lower for +K-W and 12% lower for -K W than for +K+W. The soil-driven tree water stress index was 166% higher over the first 4.5 years after planting for - W than for +W, 76% lower for -K than for +K, and 14% lower for -K -W than for +K+W. Over the study period, deep seepage was higher by 371 mm yr(-1) (+122%) for -K than for +K and lower by 200 mm yr(-1) (- 66%) for -W than for +W. Deep seepage was lower by 44% for -K- W than for +K+ W. At the end of the study period, the model predicted a higher water table for -K (10 mbs for -K+W and 16 mbs for -K-W) than for +K (16 mbs for +K+W and 18 mbs for +K-W). Our study suggests that flexible fertilization regimes could contribute to adjusting the local trade-off between wood production and demand for soil water resources in planted forests. CIRAD, UMR Eco&Sols, F-34398 Montpellier, France Univ Montpellier, Eco&Sols, CIRAD, INRA,IRD,Montpellier SupAgro, Montpellier, France CIRAD, UR AIDA 115, F-34398 Montpellier, France Univ Estadual Campinas, NIPE, BR-13083970 Campinas, SP, Brazil Univ Sao Paulo, Dept Ciencias Atmosfer, BR-05508900 Sao Paulo, SP, Brazil INRA, UMR 1391, ISPA, F-33140 Villenave Dornon, France Univ Sao Paulo, ESALQ, BR-13418900 Piracicaba, SP, Brazil Univ Sao Paulo, CENA, BR-13400970 Piracicaba, SP, Brazil Univ Estadual Paulista, Dept Solos & Recursos Ambientais, BR-18610300 Botucatu, SP, Brazil Univ Estadual Paulista, Dept Solos & Recursos Ambientais, BR-18610300 Botucatu, SP, Brazil Agence Nationale de la Recherche (MACACC): ANR-13-AGRO-0005 Agropolis Foundation: ANR-10-LabX-0001-01 CAPES: 017/2013

Em função do índice de área foliar (IAF) do Capim Tanzânia (Panicum maximum J.) e da lâmina de evaporação do tanque "Classe A" (ECA), foi gerado um modelo multiplicativo para determinar a evapotranspiração máxima (ETm) desse cultivo forrageiro. Foi adotada uma correlação entre a ETm em função da evaporação do tanque "Classe A" e do índice de área foliar (IAF), por meio de uma regressão linear múltipla dos valores logarítmicos, correspondentes a períodos diários durante 11 meses (janeiro a novembro de 2000). Considerando a dificuldade para determinar o IAF e aplicar como variável no modelo proposto, foi desenvolvido outro modelo por meio da correlação entre a ETm e as variáveis ECA e o valor equivalente de IAF, em dias de descanso (NDd), adotando-se como padrão o número de 33 dias como o máximo recomendado de descanso para capim Tanzânia, em condições irrigadas. Para avaliar os modelos, foram utilizados valores de ETm observados a campo durante quatro meses (agosto a novembro-2000) por meio do método de balanço hídrico do solo, monitorado com tensiômetros. Na validação do modelo, foram utilizados testes estatísticos recomendados na literatura, verificando-se bons ajustes entre os valores observados e estimados, recomendando-se a sua utilização para o manejo da irrigação de Capim Tanzânia, no Estado de São Paulo.

The introduction of nitrogen fixing species (NFS) in fast-growing tree plantations is an alternative option to reduce fertilizer inputs. However, the success of mixed-species plantations depends on the balance between positive interactions among species (resulting from facilitation and/or complementarity) and the negative effects of interspecific competition. Using a carbon budget approach and coupling measurements of standing biomass, aboveground litterfall and soil CO2 efflux, we assessed the influence of replacing half of eucalypt trees by Acacia mangium on total belowground carbon flux (TBCF), net primary production (NPP) and its partitioning between above- and belowground growth at two tropical sites in Brazil (Itatinga) and in Congo (Kissoko) exhibiting contrasting climates, edaphic conditions and wood productions. Annual soil CO2 efflux (F-S) was significantly lower in the acacia monocultures than in eucalypt monocultures and mixed-species stands at both sites. Annual F-S was significantly lower at Itatinga compared to Kissoko for all stands while TBCF was significantly lower in the eucalypt stands only. In the eucalypt monocultures we found a significantly lower aboveground NPP (ANPP) and wood production (wood NPP) at Kissoko compared to Itatinga that was almost fully balanced by a significantly higher belowground NPP (BNPP), leading to similar NPP. Similarly, acacia monocultures exhibited significantly higher ANPP and wood NPP at Itatinga than at Kissoko. The mixed-species stands exhibited a significantly lower wood NPP and ANPP than the eucalypt monocultures at the Brazilian site while NPP of the mixture was not significantly different than the average NPP of the two monocultures. At the Congolese site, NPP of the mixture was significantly higher than the average NPP of the two monocultures. NPP was similar in the mixed-species stand and the eucalypt monoculture with a significantly lower partitioning of NPP to belowground production, leading to a one third higher wood biomass at harvest in the mixed-species stand. A positive effect of growing eucalypts with the nitrogen fixing acacia trees on stand wood production occurred at Kissoko but not at Itatinga. Mixed-species plantations with NFS can be advocated at sites where the productive gains resulting from nitrogen fixation are not compromised by other resource limitations. (c) 2012 Elsevier B.V. All rights reserved.

Sap flow could be used as physiological parameter to assist irrigation of screen house citrus nursery trees by continuous water consumption estimation. Herein we report a first set of results indicating the potential use of the heat dissipation method for sap flow measurement in containerized citrus nursery trees. 'Valencia' sweet orange [Citrus sinensis (L.) Osbeck] budded on 'Rangpur' lime (Citrus limonia Osbeck) was evaluated for 30 days during summer. Heat dissipation probes and thermocouple sensors were constructed with low-cost and easily available materials in order to improve accessibility of the method. Sap flow showed high correlation to air temperature inside the screen house. However, errors due to natural thermal gradient and plant tissue injuries affected measurement precision. Transpiration estimated by sap flow measurement was four times higher than gravimetric measurement. Improved micro-probes, adequate method calibration, and non-toxic insulating materials should be further investigated. O fluxo de seiva poderia ser utilizado como parâmetro fisiológico para fomentar a irrigação de mudas cítricas em cultivo protegido pela estimação do consumo contínuo de água. Neste trabalho, reportam-se os primeiros resultados, indicando o uso potencial e as limitações iniciais do método de dissipação de calor para medição do fluxo de seiva em mudas cítricas em recipientes. Mudas de laranjeira-doce 'Valência' [Citrus sinensis (L.) Osbeck] enxertadas sobre limoeiro 'Cravo' (Citrus limonia Osbeck) foram avaliadas por 30 dias, durante o verão. Sondas de dissipação de calor e sensores do tipo termopar foram construídos a partir de materiais prontamente disponíveis e de baixo custo para favorecer o acesso ao método por viveiristas. O fluxo de seiva apresentou alta correlação com a temperatura do ar dentro da estufa telada. Contudo, erros inerentes ao gradiente térmico natural e a injúrias nos tecidos do caule afetaram a precisão das medições. A transpiração estimada a partir da medição do fluxo de seiva foi quatro vezes maior do que a determinada por gravimetria. Microssondas adaptadas a plantas de porte reduzido, ajustes na calibração do método e uso de materiais atóxicos para isolamento térmico do conjunto devem ser futuramente investigados.

Devido à dificuldade de se quantificar o consumo individual de água de uma árvore, tem surgido uma série de técnicas de medida do fluxo de seiva que passa por meio do caule, o qual é relacionado diretamente com a transpiração da planta. Este trabalho teve como objetivo avaliar o desempenho de uma dessas técnicas, denominada método da sonda de dissipação térmica (SDT), na medida de fluxo de seiva em plantas de lima ácida ‘Tahiti’. O experimento foi instalado em pomar de plantas jovens, localizado na fazenda experimental de irrigação, do Departamento de Engenharia Rural da ESALQ, em Piracicaba - SP, sendo a avaliação feita utilizando dois lisímetros de pesagem. Os resultados indicaram que o método estudado pode ser utilizado para essa finalidade em condições de campo; no entanto, a exatidão de suas medidas depende de certos conceitos teóricos que devem ser considerados e de certas correções que devem ser realizadas. Essas considerações, assim como as vantagens e desvantagens desse método, são discutidas neste trabalho. Because of the difficulty to quantify water consumption of a single tree, for irrigation scheduling, a series of techniques has appeared that directly measure the sap flow through the stem which can be related directly to transpiration. The objective of this work was to evaluate the performance of one of these methods, called heat dissipation probe method (HDP), in the measurement of sap flow using ‘Tahiti’ lemon trees. Experiments were installed in an orchard of young trees, located in the experimental farm of irrigation of ESALQ, in Piracicaba, São Paulo State, Brazil. The evaluation was carried out using two weight lysimeters. The results demonstrated that the method can be used to measure the transpiration in citrus; however, the accuracy depends on theoretical concepts that should be considered and of certain corrections that should be accomplished. Those considerations as well as the advantages and disadvantages of this method are discussed in this work.

A medida da transpiração de árvores no campo é de difícil consecução. Nas duas últimas décadas, tem-se dado ênfase à medida de fluxo de seiva no caule como indicador da transpiração, principalmente se a escala de tempo usada é igual ou menor que um dia. Para essas medidas, são usados métodos térmicos com fornecimento de calor ao caule. O método de dissipação térmica (MDT) é um deles e vem sendo bastante utilizado pelo seu princípio simples e pela boa sensibilidade às variações de fluxo de seiva. Entretanto, tem-se evidenciado a necessidade de cuidados no seu uso, sendo uma das causas de perda de precisão o efeito da carga radiante sobre a planta, geradora de gradiente térmico natural, que interfere nos resultados. Além disso, o desempenho do método em condições diferentes daquelas em que foi desenvolvido deve ser testado. Assim, o presente trabalho teve como objetivos analisar o desempenho do MDT em árvores de seringueira, considerando que essa espécie produz látex que poderia interferir sobre o bom funcionamento do sensor, e avaliar o efeito do gradiente térmico natural do caule sobre as estimativas. Os resultados demonstraram que essa técnica de medida pode ser utilizada nessa espécie e que, nas condições em que foram realizados os testes, não há interferência do gradiente térmico natural sobre as estimativas. Entretanto, para melhorar o grau de precisão, deve ser realizado melhor estudo de caraterização da área condutora da seiva em relação ao diâmetro do caule. The transpiration measurement of trees in field condition is very difficult. In the two last decades, some emphasis has been given in the study of stem sap flow as an indicator of plant transpiration. The methodology is particularly suitable for time scale less or equal than one day. One of the methods is the heat dissipation method (HDM), which has been used because of its simplicity and high sensitivity to the sap flow variations. However, the effect of the natural radiation, that generates a natural thermal gradient in stem, may lead to precision loss. Moreover, the performance of the method needs to be evaluated if the conditions are different from those for which it was developed. Thus, the present work aimed to analyze the performance of the HDM in rubber trees, considering that this specie produces latex that could affect the performance of the sensor, as well as to evaluate the effect of the natural thermal gradient of the stem on the estimated transpiration. The results had showed that HDM can be used with rubber trees and, in the conditions that tests were conducted, the natural thermal gradient does not effect the estimations. To improve the precision of the method, further studies, characterizing the tissue sap conductive area and the stem diameter should be made.

A crescente preocupação com o uso da água pelas culturas e a busca por maior eficiência hídrica tem sido agravada pela expansão das plantações no Brasil para áreas marginais, com menor disponibilidade hídrica, o que tende a aumentar com as mudanças climáticas. O conhecimento acerca das características morfológicas e dos principais processos fisiológicos que controlam o crescimento das árvores e o uso da água é essencial para a seleção e melhoramento de espécies florestais tolerantes à seca. Assim, o presente estudo teve como objetivos: i) avaliar as precipitações pluviais total e efetiva e monitorar as variações de umidade do solo; ii) estimar as taxas de crescimento e caracterizar a estrutura de copa de povoamentos de espécies de Eucalyptus e Corymbia, sendo estas: E. grandis (pouco tolerante à seca), E. urophylla e E. cloeziana (mediamente tolerantes à seca), e E. brassiana, E. camaldulensis e C. citriodora (muito tolerantes à seca); e iii) fazer o balanço hídrico do sistema solo-planta e avaliar a eficiência de uso de água (EUA) para a produção de lenho em povoamentos de E.grandis, E. urophylla e E. camaldulensis. O experimento foi instalado em março de 2016 no município de Itatinga-SP, Brasil. Foi instalada uma subparcela útil de 36 plantas paraa realização de avaliações não-destrutivas em cada espécie. As demais linhas daparcela foram destinadas à amostragem destrutiva. As espécies que apresentaram maior precipitação pluvial efetiva foram E. brassiana e C. citriodora. Apesar de E. grandis e E. urophylla, as espécies mais produtivas, terem sido as que mais tiveram perda de água por interceptação, também foram as que apresentaram a maior EUA para a síntese de biomassa de tronco. O E. grandis e o E. camaldulensis foram as espécies que mais transpiraram em 12 meses (1112 mm e 797 mm, respectivamente). O E. camaldulensis, embora seja muito tolerante ao déficit hídrico, mostrou-se como uma espécie dispendiosa nas condições edafoclimáticas deste sítio, o qual, praticamente, não apresenta restrição hídrica. Esta espécie consumiu muita água e apresentou baixa EUA. O E. urophylla, espécie que menos transpirou (638 mm), apresentou baixo impacto no balanço hídrico do sistema solo-planta, sendo, também, importante no processo de alocação de carbono. The growing concern with the use of water by crops and the search for greater water efficiency has been aggravated by the expansion of plantations in Brazil to marginal areas, with less water availability, which tends to increase with climate change. Knowledge about the morphological characteristics and the main physiological processes that control the growth of trees and water use is essential for the selection and improvement of drought-tolerant forest species. Thus, the present study aimed to: i) assess total and effective rainfall and monitor soil moisture variations; ii) estimate growth rates and characterize the crown structure of Eucalyptus and Corymbia species stands, which are: E. grandis (low-drought-tolerant), E. urophylla and E. cloeziana (moderately-drought-tolerant), and E. brassiana, E. camaldulensis and C. citriodora (high-drought-tolerant); and iii) calculate the water balance of the soil-plant system and evaluate the water use efficiency (WUE) for the production of wood in stands of E. grandis, E. urophylla and E. camaldulensis. The experiment was installed in March 2016 in the municipality of Itatinga-SP, Brazil. A useful subplot of 36 plants was installed to carry out non-destructive assessments on each species. The other lines of the plot were destined for destructive sampling. The species with the highest effective rainfall were E. brassiana and C. citriodora. Although E. grandis and E. urophylla, the most productive species, were the ones that had more water loss by interception, they were also the ones that presented the highest WUE for the synthesis of trunk biomass. E. grandis and E. camaldulensis were the species that transpired the most in 12 months (1112 mm and 797mm, respectively). E. camaldulensis, although very tolerant to water deficit, proved to bean expensive species in the edaphoclimatic conditions of this site, which practically has no water restriction. This species consumed a lot of water and presented low WUE. E. urophylla, the species that transpired the least (638 mm), had a low impact on the water balance of the soil-plant system, and is also important in the carbon allocation process.