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.

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 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.

Growth correlations in the shoot apical meristem during transition to flowering were studied in a quantitative long day plant,Brassica campestris L. cv. Ceres, requiring only one long day for floral initiation. During photo-inductive exposure of the plants, an overall increase in cell number could be observed at the shoot apex concomitant with promotion of leaf initiation. Release from apical dominance and decline in relative growth rate of leaf primordia are reported as early effects of photo-induction. With the onset of floral differentiation, production of new leaf primordia had stopped altogether. Maximum increase in RNA concentration could be noticed in axillary meristems following photoperiodic treatment, whereas in vegetative plants the highest RNA concentration was found in leaf primordia. The significance of these changes occurring during transition to flowering is discussed.

Effect of 2,4-dinitrophenol (DNP) was studied onNigella sativa to note the changes in mitosis, DNA, RNA and protein synthesis. The chemical affected division frequency considerably and chromosomal abnormalities like sticky bridge, fragmentation, micronucleietc. were recorded. By using precursors of nucleic acid and protein synthesis, it was found that DNP also inhibited DNA, RNA and protein synthesis. The decrease in division frequency can be correlated with the DNA synthesis.

Polyacrylamide gel electrophoresis was used to study the differences in patterns of the isoperoxidase spectrum in leaf tissues of the genome series (2n, 3n, 4n) of twoNicotiana tabacum L. cultivars,i.e. in the growth stage of the 5th-6th and 10th-11th leaf, and in the stage of elongation growth. Mutual comparisons of the cultivars showed that the variability and difference in patterns between the cultivars in later growth stages was more important. In both cultivars only one rapidly migrating main band of isoenzymes was registered within the range of Rm 0.45-0.77; only in the stage of elongation growth on the 2n and 4n levels two bands were recorded. No association between the number of genomes and the number or distribution of isoperoxidases was found.

Sucrose synthetase was purified about 130-fold from morning-glory (Pharbitis nil Choisy cv. Murasaki) callus cells, and the properties of sucrose synthesis and cleavage activities of the enzyme were compared.
The enzyme preparation gave a single band by disc electrophoresis. The molecular mass of the enzyme was estimated to be 4.2 × 10⁵ by gel filtration. The enzyme preparation gave two bands by SDS disc electrophoresis, suggesting the molecular mass of about 3.8 ×10⁴ and 7.0 × 10⁴.
The pH optima of sucrose synthesis and cleavage activities of the enzyme were different from each other, giving pH 9.0 and pH 6.5 respectively. MgCl², MnCl² and CaCl² activated the sucrose synthesis activity about two times the normal rate and conversely inhibited the sucrose cleavage activity.
F-6-P was not replaced by fructose. UDP was the only valuable substrate as a nucleotide diphosphate.
The enzyme showed the negative ecoperativity effect of UDPG suggesting to be an allosteric enzyme. The Km values of sucrose and fructose were calculated to be 167 mM and 5 mM, respectively. UDP suggested substrate inhibition. The apparent equilibrium constant varied between 1 to 3.
Based on these results, the role of the enzyme in the sucrose metabolism of morning-glory callus cells will be 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.

Esterase isoenzyme patterns were studied in seeds of 6 cultivars ofAllium cepa L. and of14 species ofAllium, namelyAllium aflatunense B. Fedtsch.,A. altaicum (Pall.) Reyse,A. Cristophii Trautv.,A. fistulosum L.,A. jajlae Vved.,A. Karsianum Fom.,A. nutans L.,A. porrum L. cv. Gigant,A. praemixtum Vved.,A. pskemense Vved.,A. ramosum L.,A.rotundum L.,A. schoenoprasum L.,A. stipitatum Regel. The cultivars differ in their isoenzyme patterns, the cultivar Kaštická stands apart from all the other cultivars, probably due to the high alkalinity of its seed extract. The examined species, arranged according to their mutual similarity of isoenzyme patterns, form several groups corresponding to individual sections of the genus. Our results corroborate the recognizing of the sectionCepa and the subsectionPhyllodolon. The maintaining ofA. jajlae andA. rotundum as well described species fits better with our results, than degrading them to subspecies ofA. scorodoprason.
Our results agree in main features with those obtained by the immunological method. Some few differences appear concerning individual species. It is evident that esterase isoenzyme patterns can be used in chemotaxonomy ofAllium on an infrageneric level, and, at least inA. cepa, also on an infraspecific level.

GA₃ as well as SA increase the protein content of the stem and the leaves at 1 day under both 8- and 24-h photoperiods. A new protein band with Rm 0.47 seems to be associated with floral bud initiation as it develops within 1-3 days in the stem as well as in the leaves of plants exposed to inductive treatments regardless of whether the induction is caused by 8-h photoperiods or by treatment with GA₃ of SA under 24-h photoperiods. Another band with Rm 0.23 developed only in the stem of water-as well as GA₃- or SA-treated plants under 8-h photoperiods. It may possibly be associated with extension growth.

The two final products of radiolytic degradation of cytosinei.e. parabanic and oxaluric acids were investigated as regards their cytogenetic effects. Broad bean (Vicia faba L.) root meristem was used as experimental material. While the oxaluric acid was not able to induce chromosomal aberrations to a greater extent, the parabanic acid acts as a clastogenic compound. When applied on a resting broad bean root meristem at concentration from 10^-3 to 10^-2 M it induces chromosome and chromatid aberrations, especially breakages. Their frequency reaches 9-12% at the highest tested concentration. The same concentrations of the parabanic acid increases mitotic index of the first cell generation of primary root.

Alfalfa (Medicago sativa; L.) plants susceptible (S) and resistant (R) to the bacterial wilt were fedvia roots with a nutrient solution labelled with⁸⁶Rb⁺, at different times after inoculating them withCorynebacterium insidiosum (McCull.) H. L. Jens. The infection did not influence⁸⁶Rb⁺ uptake per plant in the course of a 14-day-period following inoculation, however it did affect its distribution differentially in the S- and the R-plants.⁸⁶Rb⁺ uptake was significantly decreased due to the infection in the S-plants on the day 49 after the inoculation (a 4-h-exposure to⁸⁶Rb⁺), with the iona also being more slowly translocated to the shoots in diseased S-plants than in diseased R-plants. Likely factors causing these effects and their relationship to alfalfa resistance to the bacterial wilt are discussed.