Hexachlorocyclohexanes (HCHs) are persistent organochlorine pesticides with the adverse effects on human health and the environment. The effect of delta-isomer of hexachlorocyclohexane (δ-HCH) on ...germination, growth parameters and physiological parameters was studied in different Alnus glutinosa (L.) Gaertn. progeny of resistant genotypes to pathogen Phytophthora ×alni. Two experiments were performed: a short-term experiment to determine the effect of δ-HCH on total germination (GT), germination energy (GE), speed of germination (SG), shoot length and biomass of seedlings, and a long-term experiment devoted to remediation aspects. In addition, changes in the hormonal system of alders were monitored in both cases. Significant differences were found between the treated and control group in most of the evaluated characteristics. Also, the content of studied phytohormones differs between groups. Furthermore, the obtained results indicate genetically determined variability in response to δ-HCH. Of the six tested, the Březové and Tuřany progeny seem to be suitable candidates for phytoremediation because of the adaptation to stress conditions or high remediation efficiency. The rest of tested progeny seems to be unsuitable due to higher mortality, lower remediation efficiency and higher levels of stress hormones resulting in significant decrease in biomass and plant height. Moreover, results indicate the role of the plant as a remediation accelerator, probably through released exudates, and a positive effect on the soil microbiome as the presence of plants increased the remediation efficiency by 20.85 – 35.89%. The obtained research findings may be helpful in better understanding the processes involved in removing these pesticides from the soil. Further research should be focused on rhizosphere microbiome, mechanism of in-plant isomerization and metabolites identification.
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•δ-HCH influences the germination success rate of Alnus glutinosa seeds.•Germination efficiency changes are progeny-dependent.•Alder seedling uptake of δ-HCH did not exceed 2.52% of the pollutant dose.•Alder seedling’s presence enhanced the effectiveness of δ-HCH removal by 20.85–35.89%.•Alder seedling’s hormones concentrations changed both negatively and positively to some extent during the exposure to δ-HCH.
Populus nigra is an important autochthonous woody plant that can be grown as a renewable energy source. The possibility of its improvement through intraspecific hybridization was tested. Differences ...in biomass production, growth parameters, Melampsora larici-populina rust resistance and drought tolerance were evaluated among 19 intraspecific hybrids from controlled crosses, 2 clones selected from natural populations and the “MAX 4” clone (P. nigra × P. maximowiczii). These P. nigra clones from controlled crosses were chosen from more than 2000 hybrid individuals whose parents were selected from natural populations in the Czech Republic. A field trial was set up in Pruhonice, Czech Republic (320 m a.s.l., 591 mm rainfall annually, mean annual temperature of 9.5 °C). The planting density was 6061 plants ha-1, and the plants were coppiced three times at 3-year intervals. The trial was irrigated only during its establishment. Among the clones, significant differences were found in all the evaluated traits over three rotations. An average dry matter yield of the best clone “MAX 4” was 12.8 t ha-1 yr-1 over three harvests. The best black poplar clone reached up to 9.4 t ha-1 yr-1 in three harvests. Rust resistance was constant over 9 years and high for the three P. nigra clones (two from controlled crosses and one from natural populations). Moreover, the best P. nigra clones from controlled crosses showed higher drought tolerance than the “MAX 4” clone. Breeding progress was confirmed, and most of the P. nigra clones from controlled crosses performed better than the clones selected from natural populations. The trial validated the suitability of natural populations for use as gene sources for intraspecific hybridization and as sources of clones with traits comparable with those of interspecific clones. These new P. nigra clones can replace allochthonous clones in areas where autochthonous P. nigra populations are threatened by introgression.
Three clones of black poplar and a hybrid poplar clone, “NE-42”, were trialled in a short rotation coppice system. The trial was replicated in three sites located in the Czech Republic with ...distinctly different soils and climates which were judged to be respectively favorable, unfavorable and marginal for growing black poplar. In the marginal and unfavorable sites the planting density was 2222 trees ha-1 and in optimal conditions 7407 trees ha-1. The aim of the trial was: (1) to test the performance of black poplar clones as a possible replacement for commercial hybrid poplars in areas where the genetic integrity of wild black poplar populations is under threat; (2) to test the range of conditions in which it is possible to grow black poplar and its suitability for utilizing marginal agricultural land; and (3) to measure the potential yield of black poplar clones grown in these conditions. During four harvests at three-year intervals, the following parameters were measured: plant mortality, number of shoots, thickness of shoots, the total cross-sectional area (TCA) of all shoots, the dry matter weight of individual plants (DMIP) and the dry matter yields per hectare. The differences observed between “NE-42” and the best black poplar clone decreased as conditions became more favorable. During the fourth harvest at the unfavorable site for growing poplars, the yield of dry biomass was 11.7 t ha-1 yr-1 for “NE-42” compared to 3.7 t ha-1 yr-1 for the best black poplar clone. In marginal conditions the yields were 11.8 and 9.9 t ha-1 yr-1 respectively, and in the favorable conditions there was no statistically significant difference, being 15.9 and 13.2 t ha-1 yr-1, respectively. The higher yield of “NE-42” was due to the higher proportion of thicker shoots or, alternatively, lower plant mortality. The observed TCA was highly correlated with DMIP (rs = 0.87) and dry biomass yield (rs = 0.48). It was demonstrated that black poplar can be successfully grown in marginal conditions on land which otherwise would not be especially suitable for agricultural production, and also in areas where the genetic purity of native populations of black poplar is threatened by the spread of commercially grown hybrid poplars.
Differences in Populus nigra L. clone resistance to the rust fungus Melampsora larici-populina Kleb. (MLP) were studied in field trials where infected trees were compared with fungicide-protected ...trees. MLP rust infections were assessed using a 6-point scale. Four parameters of poplar growth were also measured to gauge host response to infection: shoot thickness, shoot number at the end of the growing season, individual plant dry weight, and dry matter yield per unit area. Five of eight known pathogen virulence types were detected. Cumulative growth in shoot thickness in sprayed and unsprayed plots was similar in clones with high rust pathogen resistance, but significantly different in clones with low resistance. Clones with low resistance also exhibited delayed growth initiation in the year following infection, an effect attributed to lower food storage accumulated during the previous year, reflected in a reduction in stem diameter. Based on stem thickness measurements, it was confirmed growth ceased at the end of August. Average rust severity symptoms ranged from 2.75 to 4.22 on the 6-point scale. The percentage reduction for the various growth parameters resulting from rust infection ranged as follows: individual plant dry weight 5-64%; dry matter yield 21-66%; shoot number 17-46%; and stem diameter 1-35%. Exclusive of stem diameter, these reductions correlated with severity in MLP rust infection. The one exception was tolerance to rust infection displayed by one of the clones. Clones with the lowest growth reductions were 97/152 and 97/157. Growth and yield parameter variation as a result MLP resistance difference was observed among tested P. nigra clones. This variation can be viewed as confirmation that resistance observed in this study and P. nigra clones is a suite of quantitative traits. These findings have important implications for MLP resistance breeding programs.
Cultivations of poplar short rotation coppices (SRC) over five/six 3-year rotation cycles of three clones of Populus nigra and one interspecific commercial hybrid clone were studied in the Czech ...Republic at three sites with different environmental conditions. Two sites were planted in 1998 and the other was planted in 2002. This study focused on the evaluation of the growth and biomass yields, and on the biomass aptitude to be used as a fuel. Plant mortality, ranging between 10% and 100%, was found as a determinant variable for SRC management. Biomass yield decreased comparatively with earlier harvests, with only the commercial clone delivering productivity levels higher than 11 Mg ha−1.yr−1. The sixth harvest was applied to a single mid-level site quality profile, marginal to food cultivations. This site was subjected to an intensive management during the first four rotations with fertilization, herbicide application and soil discing. These treatments were central to assure the high plant survival rate after the sixth rotation with adequate biomass productivity. The number of shoots per plant was higher in the site chosen for extension of lifecyle, supporting the hypothesis that this variable, by facilitating resprouting, allows a cultivation to withhold further rotations. The harvested biomass was found appropriate to be used as a fuel. The results suggest that the sustainability of SRC poplar cultivations can be achieved under lifecycles longer than 20 years, under 3-year rotation cycles, with proper clones, site and management practices.
•First real study of poplar biomass production in five/six three-year rotation cycles.•Biomass average yields in fifth harvests were 20% lower than in previous one.•Survival rate was a limiting factor for extending the number of cultivation rotations.•Survival rate differences were found among clones and sites.•Biomass quality does not differ among clones, sites and rotations.
Our objective was to examine the feasibility of propagating mature Alnus glutinosa trees by vegetative means that could be used to propagate trees resistant to Phytophthora alni. Both softwood and ...hardwood cuttings were taken. In the case of hardwood cuttings, two different treatments, based on differences in temperature, two growth stimulators (NAA, IBA) and rooting conditions were tested. Rooting success rate was low: only 1.3 to 5 % of treated cuttings rooting in comparison with 0 to 1.3 % of the untreated control cuttings. In the case of softwood cuttings, two treatments were used. They differed in their use of growth stimulators (NAA, IBA) and the dates when material was collected. In contrast to the hardwood cuttings, the softwood cuttings rooted better in both treatments. The cuttings collected at the later date rooted better; 30 to 42.5 % of the treated cuttings rooted when compared to 15 % in the control treatment. Softwood cuttings collected in the middle of July and then treated with 1% IBA rooted the best of all, with 42.5 % of cuttings rooting successfully.
The aims were to explore the use of wild populations of Populus nigra for breeding and to compare crosses made between genotypes from different areas with different climates. Genetic distances ranged ...from 0.175 (populations growing under optimal conditions) up to 0.875 (populations growing under marginal conditions). A total of 39 trees were chosen from these populations, and in four different years 58 different parental crosses were made, from which a total of 2,277 individuals were produced for assessment as potential biomass producers. The progenies from each cross were rated according to a selection index (SI) based on three characteristics (height, leading shoot diameter and resistance to the rust Melampsora larici-populina). Sixteen of such crosses had significantly higher SI compared to the lowest SI values observed. In 19 of the crosses, it was shown that certain individual trees had made a significant contribution to lower susceptibility to rust, and in particular, two male trees used in the parental crosses were implicated as being the source of rust resistance. Selected individuals were cloned and used in a field trial with NE-42, as a control. It was found that six clones had significantly higher SI than NE-42. In crosses between trees originating from contrasting conditions, there was a higher average SI than in crosses between trees from the same conditions. However, these differences were not statistically significant. The successful clones are recommended for use in those areas where the native populations of pure black poplar are threatened by cross-pollination with allochthonous species.
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