In vitro culture of Chenopodium murale L. (ecotype 197) green and herbicide SAN 9789 - treated "white" plants was established and the effects of benzylaminopurine (BAP), indole-3-acetic acid (IAA) and gibberellic acid (GA₃) on growth and flowering were tested. Green plants did not flower on glucose free media, while 17 % of plants flowered on 5 % glucose-containing medium. SAN 9789 (10^-5 M) inhibited growth and flowering. BAP and IAA (0.1 - 5 mg dm^-3) also inhibited growth and flowering of green and "white" plants. GA₃ (10 mg dm^-3) stimulated leaf development in green plants, but had no significant effect on "white" plants, and stimulated flowering of green (41 %) and "white" (33 %) plants.

Lead nitrate at concentration of 150 mg dm^-3 inhibits root growth of Lupinus luteus seedlings by bout 20 %, which is accompanied by an increase of K⁺ leakage from the root cells. Non-denaturing isoelectric focusing in polyacrylamide slab gel has shown that lead stimulates the activity of most lipoxygenase isoenzymes and induces one additional isoenzyme with pI 6.9.

An efficient and reproducible protocol for regeneration of plantlets at a high frequency was developed by using sugar cane buds. Disinfected buds were firstly submerged in ethanol sodium hypochlorite solution with 0.1 % polyvinylpyrrolidone, 1.5 % ascorbic acid and 1.75 % citric acid as antioxidants and subsequently treated with solution of agrimicin:captan (1:1). The upper stalk segment was better to obtain bud in vitro culture compared to lower segments. The medium for induction of multiple shoots consisted of Murashige and Skoog basal medium (MS) supplemented with 2 mg dm^-3 thidiazuron and 1 mg dm^-3 naphthalene acetic acid. An average of 24 shoots per bud was obtained for cv. Mex 68-P23 within four weeks and 29 shoots for cv. MY 55-14 within six weeks. Indole-3-butyric acid induced more roots in both cultivars compared to the untreated plantlets. Plantlets transferred to soil showed normal growth with up to four axilliary buds in each node. It was concluded that the germplasm obtained through the above mentioned technique generated stalks with more buds in each node which would give farmers more vegetative material for plantations in field with 100 % germination.

In order to establish an efficient system for in vitro plant regeneration of a short day plant Chenopodium rubrum L. and a long day plant Chenopodium murale L., optimum culture conditions for somatic embryogenesis were investigated. The effects of different growth regulators, their combination and their concentrations on somatic embryos induction in different explant types (root, hypocotyl, cotyledon and leaf) were tested. Somatic embryogenesis was induced in both plants on Murashige and Skoog (MS) medium supplemented with sucrose (3 %), agar (0.7 %) and 1 - 10 μM 2,4-dichlorophenoxyacetic acid (2,4-D) as the sole growth regulator. The largest embryogenic capacity was found in root explants of Chenopodium rubrum on 1 μM 2,4-D and in basal parts of cotyledons in C. murale plants on 10 μM 2,4-D.

Temporal and spatial variations of shoot structural parameters, including shoot silhouette to projected needle area ratio, are very important, e.g., for the correction of leaf area index estimated by indirect methods. Here we bring few examples of their evolution within mountain spruce monoculture planted in two different densities.

Tissue cultures of Armoracia rusticana L., both transformed with Agrobacterium rhizogenes and nontransformed, were screened for peroxidase activity. Most of the derived and tested strains exhibited 20 times higher activity [from 99 to 723 U g^-1(d.m.)] than the root of the intact plant [(30 U g^-1 (d.m.)]. The highest peroxidase activity was found in tumour culture growing on the medium without growth regulators. The influence of the addition of sugars and heavy metal ions in the medium on peroxidase production was tested. Increase in peroxidase activity was observed after cultivation of horseradish culture with cadmium, cobalt, nickel or lead ions.

The effects of three cytokinins, kinetin 4.5 μM (Kin), 6-benzylaminopurine 4.5 μM (BA) and N-phenyl-N'1,2,3- thiadiazol-5-yl-urea 4.5 μM (TDZ), and the effects of different treatment duration on the regeneration of adventitious shoots from quince (Cydonia oblonga Mill.) leaves were studied. In a first experiment, leaves treated with Kin for 0, 8, 16 and 24 d were transferred to BA or TDZ-containing growth medium. In a second experiment TDZ applied for 0, 4, 8, 12, 16 and 24 d was followed by BA. All treatments included 0.5 μM α -naphthaleneacetic acid (NAA). In the sequence Kin-BA, the production of adventitious shoots decreased and reddish-coloured nodular structures (RNS) of meristematic appearance increased with increasing duration of Kin treatment, while somatic embryo formation was optimal at 8 d. In the Kin-TDZ sequence, shoot production was initially pronounced, but it declined with increasing duration of the Kin treatment, while the number of roots, somatic embryos and RNS increased. TDZ-BA treatments induced marked shoot production, which gradually increased with increasing duration of TDZ treatment. The presence of TDZ and a long treatment duration appeared to be very important factors in inducing caulogenesis. Kin appeared to be effective in shoot induction but not in shoot development; the results of this work demonstrate that RNS were adventitious shoots blocked at an early developmental stage on account of insufficient cytokinin activity. BA was less effective than TDZ in inducing shoot regeneration. Finally, both Kin and BA applied after 2,4-D treatment promoted somatic embryo induction.

In vitro regeneration of four Begonia genotypes, B. semperflorens, B. rex, B.×elatior, and hybrid of Begonia with unknown parents 'Tiger' was carried out starting from leaf and petiole segments as explants. Five Murashige and Skoog's derived media were tested, three of them supplemented with α-naphthaleneacetic acid (NAA) and 6-benzyladenine (BA), and the other two with NAA and kinetin (KIN) in different concentrations. Shoot regeneration was preferentially induced on the BA containing media, quantitative differences being observed among explants and genotypes.

The distribution of amino acids in distinct tissues of Canavalia ensiformes was determined during the life cycle of the plant. Glycine was shown to be the main amino acid in mature seeds, while the nonprotein amino acid canavanine exhibited a high concentration in 7-d-old seedlings. Canavanine was lower in the seeds when compared to other tissues analyzed. This does not support the nitrogen-storage function of canavanine, however, it suggests that it is involved in the translocation of amines during the early stages of the development.

Maintenance respiration rate, R_M, irrespective of growth stages, increased with increase in nitrogen supply. The R_M increased almost in proportion with net photosynthetic rate, P_N, and biomass production during early growth stages, while it declined after anthesis. Significant positive correlation was observed between biomass production and P_N at all growth stages except tillering. Though R_M was positively correlated with biomass production during early growth stages, it was negatively correlated with the rate of increase in shoot biomass after flowering, which could indicate a possibility to identify certain cultivars endowed with low maintenance expenses despite building up biomass.

Stable transformation of Coffea canephora P. was obtained by particle bombardment of embryogenic tissue. Leaf explants were cultured on medium supplemented with 5 µM isopentenyl-adenosine to induce direct embryogenesis. Explants with somatic embryos were transferred to half strength MS medium with 9 µM 2,4 dichlorophenoxyacetic acid. After 2 weeks, the explants with somatic embryos and embryogenic tissue were bombarded with tungsten particles (M-25) carrying the plasmid pCambia3301 (containing the bar and uidA genes) using a high pressure helium microprojectile device. The bombarded explants were submitted to selection on medium containing 5 µM ammonium glufosinate herbicide as selective agent. After 6 months, putative transgenic embryos were transferred to a growth regulator-free medium for germination. The regenerated plantlets were β-glucuronidase (GUS) positive whereas no GUS activity was observed in non-transgenic controls. Incorporation of the bar gene into the genome was confirmed by PCR and Southern blot analysis of the regenerated transformed plants. Greenhouse grown transgenic coffee plants were found to withstand the recommended level of the herbicide Finale™ for weed control.

Axillary buds from adult field-grown plants of Lavandula dentata L. were used to evaluate the effect of growth regulators and culture media on the in vitro shoot proliferation and growth. The highest multiplication rate was obtained using Murashige and Skoog (MS) medium supplemented with a combination of 2.2 μM of benzyladenine and 2.5 μM indole-3-butyric acid. The best condition for rooting was MS medium plus 2.5 μM naphthaleneacetic acid. Rooted plantlets were successfully transferred to soil. Short-term culture derived plants (6 month) exhibited a normal development, but a low frequency of not heritable morphological changes were detected in long term culture derived plants (more than 1 year).

The effect of NaCl on the growth and activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were investigated in the seedlings of four potato cultivars (Agria, Kennebec; relatively salt tolerant, Diamant and Ajax; relatively salt sensitive). The shoot fresh mass of Agria and Kennebec did not changed at 50 mM NaCl, whereas in Diamant and Ajax it decreased to 50 % of that in the controls. In Agria and Kennebec, SOD activity increased at 50 mM NaCl, but no significant changes observed in Diamant and Ajax. At higher NaCl concentration, SOD activity reduced in all cultivars. CAT and POD activities increased in all cultivars under salt stress. Unlike the other cultivars, in Ajax seedlings, APX activity increased in response to NaCl stress. We also observed new POD and SOD isoenzyme activities and changes in isoenzyme compositions under salt stress. These results suggest that salt-tolerant potato cultivars may have a better protection against reactive oxygen species (ROS) by increasing the activity of antioxidant enzymes (especially SOD) under salt stress.

Protoporphyrinogen oxidase (Protox) in the porphyrin pathway is the target site of the peroxidizing herbicides such as carfentrazone-ethyl and oxyfluorfen. In an attempt to develop herbicide-resistant plants, transgenic rice plants were generated via expression of herbicide-insensitive Bacillus subtilis Protox gene fused to the transit sequence for targeting to the plastid using Agrobacterium-mediated gene transformation. Homozygous transgenic rice lines of T₃ generation selected by hygromycin resistance test were examined if they are resistant to the herbicides carfentrazone-ethyl and oxyfluorfen. The homozygous transgenic lines had single copy insertion of B. subtilis Protox gene into their genomes and express its mRNA. Compared to wild-type rice, the transgenic lines were less susceptible to the herbicides when examined with respect to growth, electrolyte leakage, chlorophyll loss and lipid peroxidation. The in vitro Protox activities in transgenic lines were about 56 % higher than those in wild-type rice. With 10 µM concentration of the herbicides in the enzyme assays, Protox activities in transgenic lines were similar to those in non-inhibited wild-type rice. Less amount of protoporphyrin IX was accumulated in transgenic lines than in wild-type rice upon the treatment of the herbicides at 10 µM concentration. Our results indicated that expression of B. subtilis Protox gene was stably transmitted into T₃ rice plants and reduced their sensitivity to carfentrazone-ethyl and oxyfluorfen.

An efficient in vitro plant regeneration system via hypocotyl segments of tetraploid Isatis indigotica Fort. was established. Murashige and Skoog's (MS) and Gamborg's (GB₅) media were found to be superior to White medium for promoting shoot regeneration. The highest shoot regeneration (92 %) was achieved from hypocotyls cultured on MS medium containing 8.9 μM benzyladenine (BA) and 2.7 μM naphthaleneacetic acid (NAA), with an average of 4.2 shoots developed per explant. Plant regeneration was also improved when the explants were cultured in MS basal medium containing 3 % (m/v) sucrose and grown under a 12-h photoperiod. The developed shoots were well rooted in a half-strength MS medium supplemented with 0.5 μM indole-3-butyric acid (IBA) and were morphologically normal after transfer to soil.

We describe the multi-step regeneration system of medicinal plant Schisandra chinensis (Turcz.) Baill. The seeds were pre-treated with 0.005 μM thidiazuron. Subsequently the zygotic embryos of the early heart stage were cultured on medium with 50 μM of 2,4-dichlorophenoxyacetic acid (2,4-D) and after three weeks the embryogenic calli were transferred to a medium with 10 μM of 2,4-D and 4 μM of 6-benzyladenine and were sub-cultured at the 4-week intervals. Abscisic acid (30 μM) and polyethyleneglycol (3 %) significantly influenced the synchronization of development of the somatic embryos (SEs) to the globular stage. The following culture on a medium without growth regulators resulted in full developed cotyledonary stage SEs. Indole-3-butyric acid (0.05 μ) contributed to their rapid conversion to plantlets.

The effects of excess Cu as affected by the application of exogenous hormones (gibberellic acid - GA₃ and indole-3-acetic acid - IAA) with respect to sunflower (Helianthus annuus L.) growth, physiology, and metabolism were studied. Application of 100 μM IAA lessened the toxic effects of 80 μM Cu in roots indicating greater root length and root hair formation, while addition of 100 μM GA₃ ameliorated the toxic effect mainly to the shoot. The content of photosynthetic pigments significantly declined under Cu stress, whereas application of hormones led to a substantial preservation of chlorophylls and carotenoids. Under Cu stress, the rate constant of energy trapping by photosystem 2 (PS2) reaction centres (RCs) was reduced as a result of physical dissociation of the light-harvesting complex (LHC) from PS2 core, while application of IAA and especially GA₃ resulted in stability of the LHC of PS2 RCs. The drop in net photosynthetic (PN) and transpiration (E) rates with preserved or slightly reduced variable to maximum fluorescence ratio (F_v/F_m) in the presence of 80 μM Cu could be explained by a possible inhibition of the enzymatic processes in the Calvin cycle. Application of 100 μM IAA and 100 μM GA₃ lessened Cu effects mainly on P _N. Water use efficiency was also improved under hormone exposure.

An efficient protocol for shoot regeneration and genetic transformation was applied to root segments of a new Lotus corniculatus L. cultivar Bokor. The shoots, that regenerated on root segments, were inoculated with Agrobacterium rhizogenes A4M70GUS, and produced hairy roots, which on media with 0.2 mg dm^-3 benzylaminopurine, regenerated shoots. After rooting and acclimation, the transformed plants were planted in the experimental field. Their morphological traits were compared to controls. No signs of the rol genes phenotype were present. The transformants were significantly taller than controls, while there were no significant differences in the leaf area. The glucuronidase activity and the presence of uidA gene was demonstrated in transformed plants of T₀ and in seedlings of T₁ generations. It is concluded that A. rhizogenes could be a vector of choice for the transfer of desirable genes into the bird's foot trefoil genome.

The special conditions during in vitro culture result in the formation of plantlets of abnormal morphology, anatomy and physiology. After ex vitro transfer, these plantlets might easily be impaired by sudden changes in environmental conditions, and so need a period of acclimatization to correct the abnormalities. This review is focused upon contemporary information on the changes in leaf structure, water relations and photosynthesis during acclimatization of plantlets to ex vitro conditions. It also describes some ways of improving plant survival and for the speeding up of acclimatization.

The ontogenetic changes in growth, and the diurnal changes in net photosynthetic rate (P_N) and stomatal conductance were studied in two peanut cultivars of different habit groups. Significant cultivar differences were noticed: the prostrate cv. M 13 was found superior to the erect cv. J 11 in all the parameters studied. Specific leaf mass and the rates of gross photosynthesis and respiration were higher in cv. M 13 than in cv. J 11. In vegetative phase, the maximum P_N was in cv. J 11, but in pod filling phase, it was in cv. M 13. The differences in growth and P_N of the cultivars were significant after the onset of reproductive sink. Therefore, the screening for higher P_N has to be made at the pod-filling phase, and between 09.00 and 10.00 of the day (at optimum temperature).

Rootstocks for sweet cherry (Prunus canescens Bois) Camil GM 79 were grown in vitro on Murashige and Skoog (MS) medium, and on MS medium with double- and half-strength macroelements. All the media contained 4.4 μM 6-benzyladenine, 0.5 μM α-naphthylacetic acid, 0.3 μM gibberellic acid, 20 g dm^-3 sucrose and 7 g dm^-3 agar. The chemical analyses were monitored on day 0 and 40 of culturing in callus, stem and leaves. Fresh and dry mass of shoots increased linearly up to the end of culture. The highest fresh and dry masses and also the content of Ca and Mg were registered in shoots grown on half-strength MS medium.

The addition of NaCl to cadmium had significant synergistic effect on the wheat root and shoot fresh mass, relative growth rate and net assimilation rate, while showed no significant effects on the dry mass production, leaf area, leaf area ratio, leaf mass ratio and specific leaf area. Additive depression of the rate of photosynthesis and the stomatal conductance was recorded, while no significant effect on the transpiration rate was observed. The Cd stress disturbed the mineral nutrition of the wheat plants either directly or indirectly, NaCl markedly reduce the uptake and internal concentration of K and Ca in the shoot. The combination of cadmium and NaCl showed no additive effects on the content of ions in the root as well as in the shoot of wheat plants.

Plant phenotype stability during ex vitro growth, one of the main requirements of plant micropropagation, was tested on tobacco. Plants cultivated in vitro in the presence of 3 % sucrose under photon flux density (PFD) of 200 μmol m^-2 s^-1 (3 % HL plants) showed the best growth and photosynthetic parameters in the course of 7-day acclimation. However, significant change in phenotype of these plants appeared under a decrease in PFD to 50 μmol m^-2 s^-1 during further ex vitro growth (in the period of 7^th - 17^th day). Much higher internodia elongation was found in 3 % HL plants in comparison with plants grown in vitro on sucrose media under PFD of 50 μmol m^-2 s^-1 (3 % LL) or without sucrose either under PFD of 50 μmol m^-2 s^-1 or 200 μmol m^-2 s^-1 (0 % LL, 0 % HL). It can be presumed that 3 % HL plants show permanent demand for high PFD. Neither ABA or chlorophyll contents nor de novo thylakoid membrane synthesis were related to the morphogenic effect of low PFD. Changeable contents of hexoses in leaves of 3 % HL and 3 % LL plants were in no direct correlation to the elongated growth.

High frequency shoot regeneration from cotyledons excised from 4-d-old seedlings of Brassica campestris L. cv. M 27 and Brassica juncea (L.) Czern. cv. Pusabold was achieved on Murashige and Skoog's (MS) medium supplemented with 1.0 mg dm^-3 N⁶-benzyladenine (BA) and 3 % (m/v) saccharose. Rooting occurred simultaneously with shoot formation on the medium containing 1.0 mg dm^-3 BA and 0.5 mg dm^-3 1-naphthaleneacetic acid. Cultures of cotyledon, cotyledon derived non-differentiating calli and differentiated calli with shoots and/or roots were analysed at different intervals for isozyme patterns of esterase and peroxidase. With the BA-induced development of shoot and/or root from non-differentiating callus, some conspicuous isozymes appeared which indicates the involvement of these isozymes in root and shoot development rather than in induction of morphogenesis in callus.

The shoot apices of ten groundnut interspecific hybrids, showing peanut stripe virus symptoms were used as explants. Murashige and Skoog (MS) medium containing 1 mg dm^-3 each of naphthaleneacetic acid (NAA) and benzylaminopurine (BAP) supported maximum callusing of the hybrids J 11 × Arachis sp. PI 30008 as well as J 11 × A. sp. Manfredi # 5 (86.3 and 82.6 %, respectively). On MS medium with 3.5 mg dm^-3 NAA and 0.2 mg dm^-3 BAP, the meristems of J 11 × A. stenosperma as well as J 11 × A. otavioi gave good response (79.7 and 77.2 %). The regeneration frequencies ranged from 16.7 to 76.9 % and was more than 30 % in all hybrids except for J 11 × PI 30085. Shoots (5 cm) regenerated from the virus-free (ELISA tested) calli rooted well (60 - 80 %) on MS basal medium supplemented with 0.4 % activated charcoal and 200 mg dm^-3 casein hydrolysate. In addition, long shoots which failed to produce roots, when transferred to soil during rainy season and protected from direct sun got established.

The dependency of radicle elongation in Abies numidica somatic embryos on germination media has been studied. No significant differences were detected between the Murashige and Skoog (MS) and Schenk and Hildebrandt (SH) medium. The addition of 10 g dm^-3 activated charcoal or 0.05 mg dm^-3 indole-3-butyric acid (IBA) into both media had positive influence on embryo germination. Difference between activated charcoal and IBA effects were significant. The high rooting percentage (85 %) was recorded on half SH medium with 10 g dm^-3 sucrose and activated charcoal. After IBA addition rooting percentage was increased to 95 %. During 7 months 73 % of plantlets survived transfer to soil and in 54 % of plantlets shoot growth was observed.

The seeds of two barley (Hordeum vulgare L.) cultivars (a drought resistant cv. Tokak-137/57 and a drought sensitive cv. Erginel-90) were imbibed either in distilled water (control) or in a solution containing 40 mg dm^-3 paclobutrazol (PBZ) and air dried. Seeds were germinated and grown in a glasshouse for 21 d and seedlings were subjected to salt stress by treating them with 100 and 200 mM NaCl for 12 d. The height of shoots was significantly decreased and root length was increased in PBZ-treated plants prior and after NaCl stress for 12 d leading to an increase in root to shoot ratio. Leaf chlorophyll and carotenoid contents in PBZ treated plants were increased in controls and especially in plants subjected to salt stress. PBZ induced increase in superoxide dismutase (SOD) activities was higher in cv. Tokak-157/37, than in cv. Erginel-90. However, an increase in SOD activity was not accompanied by an increase in peroxidase activity.

Role of superoxide dismutase isozymes and other antioxidant enzymes was studied in relation to leaf age in sunflower (Helianthus annuus L. cv. ACC 1508) at pre-flowering and grain filling stages. Relative water content (RWC) did not change much in leaves of different age and at the two stages. Protein content declined continuously from the youngest to the oldest leaf, while chlorophyll (Chl) and carotenoids (Car) contents increased down to 7^th/9^th leaf and declined in subsequent older leaves. Protein, Chl and Car contents were higher at pre-flowering than at seed filling stage. Superoxide dismutase (SOD), its isozymes, and ascorbate peroxidase (APO) and catalase (CAT) activities were highest in the 9^th leaf and declined in subsequent older leaves. SOD and APO activities were higher at seed filling, except in oldest senescent (13^th, 15^th) leaves. Among SOD isozymes, Cu/Zn-SOD and Mn-SOD activities accounted for most of the total SOD, and only marginal activity was observed for Fe-SOD. Peroxidase activity increased from youngest to the oldest leaf at pre-flowering stage and down to 13^th leaf at seed filling stage.

We have assayed different combinations of nutrient media and growth regulators to induce callus and plant regeneration from explants of root, shoot and leaf, complete seed, and isolated mature embryo of barley (Hordeum vulgare L. cv. Hassan). The best results were obtained with mature embryo in J25-8 medium supplemented with 2.0 mg dm^-3 2,4-dichlorophenoxyacetic acid where about 75 % developed friable calli. Some 80 - 85 % of these calli regenerated barley plants in the same J25-8 medium supplemented with 1.0 mg dm^-3 indole-3-butyric acid and 0.1 mg dm^-3 kinetin.