Seasonal Growing Environment Affects Quality Characteristics and Postproduction Longevity of Potted Miniature Roses

Abstract

To assess the effects of summer-like [high-temperature long-day (HTLD)] vs. winter-like [low-temperature short-day (LTSD)] growing conditions on production quality and postproduction longevity of potted miniature roses, plants of Rosa L. `Meirutral' and `Meijikatar' were grown in growth chambers using a short-cycle production schedule (potted liners grown until root establishment, pinched, and flowered). Plants grown under the HTLD environment [30C day/21C night plus 725 μmol·m–2·s–1 photosynthetic photon flux (PPF) for 14 hours per day] had more flowering shoots than those grown under the LTSD environment (21C day/16C night plus 725 μmol·m–2·s–1 PPF for 10 hours per day). The difference is attributable to fewer blind shoots (shoots with aborted growing terminals) under HTLD, because plants in both environments had the same total number of shoots at flowering. Plants in the HTLD chamber also flowered faster, were shorter, and had smaller and lighter-colored flowers than plants in the LTSD chamber. In addition, plants under HTLD exhibited greater poststorage floral longevity and whole-plant shelf life than plants grown under LTSD conditions, regardless of cultivar, simulated shipping (storage) treatment (4 days at 16C), or stage of floral development at harvest. These results suggest benefits from summer production of potted miniature rose plants and the possibility of using a higher-temperature forcing regimen than is normally recommended for winter production.