Technology of green cuttings of woody plants for landscaping arctic cities

For landscaping of northern cities, requirement for ornamental plants resistant to urban conditions is increasing, so there is a need to find a solution for multiplication at commercial scale. A technology of green cuttings of woody plants ( Syringa josikaea and Spiraea media ) has been developed as one of the promising methods of vegetative propagation of deciduous ornamental species in the Arctic region. The terms of cuttings (at the beginning of shoot lignification) have been established: for Spiraea media - July 1-10; for Syringa josikaea - July 10-25. A positive effect of the growth stimulator IBA 1000 ppm on the development of the root system and the above-ground part of the cuttings was determined with 6-hour and 12-hour treatment. It was shown that a longer treatment period (12 hours) was more effective. The length of the roots of Syringa josikaea exceeded the control with a 6-hour treatment by 52%; at 12 hours by 89%; in Spiraea media - by 27 and 42%, respectively. In both species the number of roots increased by 32-34% with a longer exposure. The treatment of cuttings for 12-hour significantly increased the formation of leaves on the cuttings of Syringa josikaea ( r = 0.87 p < 0.001) and Spiraea media ( r = 0.89 p < 0.001). The results revealed that the cuttings treated with IBA 1000 ppm (12h) registered maximum survival percentage of rooted cuttings of Syringa josikaea (95.1%) and Spiraea media (75.2%).