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.

Auxins (NAA, IAA) inhibited the seed germination of lettuce cv. Cabbage. The auxin-indueed inhibition of seed germination could be overcome if 2-chlorethanephosphonic acid (CEPA, ethrel) or kinetin was added simultaneously. Thus ethylene can also modulate the action of endogenous inhibitors in seed germination.

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.

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.

The site of anaerobic respiration in the latex is the serum. The main respiratory substrate is fructose. The CO₂ formation in serum is increased by additional fructose on the average about 2.5-3 times. Glucose does not influence CO₂ evolution by serum but slightly increases O₂ consumption.
With respect to sugars, latex serum contains essentially only sucrose and a low amount of raffinose. During the incubation of serum sucrose is hydrolysed, the fructose component is immediately utilized in respiration and glucose accumulates.
The rate of CO₂ formation in latex as influenced by fructose is negatively related to the rubber content of the latex. Latex with a high rubber content reacts only slightly or not at all on additional fructose.
The main limiting factors of latex respiration and sugar utilization are the following:
1. The deficiency of substrate, due to low activity of β-fructofuranosidase.
2. The rate of glucose phosphorylation (D'Auzac, Jacob 1967).
3. Presumably the low activity of phosphoglucoisomerase.
4. The rubber content of the latex.
5. The concentration of CO₂ in latex; this factor may be important in vivo, in the laticiferous system.

Deformities of leaves induced by 2,3,5-triiodobenzoic acid (TIBA) may be helpful in elucidating certain plant growth correlations. The different behaviour of long and short shoots as regards apical dominance may be tested with this substance. Shoots growing out through ring fasciations first form leaves lacking the teeth and marginal primordia corresponding to bud scales. Are fasciations facilitate correlative studies on anisophylly. Sylleptic branching is cleared by additional fasciations provoked by the cytokinin supply. The effect of gibberellin which decreases these deformities corresponds to the correlative influence of roots. The TIBA induced modification of aerial roots on internodes treated with naphthalenacetic acid reveals the importance of polarity and periodicity in the shoot development.

Five mm sections excised from 20, 30 and 40 mm long coleoptiles were transferred into a indole-3-acetic acid (IAA) solution after an incubation in a medium containing buffer and sucrose without IAA. The ability of sections to elongate in dependence on IAA treatment was rapidly decreased at a temperature of 23 °C within a period of time depending both on the duration of incubation and on the age of coleoptiles from which sections were obtained. Under the same conditions of incubation and age the same decrease of the ability of sections to elongate at 4 °C was, however, observed only after a period fourfold longer than at 23 °C. Incubation of sections in the presence of benzimidazole did not extend their reactivity to IAA. This phenomenon may be therefore considered as a senescence reaction which is more effective at 23 °C than at 4 °C.

The employment of the classic stand density experiments in studies of the horizontal organization of plant stands is very laborious and requires a large experimental field area. The procedure based on the regular thickening of plant stands is more convenient for plants grown in a lower density. A simplified modification of this method is described which keeps a constant square nutritional area regardless of the plant densities.

The effect of CCC and GA₃ on the growth and development of spring wheat (Triticum aestivum L.) cultivated under predominantly red (500-700 nm) or blue (400-500 nm) light was investigated. Red light enhanced the development of wheat during the exponential phase of growth. This effect presumably implicated the promotion of gibberellin synthesis under red light. The strong inhibitory action of CCC under red light (the inhibition was lower under blue light) might be interpreted in a similar way. The growth became more intensive under blue light after caring and was accompanied by increased susceptibility to giberellic acid treatment.

Barley seeds were treated with ethyl methanesulphonate (EMS), washed for 24 h, redried to 15 per cent moisture and stored at 25°C. The criteria used for expressing the effect of storage were chromosomal aberrations in root tips, M₁ germination, M₁ seedling height, M₁ survival and the frequency of M₂ chlorophyll mutants. The increase of the M₁ biological injury due to storage was not influenced:
a) by applying EMS solutions at pH 2, pH 7 and pH 10,
b) by lowering the EMS concentration and increasing the treatment time,
c) by different variations of washing with water and by washings with 0.005 N NaOH, 200 mM cysteine or 200 mM thiourea. The rate of the increase of the M₁ injury due to storage depends on the EMS dose. With a decrease in the EMS dose the storage effect is more delayed.

Nitrate reductase (NO₃R) activity, nitrite reductase (NO₂R) activity and NADH₂ dependent glutamate dehydrogenase (GDH) activity were followed in extracts from excised pea roots incubated under aseptic conditions for 9 and 24 h in nitrate containing nutrient medium to which IAA was added in concentrations promoting lateral root formation (1 × 10^-5; 3 × 10^-5; 5 × 10^-5 M) and kinetin in concentrations which reduce lateral root formation (0.1; 1; 5 mg 1^-1, that is 4.65 × 10^-7;4.65 × 10^-6 and 2.3 × 10^-5 M). NO₃R activity was not influenced by IAA, NO₂R activity was slightly depressed by IAA after 24 h incubation and GDH activity was slightly increased after 24 h incubation in the presence of IAA. Kinetin decreased NO₃R activity significantly both after 9 h and 24 h incubation, slightly increased NO₂R activity after 9 h incubation but slightly decreased it after 24 h incubation, and did not affect GDH activity after 24 h incubation. However, when applied together with IAA, kinetin abolished the promoting effect of IAA on GDH activity. IAA neither reversed nor accentuated the effect of kinetin on NO₂R activity. Nevertheless the depressing effect of kinetin on NO₃R activity was emphasized by the presence of IAA after 9 h incubation. The results obtained indicate that reduced nitrate assimilation due to the depression of nitrate reductase activity caused by kinetin probably contributes to the negative growth effect of kinetin in pea root segments grown in nitrate medium.