Abstract
ABSTRACT The objective was to determine the crop evapotranspiration (ETc) and crop coefficients (Kc) of tropical forest seedlings over a 135-day cycle, in the climatic conditions of the Cerrado-Amazon transitional region (11º 51’ 08 “S; 55º 30’ 56” W; altitude of 371 m). Five native species (Tabebuia impetiginosa, Tabebuia roseoalba, Handroanthus chrysotrichus, Parkia pendula and Parkia platycephala) and one exotic species (Adenanthera pavonina) were evaluated in seven shading conditions: 35, 50 and 80% black nets (Polyolefin); green Frontinet®, red ChromatiNet® and blue ChromatiNet® of 50% shading; and full sun. Reference evapotranspiration (ETo) was obtained by the Penman-Monteith FAO-56 method and the crop evapotranspiration of the seedlings (ETc) was given by daily weighing. The Kc values were obtained by dividing ETo by ETc. At 135 DAT, destructive analysis was performed to determine the leaf area. In full sun conditions, ETc varied from 3.9 (P. pendula) to 5.0 mm d-1 (T. roseoalba). The increase in the shading percentage promotes reduction in leaf area, ETc and Kc. Colored nets with 50% shading generate similar water demands.
Highlights
Meeting the water demand of a vegetation promotes conditions for the expression of the maximum productive potential of the plant and ensures the sustainability and preservation of environmental systems, for subsidizing the planning, project and management of hydro-agricultural systems (Gomide & Albuquerque, 2008; Carvalho et al, 2015).According to Souza et al (2014), only the knowledge on the total water requirement of the plant does not lead to an efficient irrigation management; the knowledge on the water demand in different development stages becomes essential
The adoption of irrigation systems with design errors and/or with water managements inadequate for the production of forest seedlings may lead to yields lower than the genetic potential of the species, favor the establishment of diseases, increase the consumption of nutrients, water and energy, besides decreasing germination potential and homogeneity in the development of the seedlings (Lopes et al, 2005; Gruber, 2006; Neves et al, 2010)
There were only 27.00 mm of rainfall distributed until 42 DAT, indicating the occurrence of favorable climatic conditions for the analysis of the specific influence from shading conditions on each species and condition (Figure 1)
Summary
According to Souza et al (2014), only the knowledge on the total water requirement of the plant does not lead to an efficient irrigation management; the knowledge on the water demand in different development stages becomes essential. The adoption of irrigation systems with design errors and/or with water managements inadequate for the production of forest seedlings may lead to yields lower than the genetic potential of the species, favor the establishment of diseases, increase the consumption of nutrients, water and energy, besides decreasing germination potential and homogeneity in the development of the seedlings (Lopes et al, 2005; Gruber, 2006; Neves et al, 2010). This study aimed to determine ETc and the crop coefficients of six tropical forest species in the stage of seedlings under different shading conditions, in the climatic conditions of the CerradoAmazon transitional region of the state of Mato Grosso, Brazil
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