CAMBIOS TEMPORALES DE LA EFICIENCIA EN EL USO DE LA RADIACION DE LA VEGETACION BAJO DISTINTAS CONDICIONES HIDRICAS Y NUTRICIONALES DE CRECIMIENTO

CRISTIANO P.M; POSSE G; CARBALLEDA J. M.; DI BELLA C.M.

Mar del Plata, Buenos Aires, Argentina

Congreso; XII Congreso de la Asociacion Espanola de Teledeteccion; 2007

Asociacion Espanola de Teledeteccion

Net Primary Productivity (NPP) is a key factor that summarizes important features of the ecosystem functioning. It is linearly relates whit the photosynthetically active radiation (PAR), the fraction of PAR intercepted (fAPAR)-estimated from NDVI data- and the light use efficiency (å). This model is widely used to estimate PPN from remote sensing NDVI data. Although it is well known that å was altered due to numerous factors, there are little data on bibliography. Our aim was to study the temporal dynamics of å in two forages species growing under different water and nutrient conditions. An experiment was carried out for 5 months with two species with different canopy architecture from germination to flowering. The experiment unit was a canopy of four pots.  Three combinations of water content and nutrient supply were applied. Reflectance (400-1100nm) was measured; fAPAR, NPP and å were estimated. Values of å ranged between 0.5- 3 gDM/MJ and were similar for two species but with different temporal patterns. The erectophile species reached first it maximum value of å and the other one, with a more planophile structure, reached it maximum efficiency later. For two species, maximum values of å were estimated in the treatments with optimal water and nutrient conditions of growth.