Identification of a harvest index for Monstera deliciosa and Philodendron sp. ‘Xantal’ leaves for ornamental use

Leaves of tropical ornamental plants exhibit a short vase life. Symptoms include yellowing and disease. These defects are associated with genetic and environmental factors but mainly associated with leaf age at harvest. Our research aimed to identify a harvest index to improve postharvest quality and extend vase life. Monstera deliciosa and Philodendron sp. ‘Xantal’ plants were grown under 70% permanent shading. Fifty young leaves of M. deliciosa and 25 leaves of Philodendron were tagged prior to expansion. Weekly measurements included foliar area, dry weight, color (CIE L*a*b* values, and indirect chlorophyll content (SPAD). Data were plotted against leaf age after full expansion and regression analysis was performed. In a second experiment, leaves of Monstera deliciosa and Philodendron sp. ‘Xantal’ were harvested at four developmental stages, commercially packed, and subjected to simulated shipping conditions. During vase life at 20°C with 12 h of daylight, the incidence and severity of leaf yellowing, and the incidence of mechanical damage and disease were evaluated with rating scales. SPAD value was highly correlated with leaf age (R²=0.787 for Monstera and R²=0.791 for Philodendron). In the commercial simulation trial, mature leaves (64 d after leaf expansion and with the highest SPAD value) showed less incidence of yellowing, disease, and mechanical damage during vase life. Chlorophyll content, measured as SPAD value, was a suitable harvest index and predictor of vase life.