Evapotranspiration of lettuce inside or outside a greenhouse / Evapotranspiração da cultura da alface dentro e fora de ambiente protegido

AUTOR(ES)

David Rolando Palomino Montes

DATA DE PUBLICAÇÃO

2008

RESUMO

This work was carried out at the Irrigation and Drainage Experimental Station of the Federal University of Viçosa, in Viçosa, Minas Gerais state, Brazil, from December 2007 to January 2008, cultivating Lettuce (Lactuca sativa L.) cultivar Regina, under two experimental conditions as: inside and outside a greenhouse. We aimed to a) determine the crop evapotranspiration of lettuce (ETc), b) determine the adjustment coefficient of a modified irrigâmetro device (Ki) for the first three vegetative developmental stages of lettuce, c) evaluate the effect of four water body levels established in the minilysimeters, in evapotranspiration and on the main cropping characteristics of lettuce, d) determine the water use efficiency for lettuce. All characteristics were evaluated either inside or outside the greenhouse. For each environmental condition, 560 plants were cultivated, and 336 from among them were cultivated in three blocks. In each block four treatments were carried out (T15, T20, T25 and T30) and defined by the depth of the water body (0.15; 0.20; 0.25 e 0.30 m), established in the minilysimeters of constant water body level. Each minilysimeter was connected to a modified irrigâmetro device. Over the experimental period, the meteorological data was collected in automated meteorological stations installed under the two environmental conditions. A randomized block design with split-plots was utilized to perform the statistical analysis of the crop evapotranspiration data in each of the two environmental conditions. For the production variables we did prefer to utilize a randomized block design with four water body depths and three replicates to perform the statistical analysis in each of the two environmental conditions. We concluded from our results that: seasonal crop evapotranspiration of lettuce was lower inside greenhouse as compared to outside greenhouse; crop evapotranspiration (ETc) decreased with water body depth, in each of the two environmental conditions, excepting the T30 treatment outside greenhouse; at a 15 cm depth of water body, the crop coefficient values (Kc) inside greenhouse were 0,93; 1,27 and 1,30 for the first, second and third developmental stages of lettuce, respectively, and 0,80; 1,12 and 1,39 for the same three stages outside greenhouse. There was no significant differences among fresh mass of head, leaf area, specific leaf area and fresh matter, dry matter and stem length for inside and outside greenhouse, excepting the T15 treatment which showed higher values inside greenhouse; leaf number and leaf width were higher inside greenhouse in comparison to outside greenhouse and the water use efficiency (WUE) increased with water body depth, providing the higher WUE inside greenhouse.

ASSUNTO(S)

engenharia de agua e solo coeficiente de cultura lactuca sativa crop coefficient lactuca sativa irrigação irrigation

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