The maize (Zea mays L.) plants inoculated by N₂-fixing bacterium Azospirillum showed increased activity of glutamate dehydrogenase (GDH) and glutamine synthetase (GS) in root cells free extracts over uninoculated control plants. Maximum differences in NADH-GDH activity were observed during the second and third weeks after sowing. The specific activity of GS showed a greater increase at the end of the assay. The percentage of nitrogen in leaves, root and foliage length, total fresh mass and nitrogenase activity were higher in inoculated plants than in the control ones.

Lavandin (Lavandula dentata) axillary buds were grown in Linsmaier-Skoog (LS) medium solidified with 10 % bactoagar (control) and supplemented with 0.1 mg dm^-3 benzyladenine (BA), 0.1 mg dm^-3 indolebutyric acid (IBA) or both plant growth regulators. In the studied conditions the axillary buds developed into plantlets. The addition of BA inhibited the formation of glands by 44 % as compared with the control plantlets and also inhibited their development: these plantlets had the highest number of unbroken glands (in pre-secretory state) when compared with plantlets grown in the other conditions. The presence of BA stimulated chloroplast formation, and increased the content of essential oils by 150 % with respect to the control plantlets. It also increased their secretion, and the number of lipid droplets in the chloroplasts, cytosol and plasmalemma. On the contrary, the presence of IBA decreased the essential oil concentration in plantlets by 31 % when compared with the control ones and inhibited their secretion capacity.

Detailed studies were made on changes in the quantity of 1.4 MDa rRNA precursor in barley and wheat cultivars with different degrees of frost tolerance. When analysing genotypes with different LT₅₀ values a close negative correlation was found between the quantity of 1.4 MDa molecular mass rRNA precursor and the forst tolerance of the given barley or wheat cultivar. The results suggest that a technique based on low temperature phosphorus incubation at the seedling stage could be suitable for the selection of genotypes on the basis of this character in applied research.

Shoot regeneration was achieved from immature cotyledons of five chickpea (Cicer arietinum L.) genotypes: C235, ICC4971, ICC11531, ICC12257 and ICC12873. The cotyledons cultured on Murashige and Skoog (MS) medium supplemented with 3 or 5 mg dm^-3 zeatin with or without 0.04 mg dm^-3 indole acetic acid (IAA) showed formation of cotyledon like structures (CLS) at their proximal ends. Subsequently, shoot regeneration took place in some of the CLS forming explants. CLS were also formed in cotyledons cultured on MS + 0.2 - 1 mg dm^-3 thidiazuron (TDZ); direct shoot regeneration was observed in cotyledons cultured on 1 mg dm^-3 TDZ. The shoot buds elongated on media containing indole butyric acid (IBA), benzylaminopurine (BAP) and gibberellic acid (GA₃). Complete plantlets were obtained by rooting of shoots following pulse treatment with 200 mg dm^-3 IBA for 5 min and culture on growth regulator free half-strength MS medium.

The inhibitory effects of Cd, Cu, Zn, Pb, and Fe on root elongation, contents of photosynthetic pigments, and metal accumulation in the roots and shoots of Sinapis alba were assessed. On the basis of growth inhibition metals can be arranged in a order Cu > Cd > Fe = Zn > Pb. All the metals, except Fe, were accumulated in significantly higher amount in the roots than in the shoots. Cd, Zn, Cu and Pb reduced chlorophyll a, and especially chlorophyll b content, and Zn and Pb reduced the carotenoid content, but less than that of chlorophyll a+b. The plants contained the highest concentration of Cd, and the lowest concentration of Zn.

Spermine as compared to putrescine or spermidine retarded the loss of chlorophyll and protein contents to a greater extent in wheat primary leaves during dark incubation. Activities of whole chain electron transport, photosystem (PS) 1 and PS2, and absorbed excitation energy distribution in favour of PS 1 were protected by these amines in valency dependent manner during 72-h dark incubation.

The basal segment from hypocotyl of Linum usitatissimum L. seedling readily regenerates, to produce a large number of shoots, in a short period of 5 [ndash ] 7 d. This response was stimulated by a low concentration (0.1 [micro ]M) of thidiazuron (TDZ). TDZ was also effective in inducing regeneration in dark. A drastic reduction in regeneration response on hormone-free as well as TDZ-supplemented medium was found after inclusion of an inhibitor of calcium-uptake, lanthanum (La³⁺). An essentiality of calcium in the regeneration was also evidenced by an increased response with increasing concentration of calcium. At Ca²⁺ concentration insufficient for regeneration, inclusion of TDZ resulted in shoot formation.

Two tomato (Lycopersicon esculentum L.) cultivars: Robin (tolerant) and Roma (sensitive to heat stress) were studied. Chlorophyll fluorescence induction parameters (F_v/F_p, A_max, and Rfd) at 25 °C showed that the PS2 activity was similar for both cultivars. The parameters, measured at 38 °C, decreased in both cultivars, but more in cv. Roma. Exogenous application of 4 mM spermidine improved the plant heat-resistance in both cultivars, and especially in cv. Roma. Analysis of chlorophyll fluorescence changes during linear increase in temperature showed that cv. Robin plants have higher ability to hardening and higher resistance to thermal damage of the pigment-protein complexes structure and the activity of PS2 than cv. Roma.

The effect of cadmium on the content of starch and sugars, and changes in the activities of the enzymes of sugar metabolism were studied in growing seedlings of rice (Oryza sativa L.) cultivars Ratna and Jaya. During a 5- to 20-d exposure at 100 μM or 500 μM Cd(NO₃)₂ in the growth medium an increase in the content of total soluble sugars and reducing sugars, and decrease in the content of non-reducing sugars was observed. Cd-induced increase in the sugar content was greater in shoots than in roots. No definite pattern of changes in starch content or in α-amylase activity was observed. Presence of 100 or 500 μM Cd(NO₃)₂ increased the activities of sucrose degrading enzymes, acid invertase and sucrose synthase, whereas the activity of sucrose phosphate synthase declined.

Induced mutagenesis in callus tissues was studied in the medicinal plant Scilla indica irradiated with different doses of γ-radiation ranging from 2.5 to 20 Gy. Low doses accelerated the cell division and growth rate of the tissues whereas high doses repressed growth rate and resulted in lethality of tissues. Various cytological and chromosomal abnormalities were observed in the irradiated calli, the degree of which depended upon the dosage. Low doses of irradiation also promoted the regenerating capacity of the calli tissues and plants regenerating from them exhibited better growth and vigour compared to normal plants. High doses led to loss of regenerating capacity and promoted formation of malformed and stunted plants. Cytological study of regenerants revealed both diploid and mixoploid plants but no tetraploids were obtained.

Mycorrhizal and nonmycorrhizal Pinus halepensis plants were subjected to water stress by withholding irrigation for four months and then rehydrated for 30 d. Water stress affected plants growth and mycorrhizal association was unable to avoid the effects of drought on plant growth. However, when irrigation was re-established the increase in height, number of shoots, total dry mass, and chlorophyll content in the mycorrhizal plants were greater than in non-mycorrhizal plants. The decrease in soil water content decreased the leaf water potential, leaf pressure potential and stomatal conductance. These decreases were higher for nonmycorrhizal than for mycorrhizal plants, indicating that the mycorrhizal fungi permit a higher water uptake from the dry soils. The total content of inorganic solutes was not changed by presence of mycorrhizae.

Iron deficiency induced decrease in the rate of whole electron transport chain in chloroplasts of pea (Pisum sativum L.). Such reduction was mainly due to the loss of photosystem (PS) 2 activity. The same result was obtained when the ratio of variable to maximum chlorophyll fluorescence (F_v/F_m) was evaluated. The loss in PS 2 activity was primarily due to a loss of 33, 23 and 17 kDa polypeptides. In contrast, iron deficiency induced the synthesis of 28 and 29 kDa polypeptides.

A greenhouse experiment was conducted to investigate whether small differences in UV-B irradiance would lead to changes in competition between cocksfoot (Dactylis glomerata L. cv. Athos) and white clover (Trifolium repens L. cv. Mervi). Plants were grown in greenhouses covered with different thicknesses of UV-transmittant plexi (3 and 5 mm) resulting in 82 % and 88 % of ambient UV-B radiation. Aboveground biomass was harvested at 4-week intervals and the vertical distribution of biomass, leaf thickness and specific leaf area were determined. Tillering, stubble and root biomass and crop height were also measured. There was only one significant effect: at 88 % of ambient UV-B radiation a larger fraction of the biomass was present in the lower layers and a smaller fraction was present in the upper layers.

The effect of N-(2-chloro-4-pyridyl)-N'-phenylurea (4PU-30) on the growth and content of endogenous cytokinins of adenine type in tobacco (Nicotiana tabacum L.) callus was investigated. Biomass accumulation in calli grown on Murashige and Skoog (MS) medium with 4PU-30 was higher than that on MS medium with kinetin. The obvious presence of isopentenyladenine type cytokinins and traces of zeatin type cytokinins supposes modification in the endogenous cytokinin metabolism of the tobacco callus grown on 4PU-30.

NaCl salt stress induced changes in growth and enzyme activities in blackgram (Phaseolus mungo L.) seeds during germination were studied. A decrease in germination percentage, root length, shoot length, and fresh mass was noticed with an increase in NaCl concentration. With the increase in NaCl concentration and duration of stress proline content increased and catalase (CAT), peroxidase (POX) and polyphenol oxidase (PPO) activities decreased.

The changes in soluble proteins associated with adventitious root formation in hypocotyls of radiata pine (Pinus radiata D. Don) were studied using one- and two-dimensional polyacrylamide gel electrophoresis. Protein content decreased during the first day after root excision, and kept decreasing till the end of the time course under non-rooting conditions, i.e., on medium without growth regulators, with indole-3-butyric acid (IBA) + kinetin, or with kinetic alone. During adventitious root initiation in response to IBA, however, the protein content began to increase from day 1 to its maximum at day 7, coinciding with the early stage of root initiation. A comparative analysis of protein changes by two-dimensional polyacrylamide gel electrophoresis showed 16 proteins that were probably associated with root initiation and development.

Mitochondria isolated from root tissue of maize plants grown on a modified Knop solution containing 10.9 mM nitrate ± 7.2 mM ammonium were purified on the discontinuous Percoll density gradient with polyvinylpyrrolidone (PVP) added. The presence of PVP allowed separation of several mitochondrial fractions of a different density. Contrary to mitochondria isolated from plants grown in the presence of nitrate alone, revealing only two fractions, the mitochondria from NH₄⁺/NO₃^--plants were distributed in four fractions. Total amount of mitochondria, as well as specific activities of some nitrogen metabolism enzymes and tricarboxylic acid (TCA) cycle enzymes of all mitochondrial fractions, and respiratory activities of two lower density fractions isolated from plants grown on mixed nitrogen were higher in comparison to mitochondria from nitrate-grown plants.

The behaviour of myrtle (Myrtus communis L.) plantlets during the last phase of in vitro culture before transplanting was studied. Myrtle plants were sampled from Mediterranean shrubland vegetation. In vitro growth of myrtle microcuttings was evaluated during the rooting phase using 500 cm³ containers fitted with two different types of closures. The number of gas exchanges and time in which aerated and closed vessels lose half of their gas content were calculated. Both types of vessel closure allowed photosynthetic activity in myrtle cultures even though the higher aeration rate induced higher net photosynthetic rate (P_N) during all the culture. In vitro morphogenetic and rooting of myrtle microcuttings were affected by the different environment conditions inside the culture vessels: plantlet growth and root formation of myrtle explants increased in aerated vessels in comparison with closed ones. The well developed root system, the higher P_N and dry mass accumulation during the pre-acclimatization phase in aerated vessels induced a better ability to face the transplant stress.

This work tests the hypothesis that sclerophylls (i.e. hard-leaved species) would be less efficient than malacophylls (i.e. soft-leaved species) in terms of water transport through the stem as well as within the leaf blade. Mean leaf surface area (A_L), leaf specific mass (LSM) as well as shoot (K_WL), stem (K_SL) and leaf (K_LL) hydraulic conductances were measured in eight Mediterranean evergreen sclerophylls and eight temperate deciduous malacophylls. No difference was observed between the two groups in terms of K_LL and of the contribution of leaves to the overall shoot hydraulic resistance. Leaves represented in all cases 48 to 90 % of the shoot hydraulic resistance, suggesting that the sclerophyllous habitus does not per se lead to low efficiency in water transport within the leaf blade. A weak negative relationship (r² = 0.252) appeared to exist between K_SL and LSM. This might provide an explanation for the lower growth rates of sclerophylls with respect to malacophylls.

Triglochin maritima had only 40 % germination in distilled water, but germination was substantially enhanced when seeds were exposed to ethephon, fusicoccin, proline, kinetin, and thiourea. Also, the effect of low salinity on germination was alleviated by fusicoccin, kinetin, nitrate and thiourea, whereas, the reduction in germination at high salinity was partially countered by ethephon, kinetin, thiourea and nitrate.

rRNA was labelled with RNase-gold complexes applied to ultrathin Lowicryl sections of excised Cucurbita pepo L. (zucchini) cotyledons grown in darkness. Benzylaminopurine-caused stimulation of cotyledon growth decreases the density of ribosomes in palisade cells despite stimulating rRNA synthesis. Abscisic acid inhibits RNA synthesis and transport, but does not visibly affect the number of pre-existing ribosomes in retarded growth cells. The amount of rRNA in the cells of 24 h treated cotyledons is rather consequence of the growth rate than its leading factor.

Rapid method of in vitro multiplication of date palm was developed. Shoot tips were cultured on Murashige and Skoog (MS) medium supplemented with 2 mg dm^-3 dimethylaminopurine (2iP) + 1 mg dm^-3 naphthalene acetic acid (NAA). Shoot buds were proliferated from white nodular cultures on hormone free medium. Shoot bud proliferation strongly enhanced when cultured on MS-medium contained 3 mg dm^-3 2iP + 0.5 mg dm^-3 NAA. Culturing on full-strength MS medium showed higher multiplication rate compared with half-strength MS medium. Among four concentrations of sucrose used, 30 g dm^-3 speeded up the bud proliferation more than 10, 20 and 40 g dm^-3. However, the largest shoot buds were observed with 40 g dm^-3 sucrose. Solidification of culture media by 1.75 g dm^-3Phytagel showed the highest proliferation rate, but the largest buds were observed with 1 g dm^-3Phytagel.

Two successive cycles of mature embryo-derived callus culture separated by one cycle of sexual reproduction of R₀ regenerated plants were performed using two rice (Oryza sativa L.) cultivars in order to gain information upon the nature of somaclonal variation in this species. Plants regenerated after one cycle of tissue culture exhibited higher variability and lower performances than those of initial cultivar. A second cycle performed using R₁ embryos as explants showed that the cellular component of salt resistance in terms of growth and regenerating abilities selected during the first cycle could be transmitted to the progenies. The extent and the nature of somaclonal variation depended on the identity of R₀ mother plant and culture conditions, somaclonal variation being strongly reduced in some families obtained from salt-treated calli.

Seed proteins of eleven species of Brassicaceae were investigated by polyacrylamide gel electrophoresis. In total 50 different bands were identified. Some of the bands are characteristic and represent constant markers of each species, which allow the unequivocal identification of their electrophoregram. The obtained data have been treated numerically using the cluster analysis method of unweighed pair group (UPGMA). The electrophoregram gives support to the idea that the tribe Sisymbrieae is an unnatural group and suggests its merge with the tribe Brassiceae. On the other hand the distinct position of Zilla spinosa in the dendrograms supports the traditional treatment of this taxon as a monotypic subtribe Zillinae.