Normalized difference vegetation index, and K+ in stem sap of potato plants (Group Andigenum) as affected by fertilization

Remote sensors permit forecasting the nutrient status and yields in crops of economic importance in Colombia. The objective of this study was to determine the relationships between normalized difference vegetation index (NDVI) and yield as well as concentrations of ${\rm {N - NO}}_3^ - $ and K + in stem sap of potato cultivars Diacol Capiro and Pastusa Suprema ( Solanum tuberosum L., Group Andigenum) in relation to different fertilizer rates. Increasing doses (0, 1450, 1900 and 2375 kg ha –1 ) of macro- and micronutrient fertilizers were applied to determine NDVI behavior at 55, 75, 100, 125 and 150 days after planting. For Capiro, significant differences in NDVI readings (0.84–0.88) were found between phenological stages. In both cultivars, NDVI correlated positively with yield and K + concentrations in stem sap during tuber filling and maturation, while in Capiro no correlation was established between NDVI values and ${\rm {N - NO}}_3^ - $ concentrations in stem sap. The NDVI readings could be used to forecast productivity and K status in potato Group Andigenum.