Altitude as a determinant of fruit quality with emphasis on the Andean tropics of Colombia. A review.

Due to global warming, the highlands of the tropics have become more important for planting fruit trees. The climate at high altitudes is mainly characterized by decreased temperatures and increased solar radiation. A systematic literature review using four bibliographic databases revealed 22 studies that determined fruit quality at two altitudes. With increasing altitude, duration of fruit development was prolonged, and, in most cases, higher fresh weights and sizes were found; however, fruit firmness decreased. The intensity of the fruit color increased because of greater radiation in high areas. Mostly, the total soluble solids of the fleshy fruits augmented with altitude, probably because of an increase in photosynthesis with higher solar radiation. The total acidity did not show a clear trend with increasing elevations. At higher altitudes, the content of antioxidants (mainly phenolics) increased in the fruits, especially in the epidermis as a reaction to the increasing ultraviolet (UV) light. Physiological disorders in the fruits included sunburn and damage caused by low temperatures. Different species and varieties react differently to the conditions of highlands, depending on their origin and whether climatic conditions are optimal for a specific fruit tree. There are no positive effects on fruit quality when altitude is at the limit or above the recommended range for the fruit species.