The investigation of seed water state under the action of cytoskeletal modificators

The water molecular state dynamics under swelling and seed germination after cytoskeletal modificator - colchecin and cytochalasin B - was investigated by nuclear magnetic resonance method. In virtye of spin-spin relaxation times T2 changes conclusion was done about redistribution between free and bound water, which happens at the moment of changing water absorption physical stage to physiologically regulated process. It suppose that the cytoskeletal protein inhibitors can decrease superficial and capillar forces, as a result fraction of free water increase and bound water quantity decrease. The cytoskeletal protein inhibitors show their maximum effect - expressed germination inhibition - under minimum seed humidity at the first stage of swelling

Unfreezing water quantity as a possible way of winter wheat frost resistance appreciation

The investigation of unfreezing water quantity change dynamics took place after the plant tissue suffered from the influence of membrane active substances which change water permeability: pipolphen (10-3 M), verapamil (10-4 M), CaCl2 (10-3 M), Gd(NO3)3 (2.5- 10-2 M). The measurements of unfreezing water quantity were made by a simple method on the automatic cogerent «home-made» NMR-plant working at 15 MHz. The objects of investigation were roots of different frost resistant winter wheat (Triticum aestivum) sorts: less frost resistant Mironovskya-808, and more frost resistant Kazanskya-84. The temperature range of unfreezing water quantity was -7° - -30 °C. We got to know that pipolphen and verapamil increase membrane water permeability together with the increase in the quantity of unfreezing water, and the most frost resistant sort Kazanskya-84 had the greatest quantity of unfreezing water in this temperature range. The addition of Ca2+-ions brought about the lowering of unfreezing water. The regularity of influence of the membrane active substances at-30 °C proves that changes in water permeability correlate with those in membrane hydration

Acclimation to short-term low temperatures in two Eucalyptus globulus clones with contrasting drought resistance

We tested the hypothesis that Eucalyptus globulus Labill. genotypes that are more resistant to dry environments might also exhibit higher cold tolerances than drought-sensitive plants. The effect of low temperatures was evaluated in acclimated and unacclimated ramets of a drought-resistant clone (CN5) and a drought-sensitive clone (ST51) of E. globulus. We studied the plants’ response via leaf gas exchanges, leaf water and osmotic potentials, concentrations of soluble sugars, several antioxidant enzymes and leaf electrolyte leakage. Progressively lowering air temperatures (from 24/16 to 10/ 2 C, day/night) led to acclimation of both clones. Acclimated ramets exhibited higher photosynthetic rates, stomatal conductances and lower membrane relative injuries when compared to unacclimated ramets. Moreover, low temperatures led to significant increases of soluble sugars and antioxidant enzymes activity (glutathione reductase, ascorbate peroxidase and superoxide dismutases) of both clones in comparison to plants grown at control temperature (24/16 C). On the other hand, none of the clones, either acclimated or not, exhibited signs of photoinhibition under low temperatures and moderate light. The main differences in the responses to low temperatures between the two clones resulted mainly from differences in carbon metabolism, including a higher accumulation of soluble sugars in the drought-resistant clone CN5 as well as a higher capacity for osmotic regulation, as compared to the droughtsensitive clone ST51. Although membrane injury data suggested that both clones had the same inherent freezing tolerance before and after cold acclimation, the results also support the hypothesis that the droughtresistant clone had a greater cold tolerance at intermediate levels of acclimation than the drought-sensitive clone. A higher capacity to acclimate in a short period can allow a clone to maintain an undamaged leaf surface area along sudden frost events, increasing growt

Peculiarities of the University’s Educational Environment Implementation in the Organization of Future Teachers’ Pedagogical Practice

The article addresses contradictions between the existing and predicted tendencies in the organization and content of pedagogical practices. Through the analysis of teacher training programs, the need for student educational practice has also been established, which provides a solution to a wider range of professional tasks. The revealed contradictory nature made it possible to formulate the problem: what can be a trigger for the initiative acquisition by a future teacher of the experience in solving professional problems? Primary attention in solving this problem is paid to the conditions for the manifestation of personal student initiatives: the creation of platforms for dialogue, the provision of a periodic process of transition from practice to theory and vice versa, the use of operators of semiotic diagnostics of changes in students’ personal interests. The article presents the experience of organizing the educational environment, which provides future teachers with a modern range of professional probation. The options for the organization of official student practice are presented, including the development of online classes of educational and leisure activities of schoolchildren. This model contributes to the manifestation of students’ personal initiatives, both within the training profile and in the sphere of interdisciplinary intersections. The authors adduce the results of the questionnaire survey of students after the practice, showing their satisfaction with the chosen profession, a high level of motivation for mastering professional actions. The main methods and directions of organizing practices have been determined. They make it possible to ensure the predicted level of solving professional tasks by graduates

Physiological and biochemical responses to low non-freezing temperature of two Eucalyptus globulus clones differing in drought resistance

Abstract – We have compared the metabolic responses of leaves and roots of two Eucalyptus globulus L. clones CN5 and ST51 that differ in their sensitivity to water deficits (ST51 is more drought sensitive), with regard to the effect of chilling (10/5 ◦C, day/night). We studied changes in growth, osmotic potential and osmotically active compounds, soluble proteins, leaf pigments, and membrane lipid composition. Our data showed that both clones have the ability to acclimatize to chilling temperatures. As a result of 10 days of acclimation, an increase of soluble sugars in leaves of treated plants of both clones was observed that disappeared later on. Differences between clones were observed in the photosynthetic pigments and soluble protein content which were more stable in CN5 under chilling. It also was apparent that CN5 presented a less negative predawn water potential (ψpd) and a higher leaf turgor than ST51 throughout the chilling treatment. In the case of the CN5, increased total lipids (TFA) and concomitant increase of linolenic acid (C18:3) in leaves after acclimatization may be related to a better clone performance under chilling temperatures. Moreover, a higher constitutive investment in roots in the case of CN5 as compared to ST51 may benefit new root regeneration under low temperatures favoring growth after cold Mediterranean winter

Bases fisiológicas para a distribuição de clones de Eucalyptus globulus Labill. por diferentes áreas edafo-climáticas

Congresso Florestal Nacional: a floresta e as gentes - Actas das ComunicaçõesO Eucalyptus globulus Labill., pela sua importância económica, encontra-se distribuído por todos os países de clima favorável, reflectindo o interesse que têm as suas características intrínsecas como sejam um rápido crescimento e uma superior qualidade da madeira para produção de pasta para papel. Em Portugal, a relevância económica desta espécie traduz-se quer em termos de uma contribuição positiva para a balança comercial quer em termos do investimento feito na plantação de novas áreas florestais. No entanto, devido à restrição ao aumento da área de plantações verifica-se uma crescente exigência em aumentar a produtividade das áreas plantadas, garantindo a sustentabilidade económica, social e ambiental dos ecossistemas florestais. Actualmente, a área clonal de E. globulus é de aproximadamente 15000 ha tendo vindo a aumentar nos últimos anos cerca de 2000 ha por ano, como resultado das melhores técnicas de propagação e dos programas de melhoramento. Uma vez que o nº de clones comercialmente interessantes para a produção e que são utilizados em plantações tem tendência a ser reduzido, torna-se necessário deter um conhecimento mais aprofundado das suas respostas fisiológicas de forma a reduzir o risco inerente a uma diminuição da diversidade genética. Particularmente, e porque em Portugal as plantações ocorrem em áreas onde ocorrem défices hídricos sazonais, havendo uma grande variabilidade interanual no stress hídrico e sendo previsível um agravamento da aridez num futuro próximo, é necessário conhecer detalhadamente os mecanismos de resistência ao stress hídrico de forma a sustentar as decisões de distribuição dos clones por diferentes regiões edafo-climáticas. Este trabalho constitui um primeiro passo para o aprofundamento do conhecimento dos processos fisiológicos, de modo a identificar características biológicas que sirvam de referência à selecção de genótipos, permitindo uma consolidação dos resultados obtidos nos ensaios de campo e, portanto, uma mais ajustada distribuição dos clones pelos seus locais de plantação e crescimento futuro. Especificamente, avaliaram-se em condições controladas os mecanismos de resistência à secura em dois clones de Eucalyptus globulus Labill. com diferente sensibilidade à secura no campo, com base em estudos fisiológicos, biofísicos e morfológicos

Responses to water stress in two Eucalyptus globulus clones differing in drought tolerance

We evaluated drought resistance mechanisms in a drought-tolerant clone (CN5) and a drought-sensitive clone (ST51) of Eucalyptus globulus Labill. based on the responses to drought of some physiological, biophysical and morphological characteristics of container-grown plants, with particular emphasis on root growth and hydraulic properties. Water loss in excess of that supplied to the containers led to a general decrease in growth and significant reductions in leaf area ratio, specific leaf area and leaf-to-root area ratio. Root hydraulic conductance and leaf-specific hydraulic conductance decreased aswater stress became more severe. During the experiment, the drought-resistant CN5 clone maintained higher leaf water status (higher predawn and midday leaf water potentials), sustained a higher growth rate (new leaf area expansion and root growth) and displayed greater carbon allocation to the root system and lower leaf-to-root area ratio than the droughtsensitive ST51 clone. Clone CN5 possessed higher stomatal conductances at moderate stress as well as higher hydraulic conductances than Clone ST51. Differences in the response to drought in root biomass, coupled with changes in hydraulic properties, accounted for the clonal differences in drought tolerance, allowing Clone CN5 to balance transpiration andwater absorption during drought treatment and thereby prolong the period of active carbon assimilation

Phloem sap and leaf δ13C, carbohydrates, and amino acid concentrations in Eucalyptus globulus change systematically according to flooding and water deficit treatment

Phloem is a central conduit for the distribution of photoassimilate, nutrients, and signals among plant organs. A revised technique was used to collect phloem sap from small woody plants in order to assess changes in composition induced by water deficit and flooding. Bled phloem sap δ13C and sugar concentrations were compared to δ13C of bulk material, soluble carbon extracts, and the neutral sugar fraction from leaves. Amino acid composition and inorganic ions of the phloem sap was also analysed. Quantitative, systematic changes were detected in phloem sap composition and δ13C in response to altered water availability. Phloem sap δ13C was more sensitive to changes of water availability than the δ13C of bulk leaf, the soluble carbon fraction, and the neutral soluble fraction of leaves. Changes in water availability also resulted in significant changes in phloem sugar (sucrose and raffinose), inorganic nutrient (potassium), and amino acid (phenylalanine) concentrations with important implications for the maintenance of phloem function and biomass partitioning. The differences in carbohydrate and amino acid composition as well as the δ13C in the phloem, along with a new model system for phloem research, offer an improved understanding of the phloem-mediated signal, nutrient, and photoassimilate transduction in relation to water availability

The investigation of seed water state under the action of cytoskeletal modificators

The water molecular state dynamics under swelling and seed germination after cytoskeletal modificator - colchecin and cytochalasin B - was investigated by nuclear magnetic resonance method. In virtye of spin-spin relaxation times T2 changes conclusion was done about redistribution between free and bound water, which happens at the moment of changing water absorption physical stage to physiologically regulated process. It suppose that the cytoskeletal protein inhibitors can decrease superficial and capillar forces, as a result fraction of free water increase and bound water quantity decrease. The cytoskeletal protein inhibitors show their maximum effect - expressed germination inhibition - under minimum seed humidity at the first stage of swelling

The investigation of seed water state under the action of cytoskeletal modificators

The water molecular state dynamics under swelling and seed germination after cytoskeletal modificator - colchecin and cytochalasin B - was investigated by nuclear magnetic resonance method. In virtye of spin-spin relaxation times T2 changes conclusion was done about redistribution between free and bound water, which happens at the moment of changing water absorption physical stage to physiologically regulated process. It suppose that the cytoskeletal protein inhibitors can decrease superficial and capillar forces, as a result fraction of free water increase and bound water quantity decrease. The cytoskeletal protein inhibitors show their maximum effect - expressed germination inhibition - under minimum seed humidity at the first stage of swelling