The time courses of the synthesis of diamine oxidase in pea plants grown for 14 days either in the light or in the dark are similar with the highest increase in activity occurring in the cotyledons and in the shoots during the first 6 to 8 days. Plants grown in the dark showed a 2- to 3-fold higher enzyme activity than plants grown in the light. Pea diamine oxidase could bein vivo efficiently inhibited by substrate analogues 1,4-diamino-2-butanone and 1,5-diamino-3-pentanone. The first compound inhibited proportionally to its concentration the growth of etiolated pea plants, but its instability makes an unequivocal interpretation of the results difficult. On the other hand, 1,5-diamino-3-pentanone a stable and more efficient diamine oxidase inhibitor depressed the growth of pea seedlings only at concentrations as high as 5 mM and 10 mM, at which the growth of cress seedlings not containing diamine oxidase was also strongly depressed. The results obtained indicate that tryptamine oxidation catalyzed by diamine oxidase is not involved in the main metabolic pathway leading from tryptophan to indoleacetate in pea plants.

Studying relationships between tobacco mosaic virus reproduction, anthocyanin biosynthesis and phosphorus content in cultivation medium, it was found thatMartin's (1958) finding of an indirect proportion between anthocyanin and virus synthesis is valid even under the complicated conditions of pathological anthocyanin formation induced by phosphorus deficiency. A decrease of anthocyanin biosynthesis with simultaneous stimulation of virus reproduction takes place at temperatures below 20°C. Increased anthocyanin biosynthesis accompanied with the inhibition of virus reproduction occurs at temperatures above 20°C. The obtained results suggest that enzyme systems and substrates participating in considerably increased anthocyanin biosynthesis induced by phosphorus deficiency, differ from those taking part in anthocyanin synthesis induced by virus infection.
The enhanced phosphorus content in the cultivation medium does not influence anthocyanin biosynthesis significantly. Nevertheless, a highly significant inhibition of tobacco mosaic virus reproduction takes place at temperatures above 20°C. This inhibition may be in correlation with some other metabolic systems affected probably by the enhanced phosphorus concentration in the nutrient medium.

Cauliflower plants in the juvenile phase treated on the leaf surface and at the apex with Morphactin solution (100 mg 1^-1) and this concentration failed to develop a curd and also to come to flowering. Instead of a curd the axis formed a conical or dome-shaped structure bearing 'nodal' rings. The number of rings increased with growth of the axis which either formed or did not form a small curd-like structure, which generally dried without flower formation.

The fungusLentinus tigrinus was cultivated in a synthetic medium. During vegetative growth of mycelium and differentiation of fruiting bodies samples serving for determination of endogenous growth regulators were collected. The material was extracted with methanol, separated by chromatography and the isolated fractions were tested. Substances of auxin type were assayed with coleoptile segments of oat plants, gibberellins by measuring the hypocotyl growth in the lettuce and cytokinins from the degree of chlorophyll decomposition in the leaf segments of barley. Very low content of auxins was found in all phases of growth and differentiation of the fungus. The content of gibberellin substances was relatively high during the whole life of the fungus. The highest content is found in the vegetative mycelium and in the differentiated fruiting body, especially in the cap; it decreases during the differentiation of fruiting bodies. The content of cytokinins is equally high and the pattern of its change resembles that of the gibberellins. Its maximum is reached in young vegetative mycelium, it decreases when fruiting bodies are formed and when they are growing. Minimum is reached in the differentiated stalk, where also the amount of inhibitions is the highest.
Experimental results show that during differentiation of fruiting bodies and their morphogenesis not only gibberellins and cytokinins are of importance, but also substances of an inhibitory character. A relatively high amounts of these substances was secreted into the cultivation medium. In a synthetic nutrient solution they may be easily demonstrated.

Using hydroponic cultures, the effect of high concentrations (10^-3 m) of 2-methyl-4-chlorophenoxyacetic acid (MCPA) in the root medium on the water balance of 8-9 week old plants ofPisum sativum L. and of 9-10 week-old plants ofSinapis alba L. was studied. The water balance was determined in the light and in the dark gravimetrically by measuring the intensity of water uptake and transpiration in plants cultivated by the method of root bridges according to Werner. MCPA present in the root medium in illuminated plants decreased rapidly the intensity of both the uptake and the loss components of the water balance. In permanent darkness, MCPA brought about an increase in the intensity of uptake of water and of transpiration. Simultaneous determination of water uptake and transpiration showed that the intensity of transpiration remained higher than the intensity of water uptake. This indicates that in the presence of MCPA in the root medium the relationship between the uptake and the loss components of water balance is not quantitatively equal, enboth in the light and in the dark. The existing disproportion results in the formation of a passive water balance of plants.

Beginning with the second inductive cycle the rate of nucleic acid (NA) synthesis in cotyledons and apical buds ofChenopodium rubrum is higher at the end of the dark period or 4h following transfer of the plants to light in induced plants than in non-induced ones. This is due to an increase in all NA fractions. The greatest difference between NA synthesis in induced and non-induced plants was observed at the end of the second (or sometimes third) inductivecycle. In the subsequent cycles the difference decreased or disappeared eventually. During photoperiodic induction NA synthesis shows a diurnal rhythm with a peak at the end of the dark and at the beginning of the light period. Rhythmicity of NA synthesis is endogenous. The period length of the endogenous oscillation is about 18 h. Interruption of the dark period by light causea amplitude of the first oscillation to be reduced and delays the appearance of the second peak. NA synthesis did not show rhythmicity in plants grown in continuous light. The significance of the observed phenomena for photoperiodic induction is being discussed.

The application of surface-active agents (SAA) - acrylate latexes (PVAE), synthetic fatty acids (SFA) and fatty alcohols (SFS), urea-formaldehyde resins (UF) and silicones (HS) - on leaves or into soil, induced an increase in photosynthetic rate, in the ratio of rates of photosynthesis and transpiration and in yields, with a simultaneous decrease in respiration rate. Energy dissipation into heat was minimal in treated plants.

Mutagenic activity of N-ethyl-N-nitrosourea (ENU) and of N-methyl-N'-nitro-N--nitrosoguanidine (MNG) in lentil was studied. The highest proportion of segregating progenies with chlorophyll mutants and chimeric plants was 34.8% from the total number of analysed offsprings, ENU being applied in this case in the concentration of 0.005% for 20 h at 18 to 19 °C. When MNG was applied in the concentration of 0.001 % for 10h at 22 to 23 °C the proportion was 5.1%. Progenies segregating two or more chlorophyll mutants originated with ENU only; their relative frequencies varied from 1.4% to 7.1%. The number of different types of mutants or of their combinations segregating at the same time in the same progeny was shown to be dependent with the two agent tested on the mutagenic activity of the concentration used. The most efficient concentration of ENU induced the total of 8 different mutants at the same time, together with a combination of two or three mutant types in the same progeny. With MNG no combination of chlorophyll mutants in the same progeny was ever found simultaneously. The greatest number of mutants corresponding to 1 progeny M₁ was 0.53 when ENU was applied; with MNG the maximum values were approximately ten times lower. The maximum number M₂ of chlorophyll mutants and chimeric plants was 3.58% with ENU and 0.23 with MNG.

Garex packystylis, native of Israël, has been compared in arid zones of Israël and in France under phytotronie conditions. Especially its drought resistance has been studied. Once root formation has stopped through drought action, the shoot apices situated on the rhizomes which are well protected by layers of dry scales, become active and form leaves above the ground when the plants are once again in favorable growth conditions. There is also reumption of the basal growth of leaves incompletely dessicated from the top.

The course of androgenesisin vitro was investigated with anther cultures of two chlorophyll mutants of Nicotiana tabacum. A different sensitivity to the hormonal composition of the medium was revealed between the cultures White Seedling and Sulfur; the stimulatory effect of kinetin on the frequency of androgenesis was observed only in White Seedling cultures. In addition to green plants, "aurea" (mutation Sulfur) or "albino" (mutation White Seedling) phenotypes also differentiated in both cultures. The possible causes of variability in the participation of green and mutant forms are discussed.

Fusarium solani (76%),Phyllosticta phaseolina (12%) andAspergillus flavus (10%) were isolated from bean(Phaseolus vulgaris) seeds showing lesions. Out of these the first two caused 30 per cent and 20 per cent seed rotting respectively after artificial seed inoculations. When inoculum was added into the soil before sowing the seed, 35 per cent and 10 per cent pre-emergence rot ocurred and there was 35 per cent and 15 per cent post-emergence blight when soil with healthy seedlings was inoculated withF. solani andP. phaseolina respectively.F. solani caused similar lesions on bean seeds when inoculated after an injury.F. oxysporum was isolated from the roots of dried bean plants showing necrosis.

Distribution of Cu and Fe from the cotyledons to the root and the epicotyl of Vicia faba L. was studied during the heterotrophic phase of development and growth in dark. During this phase there was no significant difference in the distribution of the quantity of Cu in the root and in the epicotyl. When the plants had changed to the autotrophic phase, the distribution of Fe was significantly higher in the epicotyl than in the root.
In roots both Cu and Fe were localized in the zone of root differentiation. The quantities of these elements in meristematic and elongation zones were about 15% and 25%, respectively. In regions of cell division and cell elongation of the root, the level of Cu was almost the same. On the contrary, the content of Fe in the zone of cell elongation was atout 3 times higher than in the meristematic zone.

The spread of mycoplasma causing potato witches' broom disease from infectious grafts of both tomato and tobacco plants intoNicotiana glauca Grah. plants is much slower than that into tomato plants. An earlier infection inN. glauca stock plants appears when infectiousN. glauca grafts are used. On the other hand, the process of infection proceeds very slowly when using infectious tomato grafts and in some cases the infection is not realized even after three months of graft symbiosis. The authors suppose that mycoplasma has a preference for tomato plants.

The nucleic acid (NA) fractions were analyzed in cotyledons and apical buds ofChenopodium rubrum plants by means of acrylamide electrophoresis at the end of the dark period of a different number of photoperiodic cycles or after transfer of the plants to light for 4 h subsequent to the termination of the dark period. The plants were labelled with³²P three hours prior to sampling. The uptake of³²P into the cotyledons was higher in light than in darkness in all cases, however, it was not in correlation with³²P incorporation into the NA fractions. After one dark period lasting 8 or 16 h NA synthesis in light did not increase in comparison with darkness. After two or more photoperiodic cycles NA synthesis was higher in light than in darkness irrespective of whether the dark period lasted 8 or 16 h. NA synthesis was distinctly highest after two inductive cycles lasting 16 h. In buds NA synthesis was slightly shifted in favour of ribosomal RNA as compared with cotyledons. In the cotyledons the increase in light was mainly duo to a raise of rRNA synthesis whereas in the buds synthesis of sRNA and DNA increased, as well.

The course of biological curves of accumulation of total (Y_biol), vegetative (Y_veg) and grain dry matter (Y_gr) in maize(Zea mays L.)was investigated in a field experiment. The different population densities from 27 777 to 121 418 plants per ha were tested in interaction with increasing fertilizer rates (NPK) ranging from zero to 780 kg of pure nutrients per ha. The grain yield (F_gr) plotted against the population density shows a parabolic trend with a maximum at densities from 64 000 to 79 000 plants per ha. An asymptotic trend was obtained for the curve of biological yield (F_biol) in relation to the population density. The optimum densities for Y_gr and F_biol were identical in the unfertilized control plot. At optimum and higher population levels the application of optimum rate of pure nutrients was 260 kg per ha. Leaf area index(L) was rising with the increasing stand density. Its value was also increased by increasing mineral nutrition but only at plant densities higher than 64 000 plants per ha. The proportion of Y_gr/ Y_biol showed an optimum atL value within 2.03 and 2.68. Its value declined with further increase of both, stand densities and levels of NPK. The optimumL estimated for Y_gr was within 2.65 and 3.87 and that for Y ol in the control variant was 2.65. Tn fertilized plots even the highestL values (5.17) did not influence neither the biological nor the vegetative dry matter yields. Relative photosynthetic potential for dry matter formation (RPP_gr) was decreasing with the increasing stand density.

In the present paper the oxidative and phosphorylative activity of mitochondria isolated from rye, wheat, barley and corn seedlings are compared. Mitochondria from the shoots as well as from the roots of rye, wheat and corn oxidized succinate and in the presence of ATP or ADP exhibited the respiratory control which reached the values mostly of about 2. In the presence of ATP or ADP the decrease of inorganic phosphorus was contemporarily remarcable. The P/O ratio reached the values mostly of about 0.8 up to 1.0. The presence of ATP effected in some cases more favorable the respiratory control as well as the P/O ratio in comparison with ADP. With regard to the fact that a trapping hexokinase system was not added, the presence of endogenous hexokinase in mitochondria of experimental plants is presumed. The barley mitochondria exhibited the respiratory control as well, but instead of the decrease in inorganic phosphorus content in reaction mixture, an increase took place. It was caused by the presence of active ATP-ase which was not effectively inhibited by present NaF.

The morphactin - chlorflurenol at 1, 5, 25, 125 and 625 μg/plant either caused total damage of the shoot apices or allowed a few inflorescences to develop with few or no flowers. The inflorescences arising in the lateral branches showed suppressed bracts and modified flowers. With time the treated plants recovered and showed a significant increase in the growth of laterals and the number of inflorescences. Thus morphactin can be used for prolonging the growth period and for obtaining more wholesome plants.

IAA, NAA and ethrel (1 × 10^-4M and 3 × 10^-4M) was applied to the plumula of Chenopodium plants at different time after the start of photoperiodic treatment and the flowering response was investigated. The inhibitory effect was found with all the applications during the first two days, whereas a stimulatory one on the third and fourth day. We assume this dual effect reflects the differences attained in developmental phase and in the degree of shoot apex differentiation.

The maximum of alcohol dehydrogenase (ADH) activity of germinating pea and broad-bean seeds sediments from 40 to 60% ammonium sulfate saturation, from lentil and kidney-bean seeds between 40 and 50%. This operation increased the specific activity of ADH preparations roughly tenfold. Chromatography on DEAE-eellulose and gel filtration increased the activity of the resulting preparation when compared with the initial preparation 178 times with pea, 334 times with broad-bean, 122 times with lentil and 77 times with kidney-bean. The ADHs resemble each other in coenzyme specificity: the reaction rate with NAD is one hundred times greater than with NADP. The substrate specificity is quite wide: besides ethanol, these enzymes oxidize 2-propene-l-ol (actually faster than ethanol), 2-butene-l-ol (at the rate of one half t h a t of ethanol) and butanol (even more slowly). In general, saturated alcohol analogues are oxidized more slowly than unsaturated ones. Methanol is a substrate for the enzym from pea only. The ADHs of the plants studied did not oxidize diols, sugar alcohols and cyclic alcohols. The enzyme from pea has the widest substrate specificity oxidizing isobutanol, phenylalcohol and mercaptoethanol. ADHs, which are widely encountered in plants, resemble each other to a certain degree - they have identical coenzymes, equal K_m values and equal values of the pH optimum, they differ in the purification process and in substrate specificity.

The presence of potassium humate (commercial sample of Humussäure Riedel-de Haën A. G., Seelze-Hannover) in distilled water led to an increase in the content of alanine, aspartic and glutamic acid in the overground parts of wheat plants as compared with the content of these substances in control plants grown in distilled water. In plants cultivated on nutrient solutions a higher level of alanine and glutamic acid and a considerably lower level of amides was found than in plants grown in distilled water and in water with humate. Generally the content of amino acids was higher in the overground parts than in the roots after a cultivation period of one week as well as of 14 day. In the overground parts of 1 days old plants the level of aspartic acid, asparagine and alanine was found to be higher and that of glutamine lower than in seven days old plants. In the roots of the examined plants a decrease of the amino acid content accurred almost in all cases after a cultivation period of 14 days as compared to one of 7 days.

Mature seeds ofTaxus baccata L. andTaxus baccata L.fastigiata Loudon contain embryos which are both immature and dormant. Embryo cultures were carried out in order to test the relative effciency of gibberellins (GA₃ and GA₄), chilling and leaching. The increase of germination percentages depends on the treatment applied and the tested variety. WithTaxus baccata, the germination of which is very difficult, a double treatment either leaching and gibberellins or leaching and chilling are necessary to obtain a high percentage of germination. Our results are compared with facts already known on mature dormant embryos of other plants.

Young seedlings ofZea mays L. andCucurbita pepo L. were grown in water culture with a layer of oil (linum or olive oil) or liquid paraffin. The seedlings transport oil and parafin into the top and in the young root.Cucurbita seedlings proved to be very sensitive and died within few days.Zea proved to be resistant. InZea this transport of oil was found to be related to the age of the seedlings and the zone of the root in contact with oil. The oil was localised in the cell walls of different tissues of root and top, in the intercellular spaces of cortex and pith and in the xylem vessels.

Our paper describes some morphological peculiarities ofMycoplasma bodies located in vascular bundles ofNicotiana glaucaGrah. and tomato infected with potato witches' broom disease. The influence of postfixation on the density of bodies and possible development of artifacts was studied in particular. It was found that bodies of adjoining cells may have a different shape. Also elementary bodies, approximately of uniform diameter, may occur in masses in close proximity to the cells containing "adult"Mycoplasma bodies. Deformed large bodies giving in a certain position the impression of "vacuolization" are evidently degenerated saucershaped forms. In addition toMycoplasma some other bodies with different inner structure were observed in the same cells.

Pea seeds were subjected to 1; 5 and 20 krad doses of⁶⁰Co γ-raýs. The irradiated seeds were planted in damp sand and in Petri vessels. After 10-daý vegetation at room temperature and under natural light conditions the content of the following components was determined in ýoung plants: free thiamine and thiamine pýrophosphate and drý substance.
It was found that 1 krad dose stimulates the growth of the plant and increases the crop of its green parts. The doses within the range of 1-5 krads do not affect the production of thiamine. The content of the latter, particularlý in its free form, increases markedlý for the dose of 20 krads. However, such doses hamper the vegetation.
In conclusion it seems that doses of the order of 1 krad lead to positive results in respect to the growth of the plants, however, neither thiamine biosýnthesis nor its phosphorýlation is stimulated under these conditions.

The analysis of diurnal oscillatory movements of tobacco leaves was used in the diagnosis of viral infection of plants. The oscillatory helices circumscribed by a growing leaf of a healthy plant were regular, but some deviations, particularly in the transition points, were recorded.
In order to make clear the cause of these irregularities of trajectory, the course of elongation of leaf petiole and blade in relation to localization and shift of zones of elongation during ontogenesis was analysed. The present analysis is similar to that described by the author's earlier experiments with pea roots. Oscillatory curves circumscribed by petiole, projected on a horizontal plane, were compared with curves circumscribed by the blade tip. The analysis of the leaves of different ages enabled us to study this process in dependence on growth rate. It was confirmed that oscillations are a result of elongation; the extent of oscillations is quantitatively dependent on the growth rate. An analysis of the zones of growth showed that in petiole the active meristems are localized near to its base while in the leaf lamina they move gradually during the ontogenesis from the apical to the basal part of the leaf blade. Active meristems of young rapidly growing leaves are localized approximately in the middle of the blade while those of old leaves were found in close proximity to the base of the lamina. The growth rate of petiole can be expressed in hundreds of mm per hour (4.8×10^-2 mm h^-1); half of this value was recorded for its apical part. The growth rate of leaf blade was found approximately ten times higher (3.2×10^-1 mm h^-1).
The oscillatory movements of growing leaf consists of two integrate components: of oscillations originating in the base of the petiole and of oscillations of leaf blade the centrum of which is localized in the basal third of the blade.
The arrangement of the experiments did not enable us to determine to what extent the phototropic response of leaf blade participates in leaf movements. The movements of leaves of an intact plant are evidently affected by rhythmic stem oscillations. Stem is an integral part of a system which participates in the transfer of information in plants.

No influence of IAA on the endogenous estrogen content in bean plants was stated. At the same time kinetin was found to increase and abscisic acid to decrease the amounts of estrogens.

To study the effect of high altitude cosmic radiation the seed material of 15 species ofAcanthaceae was subjected to 3 types of exposures in balloon flights at an altitude of 30 900 to 38 100 metres. Germination behaviour was recorded and cytological studies were made. In the material subjected to one exposure, no detectable cytological or morphological change could be recorded. Material subjected to two exposures showed a 1 1/2 to 2 fold increase in cellular dimensions. A fragmented chromosome was observed inRostellularia procumbens. Flowering inJusticia betonica was advanced by 3 weeks. Among the species subjected to 3 exposures, two species showed diminution in height, and entered into flowering earlier than the controls. A study of germination behaviour showed, in general, that the decrease in germination percentage was directly proportional to the amount of radiation. The results indicate that the treatment with cosmic radiation may be helpful in reducing the period between sowing and harvesting. Therefore, if similar experiments be conducted on crop plants, they might yiled interesting and important results from the agricultural point of view.

In pumpkin plants suffering from calcium deficiency growth of the root system is characteristically suppressed. A biochemical symptom of calcium deficiency is a decrease or even complete disappearance of activity of one of the isoperoxidases (isoperoxidaseD). In the present study the two characteristics were used to compare the effects of calcium deficiency and of IAA in the supraoptimal concentration of 10^-5 M. Peroxidases were separated by centrifugal fractionation: peroxidasesA andB were found in the sediment corresponding to the mitochondrial fraction, peroxidaseD in the supernatant. It was not possible, however, to obtain the sediment completely free of peroxidaseD. A negative correlation between the activity of isoperoxidaseD and the logarithm of concentration of IAA in nutritive solution was found and similarities in the effects of IAA in supraoptimal concentration and of calcium deficiency on the development of root system were demonstrated. Still, it would be difficult to imagine that the mechanism of the action of the two factors is the same. For this reason, a scheme of possible interactions was suggested with the aim to explain how similar changes in the content of isoperoxidases are brought about by the two factors. In this scheme, calcium is considered chiefly as a substance regulating membrane permeability.

Using regression analysis a proof of the relation between the electric capacitance and the root surface in maize, sunflower, oats and onion plants was given. This dependence is possible to exploit in the selection of plants (of the same population grown under the same conditions) for a well-developed root system.

Abscisic acid (ABA) (5 x 10^-4M and 5 x 10^-5M) and gibberellic acid (1 x 10^-4M) was applied to the plumula ofChenopodium plants with partly (one dark period) or completely (three dark periods) fulfilled photoperiodic requirements for flowering. Morphological and cytoogical criteria were used to investigate the time-course of the differentiation of the treated shoot apices. Both substances were ineffective in increasing the mitotic activity of the shoot apex at the suboptimal level of induction. The degree of branching was temporarily stimulated by ABA and GA treatment under these conditions. Moreover, GA caused the elongation of the shoot apex. With the completely induced plants ABA hastened flowering and the rise in branching was observed in all the treatment 48 h following the application of growth substances.