The barley (Hordeum vulgare L.) seeds were germinated in the non-saline conditions after 12 h imbibition in 2 % of NaCl solution. The results of treatment were: (l) the membrane system in meristematic cells of root tips developed well; (2) many profiles of endoplasmic reticulum and Golgi bodies appeared; and (3) the quantities of amoeboid plastids and amoeboid mitochondria increased. Thus the inhibitory effects of short-term NaCl stress on plants were reversible, and simultaneously NaCl treatment enhanced the metabolic activities in cells. The amoeboid form may be an adaptive form of plastids or mitochondria to an enhanced metabolic activity.

Decapitated pending vines are the most responsive parts of vanilla plants. Inflorescence localization along training vines showed a decreasing gradient from the decapitated end to the base in sun locality and was irregular and showed opposite gradient in shade locality. Soluble and ionic peroxidase activities, determined in the leaves and in the internodes, showed a marked peak during the end of June and a gradient along training vines which was inverse to the gradient of inflorescence localization and opposite between sun or shade conditions, supporting the utility of peroxidases as spatial and temporal biochemical markers of flowering processes.

Experiments were conducted to study the effect of plant type on canopy photosynthesis under field conditions. A chamber made of aluminium frame covered with clear plastic material was used to estimate canopy CO₂-exchange rates over a land area of 1.33 m². The plant type of maize "Shendan 7" [planophile type, original-type (OT)] was changed to erectophile type [altered-type (AT)] at silking stage. The rates of canopy apparent photosynthesis (CAP) were measured in both types of maize grown at five plant densities during the reproductive phase. It was shown that AT canopies had greater rates (about 17.2%) of CAP than did OT canopies and the yield increased by about 5.9-8.6% in AT canopies. The vertical distribution of photosynthetic photon flux density and CO₂ concentration in AT canopies were more uniform than those in OT ones. It was suggested that the compact architecture of maize canopy was excellent for photosynthesis and yield formation.

To determine some physiological parameters implicated in somatic embryogenesis in date palm (Phoenix dactylifera L.), peroxidases have been studied. Activated charcoal commonly used in date palm tissue culture as an essential antibrowning factor decreased cellular protein contents and peroxidase activities. During the first months of culture, the conventionally used medium (100 mg dm^-3 of 2,4-dichlorophenoxyacetic acid, 3 g dm^-3 charcoal) reduces 2 to 3 and 4 to 6 times protein contents and peroxidase activities, respectively, in comparison with the same one containing only 5 mg dm^-3 of 2,4-D and with or without 150 mg dm^-3 charcoal. In addition, the standard procedure decreased the embryogenic potential which is positively related to the intra- and extracellular (excreted into culture medium) peroxidase activities. In medium with embryogenic calli, extracellular peroxidase activity was three times as high as the activity determined in the same medium with non-embryogenic calli. There were two basic isoforms and four to five acidic bands characterizing the embryogenic calli. It can be suggested that peroxidases play a key role in somatic embryogenesis of date palm and the charcoal used at 3 g dm^-3 constitute a perturbating factor for this process.

The effect of 80 mM NaCl on the structure and ultrastructure of root cells ofPhaseolus vulgaris plants has been investigated. Roots of plants treated with NaCl were shorter and had less secondary roots than control plants. In control plants, epidermal cells were isodiametric and uniformly placed forming a thin layer, whereas in stressed plants, the shape and disposition of epidermal cells was less regular. The cortical cells of control plant were round-shaped and distributed allowing large and well defined intercellular spaces, whereas stressed plants presented irregular cells, which were interdigitated, thus decreasing the volume of the intercellular spaces. Presence of 80 mM NaCl did not result in significant differences in the number, shape or distribution of the cell organelles. Membrane vesiculation was often observed in cells of NaCl treated plants. Addition of 80 mM NaCl to the growth medium considerably increased the leakage of solutes from intact plant roots back to the solution especially K⁺ and Ca²⁺.

Hybridization between the nearly extinct speciesDiplotaxis siettiana andBrassica juncea is prevented because of strong prefertilization barriers. Use of mentor pollen ofD. siettiana irradiated with 1000 Gy gamma radiation before the incompatible pollination led to fertilization. 5 d after pollination 17% ovules showed entry of pollen tubes, 10 d after pollination 27% ovules showed small globular embryos which grew no further. No embryos were found in control pollinations. Thus , use of irradiated mentor pollen brings about fertilization in this difficult cross and hybrids can be obtained if embryos are rescued.

The influence of increasing copper concentrations on seed germination, seedling survival and radicle length ofMinuartia hirsuta, Silene compacta, Alyssum montanum andThlaspi ochroleucum was studied. Seed germination was highly affected by the higher Cu²⁺ concentrations (80 and 160 μM), while lower Cu²⁺ concentrations seemed to be necessary for seed germination, even for the plants originated from non-Cu²⁺-rich soils (i.e. A. montanum). Nevertheless, plants originated from Cu²⁺-rich soils (M. hirsuta, S. compacta) showed a higher demand of Cu²⁺ for rapid seed germination. Cu²⁺ at higher concentrations severely reduced growth rate of radicle, especially inA. montanum andT. ochroleucum. These data clearly indicate the reduced suitability of the above mentioned plant species for reclamation on Cu²⁺ soils. Lower Cu²⁺-concentrations had no influence on seedling survival inM. hirsuta andS. compacta, but a progressive reduction of a number of survived seedlings with increasing Cu²⁺ concentration was found, that was more pronounced inA. montanum andT. ochroleucum.

Lotus corniculatus has been transformed byAgrobacterium tumefaciens harbouring therolABC, rolAB, and 35S-rolC constructs. Growth, shoot and root morphology, cytokinin and auxin concentrations in the shoots, chlorophyll content in the leaves, nodulation and nodule nitrogenase activity of clonal progenies of selected transformants, in which the transferredrol sequences were proved, were compared with control plants.
The most striking alterations were observed in the 35S-rolC transformants (dwarfism, shoot and root branching, shorter internodes, delayed nodule formation, decreased nitrogenase activity, reduced content of leaf pigments) in comparison with either therolAB, rolABC, or controls. TherolAB androlABC transformants were very similar to the control plants in their morphology as well as in most other traits measured.

Growth analysis indicated that carbon gain in the alpine succulentSedum album tended to take place early during the growing season. Leaf water potential remained unchanged for a considerable length of time after the imposition of water stress in the field. Induction of crassulacean acid metabolism (CAM) by protracted water stress occurred before any signs of stress could be observed in the leaves, and appeared to be influenced by a complex interaction of environmental conditions including temperature and duration of sunshine. Increased levels of proline and betaine towards the end of the growing season appeared to reflect seasonal changes.

Several morphological characteristics differed when wheat (Triticum aestivum L. cv. Doha 88) was grown under a cool (10 °C), warm (20 °C), and hot (30 °C) regime. Development of leaves was linearly related to shoot meristem temperature, and the time between appearance of successive leaves on the main culm was independent of growth temperature. Area and dry mass of leaves and roots increased exponentially with time, and variations between growth temperature regimes were reduced when plants were compared at a similar developmental age. In isolated thylakoids thermal stability of photosystem 2 and of whole electron transport chain was enhanced with the increase in growth temperature. Therefore this cultivar is able to acclimate to contrasting temperature regimes.

Small callus pieces excised from theAgrobacterium transformed root line D₂ ofDatura stramonium, were cultured onto solidified MS medium supplemented with a 1.0 μM kinetin and three different concentrations (0.1, 0.5 and 1.0 μM) of 2,4-dichlorophenoxyacetic acid (2,4-D), and were examined for their alkaloid productivity in relation to organization level and growth rate. Growth of transformed roots (in a MS liquid medium without plant growth regulators) was greater than that of transformed calli excised from them and cultured separately. The addition of 1.0 μM 2,4-D to the culture medium had a positive effect on callus biomass production, while it inhibited root formation by this tissue (the lower the 2,4-D concentration in the medium the greater the number of roots which emerged from the calli). Hyoscyamine production was also higher in the transformed roots than in the transformed calli, and in these tissues the production of hyoscyamine was positively correlated with organogenesis index (i.e. its ability for rooting). At the same time, the epoxidation of hyoscyamine to scopolamine only took place in the transformed calli. This occurred to a greater extent at the lower concentrations of 2,4-D in the culture medium. The mode through which the 2,4-D could control the alkaloid production of transformed callus is discussed.

Anin vitro procedure for large scale multiplication ofBoswellia serrata Roxb. has been developed using cotyledonary node segments. In average 4 shoots per node were obtained on Murashige and Skoog's (MS) medium containing 0.5 mg dm^-3 6-benzylaminopurine (BAP) and 0.05 mg dm^-3 napthaleneacetic acid (NAA) within 22 d. By repeated subculture technique 90-100 shoots per node could be obtained after 88 d of initial culture. Shoots could be rooted on MS medium containing 1/4 salts, 1% saccharose, and a combination of 0.5 mg dm^-3 indole-3-butyric acid (IBA) and 0.25 mg dm^-3 indole-3-acetic acid (IAA). Addition of antioxidants like polyvinylpyrrolidone (PVP-50 mg dm^-3) and ascorbic acid (100 mg dm^-3) in both multiplication and rooting media prevented browning of cultures. Approximately 80% of shoots rooted within 8-10 d. Rooted plantlets were kept for 15 d in culture bottles containing Soilrite^TM irrigated with a nutrient solution containing 1/4 MS salts and finally transferred to pots containing soil: Soilrite^TM (1∶1), mixture with 70% transplantation success.

Agrobacterium tumefaciens induced transgenosis by treatment of germinatingArabidopsis thaliana seed embryos has been achieved with differentAgrobacterium strains including the strain LBA4404, which was ineffective in seed transformation experiments of the other authors. The frequency of transgenosis was increased several times by application of acetosyringone to the growingA. tumefaciens suspension cultures. The DNA demethylating agent 5-azacytidine partly restored the distorted Mendelian segregation ratios in the offspring of transgenic plants.

The content of lead in greening etiolated barley leaves remained the same, regardless the time of incubation of excised leaves in the presence of lead ions (8-24 h). The lead deposits have not been detected within mesophyll cells, but were found in intercellular spaces of mesophyll, in guard cells and in cuticle covering stomata. This suggests that lead may be transported in the leavesvia transpiration stream. Lead reduced the content of chlorophyll, especially chlorophyllb content and the average number of grana, whereas in the presence of kinetin the content of chlorophyll increased. In the combined treatment (lead + kinetin) kinetin diminished the inhibitory effect of lead on the chlorophyll content. The number of chloroplasts in mesophyll cells remained unchanged after lead treatment, whereas kinetin alone or applied together with lead increased the average chloroplasts number. The thylakoids system in chloroplasts of kinetin and kinetin + lead treated plants was similar to that observed in control, although the grana number was smaller. Both lead and kinetin increased the content of condensed chromatin in nuclei.

Water and osmotic potentials were measured in young and mature styles of selfcompatible (SC) and selfincompatible (SI) species ofSolanaceae. For mature flowers, the stylar water and osmotic potentials were considerably lower in SI speciesNicotiana alata andPetunia hybrida than in SC speciesN. sylvestris andN. tabacum. Stylar water content (in % fresh mass) was also significantly lower in SI species (N. alata, P. hybrida, diploid clones of potato) than in SC species (N. acuminata, N. glauca, N. paniculata, N. sylvestris, N. tabacum). For flower buds younger than 2 d before anthesis, no differences in stylar water potential betweenN. alata (SI) andN. tabacum (SC) were observed. During further flower bud development the stylar water potential inN. alata decreased more expressively than inN. tabacum. Pollen culture in media with various concentrations of sucrose or polyethylene glycol revealed that optimal water potential for pollen tube growth was lower inN. alata than inN. tabacum. The differences were similar as for differences in stylar water potential. The results are considered in relation to possible involvement of stylar water potential in unilateral interspecific incompatibility inSolanaceae.

The effect of five 3-(2-alkoxyphenylcarbamoyloxy)chinuclidium chlorides (alkoxy = butoxy-octyloxy) on survival of a wild-type strain and repair-deficient strains ofChlamydomonas reinhardtii was studied. There was a direct relationship with increased toxic effects in the algal strains as a function of the elongation of the alkyl chain of the alkoxy substituents of the phenylcarbamate acid derivatives. Repairdeficient strains were more sensitive than the wild-type strain. The recombination-deficient strain uvs10 expressed the highest sensitivity to the test agents. This suggests that a gene responsible for recombination repair is involved in an important role in DNA repair of damages induced inC. reinhardtii by the phenylcarbamic esters.

Two strains (RCR 1001 and 1044) and a commercial inoculant (Okadin) ofRhizobium leguminosarum biovarviceae were tested for their ability to survive in autoclaved clay soil for up to four months under heat, salinity and drought stress. Resistance to heat was tested by incubating rhizobia in soil at 27, 37 and 42 °C. Tolerance of rhizobia to salinity was investigated by growing rhizobia in soil salinized with 1 and 2 % NaCl (m/m). Drought resistance was tested by subjecting bacteria to soil moisture contents of 20, 10 and 5%. Strain RCR 1001 was more resistant to heat and nodulated faba bean better than other tested strains. A commercial inoculant Okadin survived more (plate count method) and nodulated faba bean (plant infectivity, most probable number, MPN) at moisture content of 5% and 2% NaCl. Although, strains RCR 1001 and 1044 resisted these stress conditions (plate count) they lost their abilities to nodulate faba bean (MPN-test). There is a possibility for selection of effective rhizobia which are more tolerant to harsh conditions.

Patchouli (Pogostemon cablin Benth.) plants grown under shade (LI) showed an increased height due to internodal elongation, leaf area, leaf area index, and chlorophyll (Chl)b, Chl (a+b) and carotenoid (Car) contents compared to the plants grown in sunlight (HI). The number of branches and green leaves decreased under LI treatment, with a marginal variation in the patchouli oil yield. A comparison between the relative contents of photosynthetic pigments indicated that Chlb and Car accumuled preferentially over Chla in the LI grown plants.

Changes in growth and phosphorus content in plants and seeds of fenugreek with increasing cadmium concentration was evaluated. Root length and shoot length ranged from 11.63 to 27.72 and from 9.70 to 54.78 cm, respectively. With the increasing Cd²⁺ concentration there was a significant decrease in root and shoot length, and fresh mass. Various phosphorus fractions of shoot decreased with increasing Cd²⁺ concentration except lipid P and nucleic acid P which increased at 65 and 95 d after sowing and protein P only increased at vegetative stage. In seeds (60 d after flowering) lipid P increased except at 2.5 μg(Cd²⁺) g^-1 (soil) while protein P decreased.

Chickpea (Cicer arietinum L. cv. 235) plants were grown in sand culture at moisture equal to 45-50% of sand saturation capacity under greenhouse conditions. 60 d after sowing, pots were divided into four lots, leaving one as control and sand moisture content of others was brought to 25-30% (S₁), 12-15% (S₂) and 5-6% (S₃) of sand saturation capacity, by withholding the water supply and then maintaining the required levels gravimetrically till the harvest. Relative water content of leaves and nodule water content were measured as indices of water stress. With increase in the severity and duration of water stress nitrogenase activity and nitrogen and leghemoglobin content of the nodules decreased and the ratio of leghemoglobin components I and II were changed. Nodules developed under limited water availability showed decreased branching, breakdown of the endodermis, greater compactness and decreased vacuolation of cells in the central symbiotic tissue as compared to the control.

The rate of germination, radicle and plumule length, fresh and dry mass of maize seedlings were increased as Ca²⁺ was added to the nutrient solution, which contained different levels of Cd²⁺, especially at low concentration of Ca²⁺ (5 mM) and high concentrations of Cd²⁺ (1.4 and 1.8 mM). The biosynthesis of pigments, respiration rate and content of soluble saccharides in endosperm were reduced sharply as the concentration of Cd²⁺ in the medium increased. This effects was alleviated by Ca²⁺ addition. Cd²⁺ content in seedlings was increased as the Cd²⁺ concentration in medium was increased and decreased sharply as Ca²⁺ was present in the culture medium. The study suggests liming of soil with CaCO₃ to improve the yield of many crops.