Detección de estrés hídrico en brocoli (brassica oleracea var. itálica), utilizando ndvi sobre imágenes multiespecttrales capturadas a corta distancia

The spectral response of the vegetation provides valuable information on its biophysical and physiological characteristics. The objective was to detect water stress during broccoli foliar development, by calculating the normalized difference vegetation index (NDVI) on multispectral images (RED, NIR), captured at a short distance (2,4mm pixel) in order to provide an alternative tool that does not sacrifice the crop and allows more timely decision making. Multispectral images were captured of 120 plants subjected to instantaneous water stress, applying different irrigation doses: T1-Anegamiento, T2, T3 and T4 at 25-50-75% respectively, in reference to the Field Capacity and T5-Control; for thirteen days, in two periods: 45 and 75 days after transplantation. In parallel, physiological variables such as: stomatal conductance and relative water content were recorded. The NDVI was calculated. Findings were validated by comparing NDVI with stomatal conductance and relative water content. The results were statistically significant with a confidence level P = 0,05, for the 45-day period, strong correlation values R = 0,71 were determined when comparing the NDVI with the physiological variables; Unlike the 75-day period, R values are weak and less than 0,45. This study allowed to deepen in the knowledge of the spectral response of the broccoli crop in its vegetative development. In addition, it shows the utility of the NDVI at the plot scale, as a rapid, alternative and non-destructive approach to estimate water stress in crops for more timely decisions.