SEASONAL GROWING ENVIRONMENT AFFECTS QUALITY CHARACTERISTICS AND POSTPRODUCTION LONGEVITY OF POTTED MINIATURE ROSES

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