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Propagation, cultivation and forcing

Session 1


Micropropagation of ornamental geophytes: a useful approach for development and valorization

Margherita Beruto1 (, Sara Yasemin, Serena Viglione, Basar Sevendik

ISHS, Sanremo, Italy
University of Siirt, Faculty of Agriculture, Kezer, Siirt, Turkey

Istituto Regionale per la Floricoltura, Sanremo, Italy
Vocational School, University of Izmir Demokrasi, Izmir, Turkey

The floriculture industry is experiencing substantial growth in production and trade rates, with bulbous and perennial flowers playing a vital role in the ornamental flower market. However, many flower bulb species are currently facing endangerment due to their attractive properties and medicinal values. Conventional cultivation of flower bulbs is hindered by challenges such as long juvenile periods, contamination of bulb structure, and limited multiplication rates. To overcome these limitations, researchers have turned their attention toward the micropropagation of flower bulbs. This method offers significant advantages, including the conservation of endangered species, mitigation of in vivo cultivation challenges, mass reproduction of high-quality plants free from viruses and diseases, and shortening of the juvenile period. Various explant sources, such as bulb scales, bulb shoot apices, roots, leaves, floral tissues, vegetative buds from tubers, rhizomes or corms, young stems, and seeds, have been used in geophytes. In most cases, culture media such as MS, B5, White, Nitsch, and Nitsch have been employed with different types and concentrations of plant growth regulators, sucrose, etc. Successful application of tissue culture methods has been demonstrated in flower bulbs such as Anemone, Colchicum, Crocus, Cyclamen, Fritillaria, Galanthus, Gladiolus, Helleborus, Hippeastrum, Iris, Leucojum, Lilium, Muscari, Narcissus, Pancratium, Ranunculus, Sternbergia and Tulipa. Both organogenesis and somatic embryogenesis have been explored for these flower bulbs. Enhancing the in vitro cultivation of flower bulbs holds great potential for preserving their species and increasing their trade value through mass reproduction. In this review, we will provide some case studies aimed to highlight the use of micropropagation for the valorization of some ornamental geophytes.

Keywords: floriculture, in vitro conservation, organogenesis, ornamental geophytes, tissue culture


In vitro techniques for tulip micropropagation, virus eradication and tetraploid induction

Małgorzata Podwyszyńska (, Dariusz Sochacki

The National Institute of Horticultural Research, Skierniewice, Poland
Warsaw University of Life Sciences, Section of Ornamental Plants, Warsaw, Poland

In Poland, there are many valuable cultivars of tulip deserve wider dissemination due to high decorative qualities and adaptability to our climate. Improvement of biotechnological methods such as in vitro propagation can speed up breeding and provides new genotypes for the market. Therefore, studies have been undertaken on the improvement of micropropagation method of tulip. As a result of our research the cyclic multiplication of adventitious shoots of this geophyte was obtain by using 1-naphthaleneacetic acid (NAA) combined with cytokinins such as isopentenyladenine (iP) with addition of thidiazuron (TDZ) or meta-Topolin (mT). Moreover, the last micropropagation stage, formation of microbulbs was also significantly improved, that is very important because only bulbs are capable of rooting and further growth in soil. It was found that modification (by replacement of TDZ with iP in a medium) and prolongation to 12 weeks of the last multiplication subculture, prior to cooling combined with the application of growth retardant enhanced shoot’s bulbing capacity. Bulbing efficiency was markedly increased by treatment with MeJA at the last phase of this process, 6 weeks after the end of cooling shoots. Due to the sever virus infection of several tulip cultivars, one of the aim of our research was to develop the in vitro method of virus eradication from plant material. Virus elimination from the totally infected tulip genotypes was possible due to application of ribavirin for in vitro chemotherapy. Currently in tulip, the polypoid cultivars are in high demand. Therefore, d uring o ur s tudy w e d eveloped i n vitro m ethod o f t etraploid i nduction using herbicidal antimitotic agents such as oryzalin, amiprophos methyl (APM) and trifluralin as alternative to colchicine.

Keywords: micropropagation, ribavirin, tetraploids, Tulipa, virus-free plants


A new nursery system for the production of high-quality propagating tubers of Zantedeschia in the Netherlands

Natalia Moreno-Pachon (, Paul van Leeuwen, Arca Kromwijk, Paul Ruigrok

Wageningen University and Research, Horticulture and Flowerbulbs, Bleiswijk, Netherlands

Bulb Quality Support B.V. Lisse, Netherlands

The cultivation of Zantedeschia (calla lily) in the Netherlands takes place from March to October. In vitro culture plantlets are used as the starting material for tuber production. This material is grown aseptically indoors only during the first year. Thereafter, it is grown for 1–2 years in the open field into propagating tubers. A high-quality propagating tuber should be healthy, have many eyes (shoot meristems), have a circumference larger than 6 cm, and have high dry matter content. The goal of this study was to develop a new nursery cultivation system for the production of high-quality and virus-free propagating tubers in half of the current timeframe. Plantlets produced in vitro were used as the starting material. The experiments took place from 2020 to 2023 at the Wageningen Plant Research – Greenhouse Horticulture & Flower Bulbs Center. Several greenhouse parameters were investigated to maximize tuber growth, such as light intensity, light spectrum and temperature. Photosynthetic activity and tuber yield were assessed. The results demonstrate the feasibility of producing clean propagating-size tubers within a year using two greenhouse cycles: a short winter cycle (November–March) at 17°C and a regular summer cycle at 22°C. The winter cycle requires a minimum of 7.8 mol/m2/day (PAR sum) for optimal tuber growth. These tubers are stored at 20°C for two months, multiplied in May and planted. During the second cycle, natural sunlight is primarily used, except when the minimum PAR sum is not reached. This nursery system could reduce dramatically the amount of chemical crop protection currently used in the Netherlands for the production of commercial Zantedeschia tubers.

Keywords: calla lily, photosynthesis, tuber biomass, tuber buds


An indoor cultivation system for the production of virus free lilies in the Netherlands. Turning lily cultivation outside in

Paul Ruigrok (, Casper Slootweg, Natalia Moreno-Pachon Wageningen University and Research, Horticulture and Flowerbulbs, Bleiswijk, Netherlands

The traditional outdoor lily cultivation requires the use of multiple chemical protection products given the high disease pressure. However, the reduction in allowed products and the increasing societal demands, requires a new and sustainable cultivation system. In the project Vital Lily Cultivation a “one way cultivation system” was developed to produce healthy commercial- size bulbs (for forcing) with minimum crop protection residue. The starting material is clean and virus-free bulblets from tissue culture and these are cultivated and multiplied in the greenhouse. The resulting planting material requires only one or two outdoor cultivation cycles to reach the commercial size. Wageningen University and Research conducted trials to optimize lily bulb growth under greenhouse conditions. Aspects that have been studied are light intensity, light spectrum, planting density, fertigation, senescence, successive cultivation and the economical aspects. The results indicate that it is possible to grow to size 14 from size 4 in one greenhouse cycle of nine months. Those can be multiplied and re-grown to size 14 in nine months, or to planting material (size 8) in just four months, which makes it possible to have a fast propagation indoors. In the indoors cultivation no pesticides have been used and no problem with diseases have occurred. The research was done with an LA, OR and OT cultivar. An issue to tackle in this system is the senescence and the preparation of bulbs for the next season. If this is not done correctly, sprouting is reduced to 50% and plants with only leaves and no stems are formed, and more bulbs with double noses were harvested. In a pilot experiment, a period of 50 days of below 13°C improved the sprouting. However, plants were not completely senesced yet and afterwards still formed double noses. A better understanding of the senescence process is needed to overcome these physiological abnormalities.

Keywords: cultivation, Lilium, propagation, senescence


Herbaceous perennial trials at Colorado State University

Chad Miller (, David Staats Colorado State University, Fort Collins, USA

Public and private plant trials are critical for the horticulture industry, providing valuable feedback about plant performance. The Colorado State University (CSU) trial gardens attract thousands of visitors each year. The trial gardens evaluate both annual and perennial species marketed in the United States (US) horticulture industry. The perennial trials were established in 1997, as there was increased interest in evaluating new perennial plant species and cultivars, and how their adaptation to the Rocky Mountain environment, which is classified as a steppe region. The trial gardens do not receive any direct state or public funding and are supported wholly through trial entry fees. The gardens do also receive donations and support from horticulture industry, associations, foundations, and other green industry affiliates. Perennial plants are evaluated for a period of three years to include three summer growing seasons and two winter seasons. Perennials are received from plant breeding companies and plant brokers early in the season, grown in the greenhouse until planting in mid-spring. Plants are evaluated for plant vigor, uniformity, flowering, and overall tolerance to environmental stresses. In the 26 years of perennial trialing, over 125 different genera have been trialed. The top 10 most trialed genera have been Dianthus, Echinacea, Coreopsis, Phlox, Salvia, Heuchera, Penstemon, Leucanthemum, Lavandula and Veronica. Plant trials will continue to be important for plant breeding companies and marketers to identify ideal and plants that perform well in specific environmental conditions.

Keywords: Dianthus, Echinacea, floriculture, horticulture, plant evaluations


Effects of supplemental lighting using LED’s on the quality of tulips forced hydroponically

Jadwiga Treder (, Dariusz Sochacki, Ewa Skutnik, Julita Rabiza- Świder, Waldemar Kowalczyk, Aleksandra Staniuk, Agnieszka Połeć

The National Institute of Horticultural Research, Skierniewice, Poland
Warsaw University of Life Sciences, Section of Ornamental Plants, Warsaw, PolanD

Tulip (Tulipa sp.) is one of the most popular bulbous plant grown for cut flowers during winter time. In Poland forcing technology in mostly based on traditional cultivation on soil beds or in containers filled with peat/sand substrates. However, in recent years the biggest farms are changing their technology to a modern, very efficient hydroponic method with automatic control of the movement of cultivation tables. Tulips do not have high light requirements during forcing and usually they are grown in natural light conditions. However, for early flowering period the lack of natural light, from November up to mid-January, can negatively influenced flowers quality and extend cultivation period. The aim of the study was to determine the effect of supplemental LED lighting on the forcing duration and quality of cut tulip flowers in hydroponics. Four commonly grown cultivars: ‘Kung Fu’, ‘Strong Gold’, ‘Strong Love’ and ‘Surrender’ were evaluated. Control plants were forced in natural light conditions. As a source of light supplementation the full spectrum LED lamps, with a power of 300 and 240 W, applied for 8 or 4 hours daily were used. The effect of LED lighting on the tulip growth dynamics and the date of flowering a s w ell a s s elected b iometric p arameters o f c ut fl owers (the length of the flower stem, flower bud and the last internode, the thickness of the stem, and the flower stem fresh mass) were determined. The studies showed that supplementing natural light during tulip forcing using LED lamps has an positive effect on shortening the forcing period and thus obtaining flowers earlier by 1 to 6 days, depending on the cultivar and the intensity of lighting. Flower buds of tulips grown with LED lamps usually showed color faster and were harvested earlier than control plants. However, control plants (without lighting) were ready to harvest for an additional few days later so, they gained more time for growth, which resulted sometimes in higher fresh weight. The obtained results showed that 3 out of 4 examined cultivars are did not increase the fresh mass of flower stems, which indicates positive effect of light supplementation with LED lamps on the mass of cut flowers. Depending on the cultivar, the supplemental lighting did not affect the total height of the plant (‘Kung Fu’ and ‘Strong Love’) or influenced the achievement of higher plants (‘Strong Gold’ and ‘Surrender’). The LED lighting also did not influenced the thickness of the tulip stems just below the bud in the ‘Kung Fu’, ‘Strong Love’ and ‘Strong Gold’ cultivars, only ‘Surrender’ grown with 240 W LEDs for 8 h increased the diameter of the stem by 0.3 cm compared to the diameter of the shoot in control, non-lighted plants. Supplemental lighting affects positively also vase life, leaf chlorophyll content and nutrient uptake of tulips forced hydroponically.

Keywords: ‘Kung Fu’, nutrient content, ‘Strong Gold’, ‘Strong Love’, ‘Surrender’ 

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