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Background. The main share in the landscaping of the city of Yoshkar-Ola is made up of such deciduous woody and shrub plantings such as Betula pendula Roth., Tilia cordata Mill., Syringa vulgaris L., Acer negundo L., Populus pyramidalis Salisb., etc. Coniferous plants are not so usually used as often as deciduous plants in landscaping urban areas. However, most of them belong to the group of evergreens and play the role of green spaces all year round. In score of the high sensitivity to gaseous pollutants in cities, the problem arises using of it in urban landscaping. But such species of introduced conifers as Picea pungens Engelm., Thuja occidentalis L., Juniperus sabina L. are notable for their significant resistance to technogenic pollution. Materials and methods. The studies were conducted during 2018 in three different zones of Yoshkar-Ola which differ with degrees of anthropogenic load (recreational, residential, industrial). The objects of the study were Picea pungens Engelm., Thuja occidentalis L., Juniperus sabina L. The content of photosynthetic pigments (chlorophyll a and b, carotenoids) was studied in the needles of the second year of life in seasonal dynamics (May, July, October, December). Results. The study found that with an increasing of anthropogenic load, the quantitative content of photosynthetic pigments decreased in the needles of introduced plant species. Needle Picea pungens Engelm. was characterized by the highest content of the studied types of pigments. Conclusions. The obtained data expand the idea of the pigment composition of conifers growing in urban environment. The quantitative content of photosynthetic pigments depends on the species, season of the year and place were, it grows.

The objective of this research was to investigate the effect of salt (NaCl) and acetate (NaC2H3O2) stresses on the pattern of biomass accumulation and photosynthetic pigments content in algae culture of the freshwater green alga Acutodesmus dimorphus (Turpin) P.M. Tsarenko IBASU-A 251. We demonstrated that sodium chloride introduced in a culture medium at various concentrations caused a gradual reduction of the microalga biomass whose maximum was recorded at the salt concentration of 1.5%. Addition of sodium acetate at the same concentrations led, on the contrary, to a sharp (more than two times) decrease of A. dimorphus biomass. On the 18th day of culturing under salt stress conditions the chlorophyll a content decreased 1.5-2.5 times, the chlorophyll b content – 1.3-1.7 times, while the carotenoids quantity increased 1.2-1.6 times. Under acetate stress conditions the chlorophyll a content decreased 2-3 times, that of chlorophyll b – 1.7 – 1.8 times whereas the carotenoids quantity increased within the range of 1.4-1.8 times. Increase in chemical stressors concentrations involved some reduction of the chlorophylls а/b ratio and total chlorophylls а+b content, and at the same time, the ratio carotenoids/a+b increased. Sodium acetate appeared to be a more powerful inducer of carotinogenesis than sodium chloride. The highest quantity of carotenoids was registered at 1% and 1.5% concentrations of NaC2H3O2 in the culture medium and 0.75% concentration of NaCl. The results obtained enable to regard Acutodesmus dimorphus (Turpin) P.M. Tsarenko IBASU-A 251 as an active carotenoids producer to be later applied in studies of hypersynthesis of individual classes of this pigment.

The developmental stages and adaptability to different light intensity (150 µmol*m-2*s-1 and 100 µmol*m-2*s-1) in Arabidopsis mutant lines with defects of photosynthetic apparatus were analyzed. Plant development in the mutant lines depended on the light intensity to varying degrees. Lines ch1-1 (lack of the chlorophyllide a oxygenase) and rtn16 (decreased chlorophyll a and b amounts) were the most susceptible to the light decrease. No one of the investigated lines demonstrated chlorophyll a/b rate alteration under the different light conditions. The depleted chlorophyll content has had the major effect on the mutant plants development under the different light conditions. The different chlorophyll a/b rate correlated with the different adaptability of mutant plants to low light.