SUMMARYThe genus Populus L. is one of the promising energy plants for growing on marginal lands. To assess its potential under steppe conditions, growth morphological parameters of 9 hybrid poplar clones grown over two years on a mix of loess-like loam and red-brown clay have been studied. In the first year, the degree of the sapling survival and the intensity of development were explored. At the end of the year, two clones which showed the best results (Ijzer-5 and Robusta), were selected for further breeding and rearing. Researches of the second year were devoted to the effect of biological agents on the survival and growth of these two clones. The treatments with vermicomposting extract (VCE), trichodermin, mycorrhiza and mixture of these agents were applied. The experiment with poplar clones Ijzer-5 showed a positive effect of all bioagents on the growth morphological parameters. The increase of the length and diameter of an annual shoots, leaf area and total assimilation surface from 10 to 38% was revealed. The treatment with vermicomposting extract gave the best result. For clones Robusta, only three agents out of four had a positive effect. The rise in morphological parameters was at the level of 9-55%. The best results were noted in the experiment with a mixture of agents. Treatment with trichodermin caused an inhibitory action on most of the growth characteristics of the clone Robusta.To obtain the wood thermal stability information a comparative thermogravimetric analysis of poplar wood samples grown on different soil types was carried out. A larger value of DTG at all stages was observed in a sample of poplar grown on sod podzolic soil. The difference in the value of the rate of mass loss is explained by the larger content of humus in sod podzolic soils, than in the phytomeliorated mix of rocks.
The physical and chemical properties of the phytomeliorated overburden rocks of the Pokrov land reclamation station of the Nikopol manganese ore deposit and two types of technogenic substrates were studied: loess-like loam, red-brown clay, grey-green clay, dark-grey schist clay and black soils placed on layers of sand and loess-like loam. Samples were taken from each type of technosol at a depth of 10-20 cm (plough layer) and 20-40 cm (sub-plough layer). Identification of the suitability of these technosols for growing crops was carried out by phytotest method. It was revealed that the main clay mineral of dark-grey schist and red-brown clays is the illite. Grey-green clay predominantly consists of montmorillonite, and in loess-like loam and black soil, the content of kaolinite, illite and montmorillonite is more or less the same. The maximal hygroscopicity level was observed in grey-green clay (20.5%). The minimal level was fixed in red-brown clay (7.6%). Phytomeliorated mining rocks are weakly humus; the humus content in them does not exceed 1.25%. Technogenic substrates contain 2.5-3.3% of humus and belong to low-humus soils. All studied technosols belong to slightly alkaline substrates in which the pH varies from 7.34 to 7.86 in the plough layer and from 6.6 to 7.91 in the sub-plough layer. In two of the investigated mining rocks (grey-green and dark-grey schist clays), weak sulfate-chloride salinity was observed. In grey-green clay, the concentration of soluble salts was increased both in plough layer (0.214%) and in the sub-plough layer (0.202%). In the dark-grey schist clay, salinity was observed only in the sub-plough layer, but it was stronger than in the grey-green clay (0.281%). The concentration of chlorides and sulfates in these technosols exceeded the toxicity threshold by 7-8 and 1.5-1.7 times, respectively. The sub-plough layer of dark-grey schist clay and both layers of grey-green clay are phytotoxic. The inhibitory action on the growth and development of plants is caused by the cumulative effect of a soil acid-base imbalance, salinity and low fertility of these technosols. Cultivation of agricultural plants on them is expedient and economically justified only under the condition of carrying out a number of meliorative measures aimed at improving the physical and chemical properties of these substrates.
Ukrainian and American sweet sorghum hybrids were studied as raw material under reclaimed lands conditions in the southeast Ukraine. Among the cultivars in the range of hemicellulose destruction the highest reactivity was recorded for American hybrids, whereas the process of cellulose decomposition was most active in Ukrainian hybrids. Thermogravimetry (TG) curves of Ukrainian hybrids were more differed for plants grown on loess like loam comparative with American hybrids. The molecular structure of sweet sorghum lignin is represented by the spatially hindered hydroxyl groups of alcohol and phenolic type with the strength hydrogen bonding between some other structural fragments of macromolecules, ordinary carbon-oxygen bonds of metoxyl groups, and double carbon-carbon bonds.
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