739 INFLUENCE OF COLD TREATMENTS ON FLOWER QUALITY OF BULBOUS ORNAMENTALS Zsolt SZEKELY-VARGA, Ildikó LIHĂT, Attila BANDI, Géza BALLA, Endre KENTELKY Sapientia Hungarian University of Transylvania, Faculty of Technical and Human Sciences, Department of Horticulture, 2 Calea Sighișoarei, 540485, Târgu Mureș, Romania Corresponding author emails: geza@ballageza.com, kentelky@ms.sapientia.ro Abstract Ornamental plants are among the most extensively grown plants worldwide. They main purpose is for different occasions, like Valentine Day, International women and Mother’s Day and bulbous ornamental plants are one of the most important parts of these special moments. The aim of the present research was to find out for how long should be kept under cold conditions in order to produce cut and potted flowers. For this study it was selected the Tulipa gesneriana, Hyacinthus orientalis, and Muscari armeniacum. Different cold treatment types and times were applied to the bulbous plants. The results indicate that the bulbous plants under the influence of 7 weeks cold treatment under controlled temperature proved to be the best and suitable for cut flowers production at all three selected bulbous ornamental plants. In conclusion, the present work could be usefully for cultivation of different ornamental bulbous plants. Key words: cold treatment, grape-hyacinth, hyacinth, tulip. INTRODUCTION A lot of flower bulbs are purchased each year for their importance in outdoor and indoor decoration, moreover their flowering in periods when few other ornamental plants can do it (Cantor & Gheorghita, 2011). Bulbous ornamental plants are also called ornamental geophytes (Kamenetsky & Okubo, 2012) or are often referred as bulbs which means underground storage organs like rhizomes, corms, bulbs or tubers (Li et al., 2023). The ornamental geophytes include more than 800 different genera (Bryan, 1995), although the ornamental industry is mostly dominated by 7 genera’s as: Tulipa, Narcissus, Gladiolus, Iris, Crocus, and Hyacinthus (Benschop et al., 2010). Their main utilization is commercial bulb production, growing as potted plants, forced fresh cut and potted flowers, and in landscaping (De Hertogh et al., 2012; Chawla et al., 2022). According to Gul et al. (2020) ornamental bulbous plants dominate the global flower market, and one of the main reasons is that they follow perfectly timed phenological period. The life cycle of the ornamental bulbous plants is actually connected with the temperature warm- cold-warm cycle which is a key factor leading to flower initiation (Khodorova & Boitel-Conti, 2013). In the recent years the Romanian flower industry produced cut flowers and potted plants from a variety of different bulbous plants (Székely- Varga et al., 2019). Hyacinthus orientalis L. beside is an excellent ornamental garden plant it could be also easily forced as cut or potted plant (Nazari et al., 2011). According to Sabo et al. (2018) in Europe firstly was introduced in the 16 th century, and it was cultivated first by the Dutch. The hyacinth is a native species from southern Turkey to northern Israel, it is a tuberous earth plant that grows primarily in temperate biomes (POWO, 2023). Tulips are outstanding potted, cut or bedding flowers and can be grown in open or protected conditions (Nayeem & Qayoom, 2015). Tulipa gesneriana L. is an endemic plant to Turkey, it is mostly found in the temperate biome and is a bulbous geophyte (POWO, 2023b). The Muscari armeniacum Leichtlin species is endemic to Southeast Europe and the Caucasus, it is mostly found in the temperate biome and is a bulbous geophyte (POWO, 2023c). The grape- hyacinth is a perennial bulbous plant with simple basal leaves and short flower stalks (Bokov, 2019). Scientific Papers. Series B, Horticulture. Vol. LXVIII, No. 2, 2024 Print ISSN 2285-5653, CD-ROM ISSN 2285-5661, Online ISSN 2286-1580, ISSN-L 2285-5653