Whole sugar beet (Beta vulgaris L. cv. Ras poly) plants were grown in the greenhouse from the same seed stock used for an in vitro shoot tip culture. In vitro produced sugar beet plants exhibited a high content of chlorophylls a and b, carotene, and total and soluble sugars. On the other hand, total protein content of in vivo plants was higher than that of in vitro plants. No differences were found by SDS-PAGE analysis in the nature and contents of soluble proteins of in vitro propagated plants and greenhouse-grown plants. Surfaces of epidermal cells were larger and palisade and spongy paranchyma tissues were thicker in leaves of regenerants than in leaves of seedlings. Vascular tissues in leaf petioles in regenerants were flat and more differentiated than in seedlings. Closed and undeveloped stomata were found on the abaxial leaf surface of regenerants, whereas in seedlings the stomata were open.

The effects of 1 mM cadmium, lead and nickel on dry mass, Cd, Pb, and Ni contents, and changes in leaf structure in young wheat plants were studied. In leaves, Cd content was highest, followed by Pb and Ni, in roots Cd content was also highest, but followed by Ni and Pb. Roots accumulated considerably larger amounts of the three heavy metals than leaves. Largest reductions of leaf and root mass were obtained with Cd. Pb and Ni effects were almost equal. Ni excess had a strong negative effect on mesophyll thickness, while Cd mostly reduced the number and size of vascular bundles and vessel diameter. High Pb reduced the diameter of vessels causing their different deformations.

New modifications of the method for pea starch and amylose/amylopectin analysis were tested with small samples size of smooth and wrinkled peas. The milling process of the sample and preliminary extraction with 40 % ethanol were very important and affected markedly the standard deviation.

Activities of alcohol dehydrogenase, hexokinase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase were significantly inhibited by cadmium in germinating pea (Pisum sativum L. cv. Bonneville) seeds. The effect was concentration dependent in the range of 0.25 to 1.0 mM CdCl₂. The magnitude of detrimental effect on these enzymes was reduced during later stage of germination (9 d) largely because of fall in the activities of these enzymes in the control seeds germinated in water. In vitro, activities of hexokinase, glucose-6-phosphate dehydrogenase, and alcohol dehydrogenase were inhibited at 0.5 mM Cd²⁺ in the reaction mixture by 62, 67, and 36 %, respectively, however, 6-phosphogluconate dehydrogenase was insensitive to Cd²⁺.

The effect of acute ozone exposure on the stomatal conductance and leaf water content during rapid desiccation was examined in leaves of two tobacco cultivars, ozone sensitive cv. BelW3 and ozone tolerant cv. Samsun. The relative rate of stomatal closure was constant during leaf desiccation in cv. Samsun but decreased in cv. BelW3 in both ozonated and control plants. Ozone exposure increased the relative rate of stomatal closure and transpiration rate (measured on the following day) in cv. Samsun, but reduced the respective parameters in cv. BelW3. As a result, the plants of ozone-sensitive cultivar, treated with ozone, lost more water during desiccation than control plants.

Two forage grasses, timothy (Phleum pratense L.) and ryegrass (Lolium multiflorum Lam.) were exposed to flooding, and activities of alcohol dehydrogenase (ADH) and their isozyme profiles were determined. The flooding stress increased ADH activities in both species. This increase was 2-times greater in timothy than in ryegrass. Only one ADH isozyme was found in non-flooded seedlings of both species, whereas two and four bands were identified in ryegrass and timothy seedlings, respectively, under flooding stress.

The aim of this work was to evaluate how the Falling Number (FN) in introgressive triticale lines is influenced by introduced Triticum monococcum genes responsive for mature spikes sprouting resistance (SR). These lines were developed in two independent series (A and B) by incorporating of diploid wheat (T. monococcum) genes in two different strains of hexaploid triticale (LT 176/10 and LT 522/6) using the synthetic allotetraploid T. monococcum/Secale cereale (A^mA^mRR) as a bridging form. In three consecutive vegetation seasons the mature spikes response to artificial wetting was tested to assess SR. FN was evaluated in full milling of seeds to characterize the level of starch-protein matrix damage in 57 introgressive triticale lines. The obtained results showed twofold higher coefficients of variation of the SR than FN. SR-FN correlation was generally significant in a B-series of lines and statistically insignificant in an A-series showing dependence on the triticale recipient parent and year. In opposite to SR, in both series there was not a line having FN comparable with that of diploid wheat parent. This demonstrates that genetic background of the FN is more complicated in relation to inheritance of SR.

Eight cultivars/lines of Gossypium hirsutum (CIM-443, CIM-448, CIM-1100, FH-634, S-111, S-113, Cedix, and LRA 5166) resistant to cotton leaf curl virus (CLCuV), one moderately-resistant (cv. NIAB-Krishma), and one susceptible (cv. S-12) were used. All the resistant lines remained free of all disease symptoms, whereas in moderately-resistant and susceptible cvs. leaf curling and vein thickening occurred. Cultivars with varying degree of CLCuV-resistance had different pattern of accumulation of macronutrients. Leaf N content was lowest in S-12, but increased considerably due to disease. Leaf K and Ca contents of S-12 were lower in the diseased leaves than in healthy ones. Chlorophyll a and b contents were highest in lines S-111, S-113 and S-12. A marked reduction in chlorophyll b content was observed in the diseased leaves of S-12. Leaf water potential in S-12 and NIAB-Krishma was also decreased due to disease. The most distinctive characteristic to differentiate between lines was epicuticular wax content, since all the resistant lines had considerably higher wax content on their leaf surfaces than the moderately-resistant or susceptible cultivars.

The influence of potassium sulfate, abscisic acid (ABA) and indole-3-acetic acid (IAA) solutions on xylem exudation rate and potassium efflux from the apical cut end of root tips of intact maize (Zea mays L. cv. Dnepropetrovskaya) seedlings was studied. Foliar application of 5 mM K₂SO₄ considerably stimulated the exudation rate. The application of ABA and IAA (1 mM) also induced a high rate of xylem exudation, K⁺ efflux being simultaneously increased.

In Solanum nigrum, the initiation of root primordia occurred directly on stem explants or microshoots cultured on half strength MS medium supplemented with 1 mg dm^-3 indolebutyric acid (IBA), indole-3-acetic acid, or naphthalene acetic acid, IBA being most effective. Initiation of shoot primordia occurred on B5 medium supplemented with 0.5 mg dm^-3 benzylaminopurine (BAP) or kinetin; BAP was more active. During shoot formation, the increased content and the expression of new isoenzymes of peroxidase (POX), esterase and malate dehydrogenase was found. On the other side, expression of new indophenol peroxidase isoenzyme was detected during root formation. Organogenesis of S. nigrum has no effect on glutamate oxaloacetate transaminase and glutamate dehydrogenase content. Differential expression of POX could be detected between basal and upper side of explants.

Activities of host ribonucleases and glucose-6-phosphate dehydrogenase were studied in three cultivars (Monosvalof, Steffi and Rimini) of sugar beet differing in their resistance to beet necrotic yellow vein virus (BNYVV). No differences were found in the susceptibility of cultivars to BNYVV between mechanically inoculated and Polymyxa betae (a natural fungal vector of the virus) infected plants, but the culmination of reproduction curves of BNYVV in mechanically inoculated plants was observed one week earlier than in plants inoculated by means of P. betae. The activities of ribonucleases corresponded with virus multiplication. In roots, activities of ribonucleases reached a maximum at day 7; in leaves, maximum activity was found at day 21 in cv. Monosvalof, and at day 14 in cv. Steffi. The relatively resistant cultivar Rimini showed much lower activities. The activity of glucose-6-phosphate dehydrogenase was only slightly increased at the time of culmination of the BNYVV reproduction curve in cvs. Monosvalof and Steffi.

A reliable protocol for plant regeneration from mature embryo derived calli of nine barley (Hordeum vulgare) cultivars has been developed. The auxins 2,4-dichlorophenoxyacetic acid, picloram and dicamba proved effective in inducing callus from mature embryos of most of the barley cultivars. The induced primary callus was loose, friable and translucent. It ultimately yielded creamy white and compact callus after 2 - 3 transfers on fresh medium of the same composition. Callus induction and regeneration capacity were highly cultivar dependent. Addition of a high concentration of picloram (4 mg dm^-3) promoted regeneration in 3 cultivars (Tallon, Grimmett and Sloop). In cv. Arapiles, abscisic acid and betaine were crucial in generating morphogenic callus from the mature embryos. Plants regenerated from these calli were hardy and developed roots readily when transferred to hormone free medium.

Sunflower (Helianthus annuus L.) seeds were germinated and grown in the presence of 50, 100 and 200 µM CdCl₂. The lower concentration (50 µM) of Cd² ions produced slight decrease in reduced glutathione (GSH) content and overall increase (except superoxide dismutase) in antioxidant enzyme activities, and in H₂O₂ concentration. Chlorophyll content, lipid peroxidation and protein oxidation were not affected under 50 µM CdCl₂. GSH content was diminished under 100 and 200 µM CdCl₂, and except for superoxide dismutase, which activity remained unaltered, overall decreases in the antioxidant enzyme activities (catalase, ascorbate peroxidase, dehydroascorbate peroxidase, glutathione reductase) and in guaiacol peroxidase were observed. These Cd² concentrations caused a decrease in chlorophyll content as well as an increase in lipid peroxidation, protein oxidation and H₂O₂ concentration. All the observed effects were more evident with the highest concentration of cadmium chloride used.

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.

Contents and functioning of photosynthetic pigments and gas exchange of Nicotiana tabacum L. leaves were studied in platlets cultivated in vitro under different CO₂ supply. The plantlets were grown for six weeks either in glass vessels tightly closed with aluminium foil (G-plants) or in polycarbonate Magenta GA-7 vessels covered with closures with microporous vents (M-plants). M-plants (better supplied with CO₂) had higher contents of chlorophyll (Chl) a. Chl b. and β-carotene, higher photochemical activities of photosystem 2 and whole electron transport chain, and lower contents of xanthophyll cycle pigments. Differences in Chl a fluorescence kinetic parameters between G-plants and M-plants were not statistically significant. M-plants had higher net photosynthetic rate, and lower transpiration rate and stomatal conductance than G-plants.

Diurnal patterns of CO₂ exchange and fluctuations of tissue malic acid concentrations were investigated in the resurrection angiosperm Haberlea rhodopensis Friv. grown under irradiances of 30 or 300 μmol(photon) m^-2 s^-1 at transition from biosis to anabiosis and vice versa. Different degree of CAM-cycling were exhibited under well-watered conditions and extreme desiccation under both irradiances. The CAM-cycling was proved as efficient mechanism of saving water.

The increase in water use efficiency (the ratio of photosynthetic to transpiration rates) is likely to be the commonest positive effect of long-term elevation in CO₂ concentration (CE). This may not necessarily lead to decrease in long-term water use owing to increased leaf area. However, some plant species seem to cope better with drought stress under CE, because increased production of photosynthates might enhance osmotic adjustment and decreased stomatal conductance and transpiration rate under CE enable plants to maintain a higher leaf water potential during drought. In addition, at the same stomatal conductance, internal CO₂ concentration might be higher under CE which results in higher photosynthetic rate. Therefore plants under CE of the future atmosphere will probably survive eventual higher drought stress and some species may even be able to extend their biotope into less favourable sites.

The effect of 50 to 200 mM NaCl on two lines (CP with solid stem and CV with hollow stem) of ×Haynaldoticum sardoum was studied. NaCl significantly reduced root and shoot fresh and dry masses, root length and less markedly shoot length of CP and CV plants. The sodium accumulated in the leaves in relation to the concentration of NaCl and length of the treatment; CP leaves contained twice as much sodium as CV leaves. The leaf chlorophyll a/b ratio was not affected by NaCl. NaCl decreased the leaf water and osmotic potentials. The pressure potential increased due to the increased concentration of dissolved solutes in the leaf, particularly sodium. The proteinase and exopeptidase activities increased during NaCl treatment.