Indices de reflectancia y rendimiento del frijol con aplicaciones de nitrogeno | Spectral reflectance indices and yield in bean with nitrogen applications
2004
Gutierrez-Rodriguez, M. | Escalante-Estrada, J.A. | Rodriguez-Gonzalez, M.T. | Reynolds, M.P.
Different nitrogen (N) rates (0, 100, and 200 kg ha(-1)) were applied in bean (Phaseolus vulgaris L.) plants cv. Flor de Durazno to determine whether the biomass and yield were related to the normalized difference vegetation index (NDVI). The study was carried out in Montecillo, Mexico under rainfed conditions (June-September, 2001) with a density of 25 plants m(-2) using a randomized complete block design. Canopy reflectance was measured with a portable radiometer (FieldSpec, USA) at 14, 25, 32, 39, 50, 84, and 88 days after sowing (das). The results showed that the high seed yield was increased with 200 kg ha(-1) N (549 g m(-2)), while N0 treatment had low seed yield (323 g m(-2)). Raceme number, pod number and seeds m(-2) were related to high yield. Biomass and harvest index were also higher in N200, 1003 g m(-2) and 46%, respectively, compared with 932 g m(-2) and 35% for the N0 treatment. The maximum NDVI values occurred during the flowering-pod filling stage (50 to 84 das); when the plants began senescence, the NDVI values decreased. NDVI showed a strong relationship with absorbed radiation (r2 = 0.62 to 0.80), biomass (r2 = 0.73 to 0.98), leaf area index (r2 = 0.89 to 0.91), and seed yield (r2 = 0.99). Seed yield and biomass production were increased with N fertilization rates. It was observed that NDVI estimated seed yield and biomass in bean plants.
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