Canopy reflectance indices and its relationship with yield in common bean plants (Phaseolus vulgaris L.) with phosphorous supply

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Common bean plants (Phaseolus vulgaris L.) were grown under three phosphorous levels (0, 100 & 200 kg ha-1) and under rainfed conditions with the objective to examine the association between vegetative indices (NDVI, normalized difference vegetation index; & GNDVI, green normalized difference vegetation index) and intercepted radiation, leaf area index, biomass and yield during the growing season. The maximum intercepted radiation, leaf area index (LAI) and biomass were reached during the pod filling stage {80 days after sowing (DAS)}, and the P treatment of 200 kg ha-1 showed the highest values. The high intercepted radiation was derived from an increase in LAI inducing a major biomass accumulation. Near to physiological maturity LAI decreased as a result of leaf abscission. NDVI and GNDVI were higher with P supply than without P at anthesis and pod filling stage (50 – 80 DAS). Near to physiological maturity NDVI and GNDVI decreased in all the treatments. When the maximum intercepted radiation, LAI, and biomass production were reached during anthesis and pod filling stage, NDVI and GNDVI also had the highest values. The association between the vegetative indices and seed yield during the pod filling stage showed a linear relationship by the P supply. The relationship between GNDVI and seed yield was higher (r2 = 0.77) than the relationship between NDVI and seed yield (r2 = 0.61).

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