Effect of abscisic acid on cell permeability in leaves ofIresine u allisi hort. and roots ofBeta vulgaris L. were examined. An increase of betacyanin leakage from leaf cells was shown by ABA at 10^-4, 10^-7 or 10^-9 M concentrations in water solution at 25 °C. The efflux of batacyanin from tissues did not change during the joint action of ABA and PEG 1000. ABA could lower the betacyanin leakage fromIresine leaves and beet-root slices under severe osmotic stress, as was found by deplasmolysis. The results suggest that ABA elicits some alteration in density of tonoplast membranes under dehydration.

A haemagglutinating material was isolated and purified from the phosphate buffered saline extract of the seeds of the jack fruit using an immobilized N-aeetyl-D-galactosamine column. This material was composed of two iso-lectins of molecular masses 11 500 and 15 000. The lectins agglutinated native washed red blood cells of the human A, B and 0 groups and sheep, rabbit and mouse erythrocytes. The lectins were found to be composed of single polypeptide chains and they contained no covalently linked sugars. The lower molecular mass material was present in considerably greater quantity than the higher molecular mass component. On isoelectric focussing on PAG the lectins gave a spread of components with calculated pI between 6.0 and 8.3.

Methyl jasmonate (JA-Me) at a concentration of 0.5% in lanolin paste totally inhibited bulblets formation induced by benzyladenine in intactMuscari bulbs. Lower concentrations of JA-Me delayed development and growth of bulblets induced by benzyladenine. It seems that methyl jasmonate acts as a powerful inhibitor of cell division induced by cytokinin in used test. In comparison with methyl jasmonate, abscisic acid did not show an inhibitory effect on bulblets formation induced by benzyladenine, even in a higher concentration.

A cabbage variety with particularly strongly developed leaves and extremely shortened stems (tight heads) was treated during the first year of its development with growth retardants (CCC and CEPA, Ethephon) at different concentrations. A 4-fold treatment with CCC, CEPA or a mixture of both proved to be most effective Leaf growth was inhibited by this treatment (head mass decreased) but stem growth increased. Only in treated plants the bud of the stem apex could break through the leaf sheath and develop generative stem. The results are discussed as examples of correlative relations between leaf and stem growth.

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.

IAA oxidase, catalase and peroxidase activities of seedlings (the first day of radicle emergence) or organs of young plants (the fifth day of radicle emergence) germinated in NaCl media (0, 25, 50, 100 or 150 mM) were measured. Three species with successively lower thresholds of salinity sensitivity were measured: tomato, radish and red cabbage. NaCl sensitivity of the above enzymes was also analysed in extracts from control seedlings or plants incubated in media with different NaCl concentrations. No relation was found between enzyme activities and protein levels or Na contents of young plants; on the contrary, a good relation was observed between enzyme activity and Na contents of seedlings. Oxidase activities have similar NaCl sensitivity in the three seedlings. Comparing the enzyme activity and sensitivity with NaCl tolerance of the species, the consequences of the oxidase activities in young plants germinated in NaCl media are discussed.

Methyl jasmonate (JA-Me) at concentration of 0.5 % and 1.0 % in lanolin paste applied to the surface of postclimacteric apples cultivars McIntosh, Spartan, and Cortland inhibited ethylene production in slices of cortex with a skin cut to a depth of about 2 mm. The level of 1-aminocyclopropane-l-carboxylic acid (ACC) was decreased in tissues of apples treated with methyl jasmonate. Methyl jasmonate stimulated ethylene production in preclimacteric apples cv. McIntosh.

The effect of indol-3-ylacetic acid, gibberellie acid, kinetin, abscisic acid and Ethrel on the growth of mycelium, sporulation and germination of spores ofFusarium culmorum of different pathogenicity to wheat seedlings was studied. The production of gibberellins, auxins, cytokinins, ethylene and growth inhibitors by these isolates was determined as well. It has been found that most pronounced and explicit effect on growth and development in fungi was produced by Ethrel which strongly inhibited these processes. ABA proved to be a strong growth and development stimulator, though to a different extent in different isolates. GA₃ strongly stimulated sporulation and spore germination in some isolates. The effect of IAA and K on growth and development in fungi was slight. More sensitive to growth regulators were the fungi in earlier stages of growth. No correlation between the pathogenicity of the isolates and their ability to produce growth regulators as well as between their susceptibility to exogenous growth substances in the processes of fungal growth and development was stated.

Sublethal doses of metribuzin applied to wheat plants at the stage of ear emergence increased endogenous gibberellin levels in the ears. The activation of hormonal systems in connection with "chemical stress" is briefly discussed.

The effect of methyl jasmonate (JA-Me) applied in concentration 1.0 % in lanolin paste to detached tomato fruits at the mature green, advanced mature green and light red stages on the ethylene production and l-aminocyclopropane-l-carboxylic acid (ACC) content was investigated at different times after treatment. JA-Me stimulated ethylene production in all stages of ripening, but the level of ACC increased or decreased in comparison with control depending on the stage of ripening. Higher level of ACC in JA-Me treated tissue was found in mature green stage and fully ripened tomatoes-treated at advanced green stage; lower one in light red stage - treated at advanced green stage and fully ripened stage - treated at light red stage.

Green islands were observed around infection spots ofAlternaria brassicicola on mustard leaves in nature. These green islands had higher cytokinin-like substances as compared to surrounding yellowed tissue and healthy tissue. Presence of starch in green islands has been correlated with formation of metabolic sinks in green islands, because of higher cvtokinin-like substances in them.

This article reports the effect of cold storage at 4 °C from December to April on chestnut cuttings. Rooting was found to increase after four months preceded by treatment with 4000 mg l^-1 IBA.
ThePhaseolus test of the biological activity of extracts of the cuttings showed the inhibition exerted by the acid fraction of the fresh (December) cuttings to have been replaced by a rootpromoting effect in cuttings stored for 4 months at low temperature. Cold storage thus seems to favour rooting.

Anodic oxidation of coumaric acid led to the inhibition of the process at the electrode due to a film which was formed after one-electron oxidation of the acid to phenoxy radical.By contrast, caffeic acid is oxidized in two steps-the phenoxy radical is formed in the first step, quinone in the second step. The inhibition of nitrate uptake by coumaric and caffeic acids is dependent on their concentration. 10^-4 M eaffeic acid totally inhibited nitrate uptake and the growth ofNicotiana tabacum cell suspension. 10^-6 M caffeic acid markedly inhibited nitrate uptake especially in the first three days after inoculation. 10^-6 M coumaric acid did not affect nitrate uptake and nitrate reductase activity, 10^-4 M coumaric acid inhibited nitrate uptake by day two after inoculation. Nitrate reductase synthesis correlated with the inhibition of nitrate uptake. Differential effects of coumaric and caffeic acids are explained on the basis of different products of their electrochemical oxidation.

The content of phenolic substances in the cell suspension culture ofCentaurium erythraea fluctuated during a 21-day-long subcultivation period in dependence on the growth phase. The total relative content of the phenolics reached its maximum at the time of transition to the exponential growth phase, similarly as the fraction of free phenolic acids, glycosides, and the fraction of phenolic acids released from the cells after alcaline hydrolysis. On the other hand, the content of phenolic acid esters decreased at this growth phase of the culture. Changes in the level of phenolic substances in the culture medium corresponded in their character to changes in the relative content of the phenolics in the cells.

With the aim to increase citrus fllowering under tropical conditions, two formulations of 2-chloroethyl phosphonic acid (Ethrel and Flordimex), Alar (succinic acid-2, 2-dimethyl hydrazide) and Cycocel (2-chloroethyl-trimethyl ammonium chloride) were applied during the flower induction period (December) to young "Valencia" orange trees at concentrations of 1000, 2500 and 5000 mg l^-1. These treatments effectively increased flowering, mainly at lower concentrations. Treatment using Flordimex at 500 and 1000 mg l^-1 concentrations resulted in flowering increase which is analyzed in this paper.

Regenerants from tobacco(Nicotiana tabacum L. cv. White Burley) leaf segments cultivatedin vitro in vessels with solid agar medium under usual conditions (plantlets) grew under very low irradiance (I = 40 μxmol m-2 s-1), very high relative humidity (more than 90%) and decreased CO₂ concentration (c_a) during light period. In comparison with seedlings of a similar number of leaves and similar total leaf area grown in sand and nutrient solution, the plantlets had lower dry mass of shoots and roots per plant and thinner leaves almost without trichomes and epicuticular waxes. Due to a low transpiration rate under high relative humidity the water potential of plantlet leaves was higher than that of seedling leaves and the difference in water potential between leaves and medium was lowei. The rate of water loss from leaves detached from plantlets was considerably faster than that from seedlings under the same conditions (I = 110 μrnol m^-2; s^-1, temperature 30 °C, relative humidity 50 %). Net photosynthetie rates (P_n) of leaves of plantlets and seedlings measured under saturating I, natural ca and the leaf temperature 20 °C were similar, nevertheless the shape of curves relating Pn to c>> indicated some differences in photosynthetie parameters(e.g. saturation of Pn under lower ca> higher CO2 compensation concentration in plantlets than in seedlings). Similarly compensation and saturating I were lower in plantlets than in seedlings. The shape of transpiration curves as well as the expressive linear phases of P_N(ca) and P_N(I) curves of plantlet leaves indicated ineffective stomatal control of gas exchance. These results were confirmed by microscopic observations of stomatal movementsin situ

Exogenous³H-thymidine is absorbed by the primary root of young plants ofDatura stramonium L. and gradually translocated into shoots: following a 3 to 72-h application of³H-thymidine the radioactivity was revealed, using the autoradiographic technique, especially in the region of primary and secondary meristems and in proximity to vascular bundles of the primary root, stem, hypocotyl and leaves. These regions may be considered as the sites of active DNA synthesis. The intensity of incorporation was dependent on the time of plant incubation in labelled thymidine.

Salt tolerance ofEchinochloa crusgalli was studied using gravel culture with root medium electrical conductivity between 3 to 25 dS m^-1. Salinity depressed germination and shoot yield. A 50 % reduction in shoot yield occurred at 15.9 dS m^-1. The plant was able to maintain its tissue water content and K concentration in the tissue water while Na, Ca and Cl increased and Mg decreased with increasing root zone salinity.

The cultivars of barley and wheat resistant to mildew had a higher level of free zeatin and its derivatives during the whole ontogeny than the susceptible cultivars. The effect of exogenous application of cytokinins on the growth ofErysiphe graminis DC. was different. Kinetin and benzylaminopurine showed only a slight inhibitory effect. Zeatin and its derivatives completely inhibited growth of this fungus.