[Tropisms in underground shoots ­ stolons and rhizomes].

In the review, the problem of plant movements (photo- and gravitropism) is discussed. The contemporary data on physiological and molecular mechanisms of tropisms in underground shoots and roots are presented. Special attention is paid to diagravitropism phenomenon in underground shoots (stolons and rhizomes) that grow in perpendicular direction to the Earth's gravitational axis. The role of phytochrome control in maintaining the horizontal growth of stolons and rhizomes is demonstrated, and physiological mechanisms of photo- and diagravitropism are discussed. It is shown that switching of an underground shoot tip from diatropic to ortotropic (vertical) growth is dependent on the carbohydrate and phytohor-mone balance. The perspectives are outlined for further exploratory studies on mechanisms of growth orientation and morphogenesis of underground diagravitropic shoots.

[Use of ion-exchange substrates for optimizing the mineral supply to plants within life support systems].

The main goal of the work is to validate ion-exchange substrates as optimizers of plant mineral supply within bio-engineering systems of life support with a high level of closure. Test objects were spring Lisovsky wheat-232 and leaf cabbage Sensuji-kyomizuna. Crops were cultivated on artificial soil (AS) in environmentally controlled plant growth chambers. Prior to seeding, AS was enriched simultaneously with wheat straw and ion-exchange substrate BIONA-312 to the extent of 2, 10 or 20% of AS dry mass. Incorporation of the ion-exchange substrate in the amount of 10% increased crop productivity and eliminated the negative effect of wheat straw. Ion-exchange substrate in amount of 20% did not yield a noticeable gain in productivity as compared with the previous test.

[Polar lipid pool modification in leaves of hoary plantain (Plantago media L.) plants during their light adaptation under natural conditions].

Polar glycerolipids and photosynthetic pigments of Plantago media L. plants, growing on limestone outcrops of the Southern Timan, have been studied. Leaves of plants growing on well insolated and heated slopes are characterized by an intensive lipoperoxidation; the accumulation of chlorophylls and carotenoids in these plants is 1.5-2 times less and the content of polar lipids is 15-20% less than in plants growing in dense grass at the bottom of slopes. The accumulation of some classes of glycerolipids in leaves in the daytime provides for stabilization of photosystem complexes and the formation of the pool of zeaxanthin, a protective xanthophyll. Changes in the content and ratio of lipids represent an important part of the adaptive reorganizations of the photosynthetic apparatus caused by excess radiation under natural conditions.

[Optimization of the mineral nutrition of plants constituting the phototrophic component of closed biological life support systems].

Applicability of a new substrate for crops cultivation in bioregenerative LSSs with a high degree of mass-exchange closure was tested. Optimization of leaf cabbage nutrition by supplementing the basic substrate fabricated of plant and animal residues with ion-exchange resins proved to have a success.