Application of remotely piloted aircraft in the evaluation of the vegetative response of coffee trees affected by frost to sun exposure

The sun exposure on the northern and southern faces of the coffee planting rows may play a key role in recovering of coffee plants affected by frost damage. This study aimed to assess coffee plants with frost damage according to the solar exposure face along the planting rows. Three experimental areas, each with plantations of different ages (one, three and eight years), were used. Evaluations were performed on the northern and southern sides of the planting rows, where the frost damage were measured. The remotely piloted aircraft (RPA) was flown over the three areas to capture multispectral images, and the derived vegetation indices were analysed. Only plants with eight years of age showed differences in frost damage between the sun exposure faces. Greater of damage was observed in the north face, with 48% of plant compromise. For coffee trees of one and three years old, the sun exposure did not exert a significant influence on the levels of damage between the faces of the planting line. The use of remotely piloted aircraft equipped with multispectral cameras demonstrated high efficiency in identifying spatial variations of crop damage. Among the indices evaluated, SAVI and MCARI2 showed a strong correlation with frost damage levels.