This work describes in vitro morphogenesis and plantlet regeneration from seeds of the naturally polyembryonic tree Syzgium alternifolium. The basal medium (BM) comprised half strength Murashige and Skoog's (MS) salts, B₅ vitamins, 2 mg dm^-3 glycine, 250 mg dm^-3 ascorbic acid and 20 g dm^-3 sucrose. Addition of auxins like indole-3-acetic acid (IAA), 1-naphthalene acetic acid or 2,4-dichlorophenoxyacetic acid to the basal medium induced formation of roots or callus from the dicotyledonous as well as tricotyledonous seeds. In contrast, cytokinins like N⁶-benzyladenine (BA), kinetin, 2-isopentenyl adenine, thidiazuron alone or a combination of BA and auxins induced development of adventitious shoots. The medium containing 3.0 mg dm^-3 BA and 0.5 mg dm^-3 IAA induced the highest number of adventitious shoots (32 - 33) from dicotyledonous seed with an average length of 4.1 cm within 6 weeks of incubation. Rooting of 80 % adventitious shoots was achieved by dipping the shoots in 100 mg dm^-3 IAA for 15 min. About 70 % of the rooted shoots were successfully established in pots after hardening.

Simulated acid rain (SAR) combined with higher concentration of aluminium (SAR+Al) influenced the ecophysiology of three arbuscular mycorrhizal fungi (AMF) in both the germination and symbiotic phases of their life cycle. Acaulospora tuberculata, an isolate from the soil with low pH, exhibited a higher tolerance to environmental stress as compared to Glomus mosseae and G. fistulosum. This higher tolerance may be related to the edaphic conditions of soil of the isolate origin. The histochemical staining of the alkaline phosphatase and NADH-diaphorase activities in the extraradical mycelium (ERM) of the AMF proved to be more sensitive indication of negative effects of the SAR or SAR+Al stress compared to commonly measured parameters of the AMF such as mycorrhizal colonisation or growth of the ERM.

21-d-old seedlings of the soybean (Glycine max) cvs. Essex and Forrest were treated with NaCl in a step-wise manner over 9 d (3 d 30 mM, 3 d 70 mM, and 3 d 100 mM) and maintained under 100 mM NaCl for an additional 14 d. During salt treatment, osmotic potential decreased more in cv. Forrest relative to cv. Essex. In non-stressed leaf tissue, cv. Forrest contained more trigonelline (TRG) relative to cv. Essex. During salt treatment, TRG amounts increased in cv. Forrest but were unchanged in cv. Essex. Both cvs. osmotically adjusted in response to salt stress; the maximal osmotic adjustment was 0.80 and 0.18 MPa in cv. Forrest and cv. Essex, respectively.

Carbon translocation was affected by shade in different tropical tree species differing in successional status and degree of shade tolerance. Plants of the early-successional shade-intolerant species Cecropia pachystachya and Schizolobium parahyba and of the late-successional shade-tolerant species Myroxylon peruiferum and Hymenaea courbaril were grown under full sun (FS) and natural shade treatments (NS) and assessed for [¹⁴C]-sucrose translocation. Most of the ¹⁴C was retained in the fed leaf after a 24 h translocation period. Under FS, the growing apical part of the plant was the most intense sink for most species. Shade affected growth and sink intensity differently in early and late successional species. Growth was more markedly affected in the early species. Whereas these continued to invest carbon into the growing apical part of the plant under shade conditions, the late successional species invested relatively more into other sinks.

In four genotypes of chickpea (Cicer arietinum L.) BG 362, BG 372, BG 329 and C235 the relationship between somatic embryogenesis of leaf explants and ethylene and methane evolution was studied. In BG 362, which was more embryogenic than other genotypes, a higher ethylene:methane ratio of 5.8:1 at day one after inoculation in the induction medium and a lower ethylene:methane ratio of 2.89:1 in the maturation medium was found. On the contrary, in BG 372 with the least embryogenic potential, a lower ethylene:methane ratio of 1.7:1 in the induction medium and a higher ethylene:methane ratio of 4:1 in the maturation medium was found. Thus, these ratios in induction and maturation stages seems to be markers for embryogenesis in leaf explants of chickpea.

Plants of bean (Vicia faba L. cv. Calvor 103) were salt-stressed with NaCl and CaCl₂ in concentrations inducing soil osmotic potentials (ψ_soil) from 0 to -1.2 MPa and were sprayed with proline (8.7 µM) and glycinebetaine (8.5 µM) solutions. Bean plants respond to increasing soil salinity by decreased leaf relative water content and osmotic potential. Salinity decreased the contents of dry mass, chlorophyll, soluble and hydrolysable sugars, soluble proteins and enhanced content of total free amino acids, Na⁺, Ca²⁺ and Cl^-. The ratio of K⁺/Na⁺ was decreased on salinization. The membranes of leaf discs from salt-stressed plants appeared to be less stable under heat stress (51 °C) than that of unstressed plants. The reverse was true for discs placed under dehydration stress (40 % polyethylene glycol 6000). Proline and glycinebetaine application reduced membrane injury, improved K⁺ uptake and growth. Also both solutes increased chlorophyll contents.

An improved version of a simple histochemical test for the in situ assaying the production of hydrogen peroxide in living plant tissue was demonstrated. The test solution containing 50 mM KI in a 4 % potato starch solution was directly applied to the fresh cut surface of the tissue to be tested. Incorporation of an enhancer potassium permanganate (1 % final concentration) into the test reagent resulted in a ten times greater hydrogen peroxide mediated oxidation of iodide ions to iodine, especially in the case when, e.g. suboptimal concentration of H₂O₂ is present or endogenous catalase decomposes the H₂O₂ in tissue as quickly as it is evolved. Subsequently, iodine is complexed by the starch to form a coloured product. H₂O₂ production by wound-induced oxidative burst or lignification can be easily discriminated due to the dual colour response.

Chlorophyll (Chl) a and b content, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) content and activity, and electron transport rate were measured in flag leaves of wheat genotypes Uniculm and Kalyansona, grown at suboptimal and optimal supply of nitrogen. The Chl content, RuBPCO activity, and electron transport rate were decreased due to suboptimal nitrogen supply only in Kalyansona. There was no change in the ratio of RuBPCO and photosystem 2 (PS2) activity at various stages which suggests that there was no alteration in distribution of N due to additional N supply.

A fully habituated (auxin- and cytokinin-independent) self-regenerating (organo-genic) sugar beet cell line (HO) and a fully habituated non-organogenic one (HNO) derived from the former one, were analyzed as to their nuclear size and DNA content. Flow cytometry and image analysis were used and cells of certified diploid leaves of the same sugar beet strain served as controls. The HNO cells had been shown previously to have many characteristics of cancerous cells. The analyses made on leaves and HNO cells indicated the presence of only one population of cycling cells. In HO cells, two cycling populations were detected: the first one had the same DNA content as the leaves while the second one contained two fold more DNA than the first population. HNO cells showed the higher nuclear size and DNA content. HNO cells also showed evidence of aneuploidy. Thus, nuclear size, DNA content and ploidy level increase together with the neoplasic progression to culminate in HNO cells with the loss of organogenic totipotency.

Using various transformation methods, T-DNA constructions for insertional mutagenesis were introduced into Arabidopsis thaliana and the pattern of segregation of hygromycin resistance selectable marker was followed in succeeding generations in individual transgenic lines up to T₄ generation. Despite the low frequency of transformation, T-DNA was often inserted in two or more independent sites. Mendelian segregation ratios 3:1, 15:1, and irregular segregation ratios were observed. We have also shown continuous decrease of the expression of the resident hygromycin resistance transgenic trait in some lines.

The protein profile of cells of control somatic embryos was compared to that of embryos that have become selected and maintained on 200 mM NaCl in order to detect salt inducible proteins. Two proteins (60 and 51.5 kDa) were more abundant in the selected embryos and one protein with molecular mass 18 kDa was unique to the selected embryos. Enhanced content of 27 kDa protein was observed in all somatic embryos indicating its involvement in the embryonal state. Similar pattern of salt inducible proteins in selected somatic embryos and the plantlets regenerated from such embryos was found.

Ultrastructure of leaf mesophyll and two-layer trap wall of Utricularia vulgaris L. was studied after 24-h and 48-h treatment with different concentrations of cadmium. The treatment of plants with 0.25 g(Cd²⁺) m^-3 caused different changes in the chloroplasts of the two organs. The thylakoids swelled in chloroplasts of leaf and the starch content increased in chloroplasts of traps. Higher concentrations of Cd (0.5 and 1.5 g m^-3) caused osmiophilisation of thylakoids in the chloroplasts of both studied organs. The secretory cells in the trap wall was resistant to Cd.

Total chlorophyll (Chl) content, leaf mass per area (LMA), and net photosynthetic rate (P_N) were studied in four cultivars of mango (Mangifera indica L.) from September to May. Maximum Chl contents were found in September and December, the period considered to be crucial for flowering in mango. P_N was maximum during October and maintained almost steady during the fruit growth period. However, LMA varied significantly in all cultivars. Mean Chl content, P_N and LMA were lower in cv. Malaviyabhog than in other cultivars.

Treatment of excised marrow (Cucurbita pepo L., zucchini) cotyledons with methyl ester of jasmonic acid (MeJA) had no effect on their growth in darkness. On the other hand, MeJA induced the synthesis of three polypeptides (69, 60 and 43 kDa) and stimulated the accumulation of other polypeptides (97.4 and 53 kDa). These changes in the polypeptide profile were accompanied by a suppression of total protein and RNA synthesis as well as the activity of nuclear RNA polymerases. In contrast to MeJA, N⁶-benzylaminopurine (BAP) significantly enhanced cotyledon growth and stimulated protein and RNA synthesis. Furthermore, BAP, when applied together with MeJA, was able to counteract some effects of MeJA including the appearance of specific MeJA-induced polypeptide bands.

Root growth of Sinapis alba seedlings was used to determine the interactions (antagonism, synergism, and indifference) among Cu²⁺, Ni²⁺, Mo⁶⁺, Mn²⁺ and V⁵⁺ (each to each). For majority of combinations the antagonistic or indifferent effect was observed. The synergism was confirmed only between Ni and V, Mo and V, and Cu and V. V and Mn had reciprocal antagonistic effect each other, and Mn was like as Mo and Cu the antagonist to Ni. Molybdenum came up reciprocal indifference with regard to Cu and Mn, Mn and Ni did not influence unfavourable effect of Cu on S. alba root growth.

Shoots of Bacopa monniera exhibited 100 % regeneration on Murashige and Skoog medium with 2 % sucrose, 0.2 mg dm^-3 1-naphthaleneacetic acid, 0.5 mg dm^-3 6-benzylaminopurine and 50 mg dm^-3 glutamine. When the medium was supplied with various concentrations (5 - 15 g dm^-3) of sodium chloride, proline content in regenerants was six times higher than in the control. With increasing NaCl concentration photosynthetic rate decreased and fresh mass and root length of regenerants declined. NaCl also induced formation of new proteins.

The effect of indole-3-acetic acid (IAA) and gibberellic acid (GA₃) applications on parthenocarpic fruit set in Rosa canina and Diospyros lotus was investigated. GA₃ induced parthenocarpic fruit set in both plants, but IAA only in D. lotus. Maturation of seedless fruits was earlier than the seeded fruits. GA₃ caused a decrease in the fresh mass and size of both fruits. IAA induced an increase in the fresh mass and size in parthenocarpic fruit of D. lotus.