Effects of simulated acid rain on the photosynthetic physiology of Acer ginnala seedlings

Extensive areas in China have been receiving high levels of acid rain. Acid rain affects plant growth by reducing the chlorophyll content, destroying leaf structure, and hindering photosynthesis. Acer ginnala Maxim. has a high economic, ornamental, and medicinal value. To clarify the acid rain resistance mechanism of maple trees, the chlorophyll content, gas exchange parameters, and chlorophyll fluorescence parameters were measured in the leaves of 2-year-old Acer ginnala seedlings 0, 15, and 30 days after simulated acid rain at pH 5.6, 5.0, 4.5, 4.0, 3.5, and 2.5. The results showed that the relative content of chlorophyll gradually decreased with the increasing acidity. The net photosynthetic rate (Pn) decreased with the increasing acidity, and the difference among the treatments was significant except for between pH 5.0 and the control. The stomatal conductance at pH < 5.0 was significantly lower than that of the control, and the intercellular carbon dioxide (CO2) concentration of the leaves with the pH < 4.5 treatments was significantly lower than that of the control. As the acidity increased, both Fv/Fm and Fv/F0 (Fv, variable fluorescence; Fm, maximum fluorescence; F0, initial fluorescence) decreased. The difference in the photosynthetic performance index based on the absorbed light energy (PIabs) between the pH 5.0 treatment and the control was not significant during the three periods after the simulated acid rain stress, whereas in the other treatments, this index was significantly lower than that of the control. Our results indicated that under mild acid rain (pH > 4.0) stress, the chlorophyll content, gas exchange parameters, and chlorophyll fluorescence parameters of Acer ginnala changed little, whereas in the other treatments, especially the severe acid rain (pH < 3.0) treatment, these indices showed significant changes that had a severe impact on plant growth and development.

ADDITIONS TO THE VASCULAR PLANT FLORA OF THE REPUBLIC OF MORDOVIA (RUSSIA): CONTRIBUTION OF THE iNATURALIST PLATFORM

"The (re)check of the iNaturalist data related to the Republic of Mordovia (European Russia) allowed us to find 16 vascular plant species, considered to be new taxa for the vascular plant flora of this region, in comparison to Silaeva et al. (2010). These species are Nonea rossica, Erigeron strigosus, Medicago × varia, Dianthus chinensis, Symphytum × uplandicum, Lamprocapnos spectabilis, Petunia × atkinsiana, Oenothera villosa, Parthenocissus inserta, Reynoutria × bohemica, Eschscholzia californica, Quercus rubra, Digitaria sanguinalis, Lysimachia punctata, Acer ginnala and Stachys byzantina. In addition, we present new data about the distribution of the five species (Silene wolgensis, Amaranthus cruentus, Cruciata laevipes, Euphorbia cyparissias and Achillea leptophylla) found in the Republic of Mordovia since publication of Silaeva et al. (2010). A majority of the species under discussion are alien plants arrived in Mordovia accidentally or considered as cultivated plants escaping in the wild. Taking into account the newly revealed species, the vascular plant flora of the Republic of Mordovia currently includes 1464 species. In this study, we highlight again the relevance and feasibility of the use of the iNaturalist platform, as an effective tool for the study and monitoring of regional and national biodiversity."

Rooting Efficiency of Amur Maple Seedless Selections Produced by Mutagenesis1

Amur maple (Acer ginnala Maxim.) is a widely planted small tree with attractive red fall foliage. In many states, it is classified as a noxious weed and regulations restrict propagation and sale, limiting customer choice. Stem cuttings are commonly used as a means of asexual propagation of Amur maple, with softwood cuttings being the easiest to root. Here we report adventitious rooting efficiency of seedless Amur maple selections using four indole-3-butyric acid (IBA; 500, 1,500, 5,000, 10,000 ppm) and four naphthalene acetic acid (NAA; 100, 500, 1,500, 5,000 ppm) treatments and a no hormone control. Overall, cuttings treated with 5,000 or 10,000 ppm IBA and 5,000 ppm NAA resulted in the highest percent rooting (PR), mean number of roots (MNR), and mean length of the longest root (MRL) across all seedless selections. Seedless selections SW-30-14 and SW-30-130 had the highest PR, 66% and 67%, respectively, and will perform well in commercial propagation. This level of rooting was greater than that of the cultivar ‘Bailey Compact' that had 46% PR, and the seedless selection SW-30-159 that had the lowest PR (10.3%), MNR (0.3), and MRL (0.2 in) averaged across all treatments. Cuttings from 4 of the 5 seedless selections treated with 1,500 ppm NAA had the greatest PR, whereas ‘Bailey Compact' and SW-30-159 had the greatest PR with 5,000 ppm NAA. Results indicate that rooting efficiency was impacted by mutagenesis in some selections, which may require optimization of propagation methods for those selections. Index words: adventitious rooting, auxin, vegetative propagation, sterile, non-native invasive. Species used in this study: Amur maple (Acer ginnala Maxim.). Chemicals used in this study: indole-3-butyric acid (IBA; 500, 1,500, 5,000, 10,000 ppm) and naphthalene acetic acid (NAA; 100 500, 1,500 5,000 ppm).

Assessment of deciduous trees introduction prospect in the taiga zone (Karelia)

The article aimed at assessing introduction prospect for 32 species of the genera Acer L., Betula L., Fraxinus L., Padus Mill., Syringa L. and Sorbus L. at the Botanical Gardens of Petrozavodsk State University (Southern Karelia, central taiga subzone). The degree of introduction prospect was assessed with the use of the integral assessment method by P. I. Lapin and S. V. Sidneva. Such indicators as annual maturing of shoots, regular growth of axial shoots, winter hardiness of plants, habit preservation, shoot-forming capability, generative reproduction capability, capability to reproduce in plantation were taken into account. It was found that Acer ginnala, Acer platanoides, Betula platyphylla, Betula ulmifolia, Fraxinus excelsior, Padus virginiana, Padus pensylvanica, Padus maackii, Syringa vulgaris, Syringa pubescens, Syringa emodi, Syringa × henryi, Syringa josikaea, Syringa villosa, Syringa vulgaris var. Congo, Sorbus decora, Sorbus virginianis and Sorbus аmericana have the highest prospect rates (80–100 points), the other studied species – fairly high prospect rates (56–79 points). All the studied introduced species of deciduous trees can be successfully used in Karelia for gardening and landscaping purposes. Acer platanoides, Betula platyphylla, Fraxinus excelsior, Padus pensylvanica, Padus maackii, Syringa vulgaris и Sorbus decora show the highest degree of introduction prospect (about100 points).

Genetic variation characterization of the boreal tree Acer ginnala population in response to environmental change of Northern China

Background: Acer ginnala is a deciduous shrub/small tree that primarily distributed across the northern regions of China. It comprises a foundation species in many terrestrial ecosystems and has significant ornamental and economic value. Owing to its increased use as an economic resource, overexploitation and environmental destruction have resulted in the vulnerability of this species. Thus, the elucidation of the genetic differentiation and influence of environmental factors on A. ginnala is very critical for its management and future utilization strategies. Results: Our results revealed that high genetic variation occurred in A. ginnala species while low genetic diversity was observed at the population level. Most differentiation has found among populations. A significant correlation existed between genetic and environmental distances. Seven climate variables (bio1, bio2, bio3, bio4, bio13, bio15 and bio18) might explain the substantial levels of genetic variation (> 40%) in populations. The most suitable areas of this species appeared in Shaanxi, Shanxi, Anhui Provinces, and Northeastern China based on ENM results. Compared to the last interglacial (LIG) period, A. ginnala migrated toward Northern and Northeastern China, and extended to the most suitable areas during the last glacial maximum (LGM) period. Shanxi and Anhui Provinces might have served as refugium owing to their relatively high genetic variation. Conclusions: Low genetic diversity at the population level that may be the source of its vulnerability. Climate heterogeneity would play an important role in the pattern of genetic differentiation in A. ginnala populations. The A. ginnala population was isolated by a heterogeneous climate and subsequently began to adapt to local selection processes resulted in high genetic divergence.