The influence of different types of cuts, the terms of cutting on green grafts rooting of Vernonia crinita

The representatives of the genus Vernonia Schreb are rarely found in the collections of Botanical gardens in Russia, but the experience of many years of introduction study has allowed identifying the most stable species promising for introduction to gardening. Currently, the collection fund of the Laboratory of Ornamental Plants of the Main Botanical garden named after N.V. Tsitsin of the Russian Academy of Sciences includes two species - Vernonia crinita Raf. and Vernonia fasciculata Michx. It is established that the most stable in the conditions of the middle zone of Russia is natural species Vernonia crinita. The purpose of the work was to study optimal methods of vegetative propagation of this little-spread ornamental plant. The study deals with the results of green grafts rooting of Vernonia crinita, depending on the species of cuts and the terms of cutting. In the experiments on studying the rooting of green grafts it was found out that such varieties as Vernonia crinita with heel cuts were rooted better than the ones having top cuts. In its turn, top cuts grafts get better rooting than side cuts, both of the first, and the second order. The cuttings were carried out in 7 terms, starting from the second decade of April and up to the first decade of November (during the period from the beginning of active growth of shoots to the end of vegetation). It was noted that the cuttings were possible from May to November, but regardless of the type of cuttings, there was a higher rooting rate in spring and summer than in summer and autumn. It was established that the highest rate of average rooting had the shanks prepared from the shoots taken in August (70.5 %), and the lowest - at the beginning of November (14.8 %).