USEFULNESS OF IRIS HOLLANDICA HOOG. BLUE MAGIC FOR FORCING IN WATER. Introduction

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1 Roczniki Akademii Rolniczej w Poznaniu CCCLXXXIII (2007) AGNIESZKA KRZYMIŃSKA, EWA DE MEZER USEFULNESS OF IRIS HOLLANDICA HOOG. BLUE MAGIC FOR FORCING IN WATER From Department of Ornamental Plants August Cieszkowski Agricultural University of Poznań ABSTRACT. Bulbs of a Dutch iris Blue Magic were planted at three dates: in, in and in. Irises were forced in Flexy-trays filled with water and s filled with water or 0.07% calcium nitrate solution. Additionally, prior to planting 50% of bulbs placed in these trays were disinfected in 8% Kaptan 50 WP solution. The control consisted of bulbs planted into plastic boxes filled with standard medium. More flowering plants obtained in trays than in boxes with standard medium. In and periods there were more flowering plants too, than in. Disinfection of bulbs did not result in improved health state of plants during forcing. Key words: Iris hollandica, forcing in water, hydroponics Introduction For many years Dutch irises have been very popular cut flowers. The most frequently produced cultivar, both in Western Europe and in Poland, is Blue Magic (Vakblad voor de Bloemisterij 2006, Krzymińska 2006). Economic reasons and the requirements of environmental protection force producers of ornamental plants to search for new cultivation technologies. Studies conducted in Holland confirm the feasibility of the application of water as a medium in forcing ornamental bulbous plants. Advantages of this type of production, apart from economical value of medium and chemicals used to disinfect it, include reduced labour costs (Dirks 2000). In Holland approximately 600 million tulips are forced in water (Tiede-Arlt and Kall 2004). So far in Poland the interest in this production technology has been limited. Only small numbers of tulips are forced in water. No information is available on forcing irises in water, especially in Poland. Thus, studies were conducted at the Agricultural University of Poznań to assess the suitability of a Dutch iris Blue Magic for forcing in water at three different dates. Rocz. AR Pozn. CCCLXXXIII, Ogrodn. 41: Wydawnictwo Akademii Rolniczej im. Augusta Cieszkowskiego w Poznaniu, Poznań 2007 PL ISSN

2 82 A. Krzymińska, E. De Mezer Material and methods In the years bulbs of a Dutch iris Blue Magic with a circumference of cm were planted at three dates. They were: the date ( and ), the date ( and ) and the date ( and ). Two types of trays and boxes were applied in the experiment. Flexy-trays consisted of a tray and a Styrofoam mould, placed on top, with funnel-like openings in which bulbs were placed. Trays were filled with water. s consisted of one part only. On the bottom of the tray there were sharpened projections, onto which bulbs were stuck. These trays were filled with water or 0.07% calcium nitrate solution. Additionally, prior to planting 50% of bulbs placed in these trays were disinfected in 8% Kaptan 50 WP solution, by immersing the underside for 2-3 s. The control consisted of bulbs planted into plastic boxes filled with substrate composed of hortisol, limed highmoor peat and sand (2:1:0.5/v:v:v). The experimental combination included two replications with 15 bulbs each. Trays and boxes were placed on tables in a greenhouse. In the and cycle the temperature of C was maintained in the greenhouse. In the it was attempted to maintain the temperature not exceeding 25 C. Water or calcium nitrate were supplemented in trays as needed. During the cultivation period plants with diseased, rotting bulbs were removed and their percentage was calculated. After flowers reached the pencil stage (coloured tips of perianth leaflets) the length of forcing period was recorded and the number of flowering plants was determined. The length of the flowering shoot was measured, along with the total weight, the weight of the aboveground part, roots and bulbs. Due to its limited volume the paper presents results concerning only several parameters. The obtained results were subjected to the analysis of variance and means were clustered using Duncan s test at α = Values expressed in per cent were converted into Bliss degrees. Results and discussion Irises are not forced in winter under climatic conditions of Poland due to the too low light intensity, while in the the substrate heats up excessively and mulching is required (Krzymińska 2006). In the conducted experiment the biggest number of irises (92.2%) flowered in the cycle, a lower number (62.2%) in the cycle, while the lowest number (34.0%) in the cycle, respectively (Table 1). However, in the cycle the length of the forcing period was 63.8 days, i.e. by over five days longer than in the cycle, and by over seven days longer than in the cycle, respectively (Table 2). No effect of forcing date was found on the number of diseased plants or the weight of the flowering shoot (Tables 3 and 4). The length of the forcing period and the number of flowering plants were also dependent on the applied container type and medium (Tables 1, 2). Forcing in boxes filled with standard substrate lasted the longest, i.e days, while it was shortest in Flexytrays filled with water (57.5 days). However, these values did not differ statistically from the length of forcing in s. Dirks (2000) reported that cultivation time in hydroponics lasts 50% shorter than in the standard substrate. The conducted experiment did not confirm this information. Dirks (2000) indicated also that the number of flowering

3 Usefulness of Iris hollandica Hoog. Blue Magic for forcing in water 83 Forcing time of Iris hollandica Blue Magic (days) Długość pędzenia kosaćca holenderskiego Blue Magic (dni) Table e 58.4 a-d 59.5 a-d 61.9 b Flexy-trey, water Flexy-trey, woda 60.2 a-d 56.5 a-c 55.7 a-b 57.5 a water woda 63.4 c-e 58.5 a-d 55.1 a 59,0 ab 64.4 de 58.4 a-d 54.6 a 59,1 ab 0.07% Ca(NO 3 ) de 58.2 a-d 55.6 ab 59,3 ab 0.07% Ca(NO 3 ) b-e 59.1 a-d 56.4 a-c 59,4 ab 63.8 b 58.2 a 56.1 a values marked with the same letter do not differ at the significance level α = 0.05 according Number of flowering plants of Iris hollandica Blue Magic (%) Liczba roślin kwitnących kosaćca holenderskiego Blue Magic (%) Table ab 23.0 a 41.5 a 44.8 a Flexy-trey, water Flexy-trey, woda b 66.0 ab 64.5 ab 76.8 c water woda 93.5 b 51.5 ab 70.0 ab 71.7 bc 96.5 b 20.5 a 66.5 ab 61.2 bc 0.07% Ca(NO 3 ) b 20.0 a 67.5 ab 61.8 bc 0.07% Ca(NO 3 ) b 23.0 a 63.0 ab 60.3 bc 92.2 c 34.0 a 62.2 b values marked with the same letter do not differ at the significance level α = 0.05 according

4 84 A. Krzymińska, E. De Mezer plants in water trays was by 40% bigger than in the standard medium. In this experiment a similar dependency was observed. The number of flowering plants in the standard medium was by 16-32% lower than that obtained in water or a calcium nitrate solution (Table 2). Especially advantageous growth conditions were found for irises grown in Flexy-treys, when water was covered on the top of the container with Styrofoam part. Disease changes observed in iris bulbs included rotting of the basal plate, followed by rotting of bulb scales. Depending on the experimental combination the number of diseased plants ranged from 0.0 to 16.3% (Table 3). However, no effect on this parameter was found for the applied container, medium or bulb disinfection. Number of diseased plants of Iris hollandica Blue Magic (%) Liczba chorych roślin kosaćca holenderskiego Blue Magic (%) Table ab 6.1 ab 2.8 ab 5.7 a Flexy-trey, water Flexy-trey, woda 3.0 ab 0.0 a 4.5 ab 2.5 a water woda 7.4 ab 5.0 ab 6.1 ab 6.2 a 11.7 ab 9.7 ab 5.0 ab 8.8 a 0.07% Ca(NO 3 ) b 6.4 ab 8.0 ab 10.2 a 0.07% Ca(NO 3 ) ab 7.8 ab 11.7 ab 10.8 a 9.9 a 5.8 a 6.3 a values marked with the same letter do not differ at the significance level α = 0.05 according It is believed that tulips forced in water form flowering shoots of lower weight than those grown in the standard substrate (Krause 1995). This character may be dependent on the cultivar (Krause and Zygmunt 2000). In the conducted experiment flowering shoots of Black Magic iris obtained from s filled with water had lower weight than shoots grown on the standard substrate (Table 4). In turn, the weight of flowering shoots of irises forced in Flexy-trays in water and in s with 0.07% lime saltpeter solution did not differ statistically from the weight of irises obtained both in s in water and in the standard substrate.

5 Usefulness of Iris hollandica Hoog. Blue Magic for forcing in water 85 Weight of flower stem of Iris hollandica Blue Magic (g) Masa pędu kwiatowego kosaćca holenderskiego Blue Magic (g) Table a 29.5 a 29.0 a 29.9 b Flexy-trey, water Flexy-trey, woda 27.5 a 24.0 a 23.5 a 25.0 ab water woda 22.5 a 19.5 a 21.5 a 21.2 a 21.0 a 21.0 a 21.0 a 21.0 a 0.07 % Ca(NO 3 ) a 24.9 a 20.1 a 24.0 ab 0.07 % Ca(NO 3 ) a 21.6 a 22.4 a 23.5 ab 25.9 a 23.4 a 22.9 a values marked with the same letter do not differ at the significance level α = 0.05 according Conclusions 1. Forcing of a Dutch iris Blue Magic in s and Flexy-trays was characterized by similar parameters. In these containers forcing lasted shorter and a bigger number of plants flowered in comparison to forcing in a standard medium. 2. Disinfection of bulbs of a Dutch iris Blue Magic in 8% Kaptan 50 WP solution did not result in improved health state of plants during forcing. 3. More flowers of a Dutch iris Blue Magic were obtained in the and cycles than in the cycle. A practical conclusion A Dutch iris Blue Magic may be recommended for forcing in Poland in the and cycle in water and in 0.07% calcium nitrate. Acknowledgement We wish to thank Mr. Michał Demby from Poznań for his kind providing of iris bulbs free of charge.

6 86 A. Krzymińska, E. De Mezer References Dirks I. (2000): Tulpentreiberei auf Wasser. Gärtnerbörse 6: Krause J. (1995): Woda podłożem do pędzenia tulipanów. W: Materiały z konferencji Pędzenie ozdobnych roślin cebulowych, , Poznań: Krause J., Zygmunt K. (2000): Ocena przydatności kilkunastu odmian tulipanów do pędzenia w wodzie. Rocz. AR. Pozn. 323, Ogrodn. 31: Krzymińska A. (2006): Kosaciec. W: Kwiaty cięte uprawiane pod osłonami. Red. M. Jerzy. PWRiL, Poznań. Tiede-Arlt P., Kall J. (2004): Einstieg in die Wassertreiberei. Dtsch. Gartenb. 14: Vakblad voor de Bloemisterij (2006): 21a. Leiden, Netherlands. PRZYDATNOŚĆ KOSAĆCA HOLENDERSKIEGO (IRIS HOLLANDICA HOOG.) BLUE MAGIC DO PĘDZENIA W WODZIE Streszczenie Cebule kosaćca holenderskiego Blue Magic sadzono w trzech terminach wiosennym, letnim i jesiennym. Zastosowano dwa rodzaje palet: Flexy-tray wypełnione wodą i wypełnione wodą lub 0,07-procentowym roztworem saletry wapniowej. Dodatkowo także połowę cebul umieszczonych w tych paletach odkażono przed sadzeniem w 8-procentowej zawiesinie Kaptanu 50 WP. Kontrolą doświadczenia były cebule posadzone do plastikowych skrzynek wypełnionych podłożem standardowym. Pędzenie kosaćca holenderskiego Blue Magic w paletach i Flexy-tray charakteryzowało się podobnymi parametrami. W pojemnikach tych pędzenie trwało krócej i więcej roślin zakwitło w porównaniu z pędzeniem w podłożu standardowym. Odkażanie cebul kosaćca holenderskiego Blue Magic w 8-procentowej zawiesinie Kaptanu 50 WP nie wpłynęło na zwiększenie zdrowotności roślin w czasie pędzenia. Istotnie więcej kwitnących roślin uzyskano w terminie wiosennym i jesiennym niż letnim.