Growth dynamics and water use efficiency of Eucalyptus spp submitted to potassium omission Studies that evaluate the performance of genetic materials resistant and/or tolerant to water stress, the dynamics and water use efficiciency (WUE) and how fertilization management acts in this process are important to achieve the sustainability of forest production. The objective of this study was to evaluate the effect of potassium omission on the development and water use efficiency of different eucalyptus genotypes. The experiment was implemented in December 2011 at the Itatinga Experimental Forest Science Station, which belongs to the Department of Forest Sciences of ESALQ/USP. In a randomized block design with six replications, each consisting of twelve treatments in a 6x2 factorial arrangement, being six eucalyptus clones and two doses of potassium fertilization. The growth evaluations of the experiment were performed in all treatments and repetitions for the variables: total height, diameter at breast height, crown percentage and volume. For the determination of the individual volume of the trees and the quantification of the wood biomass, 3 destructive samples were made along the whole rotation. In addition, the leaf area index was evaluated with the aid of LAI-2200 equipment; monthly litter deposition and soil moisture with Diviner 2000 equipment. In determining the sap flow, the Granier probe method was used, also allowing the adjustment of regression models to estimate the sapwood área. The sap flow analysis was performed on the genetic materials COP 1404 and AEC 144, in the presence and absence of potassium, from april 2017 to december 2018. With the transpirated water volume data and the wood biomass increment in the evaluated period, WUE was calculated. Throughout all evaluations, COP 1404 and COP 1407 clones were the least productive, presenting at 72 months of age 72.7% and 86.5%, respectively, of the productivity achieved by AEC 144, the most productive clone, the which was the only one not to present responses to potassium fertilization. It was observed the need to calibrate the Granier method to estimate the sap flow at the clone level and that only one calibration process is not enough to describe the sap flow throughout the entire rotation. The highest transpiration values were found for COP 1404, being higher in the treatment without potassium fertilization; AEC 144, with lower transpiration rates, showed superior transpiration when fertilized with potassium. In general, the AEC 144 clone showed higher values for the WUE and considering the entire period evaluated, the AEC 144 K-showed a value of 2.4 g / L and the AEC 144 K + of 1.60 g / L, while the COP 1404 K + showed a value of 1.20 g / L and COP 1404 K-a value of 1.02 g / L. Nocturnal transpiration negatively influenced plant growth, which may be a response to different environmental factors. The presence of potassium in the soil for clone AEC 144, may have stimulated an increase in stomatal opening over the evaluated period, causing water loss th...

Resumo O objetivo deste estudo foi avaliar o desenvolvimento, em altura (m), DAP (cm) e produção de madeira (m 3 /ha) aos 96 meses de idade após o plantio, das espécies Acacia mearnsii De Wild e Eucalyptus globulus Labill em monocultivos e consórcios com linhas simples e duplas de plantio, no estado do Rio Grande do Sul-RS. O experimento foi instalado no ano de 2005, em duas fazendas localizadas no município de Piratini-RS, onde foram plantadas as espécies Eucalyptus globulus Labill (E) e Acacia mearnsii De Wild (A), em monocultivo (100%E e 100%A) e consorciadas em linhas simples (50%E:50%A-LS) e em linhas duplas (50%E:50%A-LD). Para avaliarmos os efeitos dos consórcios no desenvolvimento das espécies, o crescimento foi avaliado anualmente nos meses de outubro entre 2006 e 2013; e no ano de 2014 foi realizada a cubagem pelo método de Smalian. A acácia-negra teve seu crescimento em altura beneficiado pelo consórcio, 13,96 m no 50%E:50%A-LS e 13,56 m no 50%E:50%A-LD, enquanto que na monocultura apresentou uma altura de 13,23 m, já para o eucalipto não foi possível observar vantagens no crescimento em altura, pois os consórcios foram iguais ao monocultivo; o DAP para ambas espécies foi influenciado pelos consórcios, positivamente para a acácia-negra, sendo até 15% superior ao monocultivo, e negativamente para o eucalipto, chegando a ser 17% inferior ao monocultivo, diferenças que são explicadas pelas variações dos espaçamentos proporcionadas ao se manter o arranjo convencional de plantio das espécies nos tratamentos consorciados. A produção de madeira da acácia negra nos consórcios (97,97 m 3 /ha no 50%E:50%A-LS e 90,93 m 3 /ha no 50%E:50%A-LD) foi superior a 50% a da monocultura (136,11 m 3 /ha), o que não ocorreu para o eucalipto. As produções totais dos consórcios foram iguais estatisticamente as das monoculturas.

The objective of this study is to evaluate the fit of Artificial Neural Networks (ANN) for height estimation and evaluation of the effects of consortium in a mixed-species plantation of Eucalyptus globulus (E) and Acacia mearnsii (A). The experiment was installed in 2005, on two farms in the municipality of Piratini - RS, where was planted the species Eucalyptus globulus (E) and Acacia mearnsii (A), in monoculture and mixed in simple lines (50%E:50%A - SL), and double lines (50%E:50%A - DL). The training and evaluation of the networks were made in R-project with the package neuralnet. All ANNs, from the simplest to the most complex, showed high values for Rŷy and low for Syx, BIAS and RMSE, with superior results in ANN 3, 4, and 6, which demonstrates that the information of DBHmin, DBHmean, and DBHmax were important stand attributes. Furthermore, the ANNs were able to capture the different growth patterns shown by the species in the different forms of consortiums, therefore is indicated for the height estimation in monocultures and mixed plantations of Eucalyptus globulus and Acacia mearnsii, and only one ANN would be necessary to represent the entire population.

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