The influence of growth regulators absorbed by the root on sex expression in hemp plants

Application, through the root system, of growth regulators to hemp (Cannabis sativa L.) plants having 2–3 pairs of visible leaves caused pronounced shifts of sex expression in the adult individuals. Treatment with gibberellic acid (25 mg/l) resulted in more than 80% of the plants being male, i.e. having staminate flowers (controls, ca. 30%). Treatment with 6-benzylaminopurine and with indole-3-acetic acid (in either case, 15 mg/l) resulted in all plants being either female (pistillate flowers) or intersexes (bisexual flowers); treatment with abscisic acid (10 mg/l) had a similar but somewhat less pronounced effect.     

Features of the Brain Functional Organization in Right- and Left-handed 6- to 7-Year-Old Children during Visuospatial Performance of Different Complexity: I. Comparative Analysis of EEG Parameters during Simple Visuospatial Performance

The spectral power density and coherence of the rhythmic EEG components of the and ranges were analyzed in 6- to 7-year-old right- and left-handed children during simple visuospatial performance. Both similar and distinct features in the time course of EEG parameters were revealed in right- and left-handed children. No asymmetry in the right- and left-hemispheric involvement in correlation with the type of manual asymmetry was observed.     

Inducible and constitutive mechanisms of salt stress resistance in <Emphasis Type="Italic">Geum urbanum</Emphasis> L.

The avens (Geum urbanum L.) seedlings were grown for 6 weeks until the expansion of five to six leaves and then exposed to salinity shock (300 mM NaCl in the nutrient medium) or to a gradual (within 4 days) increase in NaCl concentration from 100 to 400 mM. The dynamics of stress-dependent accumulation of Na⁺, Cl^?, proline, and polyamines in leaves and roots was measured, together with activities of antioxidant enzymes, namely, superoxide dismutase (SOD) and guaiacol-dependent peroxidase occurring in soluble, ionically bound, and covalently bound forms. It is shown that avens plants can adapt to gradual salinization by mobilizing stressinducible protective mechanisms (accumulation of proline and spermine) and by activating constitutive enzyme systems (SOD and peroxidase).     

Role of Phytohormones in Sex Differentiation in Plants

The role of phytohormones in sex expression in plants is briefly surveyed. The interaction of hereditary and environmental factors in sex expression is considered. A major role of gibberellins and cytokinins in the regulation of sex expression in dioecious and monoecious flowering plants and in some muscoids is demonstrated. The evidence for the effect of other phytohormones and physiologically active compounds on sex expression in plants is examined.     

Psychophysiological and neurophysiological features of the organization of visuo-spatial performance in right-handed and left-handed six- to seven-year-old children

The developmental features of individual components of the visual perception and brain functional organization during visuo-spatial activity of different complexity were studied in right-handed and left-handed 6–7-year-old children. The results of psychophysiological testing of their visual perception testify to the underdevelopment of the mechanisms of integrative brain activity. Some specific features of the brain functional organization were revealed in the left-handed children during visuo-spatial performance. More autonomous functioning of the cerebral hemispheres and the duplication of the activation processes in the right and left hemisphere during visuo-spaital performance of different complexity are characteristic of these children. This is probably associated with the involvement of compensatory mechanisms, which enable the performance reliability.     

The effects of heavy metal salts on the phytohormonal status and sex expression in marijuana

We studied the effects of heavy metal salts (Pb(NO₃)₂, CuSO₄, and ZnSO₄) on phytohormonal status and sex expression in various cultivars of marijuana (Cannabis sativa L.), a dioecious plant, grown on Knop nutrient medium. Pb(NO₃)₂ and ZnSO₄ were added to the medium at the concentration of 10⁻⁹ M, and CuSO₄, at the concentration of 10⁻¹⁰ M. Plant were grown under controlled conditions at luminescent illumination, 22–24°C, and 80% humidity. The contents of GA and zeatin were determined by HPLC. Copper and zinc salts induced plant feminization, and this effect was coupled with zeatin accumulation. Lead salts favored plant masculinization coupled with GA accumulation. Thus, a shift in sex expression in marijuana plants was correlated with the heavy metal action on the balance of phytohormones, GA and zeatin.     

Evolution of the pathways of sex differentiation in plants

The stages of formulating the theory of sex evolution, determination, and expression in plants were briefly reviewed. The role of phytohormones in sex differentiation in dioecious and monoecious plants was analyzed.     

Changes in the hormonal balance in germinating seeds after an impulse-pressure treatment

The buckwheat (Fagopyrum esculentum Moench., cv. Aromat) seeds were treated with impulse pressure (IP) of various intensities (11–29 MPa). The energy of seed germination decreased by the second day after treatment. Within eight days after treatment with 11- and 17-MPa IP, seed germinability did not change, but it decreased after treatment with 23- and 29-MPa IP. The content of phytohormones in imbibed seeds was determined. The oscillations in the ratios of ABA, IAA, GA₃ , and zeatin in germinating seeds after IP treatment were found. In their shape, these oscillations were consistent with the control ones, but they differed in their amplitude. Such increase in oscillations can be considered a defense and adaptive response. It can be suggested that the changes in oscillation dynamics point to a rearrangement of a hormonal system at 11–17-MPa IP, favoring an overcoming a negative effect of IP-caused stress.Translated from Fiziologiya Rastenii, Vol. 52, No. 1, 2005, pp. 146–150.Original Russian Text Copyright © 2005 by Nefedeva, Mazei, Khryanin.     

Effect of growth regulators and role of roots in sex expression in spinach

When 7-d-old plantlets of spinach (Spinacia oleracea L.) were immersed with their roots for 24 h in 25 mg/l gibberellic acid (GA₃), or 15 mg/l 6-benzylaminopurine (6-BAP), or 15 mg/l indole-3-acetic acid (IAA), or 10 mg/l abscisic acid (ABA) and subsequently grown on long (18-h) days, the ratio of plants with male and female flowers, which in the controls was almost 1:1 (48 and 52%, respectively), was greatly altered. The treatments with 6-BAP, IAA and ABA raised the percentage of female plants to 88, 76 and 71%, respectively; the GA₃ treatment increased the percent of male plants to 79%. When young, vegetative spinach plants (3 visible leaves) grown in 18-h days were cut a the root neck, and the shoots grown with their bases in nutrient solution, with adventitious roots either being allowed to develop or being systematically removed, 85% of the plants without roots became males, 85% of those with roots became females. But if the cut shoots were first, for 28 h, placed in a 15-mg/l 6-BAP solution and then grown in the absence of roots, the percent of female plants was restored to 84. These results fully agree with those obtained previously with hemp, namely, that plant growth regulators exert a regulating effect on the sex expression of dioecious plants when applied through the roots in early stages of development; that the root system plays an important role in determining the sex of these plants, that this role of the roots is associated with the synthesis of cytokinins in them. Dioecious short- and long-day plants do not differ in these respects.     

Adaptation of the photosynthetic apparatus of the immature broadleaf trees to the flood-plain conditions

We studied the mechanisms of adaptation of immature broadleaf trees to natural placor and flood-plain conditions. Changes in the anatomical and physiological features of plants inhabiting different ecotops are considered an adaptive response of the photosynthetic apparatus.