Reproductive features of <i>Dendrobium</i> Sw. species introduced in the Siberian Botanical Garden of Tomsk State University
The phenorythmic features of seven species of Dendrobium Sw. during cultivation in hothouses of the Siberian botanical garden of Tomsk state university were studied. The studied Dendrobium species are divided into four phenorhythmic groups on terms of flowering in garden greenhouses: blossoming during winter period, blossoming during winter and spring periods, blossoming during summer period and blossoming during autumn and winter periods. Artificial pollination of Dendrobium flowers was carried out. Biometric characteristics of fruits of the studied Dendrobium species and terms of their maturing during cultivation under conditions of greenhouses of the Siberian botanical garden of TSU were submitted. When cultivating the species of Dendrobium in greenhouses of the Siberian botanical garden, the duration of maturing of D. phalaenopsis fruits makes 155 days, D. nobile fruits - 247 days and D. kingianum fruits - 67 days. The technique of sterilization of fruits and seed crops on artificial nutrient mediums was fulfilled. The stages of the development of Dendrobium seedlings on nutrient mediums in vitro were studied. It is established that plants are ready to disembarkation in an intermediate substratum on the average in 330 days after crops of seeds. The period of adaptation of Dendrobium seedlings in an intermediate substratum made 10-15 months, then the seedlings were replaced in constant substrata. Average survival of Dendrobium seedlings in an intermediate substratum made 72.5 ± 6.5%. It is established that D. phalaenopsis is characterized by slow growth. An increase in D. phalaenopsis shoot makes 2.25 cm a year, and the average growth rate of a leaf -2.34 cm a year. For the sixth year intensification of growth of D. phalaenopsis shoots is observed; that is, connected with transition ofplants to the generative period of development. Young plants of D. phalaenopsis blossomed in greenhouses of the Siberian botanical garden on the sixth year of their life. The influence of mineral and organic nutrition on the intensity of growth and development of young plants ofD. phalaenopsis and D. nobile was investigated. It is established that optimum nutrition is solution of mineral salts on Murashige&Skoog's copy-book in concentration of 1 ml of the MS solution on 1 l of water. A way of reproduction of four Dendrobium species by «live children» was developed. It is established that from one shoot of D. phalaenopsis and D. nobile it is possible to receive up to 5 top shoots-suckers a year, and from one shoot of D. kingianum and D. delicatum - 3 top shoots-suckers a year. Survival of «children» of these Dendrobium species averaged 81.3%. It is established that Dendrobium plants multiplied by this method and blossomed for the third year of their life in hothouses of Siberian botanical garden.