Genotypes of mustard (B. juncea) were evaluated for concurrent changes in leaf water potential (Ψ), leaf osmotic potential (π), leaf turgor potential (P) and leaf relative water content (RWC) during moisture stress at reproductive stage of growth. The slope 'b' in the regression between Ψ and π varied from 0.43 to 0.97 and was positively correlated with P and RWC. The genotypes with 'b' around 0.7 were able to maintain P of about 0.5 MPa at Ψ of - 2.5 MPa and thus such value of 'b' seems to provide enough degree of tolerance against drought.

Growth and ionic relations were studied in six triticale cultivars of different geographical origins grown in a greenhouse in nutrient solution with or without the addition of 100 mM NaCl. In 21 d old plants of all the six cultivars growth was little affected in the salt treatment, whereas in the subsequent three harvests during vegetative phase (after 31, 38 and 45 d), growth reduction effects of salinity were progressively pronounced. Generally, shoots of all the six cultivars accumulated relatively more K+ as compared to Na+ or Cl-. Differential accumulation of K+, Na+ and Cl- by various cultivars was coupled with variable rates of Na+ and Cl- transport from root to shoot which were - to some extent- related to cultivar differences in growth in saline root media. Chloride content of shoots of the six cultivars was negatively correlated with the relative growth reduction due to salinity at the four harvests.

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.

The effect of the glucoainolate sinigrin applied at concentrations from 5×10^-6 to 5 × 10^-3 g cm^-3 on the infectivity of two isolates of turnip mosaic virus (TuMV) was studied. A statistically highly significant linear correlation relationship was found between the concentration of sinigrin added to the sap prepared from infectious plants ofPetunia hybrida hort. Vilm. cv. Lavina and the infectivity of the virus, expressed in the number of local necrotic lesions onNicotiana tabacum L. cv. Samsun leaves. Sinigrin caused a statistically significant decrease in the virus infectivity already at a concentration of 5 × 10^-5 g cm^-3. This virocidal effect of sinigrin was not dependent on the virus isolate applied and was not influenced by the host plantsP. hybrida andNicotiana glutinosa L. A statistically highly significant decrease in the virus infectivity was also caused by sinigrin applied at a concentration of 5 × 10^-3 g cm^-3 in the sap from infectiousSinapis alba L. andBrassica nigra (L.) Koch plants, in which case its enzymic degradation to allyl isothiocyanate was observed. When these plants were homogenized in 0.5 M phosphate buffer pH 8.5, no statistically significant decrease in the infectivity of the virus was observed. Purified virus preparations in 0.5 M phosphate buffer pH 7.5 were not affected by sinigrin applied at the concentration of 5 × 10^-3 g cm^-3. The significance of the content of glucosinolates in the pathophysiology of theBrassicaceae and in their resistance to viruses and other pathogens is discussed.

Eight to nine months old seedlings of the Cactaceae Gereus validus HAWORTH grown in soil culture were chosen to study day-night cycles of net CO₂ exchange, indicating the stomatal rhythm of crassulacean acid metabolism, CAM, in relation to day-night changes of abscisic-acid levels. Drought stress was imposed by repotting the seedlings in dry sand and keeping them without watering for up to 37-39 days while control plants were watered regularly. Abscisicacid levels were higher in the stressed plants than in the controls and higher in the light period aa compared to the dark period. In the stressed plants abscisic-acid levels increased throughout the light period. Abscisic acid reached particularly high levels in the late afternoon in plants stressed for 37 days. It is conceivable that stomatal closure during the first part of the light period of CAM is elicited by high internal partial pressures of CO₂ built up by decarboxylation of nocturnally stored malic acid. However, the elimination of late-afternoon stomatal opening and the reduction of stomatal opening during the dark period of CAM observed under conditions of drought stress must have other reasons. The analyses of abscisic acid presented allow the conclusion that this stress hormone is involved in stomatal regulation of CAM under such conditions.

The size of the spring barley root system was studied on the basis of its electric capacity in plants grown in nutrient solutions either lacking or containing nitrogen in the form of nitrate or ammonium.
Root electric capacity changed in dependence on nutrition from Day 12 after emergence, when F values increased in the root systems of plants exposed to nitrate and ammonium salts. In plants grown in H₂O, the values of electric capacity statistically significantly decreased on Days 15 to 17, in plants grown in PK solution lacking nitrogen on Day 20.
Root electric capacity of plants grown in full nutrient solution gradually increased on Day 18 after emergence. Then a marked increase in root electric capacity values followed with no statistically significant differences between NH₄ ⁺ and NO₃ ^- nutrition. Nitrate nutrition of barley plants only resulted in an increased root to shoot mass ratio.

Physiological regions of yam tubers were morphologically defined in different specie into 'Head', 'Middle' and 'Tail', while the limits of these regions were studied using phosphorylase activity. Variation in enzyme activity, pH and protein concentration was found in different regions of the tubers. Old yam tubers had significantly higher activities of saccharide degrading enzymes, hexokinase, phosphorylase, glucose-6-phosphate dehydrogenase, phosphofructokinase and pyruvate kinase, than the new tubers. However, activity of phosphofructokinase in newD. rotundata was higher than that of old tuber. The high activity of phosphorylase in different regions of all the yam tubers examined indicates a very important role of this enzyme in starch degradation inDioscorea species. The measured pH and protein concentration were also higher in old yam tubers. Except for phosphorylase, these enzymes had alkaline pH optima.

The variations in length and fresh and dry mass of etiolated hypocotyls of lupin during the growth have been studied. The growth exhibited by the different zones delimited along the hypocotyl was dependent on the localization of the zone as well as on the age of seedlings, but in both cases the pattern of growth was similar. During the period of growth studied (seedlings 7 to 21 d old), the growth of hypocotyl was basically due to cell elongation, since the relative elongation of cells was positively correlated with the relative elongation of the hypocotyl.

Both axillary buds belonging to the cotyledons (cotyledonary buds) start to grow on decapitated pea seedlings, but one of them (the dominant shoot) prevails in growth over the other (the inhibited shoot). If the dominant' cotyledonary shoot is removed, the inhibited shoot is released from inhibition and starts to grow. This release from inhibition of the inhibited cotyledonary shoot is accompanied within two hours from the removal of the dominant cotyledonary shoot by a marked increase in the level of endogenous cytokinin-like substances and by a decrease in the level of endogenous IAA. By contrast, a significant increase in IAA level and a decreasing trend in the level of cytokinin-like substances occur in the originally inhibited cotyledonary shoot between hour 4 and hour 48 after the release from inhibition of the inhibited cotyledonary shoot. The level of gibberellin-like substances in the cotyledonary shoot released from inhibition steadily increases from the beginning of the release.

Five independent tobacco regenerant clones obtained after transformation withAgrobdcterium rhizogenes strain TR101 (four clones of the T phenotype, clone 5 a mixture of plants of the T and T' phenotypes) and untransformed plants cultivatedin vitro were gradually acclimated to the atmosphere and transferred to the soil substrate in pots. During 28 d after transplanting the increase of the leaf area was in T phenotype plants greater than in untransformed plants, but 14 d later no significant differences were observed between T phenotype and untransformed plants in leaf area and dry matter. T'phenotype plants, however, had significantly lower values in all growth parameters than T phenotype and control plants. Abaxial net photosynthetic CO₂ uptake (PN) was in both T (clones 1-4) and T' plants significantly lower than that in control and clone 5T plants. Nevertheless, due to the relatively higher adaxial PN in T plants, the total PN through both leaf surfaces was significantly lower only in clone 4 and clone 5' plants. The tendency to higher transpiration rates (E) in clones 1 - 4 in comparison with the control resulted in significant differences in water use efficiency (W.U.E.). Relatively higher E in T plants of clones 1 - 4 was connected most probably with their more developed root system (greater root dry-matter) than in untransformed plants, because no influence of the differences in stornata density on E was found.

Endogenous gibberellin-like activity was determined in dry pea seeds (Pisum sativum cv. Bördi), in cotyledons and axes of germinating pea seeds and also in excised cotyledons and axes. During the first two days of pea seed germination, neither the embryonic axes nor the cotyledons show a mutual influence on gibberellin activity, but this appears after 72-96 h of germination. The gibberellin-like activity m cotyledons and axes of germinating seeds increased during the same period, but it decreased in isolated axes and excised cotyledons.

The effect of the growth substances indol-3-ylbutyric acid (IBA), kinetin (Kn) and gibberellic acid (GA3) on the alkaloid content and recovery from the stress induced by removal of roots inNicotiana rustica L. plants have been studied. All treatments, mainly GA₃, overcome the stress more effectively than the controls. The alkaloid content was increased 2.5fold with GA₃. Treatment with Kn also increased the alkaloid content, but only in the absence of roots. In contrast, treatment with IBA slightly reduced the alkaloid content. The results of this investigation indicated that a degradation of stored alkaloids did not occur in spite of the stress.

Asparagus bean (Vigna sesquipedalis Fruhw.) cuttings responded to Cu²⁺ treatments by a rapid and marked increase in ethylene production. This response showed a transient nature but was only partially reversed by returning cuttings to water after prolonged Cu²⁺ treatments suggesting that relative stable links between Cu²⁺ and the ethylene forming system may occur. Cu²⁺ treatments did not induce any visible necrosis nor affect ethane release from cuttings. The Cu²⁺-stimulated ethylene production was not attributable to a light-driven peroxidation of membrane lipids, because it was not affected by a quencher of singlet oxygen nor by a free radical scavenger, whereas it was strongly depressed by light and entirely suppressed by aminoethoxy-vinylglycine. These results support previous finding on the so-called "stress ethylene" and suggest that the Cu²⁺-stimulated ethylene production may be attributable to an enhanced conversion of S-adenosylmethionine to l-aminocyclopropane-l-carboxylie acid.

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.

Cytochemical investigations on peroxidase localization during microsporogenesis inLarix europaea D.C.,Taxus baccata L. andPinus sylvestris L. have revealed striking differences in the localization and activity level of this enzyme linked with the developmental stage.
The localization and level of activity of peroxidase, typical of each stage, changed in the course of microsporogenesis in a strictly orderly way, giving a characteristic and stable pattern. The pattern of intracellular peroxidase localization proved to be the same for microsporogenesis of all the gymnosperms in question.
It is suggested that the identity of that pattern in plants so phylogenetically distant asTaxus baccata L. andPinus sylvestris L. indicates that peroxidase activity in gymnosperms' microsporogenesis is connected with the fundamental and genetically well stabilized processes of meiotic cytodifferentiation.
Moreover, enhanced peroxidase activity has been found in the sites of callose walls synthesis of dyads and tetrads, which suggests the participation of this enzyme in callose synthesis.

Protoplasts derived from suspension cultures of the winged bean and a crown gall lineof Parthenocissus tricuspidata were enucleated by centrifugation on iso-osmotic discontinuous Percoli gradients and on discontinuous sucrose-mannitol density gradients. Enucleation was achieved according to the buoyant density of the protoplasts and preparations of both cytoplasts and miniprotoplasts were recovered. The Percoll gradients gave more satisfactory results than the sucrose-mannitol gradients. Enucleation was increased by raising the centrifugal force from 20 kg to 60 kg. The presence of nuclei was determined by the DNA specific probe 4'6-diamidino-2-phenylindole (DAPI). Membrane integrity, as measured by staining with fluorescein diacetate, showed that some 85 % of the cytoplasts were bounded by an intact plasma membrane.

Trichoblasts ofGibasis geniculata andTradescantia, fluminensis were observedin vivo under the polarizing microscope with the first-order red plate of a retardation of 530 mµ. It was revealed that the cell wall's birefringence in plane view was negative with respect to the apicobasal axis of the cell in young cells before elongation, turning positive after elongation. Birefringence has never been observed when the cellular polarity was disturbed by colchicine. Therefore, it seems that the cellular polarity of root hair formation is controlled by anisotropic structures of the cell wall.

The 18-day-old tomato vitroplants were obtained in axenic conditions by culture of expiants (including the terminal bud and the last internode of the stem) on agar-agar nutritive medium with 0 or 75 mM NaCl. The growth and the mineral content of the vitroplants were compared when the expiants were grown on media either with low or high K/Na and Ca/Na ratios, or with low K/Na and Ca/Na ratios after pretreatments of expiants by KC1, NaCl or CaCl₂ (from 0 to - 4.5 bar). The KCl pretreatment (-1.1 bar) during one day brings about an increase in vitroplant growth greater than that produced by a high Ca/Na ratio medium. The Cl accumulation was similar in expiants pretreated by KCl or NaCl. Ion content per gram of fresh matter was similar in 18-day-old vitroplants pretreated by KCl, NaCl or CaCl₂; the Na accumulation by KC1 pretreated vitroplants was not lower than that of 18-day-old vitroplants grown on a high Ca/Na ratio medium. These results show the relation between Na content of expiants and the growth of vitroplants in a NaCl medium.

A fertile plant with altered phenotype of oilseed rape (Brassica napus) spring cultivar HM-81 was regenerated from hairy root tumors incited by Agrobacterium rhizogenes 15834. Southern blot hybridization analysis revealed several copies of T_l and T_r-DNA of Ri plasmid.

The inhibitory effect of ADP on the plasma membrane ATPase from the parenchyma cells of Jerusalem artichoke (Helianthiis tuberosus L.) tubers was investigated in both physiological states (dormant or non-dormant). To begin with, several sources of ADP were employed, as many commercial ADP contain a variable and non-negligible amount of vanadate the inhibitory effect of which on plasmalemma ATPase is well known. By using vanadium-free ADP, it was possible to show that the plasma membrane ATPase was inhibited by ADP. Similar levels of inhibition were measured in dormant and non-dormant samples, showing that endogenous ADP is not responsible for the physiological regulation of ATPase activity in dormant and non-dormant materials.

Flag leaf removal at any stage of grain growth hastened senescence (reduction in chlorophyll content) of the sterile glumes whereas a removal of the latter did not alter senescence of the former. Kernel mass, grain mass per ear, harvest index and sink activity reduced more conspicuously by the removal of glumes than by the flag leaf removal. Removal of grains hastened senescence of the glumes only, although protein content increased at a later grain removal in the majority of source organs. Moisture contents of the developing grains were mostly reduced by the removal of either the flag leaf or the glumes, though flag leaf removal at anthesis affected it the most. Protein levels of the developing grains reduced at harvest only when the glumes were removed at anthesis but sugar levels in later phases always decreased irrespective of the time of removal and nature of the source organs.

Differently positioned seeds in the mature pod of winged bean (Psophocarpus tetragonolobus (L.) DC) differ in mass and content of total protein and phosphorus and starch.

Subeellular localization of the enzymes which phosphorylate hexoses was studied in photosynthesizing tobacco leaves by means of differential centrifugation and centrifugation in sucrose gradient. More than 80 % of the total hexokinase activity of leaf tissues were found to be associated with the particulate fraction of mitochondria; however, the ratio of the particulate hexokinase fraction to the soluble fraction was influenced by the extraction medium applied. The particulate hexokinases showed a high affinity to glucose (Km = 26.8 μM) and a relatively low affinity to fructose (Km = 17.6 mM). They had a broad pH optimum, because 81 % of the phosphorylating activity obtained for glucose and 75 % of the activity obtained for fructose occurred in pH range from 7.9 to 9.1 (Tris-HCl buffer). The hexokinases were Mg2+ dependent with the highest activity occurring at equimolar Mg2+ and ATP concentrations. Their activity was enhanced by KC1, NaCl, and (NH4)2SO4 at 30 to 120 mM concentrations.

Growth of Dunaliella tertiolecta was retarded when the alga was exposed to high boron (B) concentrations between 50 and 200 g m-³. Photosynthetic oxygen evolution as well as respiratory oxygen uptake were significantly suppressed with the rise of B concentration. Similarly the contents of chlorophyll, glycerol, lipid and proteins were lowered, while that of saccharides was raised.

Sulphate ion is accumulated in the cells of the algaHydrodidyon reticulatum to a concentration approximately 30 mmol 1^-1. The rate of SO₄ ^2- uptake is increased markedly in the light, however, the effect is observable only after the cells have been kept in the light for about one hour. Uptake of sulphate is strongly inhibited by phosphorylation uncouplers and also by DIDS. The two-phase sulphate uptake kinetics, reported earlier was confirmed in experiments in which competition with phosphate anion was tested. Phosphate competes with sulphate only in the range of higher substrate concentrations (from 0.2 mmol 1^-1) and does not affect the system which works at low substrate concentrations. Efflux of SO₄ ^2- is very slow; the reason of the flux hindrance is not yet known.

InTradescantia, clone 4430, diethyldithiocarbamate (DEDTC) markedly decreased the frequency of somatic mutations induced by maleic hydrazide (MH) and N-nitrosodiethylamine (NDEA). In contrast, DEDTC had no such effect on N-methyl-N-nitrosourea-induced mutagenesis. The putative degradation and conversion products of MH (maleic acid diamide, succinic acid, maleic acid, lactic acid and hydrazine) exhibited no mutagenic activity in theTradescantia mutagenicity assay.

Respiration rate of foliarPelargonium discs was insensitive to ageing. The addition of BAP or GA₃ to the ageing medium did not produce any effect.
The presence of GA₃ or BAP in the ageing medium induced an increase (27 %) or a decrease (45 %) of the phosphate uptake. The analysis of phosphorylated compound labelling showed that these two hormones decreased³²P incorporation in the non-acid soluble fraction and increased³²P incorporation in the acid soluble organic fraction. GA₃ and BAP had little effect on the distribution of radioactivity between the different acid soluble compounds, but they increased the ATP level.
These results suggest that both GA₃ and BAP increase the basal metabolism, but they seem to act differently on the development of the uptake mechanism during ageing.