All the concentrations (25-150 mgl-¹) of the phytohormones kinetin, IAA (indol-3-ylacetic acid) and GA₃ (gibberellic acid) increased the activity of DCPIP (2,6 dichlorophenolindophenol)-Hill reaction, chlorophyll and protein contents over the control data in leaves ofSechium edule Sw. on Darjeeling hill of the Eastern Himalayas; while ethrel (2-chloroethylphosphonic acid) treatments decreased these parameters in the hilly species. The most effective concentrations in increasing these parameters were 50 mg 1-¹ of kinetin, 50 mg 1-¹ of IAA and 100 mg 1-¹ of GA₃; whereas 50 mg 1-¹ of ethrel was most effective in decreasing these parameters during the induction of senescence in the hilly vegetable crop. The increase in these parameters was greatest with kinetin, followed by IAA and least with GA₃ in the hilly plant species studied.

Lycopersicon esculentum cv. Linia XXIV (L) and cv. Ostravské (O) was infected withAgrobacterium tumefaciens T37 (pTiT37). 37 L tumors and 33 O tumors were isolated. 13.5 % L tumors and 3.0 % O tumors regenerated shoots producing nopaline synthase. The shoots formed roots after transfer on R3B medium without phytohormones. From 10 primary shoots 35 plants cultivated in an unsterile soil were obtained by cutting. 6 selfpollinated plants did not produce any fruits. Fruits obtained through backcrossing had dramatically reduced seed numbers. The same is true of some other transformed plants with nearly normal pollen. Most transformed plants were susceptible to superinfection withA. tumefaciens T37 and B6-806. The incorporation of T-DNA into plant genome seems to cause not only male sterility, but also some kind of female sterility.

The study of in vitro growth of Crepis tectorum revealed 100 % callusing and 40 % plantlet regeneration. The root and leaf used as explants showed the normal diploid (2n=8) chromosome constitution. In one month old culture 95 % callus cells were diploid. The callus maintained in 2,4-D 1 mg 1-1 for two years showed 62 % diploid, 5 % tetraploid and 33 % hyperdiploid cells. The differentiation of shoot occurred in two year old calli after subeulturing in 2 mg I-1 BAP and the potentiality of regeneration was retained for more than one year. The leaf-tips of regenerated plants were homogeneous and identical to the donor plant both in number and morphology of chromosomes.

The glycollate metabolism of wheat (Triticum vulgare Vill. cv. Sonalika) and rice (Oryza sativa L. ev. Jaya) leaves was studied during senescence by estimating the endogenous levels of glycollate and hydrogen peroxide (H₂O₂) and the activities of glycollate oxidase and catalase. In comparison with light incubation the incubation of excised leaves in the dark caused a decline in the glycollate content and in the activities of glycollate oxidase and catalase, and an increase in the H₂O₂ content, more marked in the leaves of rice than in the leaves of wheat. Glycollate oxidase activity gradually decreased with incubation time, and glycollate metabolism decreased during senescence. The glycollate oxidase in particular and glycollate metabolism of rice were more sensitive to incubation time than those of wheat. Kinetin increased the glycollate oxidase activity and glycollate metabolism during senescence, while ethrel (2-chloroethylpho-sphonic acid) and ABA (abscisic acid) reduced these activities in both plant species.

Euphorbia pulcherrima, an ornamental plant, exhibits severe systemic viral infection. It grows vegetatively during summer and is dormant in winter. During the dormant period the buds on healthy stem cuttings remained dormant or rarely formed cyathia while the buds on virus-infected stem cuttings grew into leafy shoots and never became dormant. Quantitative estimation has revealed that breaking of bud dormancy in virus-infected stem cuttings may be regulated by markedly higher GA-like activity in them throughout the period than in their corresponding healthy stem cuttings.

Xylogenesis was induced in cultures of calli ofHaplopappus gracilis (NUTT.) A. Gray by metabolic shocks brought about by changes in nutrition. Xylogenesis was observed to occur in response to three changes in callus nutrition, caused by the following modifications of Eriksson's nutrient medium and culture conditions: i) omission of sucrose in the medium for 3 to 6 days and then transfer of the calli onto complete Eriksson's medium; ii) replacement of sucrose by 0.36*mol l_-1 xylose for the whole culture period; iii) omission of nitrogen sources(i.e. glycine and NH₄NO₃ omission and replacement of KNO₃ with equimolar KCI) for the whole culture period.
The induction of xylogenesis in response to nutritional stress inH. gracilis can be used as a suitable model system for research concerning plant cell differentiation.

The LpDH and NpDH activities in crown gall tumors incited byAgrobacterium tumefaciens strain C58 were followed in 7 plant species and 100 tumors were assayed in each experimental variant. The NpDH activity was found in 790 out of 800 crown galls observed. The LpDH activity was tested, after induction of tumors withA. tumefaciens strain B6-806 and 37400, in three experimental variants. The LpDH activity was found in 290 out of 300 crown galls. In the small fraction of the LpDH and NpDH negative tumors, the activity was possibly actually present, but it was below the limits of the sensitivity of the detection technique used.

Plant growth and seed yield of mung bean were studied in sand culture at different levels of NaCl [0, 50, 100, 150, 200, 250 mM] in the root medium. Results showed that both dry matter yield and seed yield of plants grown for 14 weeks at 50 mM NaCl and 100 mM NaCl were around 60 % and 25 %, respectively of those for plants grown in control solution. Higher concentrations caused wilting and necrosis of leaves. Very effective exclusion of Na and Cl from salt grown mung bean seed was observed with concommitant high accumulation of Na and Cl in the stem. It is speculated that mung bean plant stem may act as a 'sink' for NaCl during the reproductive stage of the plant growth cycle.

In the roots of 4-day-old pea plants germinated in unsterile soil from Rhizobium-inoculated seeds, a higher level of native IAA was determined than in roots of pea plants germinated in sterile soil from superficially sterilized seeds. The IAA level in plants grown from inoculated seeds increased markedly up to the age of 6 days of the plant, while in plants growing under sterile conditions it did not significantly change during the same period. Between the 6th and 10th days of the age of the plant, a decline in the IAA level was observed in roots of plante growing from inoculated seeds. It was not until after 10 days of age of the plant that the level of IAA in nodulated roots again increased.

The effect of several plant growth regulators on the number of tumors developing on potato tuber discs (Solatium tuberosum L. cv. Radka) inoculated withAgrobacterium tumefaciens, strain C 58 was studied. The plant growth regulators used in appropriate range of concentrations stimulated the formation of tumors byA. tumefaciens.
Naphthaleneacetic acid (NAA) was most active in concentration of 10^-4 mg ml^-1. Kinetin gave a biphasic response with optimal promotions of tumor initiation at 10^-4 - 2 × 10^-3 mg ml^-1. High kinetin concentration (10^-1 mg ml^-1) inhibited the formation of tumors completely. Indoleacetic acid (IAA) stimulated the initiation of tumors in the same range of concentrations as kinetin, except that very high concentrations did not inhibit but enhanced tumor formation. 2,4-diehlorphenoxyacetic acid (2,4-D) showed a biphasic response with maxima in 10^-4 mg ml^-1 and 10^-1 mg ml^-1. All the tumors scored for nopaline production showed nopaline synthase activity independently whether their formation was stimulated by l0^-1 mg ml^-1 IAA or they were initiated without any treatment by plant growth regulators.

The protoplasts of the moss Anoectangium thomsonii, isolated from protonemal cells underwent divisions in 48-72 hours on modified MS medium enriched with growth regulators, 2,4-D and kinetin, 10 % sucrose and coconut water (5 %). Subculture of protoplast derived cells in a medium of relatively low osmotic potential (5 % sucrose) produced dark green calli which could be maintained completely undifferentiated.

In short-term (1 h) uptake experiments GA₃(10^-5M) stimulated P_i uptake into maize root cortex cells by 28.7 %, Ethrel (10^-3M) inhibited it by 18.5 % and BA, IAA, and ABA were inactive. In long-term (5 h) experiments ABA remained inactive, GA₃ lost its stimulatory effect, and BA (5. 10^-6M), IAA (10^-4 -10^-5M), and Ethrel (10^-3 -5. 10^-4M) decreased P_i uptake. When the hormones were present only during 3 h preincubation ("augmentation") period ABA was inactive, GA₃ slightly raised and BA, IAA, and Ethrel slowed down subsequent P_i uptake.
BA(10^-7 -10^-5M) decreased xylem sap volume flow and P_i translocation. ABA in all tested concentrations (10^-8 -10^-5M) reduced exudation rate and P_i translocation, its effect declining with time. IAA effect strongly depended on concentration used and on application time and varied from strong inhibition to moderate stimulation of both volume flow and P_i translocation. GA₃ (10^-7M) slightly stimulated xylem volume flow but inhibited phosphate translocation. Ethrel (10^-4 and 10^-5M) increased both parameters, but P_i transloeation much more than volume flow. IAA, BA, and ABA influenced volume flow and P transloeation to the same extent leaving P_i concentration in the xylem sap unchanged. GA₃ and Ethrel influence P_i concentration in the xylem sap and it is thus probable that these hormones regulate release of phosphate ions into the xylem sap.

The analysis of growth and movements of seedling organs of kidney bean (Phaseolus vulgaris L.) provides a pattern of periodic phases of activity and relaxation. The existence of a central organ which would control the phase relationships, is not anticipated in the integrity of the plant. The cyclic activity of individual organs shows itself by growth associated with oscillation movements. One and the same organ may simultaneously accomplish oscillatory movements with a diurnal and ultradiurnal frequency. These rhythms originate during the organ development; the first pair of kidney bean leaves at first executes oscillation movements with a diurnal frequency and only after it is fully developed it exhibits a diurnal cycle with the photophil phase upwards and the scotophil downwards, the oscillations with an ultradiurnal oycle being maintained. The movements of the two leaves are synchronous, but there occur short sections with a desynchronous cycle. Simultaneously with these oscillations, in which the leaf petiole takes part, the adult leaf performs oscillatory movements perpendicular to the longitudinal leaf axis, the so-called side swings, controlled by periodical changes of the joint attaching the leaf blade. Their frequency is practically identical with that of the ultradiurnal cycle. Thus the periodic growth activity of the kidney bean results in growth oscillations passing in the diurnal cycle with a frequency of 0.043 rev.h^-1, their ascending and descending phases consisting of periodical ultradiurnal oscillations in cycles of 0.73-0.59 rev.h^-1. The epicotyl growth shows a similar pattern: into the basic diurnal nutation cycle with a frequency of 0.042 rev.h^-1 ultradiurnal oscillation cycles are incorporated having a similar frequency to that revealed in leaves (0.69-0.64 rev.h^-1). The diurnal oscillatory cycles belong to a system established on the basis of periodicity of day and night and other geophysical cycles. The ultradiurnal rhythmic oscillations are presumed to be an expression of the geocontrol system of root and shoot growth direction and orientation of the organ in space. The shape of their trajectories in bean leaves is contradictory to this; they are not spatial helices, as the kybernetic model would presuppose, but have a vertical, upwards and downwards course in one plane. Since these oscillatory movements with an ultradiurnal cycle cease after petiole excision from the stem and after shoot apex amputation, one may presume that they are coupled with the low-frequency oscillatory system of the epicotyl.

The mobilization of protein nitrogen reserves in apple shoot bark is subject to abscisic acid (ABA)-mediated regulation. At the biochemical level proteolytic activities in the shoot bark are suppressed in the autumn. As endogenous ABA levels decline during the autumn and winter tissue protease levels increase in parallel with the rate of inducible breakdown of reserve protein; metabolic demandper se plays no significant role. This process is used as a model system to explore the possibilities for chemical regulation ("bioregulation") of ABA-determined dormancy phenomena by: manipulation of tissue ABA concentrations, substitution of synthetic growth regulators and direct interference at the site of action.

An attempt is made to characterize the functional activity of the protein moleculo possessing both peroxidase and IAA oxidase activity by comparing the kinetic parameters for the two types of enzyme activity with regard to the following substrates: H₂O₂, benzidine, guaiacol and IAA. The curves expressing the dependence of the enzyme reaction velocity on the concentration of the enzyme or the substrate are different depending on the enzyme extract origin and the type of the substrate. It is established that the K_m of peroxidase for IAA decreases while its K_m for H₂O₂ increases during cell development. Both types of enzyme activity show similar pH and temperature dependence. The presented data show that IAA oxidase activity of the peroxidase develops as extension and differentiation of the root cells proceed. This is one of the possible mechanisms through which peroxidase may participate in the regulation of growth and differentiation of the primary root cells of maize (Zea mays L.)

The addition of Na₂EDTA to a minimal medium (agar, sucrose) deprived of cations produces no morphoregulatory effect. This effect is induced only by the addition of iron. Traces of iron present in the agar are sufficient for the development of globular embryoid into a complete plant. The traces of iron in distilled water and sucrose (p. a.) are insufficient for the morphoregulation. The marked difference between the necessary limiting amount of chelate and necessary limiting amount of iron in non-modified media is explained by the presence of other cations, which saturate and thereby inactivate a greater part of Na₂EDTA. It is recommended to decrease the amount of iron and leave the commonly used amount of chelate in the prepared media. Simultaneously with optimal morphoregulatory effect in androgenesis and somatic embryogenesis, vitality of tissue culture will be lengthened and ageing as well as necrosis of the cultures be decreased.

Strawberry plants have been regenerated from petioles and flower buds Petiole segments derived from strawberry plants(Fragaria vesca L. andFragaria xananassa Duch. cvs. Gorella and Redgauntlet) maintainedin vitro have been cultured on the Gambobg's. agar medium supplemented with 2,4-D (2 mg 1-¹) either alone or with kinetin or BAP (0.1 mg I-¹ or 1 mg I-¹). The calli thus obtained have been transferred to media differing from the first ones only by the nature and the concentration of the growth regulators used. One or two months later, shoots appeared on these calli. The influence of the media hormonal content on plant regeneration has been observed. Moreover, genotypic variations have also been investigated: the wild strawberry exhibited the greatest organogenic capacity.
Shoots have also been obtained from flower buds(Fragaria xananassa Duch. cvs. Fern, Hummi Gento, Gorella and Redgauntlet). In this case, shoots appeared directly on small calli derived from the peduncular base of the flower buds. These regenerations have been observed, without changes of media, on the Lee and de Fossabd's agar medium.

The caryotype (2n = 24) of crownvetch (Coronilla varia L.) and the conditions of successful cultivation of tissue cultures derived from it were determined. The Murashige-Skoog cultivation medium with the addition of indol-3-ylacetic acid (1 mg 1¹), 1-naphthaleneacetic acid (0.1 mg 1¹), or coconut milk (20 %) was found to be the most suitable. A complex of cardenolide-like substances identical in its composition with that found in leaves of intact crownvetch plants was detected by means of thin layer chromatography in the extracts of these explant cultures up to the seventh subculture. These findings are also in agreement with the results of our earlier experiments in which strong pharmacological effects of cardenolides obtained from tissue cultures of this plant were demonstrated. Further investigations must be devoted to the optimalization of cultivation conditions of crownvetch cultures with the aim of their utilization as anin vitro source of cardioactive substances.

Diurnal changes in K content in leaf blades, petioles, stems and roots of eleven lucerne genotypes were followed. Significant positive correlations between changes in K content in petioles and upper half of stems and significant negative correlations between changes of K content in leaf blades and lower half of stems reflected rapid K movement. The velocity - up to 60 μmol g-1 (f.m.)h-1 - of changes in K content from leaf blades to lower part of stems and the other way round showed that long distance phloem transport occurred. Only moderate increase of K content contemporarily took place in roots. When total K amount in the whole plant was calculated then K uptake alternatively with K release were noticed during the day. Average K release reached 1.48 μmol g-1 (f.m.) h-1. The rate of K movement correlated with irradiance and physiological activity of plants. The time course of K movement was uniform in plants of the same strain and it differed partially in different strains.

The herbicide terbutryn induced up to 11.3 % chromosomal abnormalities in cells undergoing meiosis inVicia faba. The mean number of pods/plant and the mean number of seeds/pod were considerably reduced, but the average seed dry mass was not or was only slightly affected by this herbicide. In C₂ plants chromosomal abnormalities were observed in few but significant numbers of cells.

This paper describes the successful selection of plant cell var ants with differing secondary substance productions by means of an adsorbent filter method. The method allows a simultaneous screening of up to 100 small cell aggregates per Petri dish within short time.

The scale of salt tolerance of each plant tissue can be characterized by a "critical" concentration of NaCl. At this concentration the endogenous content of free proline rises. A correlation exists between the endogenous Na⁺-concentration and this increase of proline. Calcium cations can enhance the NaCl-tolerance by inhibiting the Na⁺-permeability. Thus, the rise of the proline concentration in this case is produced only by NaCl concentrations higher than the critical concentration. The calcium pretreatment of caryopses during soaking leads to the enhancement of the tolerance under salt stress, too.

In vitro culture was established from shoot tips ofDigitalis lanata cotyledonous plants. The propagated plant material was rooted, transplanted into soil and grown under field conditions. Lanatoside C content was determined in a total of 20 clones and statistically evaluated by means of variance analysis of unequal-sized samples.In vitro clonal propagation ofD. lanata was found not to affect lanatoside C content. Drug level was dependent on a plant genotype.

During the search for compounds with insect juvenile hormone activity, the biotransformation of 2-(4-methoxybenzyl)-l-cyclohexanone, of 2-(4-methoxybenzyl)-l-cyclohexanone ethylene acetal and of both isomers of 2-(4-methoxybenzyl)-l-cyclohexanol by plant cells was examined. The compounds were metabolized by cell suspension culture of Solatium aviculare Forst. The reaction conditions were optimized and the metabolic products isolated and identified. A scheme of biotransformation pathway has been proposed.

Salinity had generally little influence on the water content of different parts of cowpea(Vigna sinensis L.), calabrese(Brassica oleracea L. var.botrylis) and red radish(Raphanus salivus L.) plants. Salinity showed a promotive effect on the growth of cowpea, while in calabrese the effect was either promotive or depressive depending upon the concentration of the NaCl, and in red radish plants salinity progressively suppressed growth.
Total nitrogen, phosphorus, potassium and sodium contents of cowpea leaves were not affected by salinity treatments, while in calabrese and red radish leaves the contents of N, P and K were generally decreased as the salinity level increased. Gibberellin (GA₃) applied to salt-treated plants had either a stimulatory or inhibitory effect on the growth, water content and contents of N, P, K and Na in the leaves depending upon the plant type, the concentration of GA₃ and level of salinity.