Similarity of seed protein spectra of 13 representatives of the genusAllium, subgenusRhizirideum, was estimated by means of immunochemical analysis; the species investigated were divided into four groups more or less corresponding to the contemporary systematic division of species into sections.

The screening of enzyme patterns in seeds ofAllium cepa cv. Všetatská revealed the presence of the following enzymes: alcohol dehydrogenase, lactate dehyd ogenase, NAD+- and NADP+-glyceraldehyde-3-phosphate dehydrogenase, glucose-6-phosphate dehydrogenase NAD+- and NADP+-malate dehydrogenase, NADH₂- and NADPH₂-tetrazolium reductase catalase, Superoxide dismutase, acid and alkaline phosphatase, L-leucine aminopeptidase, glutamate dehydrogenase, non-specific esterase, and cholinesterase. Altogether 17 enzymes were detected in onion seeds, nine of which had more than three isoenzymes, NAD+-malate dehydrogenase had 8, and non-specific esterase 9 isoenzymes. The demonstration of cholinesterase and Superoxide dismutase activities is remarkable.

The absorption of³²P-phosphate (KH₂PO₄-0.1 mM) was studied with discs ofPelargonium zonale leaves, in relation to the age of the leaf, to the ageing process and in relation to the influence of GA3 and BAP. The results show that: i) the speed of absorption reaches a maximum which is characteristic of the adult phase (stage); ii) the "ageing" (washing during 24 h) induces a general increase in the absorption velocity which is dependent on the temperature of the ageing medium (optimum at 26 °C). On the other hand, ageing appears to be a process able to increase the physiological differences which are present before "ageing". This phenomenon also appears in the case of the influence of phytohormones; iii) if BAP exercises a dose-dependent inhibitory action, in contrast, GA₃ acts by increasing the velocity of the absorption which appears to be a process independent of the hormone concentration.
These results underline a phytohormonal specificity.
All these results are discussed in relation to hormone-directed transport, cell permeability and leaf senescence.

Accumulation of phenolics in barley seedlings was examined in relation to elongation; the seedlings were cultivated at 5 °C or 26 °C in light or in darkness. It was found that a higher accumulation of phenolics (mainly saponarin) was accompanied by slower elongation. This relation was repeatedly observed regardless of whether growth retardation or stimulation was obtained by light and temperature conditions of growth or treatment with CCO orp-fluorophenylalanine (p-FPA), respectively. It is proposed that PAL and peroxidase activities are responsible for maintaining the level of phenolics in seedlings. These enzyme activities are differently influenced by temperature conditions of growth. It is also suggested that accumulation of saponarin may lead to slowing down the growth by stimulating IAA oxidase and lowering the auxin level in the tissues. Thus, phenolics may belong to the factors through which environmental conditions influence elongation of seedlings.

Cotyledons of gourd (Cucurbita maxima Duchesne) and bean (Phaseolus vulgaris L.) were used to study the changes in the activities of catalase, peroxidase, acid inorganic pyrophosphatase and alkaline inorganic pyrophosphatase during ageing and the diversion in such changes that occur when cotyledon senescence was retarded by detopping the seedlings above the cotyledons. Catalase, acid inorganic pyrophosphatase and alkaline inorganic pyrophosphatase activities declined during the senescence of the cotyledons. When cotyledon senescence was retarded by detopping as marked by the increase in the levels of chlorophyll and protein, there was also an increase in the activities of these enzymes. Peroxidase activity, on the other hand, increased during the senescence of the cotyledons and detopping the seedlings resulted in a further increase in the peroxidase activity. It can be suggested that some root factor(s) probably cytokinin(s) is (are) mobilised into the cotyledons of the detopped seedlings which otherwise would have been mobilised into the shoot apices, and help retard or even reverse the senescence of the cotyledons.

Growth behaviour, proline changes and water saturation deficit (WSD) changes were studied in two maize cultivars, Agati-76, a drought resistant oultivar, and cv. Vijay, a susceptible one after stress conditions were removed. Plants of both the cultivars showed a tendency to recover during rehydration. Phenotypically the plants appeared just normal on 7th day of rehydration, although recovery was never complete. Significant positive correlation existed between free proline content and concomitant change in water saturation deficit. Significantly higher proline content in cv. Agati-76 was reoorded in cv. Vijay, immediately after the stress was released, thereafter continuous decline was observed up to 7th day of rehydration in both the cultivars. Proline changes in relation to recovery of plants from stress conditions are discussed.

Trends in the time course, changes in the moisture, soluble amino acids, proline, abscisic acid contents and nitrate reductase activity determined byin vivo method in the developing seeds of wheat were studied. Maximum dry matter augmentation in the seed took place in the period between 10-30 days after anthesis. Per cent moisture and moisture content started declining 15 days and 25 days after anthesis, respectively. Levels of soluble amino acids, proline and nitrate reductase activity were higher during initial stages of seed development, but decreased with increasing magnitude of dehydration and accumulation of abscisic acid (ABA) in the maturing seeds.

The study summarizes the results of the influence of outer temperature gradient on the accuracy of sap flow rate measurements in tree trunks by means of thermic-based methods. Particularly it deals with those methods based on the continual accurate measurements of temperature differences between the heated part and the part with natural temperature, at the measuring point. The battery of thermometers significantly compensating the mentioned temperature gradient effect is described.

Pyruvate decarboxylase (PDC) was prepared from four-day-old pea seedlings by a procedure which involves extraction of plant material with a phosphate buffer, fractionation of the extract with ammonium sulphate, desalting by dialysis or gel filtration on Sephadex G-25 column, chromatography on DEAE cellulose and filtration on Sepharose 4B. The PDC preparation activity 10 000 U g^-1 protein was about 600 fold higher than that of the sodium phosphate buffer extract. According to the enzyme behaviour during the gel filtration on different carriers the molecular mass of pea PDS was estimated at about 10⁶. Magnesium ions and thiamine pyrophosphate were found to be coenzymes of PDC. Cofactors can be removed by 48 h dialysis followed by chromatography on DEAE cellulose. Apoenzym is activated optimally with the concentration of cofactors of 0.002 M. Magnesium ions can be replaced in their activation function by ions of Fe²⁺, Ni²⁺, Co²⁺, Zn²⁺ and Mn²⁺. Another ions,i.e. Ba²⁺, Ca²⁺, Cd²⁺, Hg²⁺ and Cu²⁺ are inactive. Assumption about the relation between the ion diameter and degree of activation is formulated.

The action of light on ribosome formation was examined in the cabbage seedlings, a system extensively used in the studies of anthocyanin synthesis. Ribosomes were extracted 18 h after the beginning of the irradiation and separated by sucrose gradient centrifugation. In the cotyledons of dark-grown cabbage seedlings, a brief red light induces an increase both in total ribosomes and in the fraction present as polysomes; the effect of red light is reversed by far red light, indicating the involvement of phytochrome in polysome formation in cabbage seedlings. Continuous red and continuous far red light are about equally effective in bringing about an increase of total ribosomes and of the polysome fraction. Streptomycin, which inhibits chlorophyll synthesis and chloroplast development, and enhances anthocyanin synthesis in cabbage seedlings, causes a decrease of total ribosomes and of the fraction present as polysomes. In hypocotyls, the red-far red reversibility is evident only for the polysome content and streptomycin does not decrease the polysome/monosomo ratio as it does in cotyledons.

The apical hook curvatures of pea seedlings are associated with a higher level of endogenous auxin on the lower (ventral) side of the curvature in comparison with the upper (dorsal) side. For this reason this curvature may be reversed by applying IAA to the dorsal side of the hook. On the other hand the analyses did not reveal any differences in the content of endogenous gibberellin between the dorsal and ventral side of the hook. Endogenous gibberellin if applied either to the dorsal or to the ventral side of the hook curvature closes the hook. Exogenous cytokinin benzyladenine closes the curvature only if applied to the ventral side of the hook, but it opens it if applied to the dorsal one.

Abscisic acid (ABA) was applied in a concentration of 1. 10^-3 M and 1. 10^-4 M to the quantitative SD plantChenopodium rubrum under various light regimes. ABA did not influence flowering in plants under continuous illumination, enhanced flowering in plants subjected to long days and inhibited it in plants induced by short days. It was concluded that ABA can not substitute for inductive treatment but its action may be additive to initial stages of reproductive morphogenesis (enhanced growth rate and branching of the apical meristem) as evoked by long days.

Biosynthesis of nucleic acids in the pea buds released from apical dominance by decapitation has been studied.
The rate of biosynthesis of all nucleic acid classes separated by means of methylated albuminkieselgur (MAK) column chromatography was found to be increased in released pea buds as judged by the extent of orotic-6-¹⁴C acid incorporation. This increase has been observed in all experimental points examined (15, 24, 36 and 48 h after decapitation), being the most pronounced 15 h after decapitation. After that a certain decrease of the specific radioactivities of nucleic acids has been registered, but even 48 h after decapitation specific activities of the main nucleic acid classes were higher in comparison with those found in dominant buds.
Variations of the free pyrimidine nucleotide pools were about 14% suggesting that this parameter did not influence the extent of the uptake of labelled orotic acid.

Four days oldAmaranthus seedlings responded to light treatment with an increase of amaranthin accumulation. With increasing irradiation time, red light caused a saturation effect. Blue light induced a high irradiation response. The blue light effect was reversible to a certain extent by far-red irradiation given at the end of the treatment with blue light. Intermittent red light (3 h red light, 3 h dark, …) caused a higher amaranthin accumulation than 24 h continuous red light. Results obtained with red and blue light are discussed on the basis of the phytochrome system.

Plant tissue connected in a d.c. circuit behaves as a capacitor, short-circuited through a resistor. Using a saw-tooth voltage (T = 2 ma, U_max = + 13 V), structural and physiological conditions in a plant tissue can be analyzed on the basis of changes in the current character.

Occurrence and distribution of trehalase were examined in cytoplasmic and cell wall fractions of cultured cells of morning-glory, soybean and persimmon. Also, some enzymatic properties and solubilization of the enzyme from cell walls were examined. Trehalase was present in both fractions of morning-glory and persimmon cells while trehalase was present only in the cytoplasmic fraction of soybean cells. Morning-glory trehalases in both fractions showed the same optimum pH at 5.5, while persimmon trehalases in both fractions showed the same optimum pH at 6.0. Soybean enzyme in the cytoplasmic fraction showed two optimum activities at 4.0 and 6.5.
Morning-glory cell wall bound trehalase was solubilized with various IM salts at about 70 to 75%. Also, the enzyme was solubilized with various buffers and the solubilization ratio increased with increasing in pH of a same series buffer. After multiple extractions with IM NaCl, about 15% of the original trehalase activity still remained in cell walls. On the other hand, Triton X-100 and the substrate, trehalose, at the various concentrations did not release trehalase from cell walls.
Invertase and cellobiase solubilized from morning-glory cell walls were re-adsorbed to the cell walls. However, readsorption of trehalase to cell walls has not yet been attained. Based on these results, physiological roles of plant cell wall-bound trehalase were discussed.

We have compared the action of light on ribosomal RNA synthesis in mustard and cabbage seedlings, two of the most frequently used systems for the studies of anthocyanin synthesis. The level of RNA (both t-RNA and r-RNA) "stored" in mustard dry seeds is much lower than in cabbage dry seeds. The kinetics of RNA synthesis in cabbage and mustard seedlings exposed to light are very different: In cabbage seedlings, light produces no apparent stimulation of cytoplasmic r-RNA synthesis, while it does increase plastid r-RNA synthesis. On the other hand, in mustard seedlings, light promotes both cytoplasmic and plastid ribosomal RNA synthesis. Streptomycin, which inhibits chlorophyll formation and chloroplast development while having no effect (mustard) or enhancing (cabbage) anthocyanin synthesis in these two systems, is in both cases an effective inhibitor of plastid r-RNA synthesis, but not of cytoplasmic r-RNA synthesis.