Direct somatic embryogenesis from shoot apical meristems of pea is described. Somatic embryos were induced directly (without callus intervention) from meristematic tissues grown on a medium supplemented with 2.5 µM picloram. Within 4 to 5 weeks, fully morphologically developed somatic embryos were obtained. Somatic embryos originated from apical as well as from basal parts of meristem explants. The initiation and development of somatic embryos was asynchronous, basal somatic embryos developed more quickly than apical ones. Abundant secondary embryogenesis was observed after isolation of primary somatic embryos and culturing them on media for germination. Morphologically normal somatic embryos germinated on medium without growth regulators; the conversion rate was increased by application of 10 µM thidiazuron (TDZ). TDZ was also able to induce shoot bud regeneration on embryos without differentiated a shoot apex, allowing to germinate up to 78 % of all harvested somatic embryos with various morphology. The protocol was successfully tested in 47 out of 48 P. sativum and P. arvense cultivars as well as in two wild peas (P. elatius, P. jomardi).

The effect of choline, acetylcholine, carbamylcholine and of the acetylcholinesterase inhibitors, eserine and neostigmine, on the germination of seeds exhibiting different photosenitivities was studied in two light variants. Both in the darkness and in continuous white light the substances in question had no effect or only slightly modified germination of photoblastically neutral seeds. On the other hand, the above substances, particularly aeetylcholine and carbamylcholine, stimulated germination of photoblastically positive seeds, and inhibited germination of photoblastically negative seeds in continuous white light.

The effect of several nitrogen compounds on the germination of the first seed of each spikelet ofAvena sterilis spp.macrocarpa Mo. was studied on Petri dishes placed in germination chamber. The compounds assayed were ammonium sulphate, ammonium nitrate, urea and calcium nitrate, generally used as fertilizer for cereal crops, as well as a control supplied with water only
The concentration of the assayed compounds were 100, 1000, 2500 and 5000 ppm either at a constant temperature of 15 ° C or at alternated temperatures 5°C and 15 °C, for 16 and 8 h, respectively
Significant increase in the germination percentages occurred when nitrate compounds were used in relation to other compounds and no significant differences were found between the urea, and ammonium sulphate. This increase became significant at 1000 ppm, and therefrom until 5000 ppm germination stabilized. In the case of urea, very high abnormal germination percentages were obtained at 2500 ppm, while the effect turned noxious from 5000 ppm
The use of alternating temperatures significantly increased the germination capacity of the wild oat seeds in the case of urea, ammonium sulphate and ammonium nitrate.
It is found that nitrates are capable of breaking the dormancy ofAvena sterilis spp.macrocarpa Mo. seeds, which according to various authors, is due to an increase of the respiratory activity of the seeds

The effects of PEG 6000 priming on germination performance of aged wheat seed lots have been studied. A correct application of osmopriming treatment indicated a relationship between the pattern of water absorption, the reactivation of mitotic activity and the start and synchronization of germination. The possibility of controlling pregerminative events by means of this treatment is discussed on the physiological basis of seed germination.

Plant regeneration was achieved from coleoptile tissue of wheat (Triticum aestivum L. cv. Kharachia-65). Coleoptiles (1.0 - 3.5 cm long) were excised from 2- to 5-d-old seedlings and cultured on Murashige and Skoog's (MS) medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D - 0.5, 2.5, and 5.0 mg dm^-3). Cream, friable callus was obtained after 6 weeks of inoculation. This callus was sub-cultured on MS medium supplemented with 2,4-D (2.5 mg dm^-3) and 5 % coconut water. After 6 weeks of sub-culturing white, cream or pale, friable, nodular callus was obtained. Plant regeneration occurred when this callus was sub-cultured on MS medium supplemented with 0.2 mg dm^-3 1-naphthalene acetic acid + 1.0 mg dm^-3 6-benzylaminopurine. For rooting, regenerated shoots or plantlets were transferred on MS medium supplemented with 0.5 mg dm^-3 indole-3-acetic acid. Rooted plantlets were directly transferred into pots and grown under field conditions. Seed setting invariably occurred in all plants.

Maturation and germination of somatic embryos of hybrids A. alba × A. alba and A. alba × A. nordmanniana were followed by protein analysis of single embryogenic -suspensor masses (ESM) and analysis of storage protein accumulation during somatic embryo development. Very important step was one week pre-cultivation of ESM on medium with polyethylene glycol (PEG) and abscisic acid (ABA). Low osmotic potential of maturation medium and addition of ABA supported development of somatic embryo. Also partial drying of somatic embryo during following three weeks was needed for its normal development. In spite of morphologically fully developed, the somatic embryos were not physiologically ready for germination at least in terms of storage protein accumulation.

Activity of Cu2+-diamine oxidase (DAO; E.C.1.4.3.6.) was measured in Vigna radiata (L.) Wilczek cultivars K851, MH8320 and Pusa Baisakhi in light and in dark during ontogeny of seedlings. DAO activity was always the highest in cv. K851. In both light and dark grown seedlings maximum DAO activity was detected on day 2 after germination. Thereafter, in light grown seedlings it declined consistently upto non-detectable levels. In dark, DAO activity was higher than in light and it had the second maximum on day 7 following a similar declining pattern as observed for the light grown seedlings. The DAO activity was higher in a shoot apex alongwith leaves than in roots and shoot axis.

Five sets of synthetic oligonucleotide (20-to 24-mers containing no intenal repeats) primers of known gene sequences [yellow lupin nodule specific (hydroxyl) proline-rich protein, pearl millet alcohol dehydrogenase, Pisum sativum heat shock proteins, Drosophila homeobox, and tRNA] were used to differentiate 73 soybean accessions, including 56 Glycine max (L.) Merr. and 17 G. soja Zucc. & Sieb. The amplified genetic markers revealed polymorphic bands for most genotypes studied. The χ²-analyses of the results showed that several fragments produced with these gene primers were associated non-randomly with resistance to Phytophothora, maturity, seed size, flower colour, seed coat colour, seed hilum colour, growth type, and leaf shape. These markers appear to be valuable for differentiation of G. max and G. soja species and genotypes within these species.

Increasing NaCl concentration (0, 50, 100 and 150 mM) progressively decreased growth and seed yield of clusterbean (Cyamopsis tetragonoloba Taub.) which was associated with decreased concentrations of potassium and calcium and increased concentration of sodium in the shoots. Supplemental calcium (2.5 and 5.0 mM) significantly ameliorated the adverse effects of NaCl due to enhanced Ca and K uptake and reduced Na uptake. Calcium also alleviated the negative effects of NaCl on activities of nitrogen metabolism enzymes as well as on contents of soluble protein and free amino acids.

The experiment was made by using different concentrations of polyethylene glycol (PEG) or salt solutions to decrease the osmotic potential of the growth medium to reveal the response of mung bean (Vigna radiata) to water and salt stresses. No germination (emergence of the seedling) occurred at medium osmotic potential lower than -1.0 MPa in all treatments. It was found that the activity of α-amylase and protease, and contents of proline, saccharides and the soluble proteins decreased in the germinating seeds during 3-d stress. However, after 10-d stress, the contents of organic solutes and the activity of the hydrolytic enzymes increased. Growth, chlorophyll content and mineral uptake were also significantly reduced under stress. The seedlings under water stress induced by PEG were affected much more than under salinity. This may be due to the maintenance of a higher succulence under salt stress than under PEG-induced water stress.

Dry matter production of shoots and roots and the diurnal fluctuation of titratable acidity of single leaves were investigated in the CAM plant Agave attenuata during the first 70 d after germination. The plants were grown either in vermiculite sub-irrigated with a nutrient solution or in in vitro cultures on an inorganic nutrient agar. Two types of culture tube covers were used: either airtight closures or polypropylene caps with membranes permeable to air.
In the earliest ontogenetic phases of development (cotyledon and primary leaf stage), the plants were already able to carry out considerable nocturnal organic acid accumulation. In vitro cultivated plants, from the beginning of their development, were also capable of diurnal acid fluctuation, though of distinctly weaker activity than the pot plants. The mean relative growth rates (RGR) of pot culture plantlets approached a third of perennial herbaceous plants. Plantlets grown in in vitro culture reached only half to the one quarter of the RGR of pot plants. The reduced yield could be attributed to the low CO2 supply in the culture tubes and the less than optimal water and nutrient supply in the agar medium.

Pollen of pigeonpea(Cajanus cajan (L.) Millsp.) cultivars H-77-216 and ICPL-151 were cultivatedin vitro at six different temperatures (12, 17, 22, 27, 32, 37 °C). Pollen of cv. H-77-216 started to germinate at 17 °C whereas the pollen of cv. ICPL-151 at 22 °C, the optimal temperatures were 22 and 27 °C, respectively. Pollen germination at different temperatures was found to be positively correlated with the tube length. Per cent pollen bursting increased with rising temperature. The indeterminate cv. H-77-216 showed a wide range of suitable temperatures (17 - 27 °C) for pollen germination while the determinate cv. ICPL-151 had optimum at 27 °C

Hydrolysis of acetylthiocholine and butyrylthiocholine has been observed in aqueous extracts from petunia pollen and pistils. The reproductive organs of self-compatible clone showed a higher rate of choline ester hydrolysis than those of self-incompatible clone. The highest rate of acetylthiocholine hydrolysis blocked by the cholinesterase inhibitors (physostigmine and neostigmine) was characteristic for the pollen of self-compatible clone. The incomplete (25 - 40 %) inhibition of hydrolysis in pistil extracts of self-compatible clone suggests the presence of unspecific esterases. The eight-fold lower hydrolysis was observed in the pistils of self-incompatible clone as compared to the pistils of compatible clone; neostigmine completely blocked this low hydrolytic activity. The treatment of flower buds with physostigmine and neostigmine (10-5 - 10-3 M) decreased the seed production by 10 - 20 % in compatible clone. When the surfaces of pistil stigmae were treated with physostigmine and neostigmine (10-5 - 10-3 M) before pollination, the seed formation was inhibited by 95 % after both self- and cross-pollination.

The effect of irradiance on the expression of the Cucumis sativus pathogenesis-related (srPRX) anionic peroxidase was studied in germinating seeds at the period when seedlings start to be photosynthetically active. The diversity in the expression patterns of srPRX was observed in both dark- and light-grown seedlings using activity staining and immunoblotting: beside the three srPRX isoenzymes also other three, serologically unrelated, peroxidase isoforms were accumulated in dark-grown seedlings and one in light-grown seedlings. Furthermore, in light-grown seedlings, it was observed a marked difference in the expression of particular srPRX isoenzymes at higher irradiance (up to 260 W m-2, 400 - 700 nm) in comparison to low irradiance. By tissue printing on nitrocellulose paper it was demonstrated that irradiance during germination induced changes in the temporal and spatial distribution of the srPRX.

Seedlings of the salt sensitive wheat cultivar C-306 evolved more ethylene than the salt tolerant cultivar Kharchia-65 under different levels of both chloride- and sulphate-dominated types of salinity. Pre-sowing seed soaking treatments with kinetin, gibberellic acid and to a lesser extent indole-3-acetic acid alleviated salt stress effects as apparent from seedling dry mass. Treated seedlings also evolved more ethylene both under saline and non-saline conditions. Ethrel did not affect seedling growth as well as ethylene production. Abscisic acid inhibited seedling growth and ethylene production under both types of salinity.

The change in protein composition of whole cotyledons and cotyledon aleurone grains ofLupinus luteus L. during seed germination was studied. SDS-polyacrylamide gel electro-phoresis showed a clear change in composition of cotyledon proteins as well as in composition of the aleurone grains during 5 days of seed germination. At this time, both in whole cotyledons as well as in aleurone grains, two subunits of β-conglutin with mol. m. 53 000 and 39 000 were rapidly hydrolyzed. After 5 days of germination traces of α-conglutin subunits could be detected in the cotyledons, whereas in aleurone grains this globulin fraction disappeared. In whole cotyledons and in cotyledon aleurone grains the γ-conglutin subunits with mol. m. 28 000 and 17 000 were not mobilized during the study period. These results indicate that the protein components with lower mol. m. were degraded later than those withhigher mol. m. during seed germination.

During 6 days of pea seed germination the depletion of legumin with mol. m. 390 000 from protein bodies was observed. SDS-PAGE indicated that the legumin subunits with mol. m. 41 700 and 21 000 were prevailing. Only the former of these, probably corresponding to α-subunit, was degraded rapidly during 6 days of germination.
Water-soluble proteins (albumins) prepared from pea cotyledons were separated by preparative IEF into proteins with pI 7.1, 6.5, 6.0, 5.4, 5.0, and 4.6. During 6 days the components of albumin with pI 7.1, and 6.5 were dramatically depleted. Major fractions with pI 6.5, 6.0, and 5.4 were subjected to SDS-PAGE and their subunit composition was determined. Moreover, albumin of pea cotyledons was resolved into 13 components by SDS-PAGE. Mobilization of albumin began from the degradation of components with higher mol. m. during germination.

Parthenin - a sesquiterpene lactone fromParthenium hysterophorus L. is an allelochemical that prevents the germination ofPhaseolus aureus Roxb. cv. ML-5 seeds. The response of the seed has been attributed to the inhibition of the respiratory electron transport ability of its embryo. It has been shown to depend directly not only upon concentration of parthenin, but simultaneously on the duration of exposure of the seeds to the chemical as well. A strong correlation exists between the quantum of the response and the product of the period of exposure and the concentration of parthenin. In order to predict the maximum possible germination ability of the seed exposed for a given period to a given concentration of parthenin, an expression X = 10000 Y³ / [e^Y/0.31-1] was formulated from the equation X = AY³/[e^Y/Y0-1], where X represents values of maximum respiratory activity, Y represents the product of concentration and time in units mg cn^-3 h, A represents a dimensional constant. The trend and nature of response that is calculated on the basis of formulation coincides with that of measured response through spectrophotometry.

The effect of crude volatile oils extracted from the young leaves ofLantana camara var.camara was studied on the parent plant itself. The contents of water and chlorophyll, of leaves apart from seed germination, seed vigour and length of seedlings of the parent plant were adversely affected with increasing concentration of theLantana oils; this indicated autotoxic potential of the oil. The correlations between oil concentration and the studied parameters were rather strong and obeyed the concentration response relationship, typical of chemical bases. The cell respiration, however, increased with increasing concentration of the oil vapours. Compared to control, less than 13 % of the seeds of the parent plant exposed to 30 cm³ m^-3 of oil showed incipient germination with no growth of radicle beyond immeasurable protuberance, and no plumule emergence.

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.

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 lengths of roots and shoots, fresh and dry matter yield, and the contents of insoluble saccharides and free amino acids were reduced with the rise in NaCl concentration. However, under combination of NaCl with Ca²⁺ ions, these parameters generally raised. Contents of soluble saccharides, proline and quaternary ammonium compounds increased with increasing NaCl concentration, but under addition of CaCl₂ or CaSO₄, contents of these compounds were decreased. Low concentrations of NaCl stimulated soluble proteins, production, but higher concentrations decreased the content of soluble proteins. Addition of Ca²⁺ in the media did not improve the soluble protein production. Insoluble proteins content was increased with the rise of salinity level, but these effects were more pronounced with NaCl and CaCl₂ or CaSO₄ than with NaCl only.

The effect of high concentrations of the simplest polyphenols on extension growth of maize (Zea mays L.) shoot ooleoptile segments, lettuce (Lactuca sativa L.) roots, and on radish (Raphanus sativus L.) seed germination, was studied. Quinone formation in the process of plant incubation in polyphenol solutions was proved. The data obtained are presumably explained by the important part that is played by the quinoid products of phenol oxidation in the ability ofo- andp-biatomic phenols to inhibit growth.

The effect of NaCl at sublethal concentration was observed on germinating seeds of salt-sensitive and -resistant rice cultivars with respect to the level of proline regulatory enzymes and the growth of seedlings on different days of early germination period. The two enzymes of proline biosynthesis and catabolism, Δ-pyrroline-5-carboxylate reductase and L-proline dehydrogenase, were taken into consideration to observe the effects of 100 mM NaCl on their activities in both rice cultivars. The activity of Δ-pyrroline-5-carboxylate reductase in salt-resistant cultivar was increased twice after 5 d in 100 mM NaCl. Simultaneously, the activity of L-proline dehydrogenase was decreased significantly. High activities of Δ-pyrroline-5-carboxylate reductase may be regarded as a biological marker for screening the sensitive and resistant cultivars of rice seed under NaCl-salinity.

Seven barley(Hordeum vulgäre L.) cultivars tested varied greatly in their responses to root medium salinity (electrical conductivity of 3, 5, 10, 15 and 20 dS nr^-1)-lant growth was relatively more adversely affected than seed germination. Dry/fresh mass ratio increased at higher salinity levels in all barley cultivars indicating reduced water uptake. Higher K/Na ratio in plant shoots compared to that in the root medium solution indicated selective uptake of K that seems to be among processes involved in tolerance of cultivars to salinity stress.

Red-light-induced (via phytochrome) germination decreased with increasing numbers of turions per germination flask (overcrowding). Three hypotheses concerning the mechanism of this germination inhibition were tested, related to abscisic acid, ethylene, and oxygen deficiency: (i) Although abscisic acid is a powerful inhibitor of turion germination it had to be excluded as a cause, because abscisic acid was not secreted from turions into the nutrient solution, (ii) Ethylene (ethrel) strongly inhibited growth of newly formed sprouts, but germination response itself was not inhibited, (iii) Germination inhibition did not appear if short light pulses were substituted by continuous irradiation. It reappeared in the presence of the photosynthesis inhibitor 3-(3, 4-dichlorophenyl)-l, 1-dimethylurea, but it was not observed in aerated nutrient solutions, or when Petri dishes instead of Erlenmeyer flasks were used. Decreased oxygen concentrations in the nutrient solution were produced by turion respiration. Consequently, anaerobiosis within the nutrient solution caused by turion respiration was the reason for germination inhibition by overcrowding.

Somatic embryogenesis was initiated from immature zygotic embryos of intraspecific cross ofAbies alba and interspecific combination ofAbies alba x Abies nordmanniana. The most responsive explants for induction of embryogenic calli were zygotic embryos in precotyledonary stage of development. Biochemically the compared embryogenic lines were uniform irrespective of their morphology or embryogenic potential. The flow cytometric analysis of single embryogenic lines suggests that no changes in ploidy levels occur during induction and culture of embryogenic callus inAbies alba what confirms the convenience of this system for propagation of valuable seed material.

Protein synthesis and accumulation in growing sunflower (Helianthus annuus L.cv.Airelle) seeds are studied. The salt soluble fraction, globulin, is the main soluble protein component. The earlier stages of seed development (10 days after flowering) are characterized by high M_r polypeptides (74, 58 and 44 kDa). Later stages mainly show nature globulin polypeptides. Thus, protein synthesis in seed occurs at a specific period of seed development which follows a period of fast cell divisions (0-14 days after flowering). Protein bodies are isolated and their protein composition analyzed. Globulin subunits are the main polypeptides of protein bodies soluble fraction. Mature globulin is only stored in protein bodies.