Work

The cycle is elucidated study of changes in biotic nitrogen-fixation, particularly in formation and functioning of legume-rhizobia symbiosis, affected by clinorotation, that is considered to be simulated microgravity. It has been established that researches of such a system required a long-term clinorotation (at least 50 days) as well as using of a mineral fiber with periodically controlled wetness for soil substitution; these conditions should be combined with illumination with light intensity about 2,5 klx; as a macrosymbiont should be used a plant with genetically determinate unerect stem and with a sufficient ecological plasticity, in particular, shade tolerance. These requirements are met by alfalfa Medicago sativa L. cv. Yaroslavna. The central part of the dissertation research elucidates the analysis of the differences in the responses of alfalfa, inoculated and uninoculated with high-effective strain Sinorhizobium meliloti 441 to the impact of clinorotation and a permanently inverted orientation. A series of indices such as an aerial part and root dry weight; linear dimensions of various parts of shoots; nitrogen metabolism intensity (nitrogen-fixing activity, crude protein and nucleic acids content); photosynthetic processes intensity (photosynthetic pigments content, photochemical efficiency), lectin-containing extracts activity (indirect indicator for adaptation syndrome passing) were applied in order to achieve this object. 50-day clinorotation has been observed to result in the rise of the smallest nodules (up to 0.1 mm3) portion. This might prove that the simulated microgravity facilitates not only the growth but the initiation of young nodules. Several indices have appeared to be the most expressive in response of the symbiotic system to clinorotation and a permanently inverted orientation impact. Thus, nitrogenase activity in 30-day-old plants set with the following ascending order: clinorotation