Using tomato as a test plant Ca absorption by the plant and characteristics of root growth in the nutrient solution has been reported. It has been shown that the amount of calcium present in the tomato shoot serves as a good index of the rate of root growth in the solution as well as in the soil. The flux of Ca, F and K into the roots of field grown tomatoes have been calculated based on such estimations of root parameters.

Starch formation was studied by means of plant anatomy in segments of maize and pea leaves, deprived of starch, floating overnight in the dark (1) on solutions of various saccharides, (2) on sucrose solutions containing auxin-type growth regulators and (3) on suorose solutions with antibiotios (proteosynthesis inhibitors). A comparison was made of mesophyll tissues of the two species used, of spongy and palisade parenchyma in pea leaves and-especially-of mesophyll and vascular bundle sheath in the leaves of maize. Although the effects of the given treatments were striking, the response of the particular tissues was considerably uniform. If the given sugar appeared as utilizable for starch formation, it was effective equally in all tissues under study. It was not possible to distinguishin situ the different ways of staroh synthesis by means of the application of growth substanoes. No striking differences in the effect of antibiotics upon staroh formation were seen in-normally-starch containing and starch lacking tissues.

In field-grown sugar beet plants (Beta vulgaris L. cv. Dobrovická A), each of66 successive leaves produoed in the course of the vegetation period was different with respect to its photosynthetic capaoity (P_c), life span, duration of leaf area expansion, and longevity after its maximum leaf area (A_max) has developed. The proportionality between the seasonal changes in these characteristics was not the same if the sequential senescence of leaves was taken into account. With aging of individual leaves, P_c increased with the leaf area expansion having attained the peak value between 75% to 100% of A_max The rate of ontogenetic changes in P_c of each leaf was specified by the rate of its growth and development so that even at comparable ages the successive leaves constituted a series of different physiological units.
The seasonal changes in quantum irradiance (PAR) were found to be responsible for differences in the growth characteristics between the successive leaves: Leaf expansion period was related with daily integrals of the incoming PAR (Io), while leaf longevity, after the A_max had been attained, was closely linked with PAR intercepted by the canopy (I). P_c expressed per the total leaf area of the plant was significantly correlated withI, while P_c calculated per unit leaf area of the plant was related toI _o Leaf potential to adapt P_c correspondingly to changes in PAR was greatest during leaf blade expansion; after the leaf had ceased to expand, changes in P_c were independent of differences in leaf irradiance.
The results stress, at least for field conditions, the inadmissibility of the extrapolation of attributes from one leaf to the other ones sequentially senescing on the plant.

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.

White mustard (Sinapis alba L.) plants, susceptible to 2,4-D, and scentless mayweed (Tripleurospermum maritimum L.) plants, resistant to 2,4-D, markedly differ in the distribution and metabolism of 2,4-D. When 2,4-D-¹⁴C was applied onto the leaf, radioactivity was found in mustard after 8 days in the entire plant, whereas in scentless mayweed radioactivity occurred mainly in the leaf onto which it was applied and in another one or two leaves, with the roots showing only traces of radioactivity. The two plant species differed both in the character and in the number and amount of metabolites detected in aqueous and ether fractions. The metabolite with R_f 0.63 -0.65, soluble in ethylether (39% of the total radioactivity applied), and that with R_f 0.35 -0.36 (23% of the total radioactivity) were present exclusively in the roots of scentless mayweed plants. The R_f values established indicate that the former metabolite may be a conjugate with the amino acids alanine and valine and the latter a hydroxylated derivate of 2,4-D. In the shoots of both plants, 2,4-D-¹⁴C was metabolized to identical metabolites with R_f 0.59 -0.61, which occurred in mustard plants only in trace amounts. Free 2,4-D-¹⁴C occurred in the shoots of both plants and in considerable amounts also in mustard roots; it could not be demonstrated in the roots of scentless mayweed. The two species did not differ in the uptake rate or in the amount of absorbed 2,4-D-¹⁴C.

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.

The growth changes of cotyledons, leaves, hypocotyls and roots due to photoperiodic induction in short day plantChenopodium rubrum were investigated in relation to flowering. Six-day old plants were induced by photoperiods with a different number of dark hours. We found that the degree of inhibition which occurred during induction in the growth of leaves, cotyledons and roots similarly as the stimulation of hypocotyl is proportional to the length of dark period. The photoperiods with 12, 16 and 20 dark hours bring about marked inhibition of growth and at the same time induce flowering in terminal and axillary meristems. The inhibitory effect of critical period for flowering,i.e. 8 dark hours, is not apparent in all criteria used and even the flower differentiation is retarded. The photoperiods of 4 and 6 dark hours did not affect growth and were ineffective in inducing flowering even if their number has been increased. The experiments with inductive photoperiod interrupted by light break have clearly shown that growth pattern characteristic for induced plants can be evoked in purely vegetative ones. Such statement did not exclude the possible importance of growth inhibition as a modifying factor of flower differentiation. We demonstrated that the early events of flower bud differentiation are accompanied by stimulation of leaf growth. The evaluation of growth and development of axillary buds at different nodes of insertion enabled us to quantify the photoperiodic effect and to detect the effects due to differences in dark period length not exceeding 2 hours.

Studies on seeds of 40 arid zone plant species have revealed that seeds exhibit differential specificity in water inhibition percentage. Most of these seeds show very poor imbibition capacity and that takes place within the first three hours, after which this uptake becomes very slow. This low hydrature and quick water uptake wherever it takes place is correlated with the erratic rainfall in the Indian arid zone. Most of the leguminous seeds are impermeable to water because of hard seed coatedness. However, those seeds which imbibed showed a very high percentage of water uptake.

Isoenzyme pattern of peroxidase, polyphenol oxidase and catalase at different intervals during germination and in different plant parts during early development of 'C-306' and 'Hira' cultivars, representing tall and dwarf wheats, respectively were investigated. The number of isoenzymic components of the three enzymes increased progressively with the concomitant increase in the stage of germination. The isoenzymic patterns, in general, were more clear and better developed during the later stages of germination. Different tissues or organs of the wheat plant possessed specific isoenzymic pattern of these enzymes. Differences between cultivars were observed both in the number and relative intensity of the various isoenzymic fractions.

The plants of two herbaceous species, namelyPulmonaria officinalis L. andSymphytum tuberosum L., growing in two deciduous forests in SW. Slovakia, were used for analysis of anatomicphysiological gradients along the insertion level of individual leaves. The gradients were established for six leaf characteristics. Specific leaf area and development of leaf area increased, while leaf tissue hydration, degrees of succulence and consistency decreased with height of insertion of leaves upon the stems. The gradients indicate the decreasing of the leaf water content and dry mass with height of the leaf on the stem. Stomatal resistance was usually the lowest in basal leaves and the highest in apical leaves of the plant. The anatomic-physiological heterogeneity of leaves of a plant is large and cannot be neglected in any anatomical or physiological investigations.

Cytokinin activity was demonstrated in the Baltic sea waters. This activity was always higher in the near-bottom water, taken from theFucus vesiculosuszone, than in the superficial zone. A cytokinin-like substance showing properties typical of 6-(3-methyl-2-butenylamino)purine (2iP) was also present in extracts from the thallus ofFucus. It was found that exogenously applied cytokinins, in some concentration ranges, markedly increased the number of adventitious branches formed on the cut surface of the thallus fragments. The growth responses of the investigated plant tissues to the different cytokinins varied according to season and kind of cytokinin applied. The possibility of exudation of some cytokinin like substances by the algal cells into the surrounding waters was considered.

Wheat seedlings were cultivated in nutrient solutions containing 10^-3 M CCC, 10^-3 M CEPA or 5 × 10^-4 M CCO and CEPA, respectively. CCC applied alone or mixed with CEPA increased chlorophyll content per unit fresh matter but had no influence on the epinastio response of the primary leaf. In contrast, CEPA had no influence on chlorophyll content but greatly increased the epinastic response. The different response to the application of these substances with regard to chlorophyll content ha been claimed in a previous paper to be due to their different effect on cell extension and cell division. The epinastic response of the primary leaf suggests that ethylene participates in the reaction chain of CEPA effect on plant tissues.

Callus culture was derived from haploid barley embryos after crossing withHordeum bulbosum. The callus tissue is cytologically heterogeneous, containing haploid, diploid and polyploid cells. Aneuploidy and karyokinetic irregularities were also observed. Some problems of chromosomal instabilities in plant tissue cultures are discussed.

Using the enzyme-linked immunosorbent assay (ELISA) beet yellows virus (BYV) could be detected reliably in the leaves of sugar beet andTetragonia expansa Pall. and in the roots of sugar beet. Specifio γ-globulin of BYV antiserum was coupled to horse radish peroxidase by periodate oxidation. Optimum dilutions of antigen (extract from infected leaves) were1: 50 to 1: 200 for BYV detection in sugar beet andT. expansa leaves and1: 2 to 1: 5 for detection in sugar beet roots. Extracts from beet roots are not to be purified by ultracentrifugation, however, by the described method virus can be demonstrated only in 80-90% of naturally infected sugar beet roots. The method is specific, no increase of extinction values was found in healthy or beet western yellows virus infected plants. Presence of virus can be demonstrated by visual as well as photometric evaluation. Results confirmed the suitability of peroxidase application for detection of plant viruses by ELISA.

The investigation of the hormonal nature of plant flowering in connection with their photoperiodic reaction has shown that flowering depends on a bicomponental system of hormones, gibberellins regulating stem formation and growth and substances of the anthesin type regulating flower formation. In agreement with the division of the photoperiodic reaction into a leaf and a stem phase the study of the internal factors acting on plant flowering was carried out by means of leaf and stem (apex, bud and callus) models. The results obtained from work with leaf models proved the presence of two groups of hormones of flowering in plants. The data obtained from the application of stem models pointed to the localization of the action of gibberellin and anthesin in different zones of the shoot apices and characterized the potential capacity for flower formation of isolated callus tissue of neutral and photoperiodically sensitive species.

The influence of growth regulators (GA and IAA) on the genetic effects of sodium azide was studied. Treatments with growth regulators were administered either prior to or after the mutagen. Post-treatments were found to be more effective against mutagen-induced plant growth injury and gave a slightly higher frequency of mutations. M₁ spike sterility however showed a rise following treatments with growth regulators.

Seeds of mung bean (Phaseolus aureus Roxb.) cv. Pusa Baisakhi were surface sterilized and sown both in Petri dishes and sand culture containing aqueous solutions of four different saltsviz. NaCl, KC1, Na₂SO₄ and K₂SO₄ each at 5 and 10 m ώ^-1 cm^-1. Malate dehydrogenase (MDH) isoenzymes were studied in different plant parts of mung bean at suitable intervals during germination under four different salts. In cotyledons, 96 h after sowing only one isoenzyme was left in control as compared to three under salt treatment. In the embryo axis, 96 h after sowing, sulphate salts resulted in the disappearance of isoenzymes with R₁ 0.43 and 0.62, whereas isoenzyme with R₁ 0.62 was missing only at a higher concentration of chloride salts. Chloride salts also resulted in the disappearance of band with R₁ 0.15, both in the embryo axis and leaves. However, in the roots the isoenzymic pattern remains the same with all the salt treatments.

The culture filtrates of the rhizosphere fungi of broad bean (Vicia faba L.) and cotton (Gossypium barbadense L.) were analysed for the presence of plant growth substances of auxin and gibberellins nature. Bioassay test and chromatographic analysis indicated that these fungi, each synthesized different auxins in their culture medium. These auxins were indole compounds. Similarly the rhizosphere fungi produced in their culture medium some gibberellins and gibberellin-like substances.

The investigation of the substrate specificity of the anionic peroxidase isoenzymes, isolated from the zone of differentiation of the primary roots ofZea mays, for some representatives of phenolic compounds and aromatic amines, as hydrogen donors, is reported. The investigation was carried out electrophoretically with peroxidase isoenzymes partially purified by a combination of gel filtration by Sephadex G-25 and Sephadex G-100. A difference in the substrate specificity of the individual isoenzymes is observed. It was established that the anionic peroxidase isoenzymes showed a similarity in total number and relative activity on staining with bivalent phenols and difference on staining with trivalent phenols, as hydrogen donors. A greater number of isoenzymes was stained with benzidine ando-dianisidine and a lesser number witho- andp-phenylendiamine. The substrate specificity of the peroxidase isoenzymes was compared for guaiacol and benzidine. The substrate specificity of peroxidase soenzymes was discussed as regards their diverse role in the plant metabolism.

No proportional changes in the photosynthetic rate,P, (measured as the dry weight increments in leaf discs) as related to the specific leaf weight,SLW (i.e. leaf dry weight per unit leaf area) were found because of different variation inP andSLW, respectively, with the age and insertion level of individual sugar beet leaves as well as with the age of the whole plant.

The distribution of endogenous gibberellin-like substances in individual organs ofZea mays L., cv. CE 250, plants was investigated during the transition from the vegetative to the generative phase of development. The gradient of the content of gibberellin-like substances and photosynthetic activity in leaf segments was followed in different parts of the Jeaves, as well as the changes in the content of gibberellin-like substances in leaf segments during an exposure in the light and in the dark. The gradient of the content of endogenous gibberellin-liko substances in the leaves, in the stem and in the spike is interpreted in terms of possible relationship of these compounds to the regulation of sink - source.

The weight of alfalfa plants, especially roots of susceptible strain, decreased when inoculated withCorynebacterium insidiosum. At the 6th week after inoculation the³²P uptake per plant and its translocation into the above-ground organs were considerably decreased in susceptible plants. On the other hand, the³²P uptake was increased and the radiophosphorus was accumulated in above-ground organs in resistant plants.

Cucumber mosaic virus (CMV) isolates obtained from spontaneously infected (1)Chelidonium majus L. and (2)Impatiens parviflora DC. plants growing in the same part of a scree forest in central Bohemia showed differences in ten test plants, but not in further 26 plant species tested and in TIP. Slight quantitative differences between both isolates were obtained in serological tests. Properties of both isolates did not suit precisely any proposed CMV strain classification.

Deficiency in Ca and P in mineral medium reduced the growth and nitrogen content ofAzolla pinnata but increased the content of soluble sugars in the plant; the deficiency in K and Mg was less effective in retarding the growth. The pH of the medium from 5 to 8 encouraged the growth and nitrogen fixation, whereas acidic pH of 4 as well as alkaline pH of 9 inhibited the growth and nitrogen fixation.

The capability of the submergentLemna trisulca L. to utilize various inorganic and organic sources of nitrogen was studied using both non-axenic and axenic cultures. When doubling time for frond production was measured, the nitrogen sources in order of effectiveness were urea, aspartic acid, nitrate, glutamic acid, arginine, ammonium and casein hydrolysate. Nitrite supported a relatively rapid growth rate after an initial lag of 7 days. Other parameters of growth such as fresh or dry weight per frond or ohlorophyll content did not oorrelate well with rate of frond production. Casein hydrolysate and urea were found to elicit a morphology different from that seen in cultures containing the other nitrogen sources. These preferences for source of nitrogen were different than those known for the emergent species ofLemnaceae. The unique value ofL. trisulca as a subject for plant physiological research is discussed. This study also provides a possible explanation for the existence of nutritional niches existing in aquatio ecosystems containing several different species ofLemnaceae.