Transpiration of tomato crop cultivated in substrate and its influence on the leaching fraction and electrical conductivity of the drained nutrient solution/Transpiracao do tomateiro cultivado em substrato e sua influencia na fracao lixiviada e na condutividade eletrica da solucao nutritiva drenada
The objective of this work was to evaluate the influence of tomato transpiration on the leaching fraction and electrical conductivity (EC) of the nutrient solution drained in the sand substrate under greenhouse growing conditions. Two fertigation techniques were used, one denoted by conventional con...
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Veröffentlicht in: | Acta scientiarum. Agronomy 2010-10, Vol.32 (4), p.721 |
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Format: | Artikel |
Sprache: | spa |
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Zusammenfassung: | The objective of this work was to evaluate the influence of tomato transpiration on the leaching fraction and electrical conductivity (EC) of the nutrient solution drained in the sand substrate under greenhouse growing conditions. Two fertigation techniques were used, one denoted by conventional control system and the other by computerized control system. In the conventional control system, the nutrient solution was applied by using fixed time intervals between fertigation events. In the other system, the application occurred according to transpiration estimates, which were performed by the control algorithm of the computerized system. Under cloudy conditions, the EC of the drained nutrient solution decreased in both systems as a result of low transpiration and high leaching fractions, which mitigated substrate salinization. However, under high values of solar radiation, EC increased due to low leaching fractions. The results demonstrated that, under cloudy conditions, the computerized control system reduced effluent volumes by 54% as compared to the conventional control system and, simultaneously, prevented substrate salinization by maintaining mean EC values of the drained solution in the range from 2.9 to 3.5 dS [m.sup.-1]. Key words: Lycopersicon esculentum, hydroponics, soilless cultivation, fertigation, greenhouse. O objetivo deste trabalho foi avaliar a influencia da transpiracao do tomateiro na fracao lixiviada e na condutividade eletrica (CE) da solucao nutritiva percolada no substrato de areia, em cultivo realizado sob condicoes de casa-de-vegetacao. Foram utilizadas duas tecnicas de fertirrigacao, sendo uma denominada de sistema de controle convencional e outra, de sistema de controle computadorizado. No sistema de controle convencional, a solucao nutritiva foi aplicada em intervalos de tempo fixos entre eventos de fertirrigacao. No outro sistema, a aplicacao ocorreu de acordo com estimativas de transpiracao que foram realizadas pelo algoritmo de controle do sistema computadorizado. Em dias nublados, a CE da solucao nutritiva drenada diminuiu em ambos os sistemas, em decorrencia da baixa transpiracao e da alta fracao lixiviada, o que amenizou a salinizacao do substrato. Entretanto, em altos valores de radiacao solar, a CE aumentou devido a baixa lixiviacao. Os resultados demonstraram que, em condicoes de nebulosidade, o sistema de controle computadorizado reduziu o volume de efluentes em 54% em relacao ao sistema de controle convencional e, simu |
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ISSN: | 1679-9275 |
DOI: | 10.4025/actasciagron.v32i4.3246 |