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.

The apical dominance in dormant tubers ofCircaea intermedia preventing the extension of lateral buds under favourable conditions differs from the apically directed growth inhibition inducing true dormancy in the tubers. This acropetal inhibition affects the tuber tip more strongly than its lateral buds, which develop into long stolon-like shoots after the tuber decapitation. The local supply of ABA shows no tuberizing effect, but enhances the dormancy of the tuber top. MH interrupts the correlation between the tuber laterals tuberizing without previous stolon formation. The uppermost leaf structures participate in the apical dominance, inhibiting their own axillaries on intact tubers. Mature scales disclose this correlative influence only on decapitated or dissected tubers on which IAA or BA release their inhibitory effect, but ABA increases it. Two scale pairs occurring regularly at the top of dormant tubers and seen later at the erect base of the stem are involved in the initiation of foliage leaves for the next-year growth period. BA applied to an axil at the top of the tuber provokes its sylleptic branching.

A test in vivo has bean realized by the author to measure the systemic activity of a fungicide.

Minimal diffusive resistances of both leaf epidermes increased during normal and retarded ageing (moving secondary leaves aside, plant decapitation). The retarded ageing of primary leaves slowed down increase in epidermal resistance (r_ep), and was also reflected in the prolongation of their growth, increase of leaf area, size of epidermal and guard cells and stomatal pores. Decrease of stomata density was to some extent balanced by an increase in the pore size; the later rapid rise in diffusion resistance was induced by the loss of stomata ability to open fully.

The nucleic acid (NA) fractions were analyzed in cotyledons and apical buds ofChenopodium rubrum plants by means of acrylamide electrophoresis at the end of the dark period of a different number of photoperiodic cycles or after transfer of the plants to light for 4 h subsequent to the termination of the dark period. The plants were labelled with³²P three hours prior to sampling. The uptake of³²P into the cotyledons was higher in light than in darkness in all cases, however, it was not in correlation with³²P incorporation into the NA fractions. After one dark period lasting 8 or 16 h NA synthesis in light did not increase in comparison with darkness. After two or more photoperiodic cycles NA synthesis was higher in light than in darkness irrespective of whether the dark period lasted 8 or 16 h. NA synthesis was distinctly highest after two inductive cycles lasting 16 h. In buds NA synthesis was slightly shifted in favour of ribosomal RNA as compared with cotyledons. In the cotyledons the increase in light was mainly duo to a raise of rRNA synthesis whereas in the buds synthesis of sRNA and DNA increased, as well.

2.5 cm long etiolated stem segments ofPopulus nigra did not root at all in water or in IAA alone, but rooted in glucose + IAA. 5-Fluorodeoxyuridine (FUDR), 5-Fluorouracil (FU). actinomycin-D and cycloheximide all inhibited rooting, the inhibitory effect of each increasing with concentration and being more marked in glucose than in glucose + IAA. The inhibitory effect also decreased with the delay in the application of cycloheximide. The DNA, RNA and protein contents of segments grown in IAA + glucose where rooting occurred were higher than in water or in IAA + glucose + cycloheximide/or + aetinomycin-D where rooting did not occur. Auxin in the presence of adequate amount of carbon nutrition increases the fresh production of protein and that the magnitude of rooting is determined by the size of protein pool that is available in tho tissue at the time of root initiation.

Between the electric impedance of the roots of healthy apple-trees and that of apple-trees infected with the proliferation disease there were highly significant differences at the beginning of November. However, the results were not necessarily the same in all roots of the same plant, but varied according to the extent of infection.

Garex packystylis, native of Israël, has been compared in arid zones of Israël and in France under phytotronie conditions. Especially its drought resistance has been studied. Once root formation has stopped through drought action, the shoot apices situated on the rhizomes which are well protected by layers of dry scales, become active and form leaves above the ground when the plants are once again in favorable growth conditions. There is also reumption of the basal growth of leaves incompletely dessicated from the top.

Both nitrite reductase and nitrate reductase were induced by nitrite, but there were differences in the time course of induction and in the response to different NO₂^- concentrations between these enzymes. NH₄⁺ depressed the induction of nitrite reductase. NADH₂ dependent glutamate dehydrogenase activity was enhanced by those NO₂-concentrations in the medium at which unmetabolized NO₂^- occurred in the roots. NADPH₂ and NAD+ dependent GDh activities were not affected. In vivo modification and (or) in vivo activation were probably responsible for the increase in NADH₂ dependent GDH activity.

The course of biological curves of accumulation of total (Y_biol), vegetative (Y_veg) and grain dry matter (Y_gr) in maize(Zea mays L.)was investigated in a field experiment. The different population densities from 27 777 to 121 418 plants per ha were tested in interaction with increasing fertilizer rates (NPK) ranging from zero to 780 kg of pure nutrients per ha. The grain yield (F_gr) plotted against the population density shows a parabolic trend with a maximum at densities from 64 000 to 79 000 plants per ha. An asymptotic trend was obtained for the curve of biological yield (F_biol) in relation to the population density. The optimum densities for Y_gr and F_biol were identical in the unfertilized control plot. At optimum and higher population levels the application of optimum rate of pure nutrients was 260 kg per ha. Leaf area index(L) was rising with the increasing stand density. Its value was also increased by increasing mineral nutrition but only at plant densities higher than 64 000 plants per ha. The proportion of Y_gr/ Y_biol showed an optimum atL value within 2.03 and 2.68. Its value declined with further increase of both, stand densities and levels of NPK. The optimumL estimated for Y_gr was within 2.65 and 3.87 and that for Y ol in the control variant was 2.65. Tn fertilized plots even the highestL values (5.17) did not influence neither the biological nor the vegetative dry matter yields. Relative photosynthetic potential for dry matter formation (RPP_gr) was decreasing with the increasing stand density.

By modifying the auxine-cytokinine ratios and with or without the addition of sugar, it is possible to direct neoformation in stem and leaf fragments ofTorenia fournieri towards the production of roots only or buds only; the buds either remain vegetative or become floral according of the treatment.

The morphactin - chlorflurenol at 1, 5, 25, 125 and 625 μg/plant either caused total damage of the shoot apices or allowed a few inflorescences to develop with few or no flowers. The inflorescences arising in the lateral branches showed suppressed bracts and modified flowers. With time the treated plants recovered and showed a significant increase in the growth of laterals and the number of inflorescences. Thus morphactin can be used for prolonging the growth period and for obtaining more wholesome plants.

Mutagenic activity of N-ethyl-N-nitrosourea (ENU) and of N-methyl-N'-nitro-N--nitrosoguanidine (MNG) in lentil was studied. The highest proportion of segregating progenies with chlorophyll mutants and chimeric plants was 34.8% from the total number of analysed offsprings, ENU being applied in this case in the concentration of 0.005% for 20 h at 18 to 19 °C. When MNG was applied in the concentration of 0.001 % for 10h at 22 to 23 °C the proportion was 5.1%. Progenies segregating two or more chlorophyll mutants originated with ENU only; their relative frequencies varied from 1.4% to 7.1%. The number of different types of mutants or of their combinations segregating at the same time in the same progeny was shown to be dependent with the two agent tested on the mutagenic activity of the concentration used. The most efficient concentration of ENU induced the total of 8 different mutants at the same time, together with a combination of two or three mutant types in the same progeny. With MNG no combination of chlorophyll mutants in the same progeny was ever found simultaneously. The greatest number of mutants corresponding to 1 progeny M₁ was 0.53 when ENU was applied; with MNG the maximum values were approximately ten times lower. The maximum number M₂ of chlorophyll mutants and chimeric plants was 3.58% with ENU and 0.23 with MNG.

The efficiency of the geocontrol system of pea and. maize roots was compared on the basis of their oscillation movements. The rate of elongation of maize roots is 3.6 times higher, the amplitudes of oscillation deviations are 10 times lower and their frequency is 5 times lower than the corresponding values recorded for pea roots. The period of time which elapses between the stimulus and growth response, i.e. the geotropic reaction time, is 4 times shorter in maize roots than in pea roots. The maize root is able to correct the direction of its elongation 3.5 to 5 times more frequently than the root of pea. This characterize the difference between the both compared control systems from the point of view of physiological economy.

In the course of the study of the effect of allylisothiocyanate in a 10^-4 dilution on the mitosis ofPisum sativum root tips, some cells with typical meiotic configurations were found. After 92 h of treatment about 2% of the dividing cells were in the state resembling a so called somatic reduction.

The spread of mycoplasma causing potato witches' broom disease from infectious grafts of both tomato and tobacco plants intoNicotiana glauca Grah. plants is much slower than that into tomato plants. An earlier infection inN. glauca stock plants appears when infectiousN. glauca grafts are used. On the other hand, the process of infection proceeds very slowly when using infectious tomato grafts and in some cases the infection is not realized even after three months of graft symbiosis. The authors suppose that mycoplasma has a preference for tomato plants.