Impact of altitude on the performance and anthocyanin concentration in five varieties of purple corn in the Peruvian Amazon

Purple corn (Zea mays L.) is known for its high anthocyanin content and its agricultural relevance in the Andean-Amazonian region. This study analyzed the impact of the altitudinal gradient (672; 2,437 and 2,892 meters above sea level) on agronomic performance and anthocyanin content in five varieties of purple corn grown in the Amazonas region, Peru. A completely randomized block design with three replications was applied, evaluating morphological, agronomic characteristics, and anthocyanin content in different plant tissues. The results revealed significant differences in vegetative development, with taller plants at low altitude (144.7 ± 21.6 cm) compared to mid-altitude (86.4 ± 35.4 cm). Anthocyanin accumulation showed clear tissue-specific fragmentation, with significantly higher concentrations in the husk (6.3 ± 3.4 mg g-1) and bracts (7.8 ± 3.5 mg g-1) at high altitude (p < 0.001). Although grain yield showed no significant differences between altitudes (p=0.612), a trend towards higher yields was observed at lower altitudes (633.3 kg ha-1). The varieties showed specific adaptations: ‘INIA 615’ excelled in yield at low altitude (1,201.5 kg ha-1), while ‘Sintético MM’ performed better at high altitude (1,381.3 kg ha-1). These findings suggest an adaptive trade-off between yield and anthocyanin synthesis, providing valuable information to optimize production according to specific goals and environmental conditions.