The tapetal layer of anthers inCapsicum annuum L. is differentiated from the archesporial complex during the early development stage of the anthers. Further development of tapetum proceeds according to the scheme of the cellular polynuclear type. The high rate of polyploidy is characteristic of the whole layer (from 4n to 8n). Cytokinesis does not follow karyokinesis which conditions the inception of two or three-nuclear cells. The majority of the mononuclear cells show the typical plant endomitosis without the chromosome spiralization, accompanied by the structural nuclear change-over. In other cells chromosome spiralization in the prophase and, after passing through the metaphase, restitution of the cell nuclei were observed. The tapetum development has been studied in 12 cultivars of sweet pepper which did not differ in the course of the karyological processes. The subtle differences during the temporal course of degeneration of the whole layer in the postmeiotic period of development were observed.

The 3-(3-indolyl)-aorylic acid previously found in ether or ethylaoetate extracts of lentil seedlings is proved to be formed during extraction from an indolic precursor.

The importance of various correlative influences on growth and vegetative or floral development of cotyledonary buds inScrofularia argutaSol. is shown. The terminal bud, on the one hand, inhibits growth of cotyledonary buds and, on the other hand, induces their early flowering. The cotyledon stimulates growth of its axillary bud, but has no action on its floral development. Leaves above the cotyledonary node have the same effect as the cotyledon. Finally, roots stimulate vegetative growth of cotyledonary buds and suppress floral expression, but only when apical dominance has been removed at an early stage of development.

The metabolism of D-and L-tryptophan-3-¹⁴C (Try-3-¹⁴C) was studied and compared for three different plant species, cabbage, maize and pea. Apical segments of the seedlings were incubated for 6 hours in solutions of L- or D-Try-3-¹⁴C (1.5 μc/ml) with the addition of chloramphenicol (10^-4g/ml) and then allowed to stand for another 20 hours in moist chambers. The methanolic extract of the tissues was analyzed radiochromatographically and by paper electrophoresis in combination with biological tests. Chloramphenicol in a concentration of 10^-4 g/ml had little influence on the growth of the segments, though the antibiotic slightly decreased the uptake of L-Try, it did not prevent the formation of IAA from L-Try. In the segments of cabbage the following metabolites were formed from L-Try-3-¹⁴C (accounting for 52% of the activity of the chromatographically separated extract): glucobrassicin (26.0%), neoglucobrassicin (3.6%), a spot corresponding according to its Rf to 3-indolylacetamide (IAAmide-10.9%), β-glucoside of 3-indolylacetic acid (IAGluc-3.3%) and traces of 3-indolylacetonitrile (IAN), IAA and indole-3-carboxylic acid (total 5%). In maize segments L-Try-3-¹⁴C (53.0%) was transformed to several unidentified hydrophilic substances, one of them possessing auxin activity (total amount 6.9%), IAGlue (9.3%) accompanied by a small amount of tryptamine, a spot corresponding according to its Rf to IAAmide (16.5%), IAA and another unidentified hydrophobic substance (4.1%). In pea segments L-Try-3-¹⁴C (66.7%) gave a zone corresponding according to its Rf to IAAmide (20.0%), a substance similar to IAGluc (10.5%) and also hydrophobic substances (3.1%) containing traces of IAA, which could be demonstrated only by bioassay.
D-Try is metabolised in the three plants by the virtually exclusive formation of malonyltryptophan.

Activities of five enzymes were followed in electrophoreograms of extracts from three growth zones of broad bean root. With ascorbate oxidase (L-ascorbate: oxygen oxidoreductase, E.C. 1.10.3.3) one new fraction was found in the electrophoreograms of extracts from the maturation zone, electrophoreograms of α-glucan phosphorylase (α-l,4-glucan: orthophosphate glucosyltransferase, E.C. 2.4.1.1), amylase (α-l,4-glucan 4-glucanohydrolase, E.C. 3.2.1.1), sucrose glucosyltransferase (disaccharide glucosyltransferase, E.C. 2.4.1.7) and leucine aminopeptidase (L-leucyl-peptide hydrolase, E.C. 3.4.1.1) were identical for all three investigated growth zones. Ascorbate oxidase activity occurred in the same regions of electrophoreograms as peroxidase activity.

The author describes the testing method for clonal selections from the original strainScenedesmus quadricaudaGreifswald/15 in biomass production. This method served for testing the clones in greater series. It was applied to clonal cultures selected on a solid medium after treatment of the coenobia with UV-light before their inoculation. The production characteristic of the clones was expressed by the temperature dependence of the constant μ from Simmer's growth equation in the last step of the testing process used. Some significant differences of this kind were found among the evaluated clonal cultures. This way of characterization facilitates a more detailed evaluation of clones in comparison with values obtained by an oneshot testing method under standard conditions.

Various methods for extracting nucleic acids from pollen were tested to find a suitable procedure for obtaining a pure preparation of nucleic acids uncontaminated by polysaccharides and polyphosphates without the use of ion exchangers. Extraction was carried out with perchloric acid, potassium hydroxide, ribonuclease and deoxyribonuclease, sodium tetraborate, and combinations of these. In all fractions, residues of precipitates and residues of extracted pollen matter, the quantity of RNA, DNA, proteins and concomitants,i.e. Polysaccharides and polyphosphates, was determined. The purity of preparations was checked by means of UV-spectra. The criterion of nucleic acid purity was agreement between the nucleic acid amounts calculated on the basis of measurement of absorption in UV-region, orcinol reaction and content of phosphorus. It was found that in our material only a few methods would be applicable and with great limitation, because many polysaccharides and polyphosphates appeared in nucleic acid fractions.

Determination of bark contraction due to tapping made simultaneously at different positions on the trunk ofHevea trees (young PR 107, S/2 ↓) provided information about the flow area and the speed of contration spreading.
The relation between truck contraction at the given distance from the cut and the amount of latex tapped was experessed in mathematical terms. A quantitative relation was also established between the yields of latex and the linear dimension of flow areas in longitudinal direction below the middle of tapping cut.
From the contraction curves it is deduced that the lateral flow of latex becomes relatively more important with increasing yields.

The authors succeeded in demonstrating accumulation of tyrosine and p-coumaric acid in three day-old roots of maize (Zea mays L.) fed with L-phenylalanine and cinnamic acid. Phenylpyruvic acid applied under the same conditions gave rise to phenylalanine, indicating the presence of the corresponding transferase activity. Even simultaneous application of inhibitors of transaminase activity-hydroxylamine and isonicotinic acid hydrazide-did not result in the formation of p-hydroxyphenylpyruvic acid.

Stomatal frequency in leaves of plants of Iris hollandica, cultivated under four light intensities, about 12%, 37%, 75% and 100% of natural daylight, was studied. The stomatal frequency decreases with lower light intensities. The gradients of stomatal frequency of successive leaves show an increase up to the third or fourth leaf with a subsequent decrease of values up to the highest leaf. The total number of stomata per leaf is not constant; differences exist in successive leaves of a shoot as well as among the leaves of plants growing under various light intensities. The character of gradients was changed at lower light intensities. The largest reaction to the light intensity appeared in leaves with higher stomatal frequency. The gradients in individual leaves depend on the insertion of the leaf. Both the shape and the slope of these gradients are influenced by the light intensity.

A study has been made of the level of naturally-occurring growth substances and inhibitors in acid-soluble fraction of peach leaves and shoots using paper chromatography and bioassay methods.
The content of substances which stimulate growth ofAvena coleoptile sections calculated on a fresh weight basis can be expressed by a one-peak curve with a maximum at 10 a.m. The shoots were higher in growth substances than leaves in all periods of time examined. The extract contained two substances which significantly stimulated the growth of coleoptile (accelerator-2 and-3). High inhibition was found in the area of inhibitor-β and to a lesser extent in the area of inhibitor-α. The changes in the concentration of inhibitors were different in leaves and shoots.

Vicia faba seeds (cv. Giza 1) were planted in the Inshas gamma radiation field where they were chronically irradiated during the whole life of the plant. The percentage of the induced abnormal P.M.Cs, as well as the frequency of abnormal P.M.Cs in the different meiotic stages were proportional with the given doses. The main types of chromosome aberrations were anaphase and telophase bridges, fragmentation and lagging chromosomes. The nearest plants to the source showed an inhibition of shoot growth, flower and seed sterility and irregular branching. At the dosage levels used irradiation had no effect on pollen fertility.
Seeds of the 1st filial generation were used for both mitotic and meiotic studies. The percentage of the mitotic abnormalities was proportional with the doses. The most dominant type of anomaly was the presence of micronuclei in the different stages of mitosis and in the resting cells. Irradiation affected also other types of anomaliese.g. lagging chromosomes, fragments, bridges...etc.
Meiosis, and pollen fertility (2nd generation) were normal.

The dynamics of the uptake by barley plants of trimer phosphonitrile-amide [PN(NH₂)₂]₃ labelled with³²P was studied. It was shown experimentally that the covalent compound [PN(NH₂)₂]₃ enters the plants more rapidly than (NH₄)₂HPO₄. Hence it was concluded that the mechanisms of the transport of [PN(NH₂)₂]₃ and (NH₄)₂HPO₄ into the cells, across the cell membranes, are different.

Phosphorus-nitrogen compounds characterized by the direct P-N bond, represented by trimeric and tetrameric phosphorus nitridoamide-[PN(NH₂)₂]_3-4, phosphorus oxytriamide-PO(NH₂)₃ and ammonium diamidophosphate-NH₄PO₂(NH₂)₂, were applied as fertilizers in a vessel experiment with barley and their agrochemical effectiveness was compared with that of ammonium phosphate-(NH₄)₂HPO₄. The results obtained indicate that the above compounds are of nutritive value for plants.

The present paper deals with the possibility of using growth regulators for the physiological emasculation of rye flowers and utilizes our knowledge of the higher sensibility of stamens to the auxin level. By means of bioassays it has been found that a relatively low content of auxins and a definite level of gibberellins and inhibitors are characteristic for normal rye spikes at the time of stamen differentiation. The higher level of auxins and expressive inhibitions occur in the later course of pistil differentiation.
Two sprayings of plants with mixed solutions of MH and NAA and two further sprayings with a solution of NAA only before the stamen differentiation change slightly the natural character of endogenous regulators in spikes and cause the destruction of mother pollen cells in anthers and the sterility of anthers in the majority of rye florets. The anthers in the basis of spikes sometimes contain pollen grains after treatment, but their fertility is substantially lowered because the spray evidently disturbed the accumulation of reserve substances in pollen grains. The development of pistil was not affected by the exogenous application of growth regulators. Normal kernels arose in the majority of flowers after supplementary pollination. Some accidental effects of exogenous application of growth regulators, as for example reduced stem growth and disorder of lodicule function were lowered to a great extent by adding GA_S to the last two sprayings of NAA.

Changes in the nucleic acid (NA) content were studied in roots of young wheat plants cultivated under various nutritive conditions, namely in a nutrient solution, in distilled water and in a solution of sodium humate in distilled water. Changes in the ribosomal ribonucleic acid (RNA) in particular and their connection with growth rate were investigated. The amount of the NA fraction investigated (more than 90 per cent of which is represented by the ribosomal RNA) changed substantially under the cultivation conditions studied. In roots of one plant cultivated in water the content of the NA fraction investigated was at the most about 25 μg and it began to decrease as early as from the second day of cultivation. After 12 days of cultivation it decreased to 15 μg. When cultivated in Na-humate the roots contained at the most 33 μg NA, between the 5th-7th day, followed by an intensive decrease after 12 days, to 17 μg. The content of the fraction investigated in wheat plants cultivated in a nutrient solution was about double the value in comparison to these two cases with the maximal value about 60 μg between the 7th-9th day. After 12 days this amount decreased to 45 μg.
The ratio between the growth rate and the NA content presented positive values only when plants were cultivated in a nutrient solution and in Na-humate until the day when the NA content ceased to increase. In the case of Na-humate this took place on the 6th day and in the case of a nutrient solution on the 9th day. Under conditions favourable for growth (in a nutrient solution and in field conditions) the precultivation of wheat plants in Na-humate resulted in a more intensive growth of roots in comparison with the root growth of plants precultivated in distilled water. In plants precultivated in distilled water for 4 days the growth rate continuously increased under favourable nutrition conditions in contrast to plants transferred from distilled water as late as on the 6th day. Their growth stopped after the transplantation and was restored only after a 2 day lag phase. On the other hand, in plants precultivated in Na-humate the transfer to favourable nutritive conditions resulted in both cases in a short term cessation of growth.

The minimum concentration of polyethyleneglycol (PEG) with molecular weights 4000, 6000, and 15000 necessary for precipitation of S, M, X and Y potato viruses was determined. An excessive amount of PEG causes the precipitation of other protein compounds from potato leaf cell sap. In order to obtain highly purified samples, it is necessary to use just the minimum sufficient amount of PEG. Using the minimum quantity of PEG is, also, advisable from an economical point of view. The minimum concentration of PEG of given molecular weight differs for different potato disease viruses. The concentration of PEG necessary for precipitation of a given potato virus depends on the molecular weight of PEG used-4000, 6000 and 15000. As the molecular weight increases, the concentration of PEG necessary for precipitation decreases.

We studied the significance of actual accessibility of ions for presence of α-amylase in roots and cotyledons of young pumpkin plants. We considered α-amylases to be-in agreement with published data-amylolytic enzymes which lose their activity after being dialysed against EDTA or a dilute solution of hydrochloric acid and which can be reactivated by addition of Ca²⁺. N connection with activity and Ca²⁺ nutrition appeared in cotyledons; it did, however, in roots: Ca-deficient plants revealed after preparation either completely inactive enzymes or enzymes with slight activity. It was, however, possible to reactivate them by addition of Ca²⁺ during preparation.
So, using polyacrylamide disc electrophoresis we present evidence for the appearence of amylase with typical characteristics for α-amylases of other sources. Its relative mobility was the same for isolates from both roots and cotyledons. Its biosynthesis was not dependent upon metal which is associated with enzyme. No conclusion can be drawn as to whether Ca-deficient α-amylases are activein vivo; therefore it was impossible to judge whether α-amylase activity is subject to feed-back regulation.

The effect of phenols and simple phenolic glycosides on the activity of IAA-oxidase isolated from gherkin seedlings was studied in experimentsin vitro. Phenol stimulated the enzyme system activity, eugenol and quinol were proven as inhibitors. Simple phenolic glycosides (arbutin, gein and phenol glucoside) influenced IAA-oxidase activity only if β-glycosidase was present: rree phenols released from their bound form increased or decreased the IAA level. The potential fegulatory effect of simple phenolic glycosides on the IAA level in plants has been discussed; this effect is thought to be mediated by free phenols and by influence on the IAA-oxidase system.

The transport of radioactivity of 6-benzyladenine-8-¹⁴C applied to one-year old apple shoots was studied. Simultaneously, labelled metabolites of this cytokinin were studied separately in the xylem and phloem above and below the place of application. According to the results obtained, it can be assumed that 6-B and its metabolites are transported in one-year old apple shoots acropetally through the xylem and basipetally through the phloem, while penetrating from the xylem to the phloem. Besides 6-B-8-¹⁴C, a complex of cytokinin with sugar, also adenosine and adenine were found in the phloem.

The effect of phenolic substances isolated earlier from cabbage, maize and pea on L-tryptophan-3-¹⁴G (L-Try-¹⁴C) metabolism in those plants was investigated. For the sake of comparison the effect of diethyldithiocarbamate (DIECA) on cabbage was also observed. A phenolic substance of unknown structure isolated from cabbage was utilised in a 0.5 mg/ml concentration, p-coumarie acid (PCA) from maize in 0.7 mg/ml concentration and quercetin-glucosyl-coumarate (QGC) found in pea in 8 mg/ml concentration were used. The chosen concentrations were on the limit of their inhibitory effect on the growth of the respective plant apical segments. The effect of DIECA was investigated at 0.1 mg/ml concentration. Using non-labelled L-Try as substrate (5 × 10^-3 M) biological tests have shown that QGC and DIECA have a weaker but distinct effect on the increase in auxin level (+ 17% and + 15%, respectively). All phenolic compounds, as well as DIECA increase the intake of L-Try-¹⁴C from the incubation solutions. Phenolic substances decrease the conversion of L-Try-¹⁴C to its metabolites. The changes were studied after a 20 hour period of L-Try-¹⁴C metabolism. On chromatograms changes in the proportion of L-Try-¹⁴C metabolites took place, especially in the areas of substances of complex character from which IAA splits off easily,i.e. in the areas of 3-indolylacetylglucose and 3-indolylaeetamide. The radioactivity of these areas is generally decreased (e.g. the decrease of radioactivity in the 3-indolylacetylglucose area under the influence of the phenolic substance ofBrassica plants is -7,4%, under the influence of PCA in maize it is -8.9% and under the influence of QGC in pea it is -17.1% DIECA also decreased the radioactivity of this zone, by -10,5%. In cabbage a large part of L-Try-¹⁴C was transformed to glucobrassicin; its biosynthesis increases in the presence of the phenolic substance of cabbage by +3%, in the presence of DIECA by +27%. The results are discussed in a working hypothesis based on the key formation of IAA, accompanied by its oxidation and detoxication.

Separate selection indices were constructed for various combinations of selective characters, in which together with components of economic yield also four separate subcharacters, yield prerequisites were used, namely: flag leaf area, length of the flag leaf, angle of the second leaf (from the top) and length of plant at heading time. Maximum genetic advance in weight of grains per plant (yield) from selections may be expected in selection indices in which three economic yield components together with flag leaf area or angle of the second leaf were used.
When as criteria for selection the flag leaf area together with yield components were used, selection indices with six different sets of economic weights for yield and weight of one grain were also computed. For the ratio of economic values 1∶1, the total expected advance was the highest, but separate advance in yield was approximately only 57% in comparing with selection made according to yield as complex character. For the ratio of economic values 1∶0.03 to 1∶0 the expected genetic advances in yield were about 22 and 24 per cent higher in comparing with selections according to yield. It may be expected that yield improvment will not be acquired by means of a great number of small, inferior grains.

Experiments were aimed at checking whether the non-stratified apple embryos are sensitive to growth factors and light. The effect of growth regulators on light sensitivity was also studied. The stimulating or inhibiting effect of GA3, benzyladenine and IAA or coumarin on the dynamics of apple embryo germination was demonstrated. Seasonal fluctuations of the effect of the growth factors were noted. The stimulating effect of light on the germination of non-stratified apple embryos was demonstrated. This effect is independent of season and seems to be independent of the effects of growth regulators.

The effects of constant soil moisture levels of 90, 60 and 40% of the maximum capillary capacity, applied beginning from the planting of the germinated kernels, on the dynamics of the foliage development of maize was studied in relation to ontogenical changes in leaf area of individual leaves. There were two maxima in the growth of total leaf area (characterized by leaf area duration and loaf area relative growth rate) unrelated to the soil mositure. The first maximum which was less marked, appeared in the phase of 5-8 leaves, the second and main increase being observed before flowering in the phase of 10-12 leaves. The effects of continued decrease in soil moisture were a correspondingly progressive reduction in leaf area and delayed development of the whole plants. Plants with 60% soil moisture attained the same leaf area as those with 90% but only after the end of the vegetative phase. The greatest differences in rate of development between watering treatments appeared at the time of greatest increase in leaf area of control plants. Continued decrease in soil moisture markedly affected the development of the leaves at different insertion levels (especially in elder leaves). Clear-cut prolongation of ontogenesis took place under dry conditions. In conditions of higher soil moisture growth was rather limited or stopped after reaching a certain maximum.

Seedlings of horse chestnut (Aesculus hippocastanum L.) originating from two different localities were cut into several parts in which the tin content was estimated. When expressed per dry weight unit the vegetative parts of plants contain about 9 μg Sn per g dry weight, its content in apical parts of stem and root being still higher. This gives evidence of good mobility of tin in the plant.

Decreased accumulation of elements, particularly of nitrogen, had in dense stand a negative influence on the plants, in spite of the supply of fresh solution and the control of the concentration of nutrients in the pots. The fresh weight and the dry matter of one plant were reduced substantially with rising stand density (from 5 to 10, 20, 40 and 80 plants per 450 sq. cm); the RGR value, the relative absorption rate I_M, the content of all tested elements calculated per one plant, the chlorophyll content in the overground parts of one plant, and the distribution index decrease. Qualitatively the same influence is caused by deficiency of nutrients. Plant dying and self-thinning of the culture occurred in denser stand in the course of cultivation. The root-weight ratio rose with stand densification, particularly at the end of the experiment. The net assimilation rate (NAR) related to chlorophyll dropped with stand density; NAR at density "80" rose slightly from the 22nd day of cultivation and did so at further lower densities. Almost all NAR values lie over the control value at the last measurement. The chlorophyll content in mg g^-1 dry matter of the overground parts rose with stand density to density "40" (41% more than at density "5"); afterwards it dropped. The accumulation (in mg g^-1 d.m.) of phosphorus ions was higher in the plants from dense cultures compared with density "5", particularly in the roots. The accumulation of potassium was near to the control value ("5"), while that of nitrogen was lower. The utilization quotients of phosphorus and potassium in denser stands were the same or negligibly lower than at density "5". They were a little higher in nitrogen than in the controls. Also the ratio RGR/I_M was a little higher than in denser stands. The root-weight ratio, the accumulation of elements in mg g^-1 d.m., the chlorophyll content in mg g^-1 d.m., NAR_ch, the utilization quotient, and the ratio RGR/I_M differed qualitatively by the densification of the culture (with complete mineral nutrition) from the influence of element deficiency (at the same stand density).

The influence of decrease of water absorption rate on the transpiration rate and the development of water saturation deficit (WSD) was studied on the leaf segments of kale. Solutions of polyethyleneglycol (0-25m, 0-50m, O-75m and 1-00m) and mannitol (0-50m) were used as osmotic agents.
The rate of water absorption decreased to zero when the concentration of polyethyleneglycol was 0-25m. At a concentration higher than 0-50m, water from the tissue diluted the external solution. The transpiration rate of samples affected by polyethyleneglycol or mannitol was only a little lower than that of control samples. WSD was noticeably increased only in the absorbing part of segment; in the adjoining, transporting part of segment WSD was practically the same in all variants. WSD in the transpiring part was slightly increased only in some cases. Due to decrease of osmotic potential of the external solution also the gradient of water potential changed. In the case of absorption from pure water, water potential gradually decreased from the absorbing to the transpiring part. Under the influence of polyethyleneglycol or mannitol solution the highest water potential was in the transporting part and from this point water potential decreased to both opposite sides.

Fractions of non-specific esterase were studied in homogenates ofVicia faba L. root tips using disc electrophoresis in acrylamide gel. With α-naphthyl acetate, 7 bands were revealed in electrophoreograms, whereas only 5 bands appeared with naphthol AS acetate; the position of bands detected with naphthol AS acetate corresponds to 5 of 7 bands which appear when using α-naphthyl acetate. If incubated with α-naphthyl acetate, 1 band is totally blocked by the inhibitor E 600, whereas the other bands are weakened slightly and-more or less- proportionally, similarly, as if incubated with naphthol AS acetate. No bands appear after detection with α-naphthyl caprylate and with α-naphthyl myristate. Electrophoreograms developed with α-naphthyl propionate differ both from those treated with α-naphthyl acetate and from those treated with α-naphthyl butyrate. Remarkable, but only quantitative differences were revealed when comparing electrophoreograms from division, enlargement and maturation zones, detected with either α-naphthyl acetate, or α-naphthyl propionate. The non-specific esterase fractions revealed by disc electrophoresis are correlated with protein fractions distinguished in the same material by the same technique using xylene brilliant cyanine G staining and with fractions of the same enzyme found in sections of the same object treated histochemically.

A simple modification of a laboratory gravimetric technique for the study of transpiration of intact plants is described, by which the process can be followed continually. The plants are grown in light vessels on a light "keramzite" or other suitable medium, either alone or in combination with agar gel. The mineral component provides for the necessary cultivation properties of the medium, whereas agar gel ensures steady and undisturbed water relations in longer experiments.
The calculation of the transpiration intensity per unite of time is described. For reliable results the number of samples must be lange chough, so that the coefficient of variation does exceed 10 per cent. The determination of the transpiration is sufficiently exact even without a correction for changes in dry solids, the absolute increments in dry solids during the time interval studied being of a smaller order of magnitude than the values of transpiration. The results are expressed per fresh weight of the transpiring unite, by which an undisturbed transpiration study of a longer duration is rendered possible and the effects on the plant are excluded.