The association between latex RNA and latex production was examined using MAK column chromatography techniques. In young untapped trees the introduction of tapping or the treatment of bark with growth regulators resulted in an increase of RNA level and of rRNA/tRNA ratio in the latex. In regularly tapped trees an increase in rRNA but not in tRNA was brought about by increasing the tapping frequency. Treatment with growth regulators had the same effect but essentially only through the related enhancement of latex export from latex vessels. During latex flow, the highest RNA level was registered in latex fractions originating from the most heavily drained areas of bark. Using³²P labeling, evidence was obtained that the export of latex results in an enhancement of rRNA migration into the inner latex containing space of the vessels. This is considered as the reason of the generally observed association of high RNA level and of high rRNA/tRNA ratio with high latex yield. It is proposed that in controlling the RNA level and RNA proportions in the latex an important role is played by changes in turgor pressure associated with the loss of latex which may influence the export of RNA from the nucleus through related induction of pressure disequilibrium between the nucleoplasm and the latex cytoplasm.

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

The dependence of ethylene production and respiration rate on the concentration of gibberellin (GA) applied in water emulsion of lanoline to young fruits was studied in Yellow transparent apples. Ethylene production and respiration rate were slightly increased by GA treatment. The increased level was maintained throughout the entire ripening period, which was also apparent from the total amount of both released gases. A gas-chromatographic method, using a flame ionization detector for simultaneous determination of ethylene and CO₂ in the atmosphere of experimental biological containers, is described in this paper. CO₂ is hydrogenated to methan on Ni - ThO₂ catalyst by hydrogen which is used as carrier gas. The gases pass the hydrogenating reactor after the separation in the Chromatographic column before entering the detector.

The cytokinin activity of a group of derivatives of N-n-butyl-N'-arylthiourea and their effect on the uptake of amino acids and the accumulation of total nitrogen in seven-day barley seedlings have been investigated. It was established that N-n-butyl-N"-2,4-dinitrophenyl-thiosemicarbazide, N-n-butyl-N'-o-,m- andp-chlorophonylthioureas, N-n-butyl-N'-3,4-dichlorophenylthiourea and N-n-butyl-N'-2-methyl-4-ehlorophenylthiourea possess a high activity with respect to the retardation of the chlorophyll breakdown. Substances with a high cytokinin activity cause an increase in the amount of total nitrogen and amino acids, mainly of glutamic acid, aspartic acid and serine in the roots and loaves of seven-day barley seedlings.

Metabolism of dry mungbean seeds(Phaseolus aureus) was compared with that of 3 h imbibed ones. Respiration rates sharply increased upon imbibition which was accompanied by large water uptake. Storage protein was degraded resulting in the rise in soluble nitrogen. RNA and water soluble protein content increased but DNA declined. It is suggested that some of the soluble nitrogen pools are diverted to RNA formation which in turn produce enzyme protein. In mungbean seeds imbibition of water thus triggers a series of metabolic changes within 3 h with the respiratory energy as the driving force.

A study was made on certain problems connected with the application of methods of stigmatal and placental pollinationin vitro in the snapdragon.
Germinable pollen without microbial contamination could be obtained only from the flowers which were left, after surface sterilization, on the stem till the dehiscence of anthers. The germination of pollen, and especially the growth of pollen tubes was better in a 0.3 M lactose solution with 10^-3 per cent H₃BO₃ than in usual sucrose media.
The seedsin vitro could be obtained only after normal pollination and the successive artificial cultivation of the entire pistil (the method of stigmatal pollinationin vitro). The seeds did not differ either in their morphology or in their size from those developed under natural conditions, they were viable and without dormancy.
Though the pollinated pistils were cultivated in the medium without growth substances, callus formation from uncovered ovules and placenta was observed in some cases. A dependence was revealed of the proliferation on pollination and on the cultivar employed.
When using the method of placental pollinationin vitro we failed to obtain seeds. The main difficulty in the use of this method seems to consist in the fact that pollen tubes are not capable of growing from the surface of ovules and placenta into the micropyle.

The relationship between the water potential (Ψ_w) and the water saturation deficit (Δ W_sat) in kale and maize leaf tissue was measured during dehydration and resaturation either of leavesin situ or of cut leaves. The curves relating Ψ_w toΔW_sat were similar in all variants, but at the same values ofΔ W_sat corresponding values of Ψ_w were always lower in leavesin situ than in cut leaves and during dehydration than during resaturation.

The effects of temperature treatments on rice seeds in the early imbibitional phase were studied with respect to changes in germination percentage, seedling growth in terms of root and shoot lengths, water uptake, respiration and hydrolytic enzymes,viz. α-amylase, adenosine triphosphatase (ATPase) and phytase. As compared with the control, the treatment for 30 min at 50 °C caused a variable degree of increase in all these characters and a positive correlation existed between seedling vigour and hydrolase activities. The treatment for 30 min at 60 °C, on the other hand, elicited a retarding influence on these characters. As regards the enzyme activities, the damaging effect of 60 °C could, however, be visualized only after 72 h of germination which was preceded by an enhancement during the early hours.

A fully normal meiosis was found inAllium sativum L. by means of PMC analysis. Quadrivalents were formed only in several cultivars. The cultivation of inflorescence stem (after the exstirpation of bulblets) in a tetracycline solution of 900 i.u. induced a formation of fertile flowers. The first pollen mitosis was studied and the pollen parameters compared with those ofAllium cepa L. Evidence for the pollen sterility was given by crossings on sterile types. A microbiological factor was not isolated.

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

The high M₁ sterility is the factor limiting the increase of the mutation frequency after treatment with nitrosamides like N-methyl-N'-nitro-N-nitrosoguanidine, N-methyl-N-nitrosourea, N-methyl-N-nitrosourethane and N-ethyl-N-nitrosourethane, whereas for ethylvinylnitrosamine-treatment the limiting factor is the toxic action on the M₁ seed germination. The decrease of mutation frequency at high dimethylnitrosamine doses is explained by the inhibition of enzymes or enzyme-like system which hydroxylate nitrosaminesin vivo and thus enable the production of a mutagenic alkylating intermediate. The increase of mutation frequency after treatment with X-rays is limited both by the decreased M₁ survival and M₁ fertility.

Three strains of three different species of chlorococcal algae(Chlorella kesslerii Scenedesmus quadricauda andScenedesmus obliquus) were compared in their physiological and genetical responses to N-ethyl-N-nitrosourea (NEU). The mutagen was applied in the basic doses corresponding to their specific tolerance to it. Exponentially-graded doses derived from the basic ones acted for the same period of time and single basic doses acted at linearly-increased periods of time in parallel experiments. The influence of the mutagen on the cell cycle just in progress was characterized by the increase in the frequency of cell divisions which yielded a lower number of autospores. The conditions of the cells during the first three days after treatment were determined according to the average increase of their lag phase. The relative toxicity of the mutagen was expressed as the survival frequencies. The mutation effects were evaluated according to the frequency of permanent changes observed in the growing cell colonies : lethal, morphological and pigmentation. NEU was found to be a relatively suitable mutagen for the chlorococcal algae studied.

In contradiction to Paulet's (1965) data, we found that kinetin/IAA strongly affected organogenesis in callus tissue derived from the stem ofNicotiana glauca Grah. plants both in primary expiants and in subcultured calli. The effect of these substances was higher in the subcultured calli derived from mycoplasma-infected plants. Evidence of the absence of the infectious agent in de novo-formed plants in subcultured calli was given by grafting and by the electron micrograph.

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

Negative linear correlations were established inMagnolia soulangeanaSoul. -Bod. andLigustrum vulgare L. leaves between the frequency and the size (length) of the stomata and between the frequency of the stomata and the area of epidermal cells. Most correlations were statistically significant at theP = 0.01 level. Positive linear correlations were established between the area and the thickness of epidermal cells. These correlations were near to theP = 0.05 level of statistical significance. A high variation coefficient "v%" of the total number of stomata per leaf was found in both plant species.

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

Two plants which were sectorial chimeras in the two tested characters,i.e. in the length of stomata and their frequency, were found among the 17 individuals regenerated from the stem pith of the same marrow stem kale plant. The chimeral character was also expressed in the size and variability of pollen grains and in the number of colpae in their exine. The different ploidy of sectors (2n, 4n) was confirmed cytologically.

Embryo development in cultured wild carrot tissue was studied by considering the relationship between DNA biosynthesis and embryo morphogenesis. Autoradiographic data of^3H-thymirdine incorporation indicated a higherpercentage of cells undergoing DNA synthesis in adventive embryos than in proembryonic masses. A definite pattern of DNA synthesis was observed during the transition from a proembryonic mass to the torpedo stage of embryogenesis. In particular the labeling pattern for both the heart and torpedo stages was found to be coincident with specific morphogenetic events.

A new method of sap flow rate determination in stems of adult trees is described in which mass flow (the transpiration flux in the present case) is estimated from a heat-transfer measurement. The device used includes a couple of thermometers in a differential connection and plate electrodes, through which a controlled heat input flows into a denned studied segment of the xylem. The present method was tested first with a laboratory simulating system, then with the stem of a living adult treePrunus avium L. The data are registered continually and automatically; continuous measurement of sap flow rate of long duration with a greater number of trees is thus made possible.

The successive staining alcian blue/aluminium lake of nuclear fast red was proved a useful tool for studies on plant root tip. A simple and reliable procedure is given resulting in blue cell walls, almost colourless cytoplasm and red nuclei. Attempts were made to apply spectrophotometry and paper chromatography to overcome the confusions in manufacturers' labelling of the dye and to check the lake formation.

The segregation of a protein (designated as protein I) was studied in interspecific hybrids ofPhaseolus coccineus x Phaseolus vulgaris. A single locus difference is suggested similarly as in intraspecific hybrids.

Anaerobic conditions, the inhibitor of aerobic respiration-sodium azide and the inhibitor of proteosynthesis-chloramphenicol did not influence the increase of toxic and mutagenic effects during the storage of ethyl methanesulphonate-treated barley seeds at 15 per cent water content.
The storage of ethyl methanesulphonate-treated seeds at - 20 °C or at 0 °C avoided all after-effects. With increasing storage temperature (5 °C, 15 °C and 25 °C) the increase of injury due to storage was more pronounced.

Evidence for the occurrence of a substance closely resembling acetylcholine inPorophyllum lanceolatun DC is presented. Its concentration in terms of acetylcholine estimated by biological assay was 0.1 ± 0.02 μmol g^-1 fresh weight of leaf.

Changes in IAA-level during the mildew pathogenesis (Erysiphe graminis f. sp.hordei Marchal) were observed in a resistant barley cultivar "Professor Schiemann" using thin-layer chromatography and biological Avena-test. A decrease in IAA-level occurred on 4th day after the inoculation by parasite, compared with control. On the sixth day, the level of IAA was remarkably increased. During further development, the IAA-level rested, on the whole, without any changes.

Water potential of roots was measured by thermocouple psyohometers in a series of two or more plants ofCynodon dactylon (L.)Pers. interconnected by overground stolons and thus forming one s.c. polycormon. Root water potential was lowest (most negative) in the oldest "mother" plant and increased in younger individua to highest walues in the youngest "doughter" plants. This gradient of root water potential was found although the "mother" plants continued to be watered while watering all daughter plants had been stopped one week before the water potential was measured. Thus the whole polycormon consisting of a series of interconnected individua behaves as one hydrodynamic system where all individual root systems act as if being parts of one sole root system.