The study was concerned with the effects of irradiation of the sodium humate on its biological activity, which was assessed by the elongation of the hypocotyl and root in young plants of lettuce (Lactuca sativa L. cv. Rapid and cv. Smaragd) growing in the solution of the tested preparation. It was found that its stimulative action on hypocotyl and root elongation in lettuce was changed due to irradiation. However, the degree was dependent on concentration; stimulation mostly decreased, only at some higher concentrations did it increase. Further, experiments showed that there was some interaction between the irradiation of the humate and the cultivar used for testing, but none between the irradiation and the light exposure of plants during the test. The response of the experimental plants to the concentration of the humate depends on the light exposure.

In an embryo shoot apex more different mutations may be induced after the mutagenic treatment of seeds. These mutations may be distributed among the apical initial cells in different ways. According to the proposed mathematical model it is possible to estimate the proportion of initial cells with 0, 1, 2, …,x mutations in the apioes with a given number of initials,k, which is characteristic for each plant object, and under a certain number of induced mutations per apex,n, determined by the conditions of the mutagenio treatment. Owing to the disadvantage of multimutations in plant breeding it is possible according to the formula P(X > 1) = 1 -e^-n/k(l + n/k). to use, at a knownk, suchn's which secure minimum multimutations.

Large complex inclusions evoked by wisteria vein mosaic virus contain cylindrical inclusions, mostly pinwheels (and bundles) and rarely also scrolls and laminar inclusions. Bundles are often abutted to cell walls at plasmodesmata and show association with endoplasmic reticulum and cisternae. Virus aggregates are attached to cylindrical inclusions, various membranes and/or plasmalemma.
Cytoplasm contains more or less disintegrated chloroplasts and mitochondria, abnormal membranes, many ribosomes, bounded vesicles with fibrillar contents, numerous and large microbodies, and membranous whorls. These phenomena are not specific.

Spring barley cv. Spartan was cultivated in a complete and nitrogen lacking Richter's solution. In other experimental variants the nitrogen was omitted after six days of cultivation in the complete nutrient solution or the nitrogen lacking solution was replaced with the complete solution after the same period of time. Anatomy of the second leaf blade was quantitatively analyzed after 12 days of cultivation. Continuous nitrogen deficiency resulted in thinning of the blade, reduction of the cross-section areas of the blade, vascular bundles and sclerenchyma region. The most sensitive reaction to the nitrogen deficiency was that of assimilation parenchyma. The values of characters of the other two investigated variants were between the control and permanent nitrogen lacking variant.

Amaranthus viridis is a quantitative SD plant in which inflorescence primordia are initiated under both 24- and 8-h photoperiods after 12 and 10 days, when 8 and 7 leaves are differentiated, respectively. Photoperiod plays a non-determinate role, whereas the maturity of plants linked with the attainment of minimum leaf number is significant and of primary importance in floral induction. This is further confirmed by the more or less identical nature of changes in the total enzyme activity and isoenzyme patterns of peroxidase, esterase and alkaline and acid phosphatase under the two photoperiods. These changes occur once the minimum vegetative growth has been achieved prior to the reproductive transformation, irrespective of the photoperiod, pointing to the activation of a general common pathway of events leading to floral induction.

Upon rooting of poplar stem cuttiags the total inductive stimulation does not take place, but the individual root primordia maintain a relative independence. This becomes evident by various time parameters of their differentiation. Under experimental conditions, in dormant cuttings from one year individuals of the hybrid I 214 the activation of the first root primordia occurs after 24 h, the pre-emergent development of the roots formed was completed after 72 h.
The activated root primordium is divided into two regions. In the distal region with the predominating cell division the root apex with histogens is formed by the action of initials. From peripheral cell layers of the distal region the so-called "Wurzeltasche" develops which covers the root cap. Due to cell elongation in the proximal region the root apex is pushed up towards the stem surface. The beginning differentiation of the connective vascular tissue is a preparative step for the connection of the vascular system of the developing root with the secondary vascular system of the maternal stem. Following the penetration of the root through the peripheral stem tissues this connection is realized with progressing development. In the developed root the protoxylem elements differentiate continuously and acropetally in direct continuity with tracheids of the basal connective region.

Shoot t ps, young internodal segments and young developing leaves ofBetula ver rucosa Ehrh. in contact with agar nutrient medium formed tissue with numerous buds if medium contained a low concentration of cytokinin (BAP) and auxin (IBA or NAA). Tissue with induced buds transferred on a fresh nutrient medium continued in a formation of new buds which developed into shoots. Excised shoots were rooted on agar medium with a low concentration of auxin. Regenerated trees showed a genetic uniformity.

Two cultivara ofCicer arietinum L. with different sensitivity to drought in the early vegetative stage were compared for their capacity to accumulate proline when subjected to water stress. Both shoots and roots of the two selected cultivara accumulated proline under water stress and this effect increased with increase of water stress level. A high positive correlation between free proline and water saturation deficit (WSD) was recorded while these two factors were negatively correlated to the dry weight of the shoot. Also effects of duration of stress on proline accumulation patterns in relation to drought resistance have been shown.

In pea alcohol dehydrogenase (PADH) four isoenzymes were detected with the same mobility in one-and two-day germinating seeds; in three-and four-day seedlings the isoenzyme fastest moving towards the anode was lacking. These isoenzymes did not differ in substrate specificity to ethanol, propanol, butanol, and allyl alcohol, but only three of them reacted with isobutanol, and two with cyclohexanol.
On germination of seeds in actinomycin D at a concentration of 30 μg ml^-1 two isoenzymes disappeared and the activity of the other two was considerably lower.

The induction of gametogenesis in the studied homothallic alga by the transfer to a nitrogen-Less medium leads to an adaptation of the cell population until a dynamic equilibrium is attained. Throughout the adaptation, the homeostatic forces regulating the number of the cells in the population assert themselves on the basis of internal nitrogen circulation. Part of the induced cells which perform no conjugation is probably destroyed by lysing, whereas the cells being just in the pre-Induction phase as well as those having passed the phase without being induced to gametes, continue their cycles by means of the released nitrogenous substances. The conditions which in some cells cause the induction of gametogenesis, produce a partial spontaneous synchronisation in other cells. The course of the cell cycles in parts of the culture may be determined according to the pulses of the increasing number of the zygotes within the whole cell population, if the cell cycles have run at a certain degree of synchrony. The culture conditions which induce gametogenesis cause a quick decrease of the biosyntheses of the RNAs while the biosyntheses of the DNAs are almost maintained at the original level. During the dynamic equilibrium of the population, the average content of the RNAs per cell remains very low, whereas the average content of the DNAs per cell virtually does not change (compared with the original state).

The optimum conditions for cell suspension culture experiments have been characterized by respiration,p-Phenylenediamine oxidase and growth of cell suspension ofNicotiana tabacum for 15 days in stationary culture. Change of 3,4-Dihydroxybenzoic and 4-Hydroxybenzoic acids both present at 10^-4 M in culture medium were studied in short term experiments. An oxidation product of 3,4-Dihydroxybenzoic acid characterized by an absorption maximum at 280 nm was isolated after 1 h of incubation. The 4-Hydroxybenzoic acid did not change when incubated for 4 h under the same conditions.

Alfalfa witches' broom manifested by an expressive increase in the number of stems and dwarfing of the affected plants was found in Czechoslovakia. The disease is not saptransmissible and was transmitted by grafting to healthy alfalfa plants. The disease occurrence is sporadic. The symptoms observed in comparison with those described in Australia and USA are mild and inconspicuous. Electron micrographs of ultrathin sections showed the presence of numerous mycoplasma-like organisms (MLO) in diseased but not in healthy phloem tissues.

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

Two barley chloroplast nuclease fractions were separated by the affinity chromatography and gel electrophoresis. Both were about 2 times more active to RNA than to native DNA and about half as active to denaturated DNA as to native DNA. Both fractions were as active to UV-irradiated (270 J m^-2) native DNA as to intact DNA but their action was inhibited by apurinic sites. The enzyme activities were inhibited by high concentrations of EDTA, NaCl, Mn²⁺, Ca²⁺, Zn²⁺ ions and by N-ethylmaleimide. They do not require Mg²⁺ ions but are stimulated or at higher concentration inhibited by their presence. Both RNase and DNase were active over a wide pH range (5.5-9), the optimum for DNase action in the presence of Mg²⁺ being 6.5, for RNA decomposing activity at pH 8.0. As no mononucleotides were detected in acid soluble form, it seems likely that DNase acts in the endonucleolytic way.

A previously undescribed disease onLupinus hybrids manifesting typical witches broom symptoms occurred spontaneously in a locality in North Bohemia. Broomed shoots appeared only in late summer and resulted from the abnormal proliferation of dormant axillary buds in leaf and fruit axils. The shoots were bushy and their leaves were dark green and not reduced in size. Electron micrographs of ultrathin sections showed the presence of numerous mycoplasma-like organisms (MLO) in diseased but not healthy phloem tissues.

Changes in glutamine synthetase activity located in the cytosol of root nodules were followed in pea (Pisum sativum L.) plants in relation to their nitrogenase activity. The highest glutamine synthetase activity was found in young nodules (15 days after inoculation) and its changes in 17-to 45-day-old plants showed a positive correlation with nitrogenase activity. In contrast to nitrogenase activity, changes in glutamine synthetase activity during the day and night period could not be unequivocally interpreted in terms of diurnal fluctuation.

Using immunochemical methods a comparison was made of a complex of water soluble (albumins) and salt soluble (globulins) seed proteins, especially vicilin and legumin, in selected species of the genusPisum, to determine the degree of their taxonomic relationship.
Within the genusPisum the interspecific differences betweenP. abyssinicum, P. cinereum,P. elatius, P. fulvum, P. sativum, andP. syriacum are much smaller, and thus the taxonomic distances are shorter than is the casee.g. in the genusPhaseolus. In spite of this fact one may state thatPisum sativum, P. elatius andP. syriacum constitute a definite group, whereasP. abys-sinicum, P. cinereum and P.fulvum have longer taxonomic distances.

The contribution deals with the distribution of β-glucuronidase in the germinating pollen grains ofPortulaca grandiflora. In non-germinating pollen grains the enzyme is localized in the pollen wall; the cytoplasmic activity is subdued. With the initiation of germination, the activity of enzyme increases and the positive granules are richly packed in the pollen grains and pollen tubes. The stigma hairs also have such an activity. The functions of the enzyme in the metabolism of germinating pollen grains are discussed.

The leaves of poplar trees (genusPopulus) contain antimiorobial agents. These antibiotic properties are markedly influenced by interspecific and intraspecific hybridizations. Fractionation of the weakly active crude extracts results in more active antibacterial fractions. There are indications that the substances which inhibit antimicrobial effects during the testing procedure remain in the methanol fractions. In addition the results show that the antibacterial agents differ from the antifungal compounds, which both are different from the antiviral substances.

Twenty-four isolates of turnip mosaic virus (TuMV) from spontaneously infectedSisymbriutn loeselii plants were collected in Bohemian localities. Single lesions on leaves ofNicotiana tabacum cv. Samsun served for inoculating petunia plants used as infection sources for twelve host species. In no case were two identical isolates obtained. 15 isolates could be transmitted toVicia faba, a new TuMV host. Almost all isolates infectedPhaseolus vulgaris cv. Prince locally andTrifolium incarnatum systemically. Seven isolates were transmissible toPisum sativum. No substantial differences between isolates were observed with infectedAn aranthus caudatus, Chenopodium quinoa, Datura innoxia andSinapis alba plants. Several isolates could not infectNicotiana glutinosa at all, other isolates caused in it latent systemic infection and some isolates only local infection contrary to normal local and systemic infections ofN. glutinosa. Attempts to transmit one isolate to cereals failed.

Ethanol-soluble and insoluble nitrogen and protease activity in maize seeds during imbibition period of 6 to 60 h at 30 ± 2 °C were determined both in light and in the dark. In light, soluble and insoluble nitrogen in the embryo were similar to that in the dark. But the increase in soluble nitrogen in the endosperm up to 38 h was higher in light than in the dark. Decrease in insoluble nitrogen was correlated with increase in soluble nitrogen, the level always being higher in the dark. Light increased protease activity also in the endosperm. Among various light qualities, red light was most effective in inducing proteolysis, and loss of nitrogen from the endosperm. Further, the growth and organic nitrogen of primary leaves from seedlings raised from light pretreated seeds were better than those from dark pretreated ones.

A study was made of the changes in the content of essential oil and its components (farnesene, (-)-α-bisabolol, (-)-α-bisabololoxide A, (-)-α-bisabololoxide B and spathulenol, α-bisabolonoxide A, chamazulene, cis en-in-dicycloether) and of the number of secretory canals in the receptacles during the beginning of flowering, full flowering and the termination of flowering of camomile anthodia. The total content of the essential oil was highest during the beginning of flowering and lowest during its termination. The proportion of the individual sesquiterpenes in the essential oil underwent changes mostly during the beginning and termination of flowering. The number of secretory canals in the basal and middle anthodial parts increased during the beginning of flowering and the full flowering.

Three days old excised tomato cotyledons were subjected to mannitol induced water stress in the presence of actinomycin D and cycloheximide. Within a few hours, in the presence of actinomycin D but not cycloheximide, water stress induced increase in ribonuclease activities and decrease in beta-fructofuranosidase activities. The water stress action in the presence of actinomycin D was reversible by addition of kinetin. It was postulated that water stress had some immediate fundamental action on the protein synthesis sites at the ribosomes.