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.

Tryptophan, tryptamine, or indolepyruvic acid were applied to 2 systems: a bacterial (pea stem sections containing the epiphytic bacteria) and a plant system (pea stem sections under sterile conditions).
In the plant system, the production of indoleacetic acid and indoleethanol (tryptophol) from each applied indole derivative is clearly reduced by the aldehyde reagents bisulfite and dimedon, respectively. Indoleacetaldehyde is chromatographically detected after alkaline liberation from its bisulfite addition product.
In the bacterial system, the production of indoleacetic acid and indoleethanol is likewise reduced by bisulfite and dimedon. However, after tryptophan or tryptamine application, we could not detect indoleacetaldehyde in the described way.
In one case only, namely tryptamine application to the bacterial system, indoleethanol production (contrary to indoleacetic acid production) is scarcely reduced by the aldehyde reagents. This indicates a bacterial pathway tryptamine → indoleethanol which bypasses indoleacetaldehyde.

The effect of the individual leaf blades of spring wheat on the dry matter of stalks, chaff and grain (caryopses), of spikes and total overground part, was studied. In the experimental plants the individual leaf blades were detached according to the scheme given, at the beginning of shooting, (A), at the beginning of earing (B), and at the beginning of flowering (C). The dry matter (fresh weight) of the stalk was least decreased if either the lowest or the uppermost leaf blade was severed during the developmental phase of shooting. The dry as well as the fresh weights of chaff were least affected in those plants where the leaf blade was removed during the developmental phase of flowering. Both the dry and fresh weights of caryopses were least decreased if either the lowest or the uppermost leaf blade was removed during the developmental phase of flowering. The dry weight as well as the relative water content of chaff and ear grains were most decreased following removal of leaf blades during the developmental phase of shooting. The relative water content of chaff, grains and ears was most decreased following removal of developed leaf blades during the developmental phase of earing. It was confirmed that in addition to the photosynthetic activity of leaves the photosynthesis of other parts of the stem system (stalk internodes, ear awns etc.) participated in the production of total dry matter of experimental plants. The photosynthetic activity of leaf blades was particularly high up to the earing phase, while subsequently the photosynthesis of extrafoliar area (stalk internodes and ears) predominated. In spite of this, participation of the total leaf area is very high in the formation of grain dry matter (over 50%), as well as of the total dry matter of plant (over 80%).

Evidence for the effect of sterols on plant mycoplasma is presented. Two essential sterolsi.e. cholesterol and stigmasterol were applied in the following way: grafts from tomato plants infected with potato witches'broom, wedge-shaped at the base were dusted on the cut surfaces with the corresponding sterol in the amount of 4 mg to one graft, inserted in freshly cut wedges of stock plants and firmly tightened with rubber tubes. Both sterols stimulated growth of diseased grafts and delayed symptom manifestation. The stimulation was more evident with stigmasterol and the delay in symptom manifestation and intensity was more distinct with cholesterol. Supplying tomato plants with sterols externally probably enables additional multiplication of mycoplasma in already infected grafts, and the plants need not provide the grafts with essential metabolites which they themselves need for the development of reproductive organs. Stigmasterol, a metabolite peculiar to the tomato plant, is probably more rapidly consumed than cholesterol which may remain in the plant as a metabolic pool of sterols for mycoplasma propagation.

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.

For three consecutive years the content of natural stimulators and inhibitors was observed in leaves and shoots of peach trees. Research was directed to the question of development of flower buds.
The substances under study were isolated from the acidic fraction of ether extracts by means of paper chromatography and their concentration was determined by biological test. The activities of substances which either stimulate or inhibit the growth of oat coleoptiles, were added up. The curve expressing the content of stimulators in shoots in relation to the fresh weight showed its maximum in the period of full growth of shoots (15 June-15 July according to the fluctuating vegetative conditions) and it showed a decreasing tendency at the end of the season. The decline of the curve showing the content of inhibitors is of similar direction but less steep. The trend of substances under study is the same in leaves as in shoots, but their quantity is lower. Stimulation and inhibition effects in individual sampling intervals were added up to make a common curve which seems to express the combined action of stimulators and inhibitors in the plant, which determines its growth pattern.

A method for determination of potato X-virus and tobacco mosaic virus in infected tobacco leaves was tested. The leaves are rubbed with isolated antibodies against homologous viruses and after 30 minutes incubation in a humid chamber at room temperature are washed with fresh distilled water 3 times. The leaves are afterwards rubbed with³⁵S-labeled pig gamma globulin against rabbit gamma globulin. The most convenient radioactivity of the labeled pig gamma globulin was 100 (µCi. Leaf discs 5 mm in diameter are punched out after half an hour incubation and their radioactivity is measured on a 27π window methane flow counter. The leaves from healthy plants are treated in the same way. The virus presence is presumed from the differences of radioactivity between healthy and infected leaves. If the mean radioactivity of the discs from healthy leaves equaled 100, the discs from potato X-virus infected leaves showed a moan value of 382.3%. This method can be used for estimation of virus distribution in the plant, and/or tracing its translocation.

Metabolites of indolepyruvic acid and indolelactic acid were investigated using 2 systems: a bacterial (pea stem homogenates containing the epiphytic bacteria) and a plant system (pea stem sections under sterile conditions). The products of spontaneous indolepyruvic acid decomposition in aqueous solution and during chromatography were investigated, too.
Biological indolepyruvic acid conversion yields, besides those substance amounts which occur spontaneously, indoleacetic acid, indoleethanol (tryptophol) and (only in the sterile plant system) indoleacetaldehyde. An inhibitor extract from pea stems decreases the indoleacetic acid and increases the indoleethanol and indoleacetaldehyde gain.
Indolelactic acid is not metabolized in the sterile plant sections. Indolelactic acid oxidation by the bacteria-containing homogenate yields indolepyruvic acid and is inhibited by the inhibitor extract.

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.

The root cap develops out of the cells of the caliptrodermatogen. The root apex belongs to the first of Haberlandt's histogen types. The velamen usually consists of three layers of cells, and develops out of the protoderm by periclinal divisions. Funnel-shaped cells later divide tangentially into two cells, and in one of these cells a fibrous body develops. Two to four thick-walled cells alternate, usually with one passage cell in the exodermis. The cortex proper consists of approximately ten to twelve layers of parenchymatic cells in the mature root. There are eight to sixteen xylem poles alternating with the same number of phloem poles in the central cylinder.
In the roots ofDendrobium cunninghamii I observed two types of mycorrhizal infection, which can be classified as transitive types between ptyophagus and tolypophagus mycorrhizae. In my opinion, a state of balanced symbiosis exists between the fungus and the plant; a part of the time the plant acts as a parasite on the fungus.

Maize mosaic and stunt, occurring to a considerable degree under Cuban field conditions, was determined as a virus disease, transmissible by the corn planthopperPeregrinus maidis Ashm. Negative results were obtained in the experiments in which aphidsRhopalosiphum maidis Fitch, served as vectors or when transmission was realized mechanically using the sap of infected plants. The incubation period in the infected plants fluctuated between 15 and 27 days. Besides maize, the virus disease could be transmitted also to sorghum(Sorghum vulgare Pees.) and to weed plants of the grassRottboellia exaltata L. It follows from the results that the disease concerned is identical with virus stripe, described in 1927 in Cuba by Stahl as corn stripe (raya del maiz).
Under field conditions the disease spread fluctuated in average from 3.4 to 46 per cent of inflected plants. Plant communities concentrated on larger areas which received good agro technique and chemical protection against pests exhibited lower infection for the most part The most suitable time for the determination of spread and infection intensity under field conditions is that shortly before and during flowering of maize.

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 effect of phenolic substances isolated earlier from cabbage, maize and pea on L-tryptophan-3-¹⁴C (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-coumaric acid (PCA) from maize in 0.7 mg/ml concentration and quercetinglucosyl-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^-3m) 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-indolylacetamide. 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.

Values of the water saturation deficit (WSD) for hydroactive stomatal movements of kale leaves were estimated using the method of transpiration curve analysis.
Stomata of young leaves started closing at WSD values of 5 to 6 per cent and were completely closed at 18 to 20 per cent WSD. During maturation and ageing of leaves these WSD values increased to 12.5 and 18 to 23 per cent respectively. Thus the stomatal reaction is more sensitive to changes in WSD in adult leaves than in young ones. After maturation is attained both values decrease. In apparently withering leaves the individual phases of transpiration curves can barely be distinguished, probably for the reason that even under optimal conditions their stomata remain half-closed and at high WSD values an incomplete closing of the aperture occurs. The injured cuticle of withering leaves affects the shape of the transpiration curve as well.

Beet yellows virus was transmitted by wingless aphidsMyzus persicae (Sulz.) after 16 hrs acquisition feeding on leaves covered with a Parafilm M membrane. Effectiveness of the virus transmission was decreased approximately to half of the original value by acquisition of the virus through the membrane. No virus was transmitted to healthy beet seedlings after 6 or 16 hrs continuous feeding on a concentrated suspension of the purified virus or on crude juice extracted from an infected plant (suspensions contained 15% of sucrose).

A study was performed on the effect of various concentrations of IAA, 2,3,6-triiodobenzoic acid, and maleic hydrazide, supplied to Richter's nutrient solution, on growth of pea plants in water cultures. After a 18-day cultivation growth was evaluated and in the plants gathered the content of total N, P, K, and Ca was estimated.
Growth of experimental plants (as evaluated from fresh and dry weight) was affected by all three regulators in dependence on the concentration used. It was stimulated by lower concentrations and inhibited by higher, the production of both fresh and dry weight of the root system being stimulated by all IAA concentrations used.
The ratio of root dry weight to that of the entire plant was markedly increased after application of IAA and 2,3,5-triiodobenzoic acid, whereas when applying maleic hydrazide it was only slightly increased in comparison with control.
Stimulation or inhibition of growth induced by IAA treatment was accompanied by an accordingly increased or decreased accumulation of N, P, K, and Ca. Thus their utilization did not change in comparison with control. On the other hand, both inhibitory and stimulatory effects of 2,3,5-triiodobenzoic acid and maleic hydrazide on growth were associated with a relatively lower accumulation of the elements in question, resulting in an increased utilization.
The distribution index of N, P, K, and Ca decreased with increasing concentrations of IAA, 2,3,5-triiodobenzoic acid and maleic hydrazide. Only the highest 2,3,5-triiodobenzoic acid and maleic hydrazide concentrations used brought about a more marked increase in the distribution index of potassium, simultaneously with a marked decrease in the distribution index of calcium.

We traced the liberation and biological effect of volatile substances released from the roots of cereals,i. e. barley, wheat, rye and oats, on seedlings of the same and other plant species. Experiments were carried out in a closed glass apparatus with a static or circulating atmosphere in which the CO₂ and O₂ were permanently absorbed and supplemented, respectively. In some experiments the air was bubbled through water or through solutions of boric acid, barium hydroxide and potassium permanganate.
The roots of all four cereals tested released volatile substances with a biological activity which appeared to be non-specific with respect to plant species. The effect of volatile substances was partially decreased by bubbling through water, barium hydroxide and boric acid and was completely removed after passing through the solution of potassium permanganate.
Volatile substances liberated from roots of barley inhibited elongation of roots and coleoptile, decreased SH-group content and caused excessive formation of root hairs as well as inhibition of both dry matter production and respiration of roots of rye seedlings.
Ethylene was found in the atmosphere of experimental vessels.

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.

In the pea test a highly positive response to the treatment with IAA reversed to a negative one or became 5 to 6 times weaker when CCC was applied together with IAA. In cultivating pea seedlings, following their decapitation, for two days in a 0.25 per cent CCC solution and then in water, growth of their cotyledonous axillaries (cotylaries) were inhibited. This inhibitive action of CCC could be made ineffective when the seedlings, following two-days' cultivation in the CCC solution, were grown further in kinetin solutions (0.37-3 mg per 1). Cotylaries of decapitated pea seedlings, when grown in kinetin solutions were inhibited. With kinetin solutions of 6-12 mg/l a strong inhibition also occured in the growth of roots at the apical parts of which spherical swellings were developing.
The CCC supplied to the roots of intact etiolated pea seedlings is translocated acropetally into the stem at a rate of about 5 cm per hour. Decapitation of the plant causes retardation of this transport, yet a coat of 0.00001-1% IAA or kinetin paste produces acceleration of the stream.
Existence of an antagonism between CCC and IAA, demonstrated earlier, was found holding true also for B-9 (N, N-dimethyl-aminesuccinamic acid) and IAA, as the inhibitive action of B-9, 0.06% solution on the growth of lettuce hypocotyls was reduced to a highly significant degree when the plants were supplied with B-9 together with IAA at a concentration of 10 mg/l.

The present paper deals with the epidermal structure and ontogeny of stomata in vegetative and floral organs ofHybanthus enneaspermus. The epidermal cells are either polygonal or elongated with straight, sinuous or arched thick anticlinal walls. The surface of the cuticle shows parallel striations radiating from the guard cells or hair bases. Unicellular and uniseriate bicellular trichomes with verrucose margins have been observed on all organs. The mature stomata are anisocytic, paracytic, anomocytic and transitional between anisocytic and paracytic. The ontogeny of anisocytic and paracytic stomata is syndetocheilic or mesogenous, anomocytic is haplocheilic or perigenous, while that of the transitional type is mesoperigenous. Four types of stomata have been observed on all the vegetative and floral organs and their ontogeny from organ to organ of this plant is constant. Stoma with a single guard cell is the result of disintegration of one of the guard cells before or after pore formation. Contiguous stomata are also occasionally noticed.

Pea enation mosaic virus (PEMV) was isolated from disea sed field pea (Pisum sativum L.ssp. arvense A.Gr.) and broad bean (Faba vulgaris Moench) plants grown as filed crops at Bohumilice in Bohemia. The virus proved to be pathogenic for the following plant species:Pisum sativum L. cv. Raman,Faba vulgaris Moench,Lens culinaris Med.,Vicia sativa L.,Lathyrus odoratus L.,Glycine soja L.,Phaseolus vulgaris L.,Chenopodium amaranticolor Coste andReyn,Nicotiana clevelandi Gray,Trifolium incarnatum L. The dilution end point of the isolate was higher in pea plants (10^-4) than in broad bean plants (10^-2). The thermal inactivation point was 65-68° and the longevityin vitro between 10 and 14 days. According to the host range, symptoms on pea plants and physical properties the virus isolate studied resembles some isolates described in the U.S.A. and represents a PEMV strain different from those reported so far in Czechoslovakia.

Grains ofTriticum monococcum L. var.sofianum Körn. were treated with 0.1mm, 0.2mm and 0.3mm solutions of N-nitroso-N-methylurea (MNH), with 0.03m solution of buthylmethane sulphonate (BMS) and with X-rays in doses of 5 000r and 10 000r. The germination and development of individual colors of chlorophyl mutants were observed by the system developed byLamprecht (1960). All the mutants induced were classified according to their color changes into three main categories-homogenous unicolor, homogenous multicolor and heterogenous multicolor. In the last type the colors of individual leaves of the same plant varied. Anthocyanin mutations "albina" and "albino-transvirgata" sometimes coincided with the chlorophyll mutations. Some chlorophyll mutations showing complicated groups of colors appeared which were beyond the scale of classification by ordinary systems. The largest proportion in the spectrum of chlorophyll mutations, induced by MNH and X-rays was occupied by mutations of thealbina type. The broadest mutation spectrum in our experiments was induced by the application of 0.3mm MNH. The doses of X-rays used induced relatively higher numbers ofalbina-type chlorophyll mutations than MNH and BMS. In our experiments we succeeded in inducing on medium size samples ofTriticum monococcum L. var.sofianum Körn not only almost all types of chlorophyll mutations, induced byFujii (1960, 1962) andMatsumura (1960), but in addition also a great number of other even more complicated chlorophyll mutations, which have never been previously described inTriticum monococcum. L.

The mutual relationship between the water potential and water saturation deficit (w.s.d.) was studied on samples of leaf tissue of fodder cabage. Definite values of water potential were obtained by long-term exposure of plant material to an atmosphere with definite constant pressure of water vapour. The resulting w.s.d. values were determined gravimetrically.
Water saturation deficit varies indirectly with the water potential. This dependence was linear for values of water potential from -4.4 to -43.9 atm.
Since the stabilization of equilibrum of water potential between the leaf tissue and surrounding atmosphere was very slow the relationship between water potential and w.s.d. was influenced by the size of samples and by the length of exposure. Therefore this method was more suitable for relative than for absolute measurement.

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.

Grains ofTriticum monococcum L. var.sofianum Körn. were treated with O.1 mM, 0.2 mM and 0.3 mM solutions of N-nitroso-N-methylurea (MNtt), with 0.03 M solution of buthylmethane sulphonate (BMS) and with X-rays in doses of 5 000r and 10 000r. The germination and development of individual colors of chlorophyl mutants were observed by the system developed byLamprecht (1960). All the mutants induced were classified according to their color changes into three main categories-homogenous unicolor, homogenous multieolor and heterogenous multieolor. In the last type the colors of individual leaves of the same plant varied. Anthocyanin mutations "albina" and "albino-transvirgata" sometimes coincided with the chlorophyll mutations. Some chlorophyll mutations showing complicated groups of colors appeared which were beyond the scale of classification by ordinary systems. The largest proportion in the spectrum of chlorophyll mutations, induced by MNH and X-rays was occupied by mutations of thealbina type. The broadest mutation spectrum in our experiments was induced by the application of 0.3 mM MNH. The doses of X-rays used induced relatively higher numbers of albina-type chlorophyll mutations than MNH and BMS. In our experiments we succeeded in inducing on medium size samples ofTriticum monococcum L. var.sofianum Körn not only almost all types of chlorophyll mutations, induced byFuji (1960, 1962) andMatsumura (1960), but in addition also a great number of other even more complicated chlorophyll mutations, which have never been previously described inTriticum monococcum. L.

Apical buds ofChenopodium rubrum from plants treated with CCC contain more endogenous auxins than buds from control plants, the level of these compounds increasing with the application of rising concentrations of the retardant. An especially marked increase was observed in the level of substance "X" which on chromatographic separation runs in the zone of tryptamine or its derivative. Since it has been shown in previous experiments that the inhibitory effect of CCC on flowering ofChenopodium rubrum may be reversed by indole-3-acetic acid (IAA) it is believed that the increase in auxins after application of CCC does not concern biologically active substances immediately available to the plant. It seems more likely that inactive precursors are involved which cannot be converted to the active substance in the presence of CCC, possibly due to blocking of the pertinent enzyme. If we assume that the wheat coleoptile used in the auxin bioassay in our experiments contains the pertinent enzyme it might convert the inactive precursors to active substances and, therefore, exhibit a growth stimulation even though the substances concerned would not necessarily be active in the buds from which they were extracted.

The following paper deals with the character of endogenous auxins and gibberellinlike substances in the maize tassel and ear primordia during differentiation. Using bioassay the character of substances extracted from tassel primordia, internodes below the tassel, ear primordia and stem base was determined and correlated with the course of morphogenesis and differentiation. A low level of auxins and a high content of gibberellin-like substances accompanies the differentiation of terminal tassel. The differentiation of an ear is associated with an increment in auxin content while the level of gibberellin-like substances decreases. The character of growth substances in primordia remains practically unchanged in the course of further differentiation. The inhibitions appear in the plant and probably start numerous morphological reductions in the pistillate inflorescence structure or inhibit the growth of lateral primordia on the stemetc. The treatment of plants with maleic hydrazide at the beginning of tassel differentiation shifts the normal levels of endogenous regulators and brings about the transformation of tassel primordia into an ear. This transformation is accompanied by a marked rise in gibberellin-like substances, by an increment in auxins and the appearance of inhibitors.

Genotypic, phenotypic and environmental correlations were ascertained in a set of 18 winter wheat varieties from experiments conducted for two years on two levels of mineral nutrients. Analysis of genotypic relationships found between yield components, area and length of the last leaf, angle of the second leaf and length of the plant at heading time was made using Wright's path coefficients.
In some instances the analysis showed, in comparison with simple genotypic correlation in reality, a different direct association of the pair of characters, the causal basis of which consisted in a relatively high indirect effect of other variables used in the experimental model.
From results cited it may be judged that the effect of the last leaf area was at least under our experimental conditions closely associated with both factors of ear productivity,i.e. with number of grains and average weight of one grain. The influence of the angle of the second leaf (next to the last at the top) was associated first with the number of productive stems, thus rather with a factor of productivity of plant stand and only in a wider action with the average weight of one grain.
In the future it will be useful to confirm the effect of subcharacters as additional criteria in the selection of plant types with higher prospective yield. From preliminary, as yet unpublished results, the use of selection indices in winter wheat may be considered an available method for estimating the expected genetic advance from the selections.

The interactions between cereals-wheat, barley, rye and oats-in combined cultivation in mixtures of always two species in relation 1:1 in the initial phase of growth were studied. During thirty days' cultivation in pots the growth of the experimental plants in pure cultures and in mixtures and the changes of the nitrate nitrogen content of the soil in the experimental vessels were followed.
The experiments showed that all tested species of cereals interacted with each other during the growth in mixture. The growth changes began soon after sowing, were of a stimulating and inhibiting character and increased during the growth. An exception was the small reaction of oats to rye.
Decrease of the nitrate nitrogen content was determined in the soil of the experimental vessels during the cultivation of the plants. The changes of the nitrate nitrogen in the soil corresponded on the whole with the exception of the last phases of the experiments to the growth intensity of the experimental plants. No essential differences, either in the content or in the rate of the decrease of nitrate nitrogen, were found in the soil of control plants and in the soil of plant mixtures. Small differences which were manifested cannot be considered the primary cause of the mutual relations of cereals. The cause of the mutual relations may be attributed to allelopathic factors.

In lupin (Lupinus albus L.) and pea (Pisum sativum L., cv. Raman) it was shown that the uptake of⁸⁹Sr from Knop's nutrient solution is significantly increased from a solution with decreased calcium content (one tenth of the normal content) and is slightly decreased from a solution with higher calcium content (150% of the normal content). The calciphile pea absorbs approximately 50% more calcium than the calciphobe lupin, and accordingly 50% radiostrontium less. The pea plant more strongly blocks the translocation of radiostrontium from roots to overground parts, as is proved by the higher discrimination factor of pea (i.e. by the ratio of specific activities of mCi⁸⁹ Sr/g Ca of roots to overground parts). The presence of chlorine in the nutrient solution decreases the content of radiostrontium per gram of dry matter, both in pea and lupin. Radiostrontium is absorbed quickly by both species of plants and is autoradiographically detectable as early as 2 hours after the introduction of radiostrontium to the nutrient solution. *** DIRECT SUPPORT *** A01GP049 00004