ABSTRACT:The paper analyses the influence of an extended period of cold stratification on the germination capacity, emergence rate and yield of seedlings in the Douglas fir as well as on the morphological parameters of one-year-old seedlings. A total of ten seed lots were used for evaluating germination capacity, originating from the Czech Republic, Slovakia, France and the USA. Germination capacity, emergence rate and yield of seedlings were analysed for two seed lots of Czech provenance on seed beds in the settings of a forest tree nursery. Tested variants involved (a) no pre-sowing treatment, (b) seed stratified for 21 days, and (c) seed stratified for 49 days. The germination capacity of the stratified seed was higher than that of the control variant for all of the seed lots. The effect of the stratification period length was zero for both germination capacity and emergence rate. Differences were identified between the stratification variants as regards germination energy and emergence rate. For the control variant, seedling yield reached only 1% and 2%. For the stratified seed, yield of seedlings of two selected Czech provenances was 18% and 16% (variant 21) and 26% and 36% (variant 49). Differences in the morphological parameters of seedlings were not straightforward.

ABSTRACT:One of the critical points of Douglas fir seedling production is to optimize the time of sowing and length of pre-sowing treatment. Germination and emergence of Douglas fir seed lot of the Czech origin (CZ-2-2A-DG-1740-6-3-P) were observed in simulated warm and cold conditions in two phytotrons for 3 months. Before this procedure the seeds were exposed to different prechilling duration. The temperature in control conditions of phytotrons was stable for 28 days and then it was increased: 11, 13, 17°C in cold phytotron and 13, 17, 20°C in the warm phytotron. Seeds without stratification and stratified for 3, 5, 7, 9 and 16 weeks were tested. The laboratory germination capacity of non-stratified seeds was only 58% and it was significantly (P < 0.05, Tukey's test) lower than in stratification treatments when it varied from 92% to 96%. Non-stratified seeds did not germinate in cold phytotron and they germinated very slowly (germination rate at the end of experiment was 7%) in warm phytotron. The germination capacity of seeds both in the phytotron and in the laboratory was observed in treatments with prechilling of seeds longer than 7 weeks in warm conditions and only for seeds after 16 weeks of prechilling in cold conditions. The highest emergence rate of seeds (84%) was found in the warm phytotron after 16 weeks of stratification. Comparable results were reached only for 9 weeks of stratification in the same phytotron. The results suggest that the prolongation of the standard 3-week prechilling period helps to increase germination capacity and emergence rate of seeds. Future research should focus on optimal length with regard to more seed lots and also on seedling quality parameters. JOURNAL OF FOREST SCIENCE, 60, 2014 (7): 281-287From the aspect of forestry, Douglas fi r is considered a promising tree species for the region of Central Europe (Kenk, Ehring 1995;Kantor et al. 2001;Tauchman et al. 2010). In the region of the Czech Republic it is recommended to increase its share from 0.2 to 2-4% of the total stand area (Beran, Šindelá 1996; Kantor et al. 2010). On sites without seed-producing trees and in areas where Douglas fi r has not been present so far, artifi cial regeneration is necessary. One of the critical points in artifi cial regeneration of Douglas-fi r is a small yield of seedlings in nursery practice of the Czech Republic. From many aspects which infl uence the yield of Douglas fi r seedlings the presowing treatment seems to be important because the seeds exhibit dormancy (Heit 1968;Gosling, Peace 1990;Müller et al. 1999).Cold stratifi cation of seeds has a favourable eff ect on subsequent germination and shows an increase in total germination capacity, increased germination rate and extended range of temperatures at which the seeds germinate (Gosling 1988). Th e main prerequisite for successful stratifi cation is its suffi cient duration. According to Jones, Gosling (1994), short stratifi cation (2-6 weeks) of seeds with relative dormancy improves the germination capacity as well as the germ...

Mauer O., Houšková K., Mikita T. (2017): The root system of pedunculate oak (Quercus robur L.) at the margins of regenerated stands. J. For. Sci., 63: 22-33.The paper aims to contribute to the determination of reasons causing the irregular growth of young pedunculate oaks occurring at the margins of naturally and artificially regenerated plots neighbouring with adult stands on alluvial sites. It presents analyses of aboveground biometric parameters, mortality, root system architecture of young trees, root density in the soil profile, global solar radiation and soil moisture content in dependence on the location of oaks at the northern, southern, eastern or western margins of the regenerated area and on the distance from the stand margin. The highest impact of the neighbouring adult stand is always recorded on the margin of the regenerated plot while its effect is weakening towards the plot centre, and fading away ca. 7 m behind the crown projection of adult trees. Regardless of the oak location (northern, southern, eastern or western margin), the cause is a high root density of marginal trees of the adult stand, which induces the critical lack of water under their crown projections.

Research highlights: This study is focused on the germination of Dracaena cinnabari seeds in order to discover the possibility of natural and artificial regeneration of this species. Background and Objectives: This study aimed to determine the optimal temperature for D. cinnabari seed germination, e.g., the temperature at which the germination percentage and germination rate (vitality) are the highest. The objectives of this study are to: (1) determine the optimal temperature for the germination of D. cinnabari seeds, (2) compare the suitability of different seed collection methods, and (3) compare the germination parameters of seeds that were collected from different localities. The results of this study will contribute to obtaining the highest number of seedlings from limited seed material for reforestation of the most endangered localities of D. cinnabari species. Materials and methods: Four seed sections were employed. These sections were directly collected from either the fruits of a cut panicle or the ground and were obtained from different localities that differ in altitude. The seeds were tested in a greenhouse while using Petri dishes at three different temperatures—22, 26, and 30 °C—with four replicates of 25 seeds of each section. ANOVA and the t-test were employed for data analysis. Results: The highest germination percentages (GPs) were achieved at 26 °C and 30 °C, which were 84.6% and 82.5%, respectively. The ANOVA and t-test results showed that the germination index (GI) of the species was relatively higher at a temperature of 30 °C relative to that at other temperatures in the study. Although seeds that were collected from the tree achieved a higher GP, the t-test result showed no significant differences in the GI of D. cinnabari seeds that were collected from the ground and from the tree (p > 0.05). Overall, the findings of this study show that temperature has substantial influence on the germination of seeds of D. cinnabari. Therefore, we recommend a temperature of 30 °C to facilitate the germination of D. cinnabari, as it achieved the highest GI at this temperature relative to that at the other temperatures (22 °C, 26 °C) applied in this study.

In 2013 -2016, the growth and post -planting losses were monitored of bare -rooted and containerized planting stock of European beech, Norway spruce and Douglas fir together with the course of weather in seven regions of the Czech Republic, most endangered by drought. Precipitation deficits occurred especially in the spring period of 2015 and in the summer period of 2016, significant drought spells being recorded also in the summer periods of years 2013 and 2015. If there is a normal weather after planting, the containerized planting stock exhibits better growth. If the planting is followed by severe spells of drought, both the bare -rooted and the containerized planting stock dies, the containerized planting stock more so. The containerized planting stock responds worse to repeated drought spells. Drought spells are at all times better endured by the containerized planting stock with the large root balls, root ball coverage and strong root collar. Coverage of clear -cut areas is significantly affected by the success of regeneration, which depends on the used type of planting stock, as well as by the spells of drought. Good growth in the first year after planting does not guarantee the success of regeneration, particularly if the containerized planting stock is concerned.

The aim of the study was to confirm and compare efficiency of methods enhancing the vitality of Scots pine and Norway spruce seeds: soaking in water, cold stratification, additional moistening and incubation according to IDS method. The examined parameters included water content in the seeds, germination energy, mean germination time and germination capacity before the seed treatment, after its treatment by the tested methods and after drying. Results show that all the tested methods accelerate germination of seeds; cold stratification is the most efficient and recommended method for Scots pine and soaking of seeds in water is the most efficient and recommended for Norway spruce. The best results in spruce were also obtained with cold stratification (comparable with soaking in water) but the method is complicated, longer-lasting and more costly than soaking in water.

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ABSTRACT:The subject of our research was to verify effects of the mechanical preparation of soil in the natural regeneration of pedunculate oak in a floodplain forest. On the site of a hard-wooded floodplain forest at the confluence of the Morava and Dyje rivers (Czech Republic), several sample plots were established differing in the preparation of soil during regeneration, in weeding the plots and in the period of the implementation of soil surface scarification before and after the fall (or distribution) of acorns. On the basis of results obtained, mechanical preparation of soil on nonweed-infested plots in the heavy seed year is not necessary, however, it supports seedling emergence from acorns and eliminates weed tree emergence and weed. However, it is better to realize it only after the fall of acorns and to incorporate them into soil and thus their emergence will be increased. Soil scarification can be carried out also in the course of harvesting the parent stand through the extraction of wood and slash from the regenerating area. In weed-infested stands, however, the thorough preparation of soil before the fall of acorns appears to be a necessity.