115 research outputs found

    Rubber tapping system effect on the productivity of Hevea brasiliensis in the Colombian Middle Magdalena

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    P√°ginas 184-192.Los sistemas de sangr√≠a con estimulaci√≥n se usan para minimizar costos y aumentar la producci√≥n de l√°tex. Por ello, se evaluaron sistemas de sangr√≠a con diferentes frecuencias con y sin estimulaci√≥n con Ethrel√í y niveles de fertilizaci√≥n en un cultivo del FX3864 de Hevea brasiliensis de 9 a√Īos de edad en Barrancabermeja, Santander. El estudio se realiz√≥ con un dise√Īo de parcelas divididas distribuido en bloques al azar, considerando como parcela principal los sistemas de sangr√≠a con diferentes frecuencias con y sin estimulaci√≥n y como subparcela los tratamientos de fertilizaci√≥n con dosis combinadas de N, P y K. La producci√≥n de caucho seco, consumo de corteza, incidencia de seca fisiol√≥gica, contenido de caucho seco y la rentabilidad econ√≥mica se consideraron como variables de respuesta. La producci√≥n m√°s alta se obtuv√≥ con los sistemas d/3 E y d/4 E (1.446 y 1.281 kg ha-1 a√Īo-1, respectivamente), con diferencias significativas con los sistemas d/3 S.E y d/5 E. Entre los tratamientos de fertilizaci√≥n no se encontr√≥ diferencias significativas, aunque la mayor producci√≥n se obtuvieron con los niveles 40-40-40 kg ha-1 y 80-80-80 kg ha-1 de N, P y K. En cuanto a los mayores niveles foliares de N, P, K y Ca se encontraron en el sistema d/4 E. Con estos resultados se recomienda el sistema de sangr√≠a d/4 E por tener la mejor rentabilidad econ√≥mica bajo diferentes rendimientos del sangrador, menor consumo de corteza (3,86 cm), mayor vida √ļtil de la plantaci√≥n (3,85 a√Īos) y menor incidencia de enfermedades de panel.ABSTRACT: Tapping systems with stimulation are used to minimize costs and improve latex yield. For this, tapping systems with different frequencies and with or without Ethrel¬ģ stimulation and fertilizer levels were evaluated in a 9-yearold crop of FX3864 of Hevea brasiliensis in Barrancabermeja, Santander. In this study, a split plot design with randomized complete blocks was used, where the tapping systems with different frequencies with or without stimulation were considered as the principal plot and the fertilization treatments with combined dosages of N, P and K were considered as the subplots. The dry rubber yield, bark consumption, tapping panel dryness incidence, dry rubber content and profitability were considered as response variables. The systems d/3 E and d/4 E obtained the highest yield (1,446 and 1,281 kg ha-1 yr-1, respectively), with significant differences with the systems d/3 S.E and d/5 E. For the fertilization treatments, there were no significant differences. Notwithstanding, the highest yields were obtained in the 40-40-40 kg ha-1 and 80-80-80 kg ha-1 of N, P and K balanced treatments. The higher foliar levels of N, P, K and Ca were founded in the d/4 E system. According to these results, the d/4 E tapping system is recommended to be the most profitable under different tapping yields, with less bark consumption (3.86 cm), longer life plantation (3.85 years) and less disease panel incidence.Bibliograf√≠a: p√°gina 192.Art√≠culo revisado por pares

    Escala diagramática para quantificação da severidade de manchas em folhas de Eucalyptus globulus Labill. causadas por Teratosphaeria nubilosa (Cooke) Crous & U. Braun

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    http://dx.doi.org/10.5902/198050989296The leaf spot (Mycosphaerella leaf disease = MLD) caused by Teratosphaeria nubilosa has caused damage in eucalypt plantations in southern and southeastern Brazil. The need to assess the disease in the field to evaluate of this damage, efficiency control, evaluation of germplasm induces to the necessity of having a visual scale for evaluation of disease. The objective was to develop a diagrammatic scale for young leaves and one for adult leaves of Eucalyptus globules for MLD. To do so, the leaves collected in the field were scanned for image analysis. The damaged area, the healthy leaf area and the external area of the same scale RGB (Red, Green, Blue) were determined. Subsequently, it was determinate the levels of severity depending on the sample distribution with seven levels for young leaves and six for adult leaves. For the visual acuity test and validate the scale, the leaves were evaluated for severity, with and without scale. With this proposed scales, the assessors showed good accuracy both for young and adult leaves with R2=0,98 and R2=0,80, respectively. The importance of the development of diagrammatic scales for assessing MLD in eucalyptus must to the fact that allows quantification of the symptoms accurately and precisely.http://dx.doi.org/10.5902/198050989296A mancha foliar (mancha de micosferela) causada por Teratosphaeria nubilosa tem acarretado preju√≠zos em plantios de eucalipto na regi√£o Sul e Sudeste do Brasil. A necessidade de avaliar a doen√ßa no campo e os danos causados pela mesma, bem como a busca de formas eficientes de controle e a utiliza√ß√£o de germoplasma, leva √† necessidade em ter uma escala visual para quantifica√ß√£o da severidade da doen√ßa. O objetivo deste trabalho foi elaborar uma escala diagram√°tica com folhas jovens e com folhas adultas de Eucalyptus globulus, para avalia√ß√£o de mancha de micosferela. Para tal, as folhas coletadas em campo foram escaneadas para digitaliza√ß√£o da imagem. Determinou-se a √°rea lesionada, √°rea foliar sadia e √°rea total em escala RGB (Red, Green, Blue). Posteriormente, determinaram-se os n√≠veis de severidade em fun√ß√£o da distribui√ß√£o da amostra, sendo sete n√≠veis para folhas jovens e seis para folhas adultas. Para o teste de acuidade visual e valida√ß√£o da escala, as folhas foram submetidas √† avalia√ß√£o da severidade, com e sem escala. Com a ado√ß√£o das escalas propostas, a totalidade dos avaliadores apresentou boa acur√°cia, tanto para folhas jovens como para adultas com R2=0,98 e R2=0,80, respectivamente. A import√Ęncia da elabora√ß√£o de escalas diagram√°ticas para quantificar a severidade de mancha em eucalipto deve-se ao fato de permitir a quantifica√ß√£o dos sintomas de forma acurada e precisa
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