Reduced End-of-production Fertilization Rate Increased Postproduction Shelf Life of Containerized Vegetative Annuals

Abstract

Twenty-one cultivars of vegetative annuals were treated with 0%, 50%, or 100% of the production fertilization rate of 300 mg·L−1 N starting 2 weeks before and continuing until harvest. At harvest, plant width, flower number, and quality rating were measured. The plants were then placed in a simulated interior environment where flower number was counted and quality rating was assigned to each plant weekly for 3 weeks. Overall, 14% of the cultivars maintained a marketable quality (i.e., quality rating of ≥3.0 of 5) for 3 weeks, 43% for 2 weeks, 38% for 1 week, and one cultivar did not maintain quality during the postharvest evaluation. Reduced end-of-production fertilization rate (EPFR) resulted in higher quality ratings for at least one additional week of simulated shelf life for three cultivars, including ‘Dreamtime Copper’ bracteantha (Bracteantha bracteata), ‘Vanilla Sachet’ nemesia (Nemesia ×hybrida), and ‘Bridal Showers’ sutera (Sutera hybrida). ‘Comet White’ and ‘Sunlight’ argyranthemum (Argyranthemum frutescens) retained flowers an additional 2 weeks and ‘Caritas Lavender’ angelonia (Angelonia angustifolia), ‘Dreamtime Copper’ bracteantha, ‘Liricashowers Deep Blue Imp.’ and ‘Starlette Trailing Purple’ calibrachoa (Calibrachoa hybrid), ‘Vanilla Sachet’ nemesia, ‘Cascadias Pink’ petunia (Petunia ×hybrida), and ‘Bridal Showers’ sutera retained flowers an additional 1 week when treated with 0% compared with 50% or 100% EPFR. Four cultivars had decreased plant width at harvest with 0% EPFR. These results indicate that reducing fertilization 2 weeks before harvest can prolong shelf life of some vegetative annuals. Differences in the length of shelf life and responses to reduced EPFR occurred among cultivars of all the affected species. Reduced EPFR did not increase the shelf life of two species, including diascia (Diascia ×hybrida) and lantana (Lantana camara).