“…Despite the large market availability of the latter, presenting different levels of portability, spectral ranges, sizes, and prices, only a few studies have focused on its application to assess the quality and ripening of oranges and mandarins on-tree (Table 4), perhaps due to the complexities involved under field conditions, and the performance deterioration of calibration models, in spite of the spectral range used [63][64][65][66][67][68]. Nevertheless, the QA assessed on-tree (Table 4) comprise fruit mass and size, color parameters [63,67,68], pericarp thickness, SSC, TA, firmness, MI, juice pH and mass, and BrimA index, which measures the balance between sweetness and acidity as described by [12]. Noteworthy, the majority of the calibration models exhibited R 2 < 0:8, despite the range used, and did not include external validation, except for [65,66].…”