Resumo

DE LA CASA, Antonio et al. Leaf area index in potato estimate from canopy cover. Agronomía Trop. [online]. 2008, vol.58, n.1, pp.61-64. ISSN 0002-192X.

Leaf area index (LAI) determinations and the photosynthetic active radiation intercepted by crops canopy are both required in evapotranspiration and yield crops models. The objectives of this work were: i) to evaluate a simple model for lai estimation in potato crops; ii) to verify its predictive performance for different planting densities. The experiment was carried out next to Córdoba city, Argentina, during 2005 and 2006 potatoes autumn cycles, with first year data used to develop the model and the second one to validated. In both years different planting densities were used. The fraction of the ground covered by foliage (f) was obtained with digital photographs taken vertically above the crop, and the solar radiation intercepted by foliage (i) was measured with a photons photosynthetic active density flux (ceptometer) located above and below canopy. The relationship between i and f was used to estimated an extinction coefficient (k = ki/kf) of 0,7 (being ki the extinction coefficient obtained with the ceptometer and kf from cover foliage), with a range between 0,66 and 0,72 for different density treatments. The ki values were relatively constants from emergence to maximum foliage cover. The lai calculated with f and kf showed a good performance compared to the ceptometer measurements (R2 = 0,86; P<0,01) and with the advantage of using photographic measures of foliage cover.

Palavras-chave : Solanum tuberosum; LAI; foliage; model.