Nitrate (20 mM) applied to the root medium of 28-day-old nodulated pea plants (Pisum sativum L., cv. Jupiter) immediately retarded nodule growth and inhibited root nodulation. Acetylene-reducing and H₂-evolving nitrogenase activities were also significantly inhibited. The inhibitory effect of nitrate on nodule respiration was less pronounced while the respiration of roots was increased after the addition of nitrate. The levels of cytosol glutamine synthetase and nitrate reductase in nodule cytosol were permanently decreased from the 4th day after nitrate application. These results indicate that the inhibitory effect of high nitrate concentration on whole nodule metabolism is nonspecific in nature.

Salinity caused a consistent reduction in the growth of cowpea plants and water content in their leaves. The total as well as the pigment fractions, except carotenoids, exhibited lower values than those of control plants at almost all salinity levels. With the rise of salinization, the total nitrogen and potassium contents in the leaves were decreased but the sodium content was increased and phosphorus content was not significantly affected as compared with the controls.
The application of IAA to salt-treated plants increased the water content in the leaves but it had no effect on the number of leaves and the stem length. The pigment contents in the leaves were either promoted or inhibited with the application of IAA, depending upon the level of salinization. The application of IAA to plants irrigated with water of the highest salinity level was effective in increasing the potassium content in the leaves as compared with the control, but it had no effect on the other mineral elements.

The mature nodules ofLens esculenta Moench. contained higher levels of indolyl acetic acid (IAA), cytokinins (CK), gibberellic acid (GA)-like substances and more active in nitrogenase (N₂-ase) activity than young or old ones. Synthesis of IAA and its metabolism was found to be controlled by tryptophan (tryp) and phenol metabolism, respectively, in nodules of different ages. An abscisic acid (ABA)-like substance being a 'late growth phase' hormone, was highest in old nodules.
IAA and CK were highest in winter when N₂-ase activity was also highest but then GA and ABA were low. The IAA metabolic pattern of both roots and nodules was regulated by phenols. The hormones hardly changed seasonally in the roots and showed higher activities of IAA oxidase, MeOx reductase, peroxidase and polyphenol oxidase than nodules.
The nodular anabolic changes are more pronounced in winter as lentil is a winter crop. The size of nodules at a particular age was the same in different seasons, even though their hormone content varied with the season showing that the nodular hormones were not solely utilized for nodule development and growth.

Influence of high intensive flashes on the yield of free radicals in intact seeds and excised embryonic axis, endosperm, and seed coat, and its resulting effect on seedling growth, total biomass production and phosphorus metabolism in wheat (Triticum aeativum), vetch (Vicia sativa L.) and onion (Allium cepa L.) was studied. Free radicals (f.r.) were formed mainly in seed coat and not in the endosperm. Vetch seeds after irradiation had 20.76 X 10¹³ f.r. g^-1 dry intact seed and 17.30 X 10¹³ f.r. g^-1 dry seed coat. Excised seed coats exposed to irradiation also yielded 17.28 × 10¹³ f.r. g^-1 dry matter. High irradiance "white light" flashes induced more f.r. than a monochromatic one of the same photon content. Red (650 nm), farred (750 nm) and even infra-red (1100 nm) radiation did not initiated f.r. formation but resulted in their decay in samples irradiated earlier by "white", blue and green parts of the spectrum. Blue irradiation of seeds led to the decrease in the length of shoots and roots in comparison to "white", green and red irradiation but their biomass increased faster than in the seedlings obtained from non-irradiated or irradiated with "white" and green radiation. The quantity of total acid soluble phosphorus followed a sequence with respect to wavelength of radiation: 436 nm > 650 nm> > 540 nm > non-irradiated > 300-800 nm. Quantity of inorganic phosphorus remained unaffected by different spectral character of radiation. The quantity of organic acid soluble nucleic phosphorus and acid insoluble polyphosphates was higher in samples irradiated with red beams (650 ± 6 nm).

The effects of vanadium and tungsten on growth of the heterocystous cyanobacteriumNostoc linckia (Roth.) Born. and the activity of its nitrogenase and nitrate reductase were studied. While vanadate stimulated the growth of molybdate-limited cells and also their acetylene-reducing ability, it did not stimulate nitrate reductase activity. Tungstate inhibited growth in molybdate-limited cells and also their acetylene reducing and nitrate reductase activities. Acetylene reduction response of cells grown in a tungstate-containing medium indicated certain difference between the modes of action of vanadium and molybdenum. Tungstate caused a slight increase in heterocyst frequency both in nitrogen-fixing and nitrate-grown material. Cyanophycin granules and polyhedral bodies disappeared in molybdate-deficient cells in which thick deposition of polyglucan-like granules occurred throughout the breakdown of cytoplasm and the thylakoids.

Studies performed on spring wheat (Triticum aestivum L. var.lutescens), cv. Kaspar and Kolibri revealed differences between cultivars in leaf dehydration tolerance. The differences were found to be responsible for the changes in plant growth and productivity observed under drought conditions. Thus, determination of leaf dehydration tolerance may allow the prediction of the plant response to the water stress in terms of plant growth and grain yield. Differentiated drought responses of both cultivars are described.

The growth ofArabidopsis thaliana calli on media without growth regulators was studied Calli under study showed autonomy for cytokmms independently whether cultivated on the light or m the dark When cultivated in intense light, they were able to grow, either transiently or permanently, on the medium without any growth regulators In the dark, they were strictly dependent on 2,4 D m the medium Both the intensity of growth and the duration of the transient growth on the medium without growth regulators m the light decreased with the duration of the previous cultivation on the medium with growth regulators The intensity of growth on the medium without grow th regulators was best and the growth was permanent m the callus clone of spontaneous origin which was never treated by growth regulators The degree of chromosomal variability (assessed as the number of chromocentres) m this callus line was lower than that in calli induced on media with growth regulators and then transferred onto medium without growth regulatois.

The metabolism of exogenously supplied abscisic acid (ABA) during translocation attracted under the influence of indolyl-3-acetic acid (IAA) was studied in etiolated segments of pea (Pisum sativum L.). After 8 and 24 h 90% and 60% of the ABA, respectively, were found in the segments in unchanged form. Phaseic acid, dihydrophaseic acid and the glucose ester of ABA were found as ABA metabolites. Results indicated that the growth processes initiated by the application of IAA were associated neither with an increased immobilization nor increased metabolization of this growth regulator.

The elongation of pine seedlings (Pinus silvestris L.) is associated with nutation movements. Trajectories of these growth oscillations were recorded by film technique in horizontal and vertical projection during a three day period of growth. On the basis of these data the parameters of elongation and nutation oscillations,i.e. rate, amplitudes and frequency of oscillations, were calculated and their changes during plant development compared. Oscillation trajectories are circular or elliptic spirals the amplitudes of which are increasing with the age of hypocotyl from 1.5 mm to 7.5 mm. The frequencies of nutations are decreasing during the growth from 0.5 to 0.2 rev. h^-1. On the other hand, the growth rate of hypocotyl increased from values near to 10^-3 mm h^-1 at the beginning of the experiment to 4×10^-1 mm h^-1 recorded at the end of the third day. The zone of nutation curvature was slightly transferred from the middle of the hypocotyl toward the apex and its location has not been identical with that of elongation. This indicates that the system controlling nutation oscillations need not be identical with that controlling direction of elongation. At a certain stage of development behaviour of the decapitated pine hypocotyl is analogical to that of the root without the centre of georeception. A possibility of analogy of the system controlling direction of hypocotyl growth and of the system proposed for geotropical control of root growth is discussed.

Sucrose was markedly superior to fructose and glucose in promoting growth of plantlets from immature maize embryos. The elongation of roots is shown to be more sucrose dependent than that of shoots. On the other hand, the exogenous sucrose was less effective than fructose as substrate for carbohydrate catabolism and for the synthesis of alcohol-insoluble compounds at the beginning of embryo cultivation. The absorbed fructose was found to be rapidly converted to sucrose and the level of endogenous sucrose derived from sugar supplied to the medium was higher in fructosethan in sucrose-fed embryos. The preferential utilization of fructose over sucrose, however, declined with the progress of germination which may be related to the decrease in proportion of scutellum in total mass and physiological activity of the embryo.

Protoplasts isolated from cell suspension cultures of potato were cultured as far as the level of regeneration of substrains. The influence of various factors (age of the cell culture, mode of precultivation, composition of the enzymatic mixture, incubation period) on the efficiency of isolation as well as the viability of protoplasts, has been studied. Various cultivation procedures have been screened and the effect of especially the hormonal composition of the medium on different phases of the regeneration of cell colonies (regeneration of the cell wall, growth and elongation, cell division) evaluated.

Effects of various concentrations of streptomycin sulphate either alone or in combination with different cations and hormones on mungbean (Phaseolus aureus L.) seedling growth were studied. The relative inhibition of root growth was stronger than that of hypocotyl growth. Root growth inhibition was completely overcome by calcium, while other cations were ineffective. Inhibition of hypocotyl elongation could not be prevented by cations. IAA and GA₃ were capable of relieving streptomycin inhibition but kinetin was ineffective.
In the coleoptiles of streptomycin-treated rice (Oryza sativa L.) seedlings, there were accumulation of nucleic acids and decline in protein content resulting in increased RNA/protein and DNA/protein ratios. High nucleic acid content induced by streptomycin could be correlated with reduced activity of the nucleases.

Growth parameters and esterase isoenzyme patterns were studied in developing cotton fibre. Fibre length and dry weight when plotted against boll age showed four distinct stages; (i) initiation, (ii) elongation, (iii) secondary thickening, and (iv) maturation. Stage specificity and changing intensities of esterase isoenzyme suggested a finely modulated control of gene expression during fibre development.

Callogenesis was induced in mature embryos. The efficiency of induction and the growth of calli were dependent on 2,4-D concentration. No regeneration of buds or shoots was observed in 720 calli studied, but most calli showed intensive root proliferation on the regeneration medium. Most of the root meristem cells maintained diploid chromosome number. Only a low proportion (about 3.5%) of tetraploid cells was found. No other chromosomal changes were observed. Chromosomal variability does not contribute to the inability of calli derived from mature barley embryos to form buds and shoots.

The degree of tolerance of two crown gall tumors and leaf calli ofArabidopsis thaliana to BUdR was compared. The nopaline producing teratoma tumor tolerated BUdR in concentration as high as 2.10^-4 M. The tolerance of octopine producing unorganized crown gall tumor to BUdR was lower, but both exceeded significantly the degree of tolerance to BUdR of untransformedA. thaliana calli, where 10^-5 M BUdR already show some inhibitory effect on the growth rate.

Crude enzyme extracts from the zones of division, elongation and differentiation of cells of primary maize (Zea mays) root show peroxidase activity but lack IAA-oxidase activity. After partial purification of the extracts by gel filtration on Sephadex G-25, the specific peroxidase activity increases almost twice and a high IAA-oxidase activity appears.
The partial purification of the enzyme extracts does not change the electrophoretic pattern of the peroxidase isoenzymes, but significantly improves the separation and the visualization of isoenzymes with IAA-oxidase activity.
The data obtained were interpreted in connection with the different modifying effect of the low molecular compounds (mainly phenolics) on the activity and the isoenzyme patterns of the peroxidase and the IAA-oxidase.

Growth ofSilene alba (MILLER) E. H. L. KRAUSE cells, as well as their peroxidase pattern and activity are studied. Cells were grown in the presence and absence either of IAA, or NAA or 2,4-D. The subculture is dependent upon the growth regulator used to sustain the growth of cells. For 14 days' passages, subculture is possible with 2,4-D (5 x 10^-7M) or NAA (10^-5M) but impossible with IAA or without any growth regulators. Cells grown using 2,4-D or NAA in the medium contain a smaller number of isoperoxidases and have lower activities than those grown using IAA or no growth regulator. The nature of growth substances does not affect the compartimontation of the peroxidase; in fact the bulk of the peroxidaso activity is always liable to the ionic wall bound fractions. Tho electrophorotic mobilities of peroxidase isoenzymes detected in the modium are not the same as those of tho eytoplasmic isoenzymes. Cell cultures grown with and without growth regulators show different patterns of modium peroxidase activities. Some forms are present both in cells and media and some other only in the media; this may indicate that there is some selection made in tho cells for retention of particulars forms; the others could be secreted as exoenzymes shortly after they are synthesized in the cells. The nature of the growth regulator used could act on the release of certain isoperoxidases. These results are discussed from the viewpoint of the correlation of isoperoxidase patterns with the possibility of subculture.

The results of experiments conducted with autumn rye and summer wheat on sandy loam soil at the Institute for Cereal Production of the Martin-Luther University, Halle-Wittenberg (G.D.R.) have revealed that an increase in soil moisture improved the plant water balance, width of stomata, shoot growth, tiller density, leaf area and growth rate. Net assimilation rate, however, decreased with the increase in soil moisture above 50 per cent water holding capacity. Increased soil moisture improved contents of nitrogen, potassium and phosphorus only during early stages of growth, but their uptake was not reduoed at maturity. Air conditioning irrigation proved superior in respect to all above mentioned characteristics, except the uptake of potassium, which decreased with air conditioning irrigation at higher soil moisture relations.

The effects ofo-, m- andp-hydroxyphenylacetic acids on total peroxidase activity and isoperoxidase patterns of wheat coleoptile sections were studied.o-andm-HOPA reduced the total peroxidase activity whilep-HOPA increased it. Electrophoresis in polyacrylamide gel revealed thato- andm-HOPA diminish the intensity of some anodic and cathodic bands, but thatp-HOPA increases anodic and reduces cathodic isoperoxidases. These results may explain the apparently paradoxical positive effects ofp-HOPA on both growth and total peroxidase activity.

Stem tips ofSpinacia oleracea were isolated and grown in sterile culture, with Sandoz 9789 added to the medium. Although the herbicide provoked a complete loss of all chloroplast pigments, developed shoots were able to flower, in response to long days; in short days flowering was inducible by adding gibberellins. Sandoz 9789 decreased the elongation of stems by up to 30%; the percentage of flowering plants in culture was also decreased. However, among those plants that flowered, the majority were male, so that Sandoz 9789 produced a shift of the sex ratio toward maleness.

Two cultivars of pigeon pea (Cajanus cajan (L.)Millsp.) UPAS-120 and Parbhat were grown in the field under two irrigation treatments: no irrigation and irrigation when cumulative pan evaporation was equal to 50 per cent depletion of available water content in one metre root zone depth. Diurnal changes in leaf water potential and stomatal conductance were recorded on two daysi.e. October 1, 1979 and October 28, 1979 which corresponded to reproductive growth stage of the crop. Plant water potential decreased rapidly during the day up to about 15.00 and increased during evening hours. Higher leaf water potential was recorded in irrigated treatment on both dates. Adaxial and abaxial stomata differed in their response to water stress. Adaxial stomatal conductance started declining during early morning hours, however, abaxial conductance firstly increased up to 09.00 then decreased and increased again in the afternoon except in irrigated crop of cv. UPAS-120 on 28th October, where conductance never increased after 09.00. The reduced rate of stomatal conductance during day hours may be identified as one of the characteristics responsible for drought tolerance in pigeon pea.

The winter rape hypocotyls grown in darkness or in light were found to differ markedly both in the elongation rate and in the sensitivity to desiccation. Light arrested the elongation of hypocotyls and markedly increased their resistance to desiccation. It was found that the former effect was due to 2 factors: better avoidance of water stress and higher desiccation tolerance in the light-treated tissue. Comparison of WSD (waret saturation deficit) and water potential developed by 5 day-old hypocotyls subjected to different degrees of desiccation indicates that better water relations in the light-grown tissues might be due to the decreased elasticity of the cell walls(e.g. - to the higher turgor pressure of the cell).

In comparison with primary leaves of French bean plants grown under a photon flux density of 100 μeinstein m-2 s-1 (LP), leaves grown under 400 μeinstein m-2 s-1 (HP) were thicker (contained 82 to 104% more dry matter per blade area), had 44 to 48% higher stomatal frequency, 18 to 26% more chlorophyll (a + b) per leaf area unit and 31 to 42% less chlorophyll (a + b) per dry matter unit, 41% higher photosynthetic and 38% higher transpiration rates at light saturation, 33% higher stomatal conductance and 40% higher Photosystem 2 (H2O → K3[Fe(CN)6]) activity of isolated chloroplasts. There were no significant differences in the Photosystem 1 (TMPD/Ascorbate → MV) activity per unit amount of chlorophyll. Higher growth irradiance increased the ratio of frequencies of stomata in the upper/lower epidermes.

During high altitude acclimatization soluble sugar contents were highest in temperateArtemisia species when grown at 550 m and tropicalArtemisia species at 3600 m in the active growth phase. During the senescence in all the species the soluble sugar contents were low in plants grown at 3600 m.
The starch content was low in the leaves of the tropical and sub-temperate species when grown in the alpine zone but in the temperate species a significantly higher amount of starch was observed at 3600 m altitude.
The amount of lignin acids was lower in the tropical and sub-temperate species but higher in the temperate species when these were grown at a higher altitude.

The effect of silymarin complex on various types of expiants differing in their nutrition requirements was investigated. The growth of tumorous periwinkle (Catharanthus roseus [L.] G. Don) callus tissue was still identical with the control tissue at the silymarin concentration of 35 mg in 1000 ml of the nutrient medium. However, this silymarin concentration totally inhibited the growth of habituated periwinkle callus tissue; in the presence of 10 mg of silymarin, the growth of this tissue was similar to that of the corresponding tissue grown without silymarin. The growth of tobacco callus tissue (D-strain) requiring for its growth kinetin was reduced by 46.2% at the concentration 10 mg of silymarin in 1000 ml of nutrient medium, but its dry weight was increased by 21% in comparison with the control. Silymarin was most effective on the growth of callus derived from tobacco (Nicotiana glauca Grah:) stem pieces; callogenesis was observed in control tissue in 89.5% cases while in the presence of silymarin (10 mg) only in 48.6%. The primary callus growth was strongly inhibited, too (by 89.9%). The organogenesis onset was never observed on tobacco stem pieces cultured on a nutrient medium with kinetin and IAA in the presence of silymarin. When all types of expiants were transferred from the medium with silymarin on control medium, normal growth appeared very soon and the differences between the experimental and control expiants were smoothed out during two months. These results indicate that the observed changes might be due to the blocking of membrane system permeability leading to an insufficient supply of cells with nutrients and growth substances.

A new undescribed yellows-type disease ofGypsophila paniculata L. was found. Since a stunted growth is the predominant symptom the disease has been termed stunting. Electron micrographs of ultrathin sections revealed numerous mycoplasma-like organisms in diseased phloem tissues. Attempts to maintain the diseasedGypsophila plants for further investigation of this disease failed for the present in spite of all applied modifications in nutrient media.

This paper deals with the verification of a test of crop seedlings for the determination of the salt tolerance. There is a typical concentration of NaCl in the culture medium above which an enhancement of the free proline content is induced (critical point, critical concentration). The determination of this critical concentration in 19 cultivars of crop plants has proved that plants grown in aride areas (i.e. Hordeum, Triticum durum) have a critical concentration that is by about 50 to 80 mmol l^-1 of NaCl higher than that of plants grown in more humid regions (i.e. Triticum aestivum). The critical concentration is not influenced by pH changes of the external solution. Calcium application leads to an enhancement of tolerance. The different increases of growth and fresh mass of salt sensitive and salt tolerant plants selected by this test system proved the aptitude of the critical concentration in culture medium for proline augmentation as a test parameter.

It has been shown that intensive elongation of wheat coleoptile sections is correlated with indoleacetic acid-1-¹⁴C metabolism. In tissues actively growing the disappearance of indoleacetic acid-1-¹⁴C and formation of conjugates and metabolites (indoleacetamide, indoleacetyl-β-D-glucose, indoleacetyl aspartic acid) is twice as high as in sections where growth has been stopped by physical constraint (plaster) or in tissue which did not elongate by an unknown reason.

The analysis of growth and movements of seedling organs of kidney bean (Phaseolus vulgaris L.) provides a pattern of periodic phases of activity and relaxation. The existence of a central organ which would control the phase relationships, is not anticipated in the integrity of the plant. The cyclic activity of individual organs shows itself by growth associated with oscillation movements. One and the same organ may simultaneously accomplish oscillatory movements with a diurnal and ultradiurnal frequency. These rhythms originate during the organ development; the first pair of kidney bean leaves at first executes oscillation movements with a diurnal frequency and only after it is fully developed it exhibits a diurnal cycle with the photophil phase upwards and the scotophil downwards, the oscillations with an ultradiurnal oycle being maintained. The movements of the two leaves are synchronous, but there occur short sections with a desynchronous cycle. Simultaneously with these oscillations, in which the leaf petiole takes part, the adult leaf performs oscillatory movements perpendicular to the longitudinal leaf axis, the so-called side swings, controlled by periodical changes of the joint attaching the leaf blade. Their frequency is practically identical with that of the ultradiurnal cycle. Thus the periodic growth activity of the kidney bean results in growth oscillations passing in the diurnal cycle with a frequency of 0.043 rev.h^-1, their ascending and descending phases consisting of periodical ultradiurnal oscillations in cycles of 0.73-0.59 rev.h^-1. The epicotyl growth shows a similar pattern: into the basic diurnal nutation cycle with a frequency of 0.042 rev.h^-1 ultradiurnal oscillation cycles are incorporated having a similar frequency to that revealed in leaves (0.69-0.64 rev.h^-1). The diurnal oscillatory cycles belong to a system established on the basis of periodicity of day and night and other geophysical cycles. The ultradiurnal rhythmic oscillations are presumed to be an expression of the geocontrol system of root and shoot growth direction and orientation of the organ in space. The shape of their trajectories in bean leaves is contradictory to this; they are not spatial helices, as the kybernetic model would presuppose, but have a vertical, upwards and downwards course in one plane. Since these oscillatory movements with an ultradiurnal cycle cease after petiole excision from the stem and after shoot apex amputation, one may presume that they are coupled with the low-frequency oscillatory system of the epicotyl.