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1

Growth and development of the introduced Fraxinus L. species in the taiga zone (Karelia)

Автор: Kishchenko

Most species of woody plants indigenous to the Russian taiga are extremely sensitive to pollutants. However, many species of deciduous trees that grow in other geographical areas, including the genus Fraxinus, are fairly tolerant to progressive environmental pollution. For the introduction of cultivated plants into new environmental conditions, an impartial assessment of their introduction potential is required, which is possible only on the basis of comprehensive studies. The most important processes characterising the condition of plants are growth and development. The present study examined the introduction of three species of the Fraxinus L. genus to the middle taiga subzone. These were F. excelsior L., F. americana L. and F. pennsylvanica Marsh. The stems and leaves of the plants were measured once every 2–3 days over the course of two growth periods. Phenological observations were carried out between May and October over the course of 17 years. The introduction potential of the studied species was determined through visual assessment carried out in the autumn. The findings showed that the growth of shoots and leaves in the studied Fraxinus species began in late May-early June, varying between species by 1–5 days. The cessation of shoot and leaf growth in the studied Fraxinus species, which occurred in July, varied by up to ten days. The dates of onset and culmination of the growth of shoots and leaves appeared to be determined primarily by air temperature, with a year-by-year variability of 3–7 days. All the studied Fraxinus species showed a high degree of introduction potential and can be successfully used for gardening and landscaping purposes in the middle taiga subzone.

2

Genetic Variation in Growth Characteristics of Hippophae rhamnoides L. Grown under Controlled Conditions

Автор: Demidova
Северный (Арктический) федеральный университет имени М.В. Ломоносова

The Sea Buckthorn (Hippophae rhamnoides L.), being one of the most useful plants in the food and medical industry, is widely used for field amelioration, soil recultivation and restoration of disturbed lands. Knowledge about genetic parameters for important traits is a prerequisite for a successful breeding of any species. There are limited number of publications on within- population variation for growth traits and frost hardiness of Sea buckthorn. The experiments were done under the controlled conditions in a climate chamber at the Department of Forest Genetics, Swedish University of Agricultural Sciences. Seedlings of Sea Buckthorn, originating from a controlled cross between three female plants and six male plants, as well as from an open pollination of mother plants, were grown under the controlled conditions until bud-set, a period of dormancy and an ensuing bud flush. Variation in growth, duration of growth period, earliness in bud flush and the fraction of frost-damaged buds after freezing were studied. Confirming previously reported observations, we found that Sea Buckthorn seedlings do not terminate growth at long nights, but low temperature treatment is needed. This lack of photoperiodic response stands in contrast to the majority of tree species in the temperate region. In this experiment, Sea Buckthorn reveals high level of genetic variance for growth and growth rhythm. The female variance component for the characteristics studied was higher than the male variance component, probably owing to seed size. The results analysis suggest that estimation of genetic parameters in Sea Buckthorn shall be based upon controlled crosses rather than on open pollinated progenies. The observed maternal effects indicate that seed weight may be a significant covariate in analyses of variance. The freezing test used in this experiment did not disclose any major genetic variance components responsible for the variation in fraction of damaged buds after freezing.