Coffee crop coefficient for precision irrigation based on leaf area index

Bragantia

Antonio Roberto Pereira²  Marcelo Bento Paes De Camargo¹  Nilson Augusto Villa Nova² 

[1] ,USP ESALQ Departamento de Engenharia de BiossistemasPiracicaba SP ,Brasil

关键词: Coffea arábica L.;    reference evapotranspiration;    soil water balance;    planting density;    Coffea arábica L.;    evapotranspiração de referência;    balanço hídrico do solo;    densidade de plantio;   

DOI  :  10.1590/S0006-87052011000400030

来源: SciELO

【 摘 要 】

Crop coefficient (Kc) for coffee plantations was found to be linearly related to the leaf area index (L) up to 3, i.e., Kc = b L. The basic assumption is that for irrigated trees the water use per unit leaf area (ET LA) is equal to the reference evapotranspiration (ETo) expressed also on a unit leaf area basis of the reference surface (ET LA = ETo/Lo). As recommended by FAO-56 the leaf area index (Lo) for the hypothetical reference surface (grass) is equal to 2.88, then the most likely value is b = Lo-1 = 2.88-1 = 0.347. However, for L > 3 (completely covered ground surface) Kc decreased from a peak value (~1.05) tending to an asymptotic low value around 0.7 for L > 6, but the linear model gives unrealistic Kc estimates; tentatively the empirical function Kc = 1.8 L-0.5 is offered here as an initial guess due to the lack of experimental results for the interval 3.5

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