Tartaric acid is synthesized on light in the leaves ofTamarindus indica L. and is translocated to the flowers during flowering seasons. The translocation of this acid to fruits keeps peace with their growth rate. The decline of the tartaric acid content per unit fresh weight in mature fruits is not due to their utilization or conversion, but largely due to the setting up of the seeds which are devoid of any tartaric acid. Tartaric acid content in both the leaves and fruits show variation in different seasons, while malic acid does not show any change excepting a small increase in March.

The study deals with the distribution of non-specific esterase in germinating pollen grains ofPortulaca grandiflora. Intense activity of the enzyme is seen in small granules distributed homogeneously in pollen grains stigma hairs and throughout the length of pollen tubes. Further the walls of pollen grains also demonstrate intense activity. The functional significance of the enzyme in these locales has been discussed.

Leaf angles, frequency distribution of leaf area inclinations, leaf area index, amount of intercepted radiation, biological, vegetative and grain yields and grain yield proportion of biological yield were determined in maize stands of two population densities, 55 555 plants ha^-1 (S₁), and 80 000 plants ha^-1 (S₂). Also the effect of the artificial change of leaf angle upon these indices was studied. We classified normal maize stand (N) as the interstage between a planophile and a plagiophile type of canopy, that with artificially changed leaf angle (V) as an erectophile type of canopy. The relative interception of the incoming radiation in the variantsV S₁ andV S₂ was lower than in the variantsN S₁ andN S₂. The variantsV in comparison with variants N increased grain yield and biological yield.

The interaction between exogenous 2-chloroethylphosphonic acid (Ethrel, CEPA) and auxin (both native and synthetic-IAA) was studied on pea and bean seedlings, potato tubers, and processed flax plants. After the addition of ethrel the inhibiting effect of IAA was decreased in all objects and it was found that the concentration of the growth of the regulators played an important role. The growth response of a part of flax hypocotyl, as induced by exogenous auxin produced in the cotyledon, was reversed by ethrel, too. The application of ethrel on the epicotyl apex in beans resulted in the lost of apical dominance of epicotyl and in the growth of lateral buds together with the epicotyl. When stimulating the growth, ethrel reverses the inhibitions through the decrease in the auxin content (from an inhibiting, supraoptimum level to an optimum one which already stimulates growth). In objects with a low content of endogenous auxin the ethrel induced the decrease in the auxin content and shows an inhibiting effect on growth.

Lactate as well as ethanol is formed in seeds of soybean, maize, pea, bean, lentil and broad-bean in the course of germination during the so-called natural anaerobiosis. After 0 to 30 h of germination a concentration peak of lactate appears. Maximum in ethanol content is found after 40 h. The amount of ethanol is higher big more than one order of magnitude as compared to the amount of lactate. Both products of anaerobiosis occur in germinating seeds irrespective of the type of reserve substances.
In contrast to alcohol dehydrogenase lactate dehydrogenase (EC 1. 1. 1. 27) is present in the dry seeds too. Its activity decreases during the first 12 h of germination. It is in this stage that its substrate, lactate, is usually present at a maximal concentration. During the later stages of germination the amount of lactate decreases and enzyme activity rises. There exists a reciprocal relationship between enzyme activity and substrate concentration. In the case of alcohol dehydrogenases (EC 1. 1. 1. 1) the maximum concentration of ethanol precedes the peak of enzyme activity.

The dependence of the frequency of recessive lethal (two groups), chlorophyll and morphological mutations on the mutagen concentration was determined in M₂ after subjection to N-nitroso-N-methylurea applied to seeds ofArabidopsis in three concentrations (0.05, 0.10 and 0.20mm). The observed frequencies were compared with the theoretically expected ones for the linear and for two exponential types of dependence, by using the t-test, according to the formulas m=k. C, m=k. C^3/2, m=k. C². No satisfactory agreement with any expected type of dependence was found when directly observed frequencies were used. Since a considerable deficit of mutation frequency was observed in high concentrations, the correction of frequency values was done with respect to the probability of occurence of double mutations. After such a correction, a clear exponential relation was found in both types of lethals and a linear one in chlorophyll and morphological mutations. The probable occurence of multiple mutations should be, therefore, taken into account if the dependence of mutation frequency on the concentration of mutagen is discussed.

The homogenate of different strawberry organs inhibits the degradation of IAA in the presence of horse radish peroxidase, while intact strawberry tissues are able to degrade IAA. The chemical nature of peroxidase inhibitors present, in strawberry tissues was in vestigated. Using paper chromatography the following polyphenolic substances inhibiting peroxidase activity were identified: chlorogenic, caffeic, ellagic, gentisic, gallic, and vanillic acids, quercetin and pelarginidin. Monophenolic compounds, also present in strawberry, such as p-hydroxy-phenyloacetic acid and p-hydroxybenzoic acid, are strong stimulators of IAA oxidase. Abscisic acid in very high concentration (1×10^-4M) enhances degradation of IAA by peroxidase.
When both poly-and monophenolic compounds at equimolar concentrations are present in the system, only the inhibition of IAA degradation occurs.
Tissue explants from the strawberry leaves and petiole degrade less IAA if they are previously forced to synthetize more polyphenols under illumination. Although the difference in IAA-decarboxylation activity between the illumination and dark treated explants was relatively small, nevertheless it was consistent and appears to be very important from a physiological point of view suggesting that there exists a regulatory relationin vivo between IAA degradation and the presence of phenolsin plant tissue.
Electron microscope data revealed that phenolic substances are specially isolated from cytoplasm of the receptacle cells.

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.

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.

In pumpkin plants suffering from calcium deficiency growth of the root system is characteristically suppressed. A biochemical symptom of calcium deficiency is a decrease or even complete disappearance of activity of one of the isoperoxidases (isoperoxidaseD). In the present study the two characteristics were used to compare the effects of calcium deficiency and of IAA in the supraoptimal concentration of 10^-5 M. Peroxidases were separated by centrifugal fractionation: peroxidasesA andB were found in the sediment corresponding to the mitochondrial fraction, peroxidaseD in the supernatant. It was not possible, however, to obtain the sediment completely free of peroxidaseD. A negative correlation between the activity of isoperoxidaseD and the logarithm of concentration of IAA in nutritive solution was found and similarities in the effects of IAA in supraoptimal concentration and of calcium deficiency on the development of root system were demonstrated. Still, it would be difficult to imagine that the mechanism of the action of the two factors is the same. For this reason, a scheme of possible interactions was suggested with the aim to explain how similar changes in the content of isoperoxidases are brought about by the two factors. In this scheme, calcium is considered chiefly as a substance regulating membrane permeability.

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.

The changes n dry weight and in the content of sugars and starch of leaves of the evergreen species Prunus laurocerasus L. were studied in the field and in laboratory conditions. The leaves of field-grown bushes as well as those kept under controlled conditions were analyzed at one week intervals at the end of the winter and in early spring from March 11 to May 6, 1970, The effect of four different temperature regimes was compared (day/night) : A : - 2 to - 6 °C/ - 6°C. B: 6°C/ -6°C, C: 6 °C/6 °C and D: 12 °C/ - 6 °C. During the whole experimental period of 56 days a net increase in dry weight 246.84 mg dm^-2, i.e. 21.7 % was found under field conditions. A negative balance in assimilate management was recorded only during the one week period. The total content of sugars decreased from 11.68 % to 6.42 % while the content of starch rose from zero to 3.12 %. The net increase in dry matter found under controlled conditions was 6.69 (A), 4.68 IB). 6.88 (C) and -0.43 (D) mg dm^-2 d^-1.

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.

When aerated suspensions of whole yeast cells were either made anaerobic or were supplied with substrate (glucose), changes in absorption occurred which indicated cytochrome reduction. No such change was observed on addition of substrate to anaerobic suspension of yeast. These results were confirmed by obsevations of changes in absorbance at a series of fixed wavelengths corresponding to the reduced absorption peaks of cytochromesa, b andc. NAD* on the other hand was reduced on addition of substrate under both aerobic and anaerobic conditions. These results are discussed in relation to the possible role of NAD* in the Pasteur Effect.

Beginning with the second inductive cycle the rate of nucleic acid (NA) synthesis in cotyledons and apical buds ofChenopodium rubrum is higher at the end of the dark period or 4h following transfer of the plants to light in induced plants than in non-induced ones. This is due to an increase in all NA fractions. The greatest difference between NA synthesis in induced and non-induced plants was observed at the end of the second (or sometimes third) inductivecycle. In the subsequent cycles the difference decreased or disappeared eventually. During photoperiodic induction NA synthesis shows a diurnal rhythm with a peak at the end of the dark and at the beginning of the light period. Rhythmicity of NA synthesis is endogenous. The period length of the endogenous oscillation is about 18 h. Interruption of the dark period by light causea amplitude of the first oscillation to be reduced and delays the appearance of the second peak. NA synthesis did not show rhythmicity in plants grown in continuous light. The significance of the observed phenomena for photoperiodic induction is being discussed.

A procedure was developed for satisfactory freeze-sectioning of root tips. The use of Ca formol-fixed material kept and frozen in Holt's syrup is recommended. The existence and different localization of 2 fractions of non-specific esterase was verified in root tips ofVicia faba. The same results were revealed in fixed and unfixed material. The dynamics ofin situ reaction was followed with respect to optimal incubation time. The results with substrates of different chain length support the existence of 2 fraction of the studied enzyme, none of which, concerning substrate specificity, is a lipase. It follows from the present studies inVicia faba and other species (Cucurbita pepo, Lupinus albus, Pisum sativum Zea mays), that non-specific esterase localization is not directly given by histogenesis.

Two typical dark-responses namely the excessive elongation of sprouts and the formation of sprout hook, are adversely affected by chloroflurenol. It also affects the polarity of sprouts and the formation of roots on tubers, the effect varying with the concentration and the light condition. The significance of these effects of chloroflurenol used in potato production has been discussed.