Cultivation of Cypripedium calceolus L. ex vitro seedlings in outdoor conditions: Short communication

The paper presents first positive results of the experiment with three-year outdoor cultivation of Cypripedium calceolus L. ex vitro seedlings in the Czech Republic. They were propagated in vitro from mature seeds of Carpathian provenance in a Prague private laboratory. In April 2006 after three months cool refrigerating at 4°C the seedlings were prepared for planting. The rhizomes with 4 to 12 roots and visible dormant buds were used. They were planted in two types of substrates: mixture AN on the basis of liadrain (burned clay pebbles) and mixture BN on the basis of granodiorite. Both mixtures were amended with perlite, pumice, sand, zeolite and dolomite lime powder. The mineral substrates proved to be stable and convenient for transfer and cultivation of ex vitro seedlings. Additional treatment with lignohumate in other two variants of the experiment did not improve the effect. The seedlings were grown outdoors on a shaded bed till the retracting leaves. They overwintered in a cold glasshouse with temperature close to zero from late November to March. The substrates did not visually influence the phase of sprouting, the phase of growth and retracting of the plants. At the end of the third growing season the yield of 4-year-old seedlings with two to four leaves ranged from 83% to 98% in four variants. In November 2008 seedlings were taken up from the mixes and were evaluated as bare root plants. The number of the living plants with visible new buds and the quality of root system were recorded and evaluated. The average length of roots in mixture A on the basis of liadrain and B on the basis of granodiorite was 14.5 cm and 12.1 cm, respectively. The rhizomes were planted into new mixtures immediately. These seedlings will be able to grow up to the blooming size during two or three seasons. Seven year-old potted seedlings of C. calceolus will be planted into gene resource area of the Silva Tarouca Research Institute for Landscape and Ornamental Gardening at Průhonice.