Relationship between roots and shoots ofPimpinella saxifraga L.,Petroselinum hortense Hoffm.,Lactuca sativa L., andBeta vulgaris subsp.esculenta (Salisbury) Gürke var.altissima Roessig was studied in irrigated and non-irrigated plants. It was found that the irrigation water did not influence distinctly the root-shoot ratio of the experimental plants. From the statical point of view, this relationship could be expressed by the following quantitative ratios for irrigated and non-irrigated plants: 3∶1 forPimpinella saxifraga L., 2∶1 forPetroselinum hortense Hoffm., 9∶1 forLactuca sativa L., and 1∶1 for beetroot. From the dynamic point of view it is possible to state that this ratio changes in the course of individual development. With plants cultivated for their aerial parts, it increased with age, while with plants cultivated for their roots, it decreased with age. The irrigation water produced much greater morphological changes (the shape and the surface area) in the root and shoot system of experimental plants.

The effect of different exposures to RTG radiation (100 r, 250 r, 500 r, 1000 r, 2500 r, 5000 r) on the changes of the permeability of the epidermal cells ofAllium cepa L., variety Všetaty, bulbs was studied during three vegetation periods. Bulbs from growing plants (followed from the development phase of bulb growth) and bulbs immediately after harvesting were used for the experiments.
It was demonstrated in our experiments by plasmolysis that the radiation-induced changes of cell permeability were irreversible. When plasmolytic agents of non-electrolyte character (1M sucrose, 1M glycerol, 1M urea) were used, the equilibrium state (total plasmolysis) was reached more rapidly with the irradiated bulbs than with the unirradiated controls. When electrolytes were used (0.5M KNO₃, 0,5M KBr), total plasmolysis occurred less rapidly with the irradiated objects than with the controls. These relationships were manifest during the whole ontogenesis ofAllium cepa L. An exposure to 100 r was sufficient in our experiments for causing the mentioned changes, proving a considerable sensitivity of the osmotic properties of the epidermal cells ofAllium cepa L. bulbs to ionizing RTG radiation.
Plasmolytic experiments after smaller exposures than 100 r of RTG-rays are in preparation.

In studying inhibitors and activators of enzymes it has often been found that inhibitors act as activators when in very low concentrations and that certain activators (in suitable concentrations) show inhibition. Similar results were obtained in the present work in studying urease from soya bean in the presence of lead acetate. Lead acetate is normally an inhibitor of urease. It was found, however, that in small concentrations of lead acetate increase in the activity of urease occurs. On prolonging the time of the reaction inhibition develops and still later increased enzymatic activity again occurs. The results were elaborated statistically and are discussed in relation to the use of "adaptation" of urease in unfavourable conditions in reaction mixtures by the action of lead acetate.

Während Assimilations- und Transpirationsmessungen die Durchlüftung den Pflanzenteile und die Reaktion der lebenden Zellen mit der sie umgebenden Luft nur gemeinsam widerspiegeln, lässt sich mit dem radioaktiven Edelgas⁸⁵Kr der Gaswechsel zwischen Aussenluft und Interzellularluft unabhängig vom Stoffwechsel und ohne künstliche Druckdifferenzen erfassen. Der Gassaustausch zwischen der Interzellularluft und der Aussenluft wird dabei durch die Austrittsgeschwindigkeit des vorher kurzfristig durch Diffusion oder Unterdruck eingeführten⁸⁵Kr aus dem Pflanzenteil charakterisiert.
Orientierende Versuche unter Freilandbedingungen an den benadelten Zweigen einiger Koniferen sowie Zweigstücken mit und ohne Rinde erbrachten Unterschiede in der Geschwindigkeit des Gaswechsels sowohl zwischen verschiedenen Pflanzen unter gleichen Bedingungen als auch bei der gleichen Pflanze unter verschiedenen Bedingungen.

Investigating weeds for viruses in ruderal localities of Greater Prague two forms of mosaic diseases inSisymbrium loeselii Jusl. were demonstrated (green and yellowish-green mosaic). Transmission tests carried out on differential host plants showed that the green mosaic is caused by cabbage black ringspot virus (CBRV) and the yellowish green by mixed infection of CBRV and tobacco mosaic virus (TMV).
TMV-isolate is characterized as an unusual necrotic strain; its capability to reproduce in cruciferous plant in nature is unique.
It was ascertained that green mosaic was commonly spread overSisymbrium plants in ruderal ***DIRECT SUPPORT *** A01GP029 00004 associations on Prague territory; epidemiological significance of this discovery is discussed.

The primary roots ofVicia faba seedlings were placed in a solution of 5-azacytidine and their further growth was observed after being replaced in running tap water. No inhibition of elongation occurred during the action of the 10^-5 M solution of 5-azacytidine for 24 hours, but during subsequent cultivation in water in the absence of inhibitor, further growth was blocked. This inhibition could be overcome by cytidine, uridine, sodium azide, 5-azidomethyluracil and simultaneously with the 5-azacytidine solution. Inhibition was accompanied by a high incidence of chromosome stickiness and to a less extent by an incidence of chromosome aberrations. The occurrence of stickiness and chromosome aberrations was prevented by adding excess cytidine to the 5-azacytidine solution.

In dieser Arbeit wurden allelopathische Eigenschaften von Roggen, Weizen, Gerste und Hafer studiert, die sich bei gegenseitigen Beziehungen dieser Getreidearten geltend machen können.
Als Beweis für die Wurzelbeeinflussung der angeführten Getreidearten wurde eine Methode verwendet, bei der die erwähnten Getreidearten in derselben Kultivierungserde wuchsen, und zwar teils unmittelbar nacheinander, teils in abgestuften Zeitintervallen nacheinander mit verschiedenlanger Lagerungszeit der Erde.
Die Versuchsergebnisse haben die Ansichten zahlreicher Verfasser bestätigt, die behaupten, dass die angegebenen Getreidearten allelopathish aktiv sind. Roggen, Weizen und Hafer beeinflussten signifikant das Wachstum der nachfolgenden Kulturen; dabei erwiesen die Ergebnisse nicht deutlich jene Beeinflussung, die durch das Erschöpfen der Nährstoffe durch die vorhergehende Pflanze bedingt worden wäre.
Die angewandte Methode einer nachfolgenden Kultivierung erwies sich geeignet als Beweis für die allelopathischen Eigenschaften der Pflanzen unter natürlichen Bodenbedingungen. Die erwähnte Methode lässt sich vorteilhaft insbesondere in jenen Fällen anwenden, bei denen der Unterschied im Habitus der oberirdischen Teile der Pflanzenarten das Studium des Charakters ihrer gegenseitigen Beziehungen bei gemeinsamem Wachstum unmöglich macht. Diese Methode könnte ebenfalls eine Anwendung in der landwirtschaftlichen Praxis finden, wenn eine geeignete Zeitfolge der Pflanzen bei der unmittelbare Reihenfolge auf demselben Standort ermittelt werden soll.

NaN₃-a respiratory inhibitor and anaerobic conditions (nitrogen) decrease the mutagenic activity of N-ethyl-N-nitrosourea and N-methyl-N-nitrosourea inArabidopsis thaliana. DNP-an uncoupling agent increases the effect of both nitrosoureas, but this may not be caused by the specific action of DNP.

The polymorphism of the dictyosomes in the root meristeme ofFagopyrum is connected with their various functions in secretory processes and cell differentiation. The dictyosomes containing vesicular dilatations of the cisternae, which in this object occur more frequently than in others, probably participate in a similar way as the Golgi apparatus of the animal cell in the formation of lysozomes, in the formation of elements belonging to the group of dense bodies analogical lysozomes. These bodies are present in large numbers in the cytoplasm of cells, containing dictyosomes with vesicular dilatations. The other forms of the dictyosomes reveal indications of their participation in the production of the carbohydrate material of the cell walls, like most dictyosomes of other plant objects. However, no fusion of the Golgi vesicles with the plasmalemma was observed. According to their morphological appearance the typical forms of dictyosomes were classified on the basis of their relationship to secretory processes. Simultaneously the morphology and function of the Golgi apparatus was compared in the animal and plant cell. Several morphological varieties of the dictyosomes of plant cells, observed after the action of pathogenic factors and the effect of the fixation procedures, were also noticed in small quantities in the cells of the investigated objects.

Plants of two varieties of winter wheat-Besostoya 1 and Etoile de Choisie- were raised in the field. The same number of selected plants from each variety were frozen once in a refrigerator at a temperature of -15°C for 24 hrs. After freezing, the plants were gradually thawed and returned to the field. Early in the spring, test and control plants were treated with one of following diluted solutions: vitamin B₁, vitamin B₆, indolyl-3-acetic acid and adenine (the four solutions at a concentration of 0.01% and 5% urea solution in water) by immersion for 15 hrs. at a temperature of 18-20°C. The plants were measured in the spring and in the summer, the yield being determined after ripening.
It was found that all substances used helped to diminish the deleterious consequences of overwintering and to raise the yield of the plants. Vitamin B₆ exerted the strongest influence. Vitamin B₆ treated plants produced higher or slightly lower yields than those of the non-frozen control. Plants treated with vitamin B₁ gave yields close to, but in most cases lower than those of the non-frozen control.
The yields of plants treated with solutions of the remaining substances were appreciably lower than those of the non-frozen controls.
Plants of the more winter-hardy variety Besostoya 1 recovered relatively more easily under the effect of the substances used than the plants of the less winter-hardy variety Etoile de Choise.

The authors investigated the transport and localization of radioactive phosphorus in ownroot and grafted fruit trees. Radioactive phosphate was usually applied to conductive tissues of a thinner root (about 5-8 mm. in diameter). By periodic measurement of the radioactivity of leaves, the localization of radioactive phosphorus was determined in all top branches, and after 2-2.5 months in the four opposite sectors of the root system.
The experimental trees were grafted fruiting apple trees from 6 to 8 year-old (24 trees), own-root 5-6-year-old apple-trees (20 trees), own-root 4-6-year-old plum-trees (4 trees) and grafted 4-6year-old apricot-trees (4 trees). By applying radioactive phosphorus directly to the conductive tissue of roots a high radioactivity of some top branches was achieved, which made it possible to examine the localization of radioactive phosphorus in the tree-top and in tree roots two to three months after application.
As with separated nutrition (Belavin 1958), radioactive phosphorus injected into a thinner root is transported to most top branches, but most of it is localized only in some of them. After a two-month exposure, no marked equilibration of phosphorus concentration is observed to take place among the principal top branches.
It was demonstrated by measuring the radioactivity of 4 opposite sectors of the root system of grafted trees (16 apple and 4 apricot trees) that two months after exposure radioactive phosphorus can also be found in the roots of the sector opposite to that where radioactive phosphorus had been applied.
It was found by autoradiography that radioactive phosphorus is transported by a definite part of trunk xylem. A small portion, however, is transported horizontally through the trunk. No significant difference was found between own-root (no seedlings) and grafted trees with respect to the transport and localization of radioactive phosphorus. After a certain time the tree distributes the radioactive phosphorus throughout the organism, but the half-time of³²P does not permit of tracing its transport from the root system to the entire top during the subsequent vegetation season.

The "injection method" is recommended for maintaining a constant soil moisture at values lower than maximum capillary capacity in pot experiments. The appropriate amount of water is injected into the soil by means of a puncture needle connected with a syringe. The reliability of the above method in relation to the uniformity of the vertical and horizontal distribution of soil moisture was tested in pot experiments with maize. The fortuity of the changes in the soil moisture distribution within the scope of the given variability restricts the "growth of roots towards the water".

A very low, for the most part unmeasurable glutamic-aspartio transminase activity and a very high glutamic-alanine transaminase activity was found in the overground parts and roots of young wheat plants. The roots had a higher glutamic-alanine transaminase activity than the overground parts in the first and second leaf stage.
Plants cultivated in Knop's nutrient solution (variant with humate and without) showed a higher glutamic-alanine transaminase activity than poorly growing plants, cultivated in distilled water (with humate and without). In plants cultivated in nutrient solutions, transaminase activity increased with the age of the wheat plants.
As in the previous experiments, the effect of humate was only significant, in the roots of plants cultivated in distilled water with humate, where transamination activity was greater than in the control without humate. The roots of this variant with a stimulatory growth effect showed a large accumulation of free sugars in the previous experiments.
The connection between these effects of humate on the roots of young winter wheat plants is discussed.

A study was made of the effect of substituting a short day for vernalization as a varietal characteristic of winter wheat. Varieties representing certain ecotypes were vernalized for different lengths of time and it was studied how a short day can replace or accelerate vernalization. At the same time data were obtained on the effect of a short day on individual criteria of growth. The results showed that there are ecotypes in which a short day does not replace vernalization (the varieties San Pastora and other Italian varietis). In this case growth inhibition did not occur either. Otherwise it usually accompanies the substituting affect of a short day. This finding permits the interpretation of varietal differences observed in association with short day growth inhibition and changes in carbohydrate metabolism conditioned by it. Growth inhibition produced by a short day is a general reaction which is not only associated with vernalization. The author found varieties (Chlumecká 12) in which growth was inhibited by short day without accelerated development occuring (alternative types).

The seeds contain such a high percentage of phosphoric acid that it interferes with the obtaining of correct results in analysis. Its prior removal from the solution of ash is therefore necessary. A new method is suggested for the entire analysis which is a combination of percolation through an ionexchanger column and colorimetric and gravimetric determination.
The oxide values and the average content of ash per 100 g. dry weight of seeds ascertained by analysis were used to calculate the weight of each determined element per 100 g. of dried substance.
The analysis showed that traces of tin are present in the ash of the seeds tested.
Under the given conditions each species maintains its characteristic way of storing ash constituents in the seeds and this is not obviously affected by the affinity of the plants or the influence of the soil.

The barley variety "Browarny P.Z.H.R." was grown in pots. Experiments on the course of development were conducted for two years. The increase in the dry weight of roots, leaves, stems and grain was recorded. The assimilation area of the plants was measured periodically and the rate of respiration in detached leaves was determined. Photographic records were kept of growing point and ear development. The dynamics of growth and development were studied during the whole vegetation period. The present results are similar to those previously obtained for spring wheat. The short period of leaf activity is the chief factor limiting barley growth.

In der Arbeit wird eine Möglichkeit der Kombination von Humusstoffen mit mineralischen Nährstoffen und Substanzen mit fungiziden Eigenschaften beim Bespritzen von Pflanzen geprüft. Es wurde die fungizide Wirkung der Präparate Heryl, Novozir N, Sulka und Kuprikol, die mit Humusstoffen kombiniert worden sind, an Sclerotinia fructicola (WINT.) REHM., Alternaria brassicae (BERK.) SACC. und Erysiphe graminis var. tritici MARCHAL getestet. Es zeigte sich, dass Humusstoffe die Wirksamkeit der benutzten fungiziden Stoffe nicht herabsetzen. Beim Testen der Wirksamkeit von Novozir N von 0.5 bis 0.03% ist festgestellt worden, dass eine Zugabe von Humusstoffen die fungizide Wirkung des Präparates bis um 12% erhöht.
Weizen, der im Gewächshaus in Wasserkultur gezogen wurde und künstlich mit Erysiphe graminis var. tritici MARCHAL infiziert worden war, wurde während der Kultivierung wöchentlich mit einer kombinierten Lösung gespritzt, die Humusstoffe, Mineral-Nährstoffe, und Novozir N enthielt. Die Ergebnisse zeigen zweifache Wirksamkeit solcher kombinierter Lösungen: eine stimulierende Wirksamkeit der Huminsäuren mit der Mineralstofflösung auf das Wachstum des Weizens und eine fungizide Wirkung auf den parasitischen Pilz. Am allerwirksamsten erwiesen sich eine Doppelkombination von Novozir N mit Humusstoffen und von Novozir N mit Mineral-Nährstoffen. Bei Verwendung aller Kombinationen mit Novozir N konnte die Infektion der Blätter unterdrückt werden, während sie bei anderen Varianten bedeutend fortgeschritten war. Das Wurzelsystem reagierte empf indlich auf das Bespritzen der Weizenblättter.

Zwanzig neu synthetisierte Derivate der Phenoxyessigsäure VII-XXVI, die in der vorgehenden Arbeit (Makovcová, Vaculík 1963) bereits beschrieben worden sind, wurden mittels empfindlicherer Teste bei einer Konzentration von 10^-10 nochmals überprüft. Es wurde der Kressenwurzeltest und derTurfitt-Test mitSacharomyces cerevisiae benützt. Im Vergleich zur Wirkung von neun bekannten Wuchsstoffen Ia-VI unterschiedlicher Wirkungsweise zeigten die geprüften Substanzen weder eine Wirkung auf das Längenwachstum, noch auf die Zellteilung. Bei diesen Untersuchungen zeigte sich, dass die chemische Struktur selbst nicht immer massgebend für die Wirkungsweise ist. Bei den Substanzen, die von uns geprüft wurden, zeigte sich die Art und Zahl der Substituenten im aromatischen Kern für sehr wichtig. Die Resultate dieser Arbeit beweisen, dass der sonst sehr empfindlicheTurfitt-Test eine unge-eignete Methode zur Ermittlung der Wirkung von Wuchsstoffen des Typus 3-Indolylessigsäure (IIa) ist.

Im Rahmen des Versuches wurde der Einfluss des Alters der männlichen und weiblichen (maximal fünf Tage alten) Blüten auf das Geschlechtsverhältnis der Nachkommensehaft beiMelandrium album Garcke untersucht.
Es konnte festgestellt werden, dass der Prozentsatz an weibliche Pflanzen in der Nachkommenschaft zwei Tage alter, bestäubter weiblicher Blüten nachweisbar erhöht schien.
In der Nachkommenschaft bestäubter weiblicher Blüten, die älter als zwei Tage waren, äusserte sich im Auftreten weiblicher Individuen eine absinkende Tendenz.
Das Alter der männlichen Blüten hatte keinerlei Einfluss auf das Geschlechtsverhältnis der Nachkommenschaft.

5-Bromo-2'-deoxyuridine-2-¹⁴C was prepared from 5-bromouracil-2-¹⁴C and 2'-de-oxyguanosine using trans-N-deoxyribosylase fromLactobacillus helveticus and incorporated into DNA ofAllium cepa roots. After isolating the DNA and hydrolyzing it enzymatically to deoxynucleoside-5'-phosphates a radioactive nucleotide was detected which yielded 5-bromo-2'-deoxyuridine-2-¹⁴C on enzymatic dephosphorylation. The incorporation of 5-iodo-2'-deoxy-uridine-2-¹⁴C was followed only by microautoradiography.

Attempts to elucidate the physiological basis of cold-resistance during germination led to the investigation of the germination of seeds at low temperature, the effect of pathogenic and parasitic microorganisms being excluded.
At the various experimental temperatures (4°, 6°, 8°, 10° and 14°C) it was found that seed samples of different varieties of maize respond to conditions close to the temperature minimum for germination in three quantitatively different ways. Firstly, caryopses germinate considerably later than at higher temperatures, secondly, the kernels will not germinate even after a prolonged period, without losing their viability and, thirdly, in some of the caryopses the embryos perish.
The lower the temperature used the greater the inhibition of germination and the higher the mortality of the embryos. The increase in mortality with decreasing temperature indicates that the mortality is primarily due to the actual effect of the low temperature. Samples of seeds displayed quantitative difference in the above mentioned response.
Only when fungicide-treated seed material was used for the cold-resistance experiments was a significant relationship found to exist between this property and the general germinating capacity or mortality at the same low temperature.

In der Arbeit ist der Entgiftungseffekt von Humussäuren und dessen näheres Studium beschrieben. Die Blätter von Wasserpest (Anacharis canadensis [MICHX.] PLANCH.) sterben in der aus gemeiner Quecke (ropyron repens [L.] P. BEAUV.) gewonnenen Agropyrenlösung nach einer Zeit ab, welche von der Konzentration dieses Giftes abhängig ist. Durch Zugabe von einigen Humusfraktionen wird diese Zeit je nach der Konzentration dieser Stoffe mehr oder weniger verlängert. Ein Versuch mit Fulvosäuren zeigte, dass die Schutzwirkung dieser Fraktion auch dann zur Geltung kommt, wenn die Wasserpestblätter vorläufig in ihrer Lösung adaptiert und erst dann der nachträglichen Wirkung der Agropyrenlösung unterworfen werden. Man kann also die Schutzwirkung der Fulvosäuren nicht bloss auf die chemische oder physikalisch-chemische ausserhalb der Zelle durchlaufende Herabsetzung der biologischen Aktivität Agropyrens zurückführen. Sie ist ausserdem auch durch eine von Fulvosäuren hervorgerufene Erhöhung der biologichen Resistenz der Zelle zu erklären.

Wenn sich polyploide Zellstrange oder Sektoren an der Peripherie der Wurzelspitze befinden, so können Initialen, durch deren Teilung sie entstanden sind, ihre weitere Teilung einstellen, und die polyploiden Zellenstränge werden durch Verschleimung der Zellmembran abgetrennt. Es ist ein Chorisevorgang, analog der Abschälung der lateralen Haubenschichten. Nur werden in mixoploiden Wurzelspitzen polyploide Zellstränge abgetrennt, die allerdinga auch vereinzelte diploide Zellstränge enthalten können. Der Vorgang kann zur Diploidisierung der Wurzelspitze wesentlich beitragen. Seltener kann eine Wurzelspitze, wenn sie eine starke Majorität von polyploiden Zellen - insbesondere im Plerom - enthält, die peripheren diploiden Initialen aus der weiteren Teilung ausscheiden, wodurch sie polyploid werden kann. Auch solche Chorisevorgänge beweisen, dass die polyploiden Zellen im Verbande von diploiden Zellen als fremde Elemente - wahrscheinlich stofflich - wirken können.

The preparation of MCPA had no formative effect on the shoot apex although it affected the development of lateral buds formed at the sides. As soon as the compound ceased to act the development of the spike continued normally. The formative effect of MCPA is displayed in the structure of the ear by a partial or complete reduction of its internodes. The inhibitory action of the preparation is sometimes reflected in a blockade of the formation of lateral shoots in a part of one or both orthostichs, or else the lateral bud is initiated but does not continue to develop and thus a branchless node is produced. Occasionally, on the contrary, the preparation has a stimulating effect; segments of the lateral stem of the first order are elongated and develop similarly to the main stem which brings about the so-called "branching" of the spike frequently imitating dichotomy. Rich branching occurs on stimulating several lateral stems. A frequently met morphosis is a locally disturbed distichy, and a decussation of orthostichs or their rotating by an angle of less than 90° and a disturbance in the normal course of mesotonic branching. The formation of apparent or true flower whorls formed in consequence to a reduction of the ear internodes or a disturbance of distichy is usually connected with the reduction of individual inflorescence parts, with an increase in the number of inflorescence parts, with their partial or complete cohesion and with a change of their position.

The localization of acid phosphatase was studied by Gomori's newer technique and by azo-coupling methods (α-naphthyl phosphate + fast red ITR or fast garnet GBC; AS or AS D phosphate + fast blue B or fast red violet LB) in the root tips ofVicia faba L. on paraffin sections (fixation with Wolman's acidified ethanol) and on frozen sections (fixation with Baker's calcium formol). Analogous results were obtained on the material treated in various ways and using different methods. In the broad bean, the reaction is most intense in the cap. In the meristematic zone, the primary core is more intensely stained than the ground parenchyma of the central cylinder. The phloem and xylem poles are usually strongly positive. Using both types of methods on Wolman fixed paraffin embedded material, essentially the same localization of acid phosphatase was found in the root tips ofRicinus communis L.,Lupinus luteus L.,Sinapis alba L.,Allium cepa L. as in the broad bean. InZea mays L. the rhizodermis and the hypodermic layers of the primary core were found to be most active. On sections of Wolman fixed paraffin embedded broad bean the most intense reaction was observed at pH 4.2-4.8. In the same material, both the azo-coupling and the Gomori reaction is inhibited by 10⁼² M NaF, but 10^-2 M tartaric acid only inhibits the Gomori reaction.

A study was made of the influence of accentuators (phenol, aniline) and pH on the stainability of vegetable tissue (roots ofAllium cepa L.) with light green and methylene blue with reference to the theory of the electrostatic basis of staining. - The results obtained on the whole confirmPischinger's theory of the electrostatic basis of staining for light green only, but with methylene blue the situation was found to be much more complicated. Only the alkalization of a watery solution of methylene blue increases its staining ability, whereas the accentuators markedly disturb staining. Prischinge's theory is thus not of general validity, but applies only to one factor of this complicated process. Electrostatic influences acting on staining ability are not so important as other factors in this complicated process in some dyes.