Uptake of phosphate ions by 1 mm segments of isolated maize root cortex layers was studied. Cortex segments (from roots of 8 days old maize plants) absorb phosphate ions from 1 mM KH₂PO₄ in 0.2 mM CaSCO₄ at the average rate of 34.3 ±3.2 μg P_i g^-1 (fr. m.) h^-1,i.e. 0.35± 0.02 μmol P_i g^-1 (fr. m.) h^-1. Phosphate uptake considerably increases after a certain period of "augmentation",i.e. washing in aerated 0.2 mM CaSO₄. This increase is completely blocked by the presence of 10 μg ml^-1 cycloheximide.
The relation of uptake rate to phosphate concentration in the medium was shown to have 3 phases in the concentration range of 0.02 - 40 mM. Transition points were found between 0.8-1 mM and 10-20 mM. Following K_m and V_max values were found: K_m[mM] : 0.37 - 3.82 - 27.67 V_max[μg P_i g^-1 (fr. m.) h^-1] : 3.33 - 39.40 - 66.67
We have found no sharp pH optimum for phosphate uptake. It proceeds at almost constant rate till pH 6.0 and then the uptake rate drops with increasing pH. At low phosphate concentrations (1 mM) the lowest uptake rate was found at 5 and 13 °C, while the uptake is higher at 5 °C than at 13 °C at phosphate concentrations higher than 1 mM. At these concentrations uptake rate at 35 °C is lower than at 25 °C.
Phosphate uptake considerably decreased in anaerobic conditions. DNP and iodoacetate (0.1 mM) completely blocked phosphate uptake from 1 mM KH₂PO₄, while uptake from 5 and 10 mM KH₂PO₄ was left unaffected by these substances. The inhibitors of active - SH groups NEM and PCMB inhibited phosphate uptake: 10^-3 M NEM by 81.6%, 10⁴ M NEM by 42% and 10^-4 M PCMB by 42%.

A pot culture experiment was performed to evaluate salt tolerance potential ofSesbania aculeata Poir. The plant can tolerate salinity levels up to electrical conductivity (ECe), 10 mS cm^-1 and at 15 mS cm^-1 thero is about 40% reduction in dry matter production. The analysis of inorganic constituents in different plant parts revealed that the plant has the capacity to regulate sodium uptake under saline conditions and chloride uptake always exceeded that of sodium. The potassium: sodium ratio is also maintained at a fairly constant level in leaflets while it is reduced in leaf rachis, stem and roots. Salt stress caused accumulation of calcium and magnesium in all plant parts. A considerable decline in phosphorus uptake was observed due to salinity. Iron was found to be accumulated more in salt stressed roots only. Nitrogen accumulated in both roots and leaves while considerable proline accumulation was observed in leaves of salt stressed plants. The amount of soluble sugars was increased in roots and leaves due to salt stress, while starch content of roots decreased. Those changes induced by salinity are discussed in relation to salt tolerance capacity of the plant.

Supply of KNO₃, NH₄Cl or NH₄NO₃ to the maize seedlings increased total chlorophyll and carotenoids (over zero nitrogen control) amounts per fresh matter unit of the primary leaves. The increase was most apparent when the pigment level in control plants started declining,i.e. between days 14 and 16. Supply of inorganic nitrogen increased pigment synthesis in excised leaf segments from dark grown seedlings, although the increase during a 24 h incubation was not as high as with either glycine or glutamine. Salicylic acid at 0.01 to 1 mM concentration increased and at 10 mM lowered the pigment biosynthesis. The increase at lower concentrations of salicylic acid was unaffected by KNO₃ but it was suppressed by NH₄Cl. When 12-day seedlings were transferred to the dark, total chlorophyll and carotenoids declined appreciably, but the supply of inorganic nitrogen protected them from decline to same extent. Thus inorganic nitrogen, especially the nitrate, is more important in protecting from degradation of chlorophyll and carotenoids than in increasing their biosyntheses.

IsolatedN. tabacum andV. faba protoplasts were used as a model to examine the DNA-fuchsin changes during the dedifferentiationin vitro. Using the pattern recognition method for the evaluation of cytophotometric data obtained we have established: 1) the major fraction of cells of the original tobacco and bean leaf tissue is in G₁-period of the cell cycle; 2) the significant decrease to 1C DNA-fuchsin content in nuclei in the first hours of cultivation and then a reconstitution of 2C pool followed by entering of these cells into S-period of mitotic cycle; 3) only 2% of tobacco and 4% of bean mesophyll cells contain 4C DNA.

The seed protein patterns of 12Arachis species were compared by polyacrylamide gel electrophoresis (PAGE), similarities between patterns were measured by the Jaccard index. Results obtained confirm the close relationships established between members of the genus on morphological grounds and support the more recent classification schemes.A. villosa andA. correntina could well be regarded as distinct species on grounds of protein differences whileA. macedoi andA. villosulicarpa (although members of the same section, Extranervosae) show considerable differentiation of their protein patterns. Surprisingly, the formA. ×batizogaea showed less similarity in protein pattern to those of its parental species than might have been expected. The principle value of seed protein pattern data appears to be in distinguishing species within sections.

Proteins from two species of the genusArtocarpus (A. integrifolia L. andA. incisa L.) were compared by ammonium sulphate fractionation, molecular sieve chromatography and SDS-polyacrylamide gel electrophoresis, with special attention to the lectins. The protein content and hemagglutinating activity were markedly different in the two seeds. The protein pattern obtained by both molecular sieve chromatography and SDS-polyacrylamide gel electrophoresis were quite different. The only similarities found were the elution volume of the lectins in the Sephadex G-100 column and the lectin bands (11 500 and 15 000 daltons) in SDS-polyacrylamide gel electrophoresis.

Foliage and tuber fresh matter and chlorophyll content in cvs. Atom alue, Multa, Kufri, Desiree and Patrones were decreased with the increase in soil acidity. However, tuberization was enhanced at pH 5.5 and decreased significantly at pH 4.5 in all cultivars tested. At pH 4.5 the specific mass of all the cultivars was slightly increased. The highest content of reducing sugars and proteins was found at pH 5.5. No definite pattern was observed in total glycoalkaloids content under different acidic range.

Stem tips ofSpinacia oleracea were isolated and grown in sterile culture, with Sandoz 9789 added to the medium. Although the herbicide provoked a complete loss of all chloroplast pigments, developed shoots were able to flower, in response to long days; in short days flowering was inducible by adding gibberellins. Sandoz 9789 decreased the elongation of stems by up to 30%; the percentage of flowering plants in culture was also decreased. However, among those plants that flowered, the majority were male, so that Sandoz 9789 produced a shift of the sex ratio toward maleness.

A new undescribed yellows-type disease ofGypsophila paniculata L. was found. Since a stunted growth is the predominant symptom the disease has been termed stunting. Electron micrographs of ultrathin sections revealed numerous mycoplasma-like organisms in diseased phloem tissues. Attempts to maintain the diseasedGypsophila plants for further investigation of this disease failed for the present in spite of all applied modifications in nutrient media.

The effect of macroelements on nitrogen assimilation, level of nitrate reductase (NR), glutamine synthetase (GS) and glutamate dehydrogenase (GDH) and content of nitrate nitrogen were studied in 17 day-old pea seedlings. The highest inhibition of NR was found at deficiencies of Mg and Ca while deficiency of K was less effective. The level of GS was decreased only in roots exclusively at deficiency of Mg. On the other hand, the deficiency of Mg and Ca increased the level of GDH. The lowest level of endogenous nitrate was found at deficiency of K. Present results show that assimilation of nitrate by plants was decreased by Mg and Ca deficiency while assimilation of ammonium was not affected.

Four strains of the phytopathogenic bacteriumCorynebacterium fascians (Tilford)Dowson were selected from our isolates and deposited in the Czechoslovak National Collection of Type Cultures (CNCTC) of the Institute of Hygiene and Epidemiology in Prague. Two very virulent (Cor 83/82 "UPR" and Cor 82/81 "UP") and one avirulent (Cor 81/80 "CP1b") pelargonium strains, producing acid from rhamnose, were isolated from fasciations onPelargonium zonale W. One avirulent celery strain ofC. fascians (Cor 80/80 "CF4a") was isolated from a root expiant ofApium graveolens L. growing on a nutrient mediumin vitro. Morphological, cultural, physiological and biochemical characteristics of these selected Czechoslovak isolates were compared with the American patented strain cotype ATCC 12974.

A closed gas exchange system has been designed for connection to the Hewlett-Packard programmable calculator controlled data acquisition system to provide a complete process of measuring and control. The system enables routine measurements of photosynthetic and dark respiration rates at different irradiances and different carbon dioxide and oxygen concentrations and leaf temperatures, and also a simple and rapid automatic control of irradiance according to the actual photosynthetic rate.

Willows were rapidly propagated by repeated division of cultured rooted shoots into a larger number of nodal segments. Rapid clonal propagation of mountain-ash and black locust was achieved by induction of shoots from axillary buds and a multiple shoot culture was used for rapid multiplication. Excised shoots were rooted in an agar medium with a low concentration of auxin and rooted plantlets were transplanted to soil.

Net CO₂ exchange rates, stomatal and internal resistances for CO₂-transport were followed on fully expanded Witloof chicory leaves (Cichorium intybus L. cv. Foliosum) for several months during vegetative growth. Maximum net CO₂ exchange rate (P_max) stayed high with a sudden drastic drop at the end of the growing season largely due to an increase in internal diffusion resistance.
During an analogous growth period the H₂O vapour diffusion resistances of leaves for four selections were measured. The adaxial stomatal resistance was always higher than the abaxial one. Stomatal densities calculated for those selections showed higher values at the abaxial leaf side.

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.

Three different treatments by calcium (10²M), namely seed treatment, foliar spraying and their combination were applied on field-grown rice (Oryza sativa L. cv. Ratna) under both water stressed and non-stressed conditions in the course of plant development. The relative water content and leaf water potential decreased with increase in age of stressed and non-stressed plants. Pretreatment of seeds with Ca improved the water status of the plants most prominently at the vegetative stage but the effect gradually faded away with plant development. The foliar spraying by Ca was more effective in improving the water status of the plants at the reproductive stage. The combined Ca treatment significantly improved water status of the plants both at the vegetative and reproductive stages. The contents of chlorophyll and protein decreased and the activities of protease and RNase increased in the course of plant development in both non-stressed and even more in stressed plants. Ca treatments of seeds or plants or their combination inhibited the decline in chlorophyll and protein contents and the rising trends of protease and RNase activities, the combined treatment being most effective. During plant development free proline content increased significantly more in water stressed plants. In non-stressed plants there was a marked increase in the free proline content at the mature fruit stage. Ca treatment inhibited the rise of free proline in stressed plants. A significant reduction in yield components and yield of the crop in water stressed plants was increased by Ca treatment.

Plants were regenerated from mesophyll protoplasts of axenically growing plants of four dihaploid clones and five tetraploid cultivars ofSolanum tuberosum L. andSolanum phureja Juz. etBuk.

The effect of herbicides N-(phosphonomethyl)glycine (glyphosate), 2-methyl-4-chlorophenoxyacetic acid (MCPA), 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine (atrazine) and the respective commercial preparations "Round-up", "Aminex", and "Zeazin", on the activity of lactate dehydrogenase isolated from germinating soybean seeds and beef heart were compared. The main aim of the work was to compare the effect of the herbicides on lactate dehydrogenase isolated from animal and plant material. Simultaneously the effect of herbicides and the respective commercial preparations was compared. Substantial differences resulting from the two comparisons indicate differences in the structure of active centres of lactate dehydrogenase isolated from animal and plant material, and also a considerable effect of additives and surfactants in commercial preparations.

The lectins from the seeds of two species of the genusArtocarpus (A. integrifolia L. andA. incisa L.) were isolated by affinity chromatography on an AB (+) human stoma column, and compared by physicochemical and immunochemical methods. Although with marked differences in the hemagglutinating activity, the elution pattern of the albummic and globulinic fractions from both seeds were comparable by affinity chromatography on a human-stroma column. The two isolectin families presented many similarities. All the lectins presented the same subunit pattern by SDS-polyacrylamide gel electrpphoresia, were recognised by both rabbit antisera prepared against the crude extracts from the two seeds, and presented fused rockets when electrophoresed in agarose gel containing one or the other antiserum.

Two cultivars ofCicer arietinum L. with contrasting sensitivities to water stress, cv. C 214 (relatively resistant) and cv. 130 (susceptible) were compared for their protein content and soluble nitrogen (sol-N) under water stress. During water stress shoots of the cv. C 214 showed an increase (over the control) in both protein and sol-N content. The total nitrogen (total-N) also increased in the cv. C 214 while remaining almost unaffected in the cv. G 130. Cultivar C 214 shoots recorded lower protein/sol-N ratios. The results have been discussed in relation to resistance to water stress.

Complexes of water soluble proteins (albumins) were investigated in three cultivarsof Phaseolus vulgaris, viz: Yeltruská Saxa, Vainica Saavegra B, and Krupnaya sakharnaya. The first two cultivars exhibit haemagglutinating activity against rabbit erythrocytes, but have different elution profiles on Sephadex G-100. Their individual peaks have a different subunit composition, as revealed by SDS gel electrophoresis, as well as a different immunoelectrophoretic pattern, although proteins I and II of the specificity Veltruská Saxa are present in both cultivars. The cultivar Krupnaya sakharnaya expressively differs from the preceding lectin cultivars; it has no erythroagglutinating activity, its albumin complex has a high-molecular component, absent in the preceding ones, and has no lectin peak in the region of molecular mass of 100 000 to 200 000. Immunoelectrophoresis gave no evidence of protein I and II of the specificity Veltruská Saxa.