Ten centimeter long stem cuttings of sweet potato (Ipomoea batatas L. cv. Georgia Jet) with intact apex and leaves were cultured in distilled water as well as in varying concentrations of abscisic acid (ABA) in open top chambers at 364, 438 and 666 cm³ m{-3}CO₂. Low concentration of ABA promoted rooting and elongation of roots at 364 cm₃ m{-3} CO₂ while rooting was suppressed at enriched levels of CO₂. However, biomass production in shoots and roots was higher in 666 than in 364 cm³ m^-3 CO₂.

A reduction in abscisic acid (ABA) content was not a pre-requisite for the breaking of dormancy of vegetative lateral buds of both field-grown trees and shoots of willow (Salix viminalis L.) maintained in controlled conditions. Similar variations in bud ABA levels were observed whether the shoots were stored in a warm (22 ± 1 °C) or cold (6 ± 0.5 °C) environment. Following transfer to a growth room the ABA content of chilled buds declined more rapidly than did that of non-chilled buds.

In the roots of 4-day-old pea plants germinated in unsterile soil from Rhizobium-inoculated seeds, a higher level of native IAA was determined than in roots of pea plants germinated in sterile soil from superficially sterilized seeds. The IAA level in plants grown from inoculated seeds increased markedly up to the age of 6 days of the plant, while in plants growing under sterile conditions it did not significantly change during the same period. Between the 6th and 10th days of the age of the plant, a decline in the IAA level was observed in roots of plante growing from inoculated seeds. It was not until after 10 days of age of the plant that the level of IAA in nodulated roots again increased.

Recurrent application (17 administrations in 38 days) of 14 pesticides (Karathane FN 57, Fundazol 50 WP, Dithane M 45, Topsin M 70 WP, Perozin 75 B, Fademorf EK 20, Novozir MN 80, Metation E 50, Pirimor DP, Decemtion EK 20, Zeazin 50 DP, Fatex EK 80, maleic hydrazide and Ethrel) did not increase (with the exception of maleic hydrazide) the frequency of somatic mutations in a heterozygous chlorophyll mutant ofNicotiana tabacumL. var.xanthi n. c. None of the four tested pesticides (Fademorf EK 20, Decemtion EK 20, maleic hydrazide and Ethrel) were transformed in tobacco plants to a stable mutagenic or promutagenic product active in theSalmonella (Ames) mutagenicity assay.

An enzyme extract from apple(Pyrus malus Borb.) seeds which causes the disappearance of free indol-3-ylacetic acid (IAA) requires the presence of oxygen, but is not inhibited by cyanide. Using 1-¹⁴C-IAA it has been demonstrated that the IAA transformation is not accompanied by its decarboxylation. Decarboxylating IAA oxidase is absent during the whole period of apple seed cold stratification. Free IAA has not been detected in dormant apple seeds and in seeds stratified at low temperature. It appears during stratification at 25 °C. Ethyl ester of IAA and indol-3-ylacetyl aspartate have been identified in dormant and after-ripened seeds. Exogenous 1-¹⁴C IAA taken up by apple embryos is converted into conjugates with aspartate and short peptides containing an aspartate moiety.

The photoblastic seeds of two pioneer trees from the tropical rain forest-Cecropia obtusifolia andPiper auritum - require long diurnal periods of red light to germinate. In the field, the establishment of the trees takes place only in light gaps produced by falling trees. Experiments were performed in order to ascertain the relationship between the light requirements of the seeds and the germination control in the field. Results show that phytochrome regulated germination allows the detection of light gaps.

The extracellular nuclease fromPinus silvestris pollen was isolated and characterized. Molecular sieving produced only one peak of nuclease with apparent molecular mass of about 30 kDaltons, while molecular mass of the enzyme as determined by means of sodium dodecyl sulphate-DNA gel electrophoresis was 25.7 kDaltons or less. The nuclease exhibited one electrophoretic molecular form only.
Specific antiserum against this nuclease was prepared and the nuclease was shown to be immunochemically cross-reactive with extracellular nuclease from Pinus nigra pollen. No immunochemical relationships were observed between pine nuclease and the pollen extracellular nucleases from the angiosperm species,Nicotiana tabacum, Corylus avellana, Alnus incana andBetula pubescens. No cross-reactivity was detected by double diffusion between the pine nuclease and the extracellular proteins from vegetative spores ofEquisetum arvense.

The free proline and chlorophyll contents, and the chlorophyllase, peroxidase and nitrate-reductase activities were determined in sunflower seedlings grown under controlled conditions and submitted to water stress induced by 14 % polyethyleneglycolj (M_r = 4000) or isotonic NaCl solution. Combined free proline content and peroxidase activity may be used for detection of the factor inducing water stress.

Free proline and chlorophyll contents, chlorophyllase, peroxidase and nitrate reductase activities were determined in maize seedlings grown under controlled conditions and submitted to water stress induced by 14 % PEG-4000 or NaCl (isotonic). All the parameters studied showed a significant response to the water stress, but the level of free proline and peroxidase activity together may preferentially be used for the diagnosis of osmotic stress or saline-osmotic stress.

A histochemical method for the determination of IAA-oxidase has been used in sections of various aerial parts of winter wheat plants. High IAA-oxidase activity was localized in the cell walls of sclerenchyma near the periphery of the stem, in the vascular bundle sheath of sclerenchyma and in xylem, both in the stem and in the leaf. The cell wall-bound IAA-oxidase activity therefore appeared in lignifying tissues. The staining was very weak or absent in the cell walls of parenchyma tissues and phloem. The positive reaction of the cytosol at the bulbous ends of guard cells and in the leaf primordia is presumed to be due to cytosolic IAA-oxidase. These results are discussed in relation to peroxidase localization and to our previousin vitro studies.

The values of influx (Ji) and efflux (Jo) of phosphates through intact maize roots (primary, seed roots) have confirmed the dependence of the P concentration in nutrient medium on the activity and efficiency of transport mechanism with respect to the accumulation of phosphates (J) by roots. The phosphate accumulation is about 97-99 % of the total uptake. If the P concentration is < 1 mM the efflux is negligible, and Ji <=g Jo. In contrast, if the P concentration is τ 1 mM, the proportion of efflux significantly increases, up to 45 % of the whole influx. The approximation to the conditions of equilibrium of phosphate flows ( Ji = Jo) depends on the P concentration in root cells, the accumulation of phosphates being determined by the relation Ji τ Jo. In the roots growing in P-containing medium the values of efflux are much higher than in the roots lacking P.
The positive effect of Ca²⁺ ions on the accumulation of phosphates is caused by the decreased proportion of efflux. The factors instigating the integrity or non-integrity of the cell structure (Ca²⁺, SDS, EDTA, Sorbitol,etc.) and thus its effectiveness determine the accumulation of phosphates by roots. Analogously, the factors stimulating the ability of accepted phosphate to be metabolized, and their use in the form of organic compounds decrease the proportion of efflux; these activities are shown in the increased efficiency of the phosphate uptake. The presented results show the importance of the integrity of the cell structure, the functioning of membranes and of metabolism efficiency for the accumulation of phosphates by plant roots. The main form of phosphorus transport in xylem exudate is inorganic phosphorus. Its share is from 79 to 82 % of the total amount of transported P. The utilization of P in the roots in the form of organic, slowly motabolizable P compounds (mannose-6-phosphate) and inhibition of acid phosphatase activity effectively restrains P transport over long distances. The correlation of P transport from roots into shoots with phosphatase activity was established (correlation coefficient is 0.74⁺⁺). It can be summarized that long-distance P tran sport is a function of dephosphorylating reactions.

Major differences betwean the determinate (dt₁Dt₂,dt₁dt₂), semideterminate (Dt₁Dt₂), and indeterminate (Dt₁dt₂) near-isogenic lines of glycine max (L.) Merr, mainly appeared after R1 (reproductive) stage. Increases in specific leaf matter (SLM) between Rl and R6 stages showed that determinate lines have higher SLM than semideterminate or indeterminate lines. Soluble protein and starch also accumulated more rapidly in determinate lines. Insoluble protein, ribonucleic acid (RNA), and deoxyribonucleic acid (DNA), reducing saccharides, chlorophyll, and soluble saccharides contents of leaf from determinate lines resembled those of semideterminate and indeterminate lines.

Karyotypes ofAllium fistulosum, A. altaicum andA. cepa cv. Karmen are described and protein patterns of their seeds determined by immunoelectrophoresis are compared. Esterase isoenzymes were evaluated by polyacrylamide gel electrophoresis and isoelectrofocusing. Karyological and chemotaxonomical analysis confirmed thatA. fistulosum andA. altaicum are closely related and both species are taxonomieally distant fromA. cepa cv. Karmen.

Needle primordia were isolated from embryonic shoot expiants of 88 year oldPicea abies (Norway spruce) in order to develop a method for micropropagation using adult mother trees. The isolation of needle primordia in combination with frequent subculture, stimulated the formation of peripheral meristematic tissue in expiants cultured on a modified Murashige & Skoog medium supplemented with cytokinin. Transfer of isolated needle primordia with peripheral meristematic tissue to medium without growth regulators, and with a reduced ratio of NH+4/ NO-3, resulted in the formation of adventitious buds.

White light suppressed the stem growth and promoted leaf expansion. With increased irradiance the light effect was enhanced. The morphogenetic effects induced by light and by dwarf-mutation are similar. However, the nature of phenotyplc and genotyplc dwarfism is different. In the dwarf mutants the auxin level is not changed in contrast to the GA, ABA and QGC contents. Under high irradiance which depressed the stem growth, auxin and GA-levels were lowered while the content of QGC and of growth-inhibitor non-identical with ABA increased, but the level of ABA was not affected. The sensitivity of various pea forms to the light and to exogenous phytohormones (GA and IAA) is different. The plants with the shortest stems were more sensitive to light and GA. Data on the stem growth and rhizogenesis induced by light and by GA are presented. The metabolism of 2-¹⁴C-PCA (precursor of QGC) in tall and dwarf forms is different. The possible role of phytohormones and some phenolic compounds in the regulation of growth and morphogenesis of phenotyplc and genotyplc dwarf forms is discussed.

Primary explants from the inflorescence stem of tobacco and primary explants from the stem of vegetative plants, cultivatedin vitro under the same conditions, display different morphogenetic ability. The former give rise mostly to floral buds, whereas the latter exclusively to vegetative ones. Histological and histochemical analyses of both original andin vitro cultivated explants were made. They showed differences in chlorophyll content and alcohol dehydrogenase (AD) activity of the original explants reflecting their different metabolic status. Bud primordia were initiated in the superficial meristematic layer derived from epidermal tissues. Floral or prefloral apices were characterized by a strong AD activity in all cells of the meristem, while in vegetative apices AD activity was restricted to their uppermost parts. A high rate of procambium differentiation connected with leaf primordia formation was typical of vegetative buds. A higher concentration of glucose (5 %) enhanced cell division in explants, which is also correlated with a higher AD activity. The significance of vascular tissues for differentiation of vegetative buds is discussed.

The caryotype (2n = 24) of crownvetch (Coronilla varia L.) and the conditions of successful cultivation of tissue cultures derived from it were determined. The Murashige-Skoog cultivation medium with the addition of indol-3-ylacetic acid (1 mg 1¹), 1-naphthaleneacetic acid (0.1 mg 1¹), or coconut milk (20 %) was found to be the most suitable. A complex of cardenolide-like substances identical in its composition with that found in leaves of intact crownvetch plants was detected by means of thin layer chromatography in the extracts of these explant cultures up to the seventh subculture. These findings are also in agreement with the results of our earlier experiments in which strong pharmacological effects of cardenolides obtained from tissue cultures of this plant were demonstrated. Further investigations must be devoted to the optimalization of cultivation conditions of crownvetch cultures with the aim of their utilization as anin vitro source of cardioactive substances.

The mature nodules ofPhaseolus aureus Roxb. var.mungo possessed, in comparison with young and old nodules, higher activities of nitrogenase (N_2ase), and indol-3-ylacetic acid (IAA) metabolic enzymes like IAA oxidase, methylene oxindole reductase and peroxidase; higher levels of IAA-like, gibberellic acid-like (GA), and cytokinin-like (CK) substances and tryptophan, and lower level of phenol. The abscisic acid-like (ABA) substance level was higher in the old nodules.
The N_2ase activity in the mature nodules changed parallelly with IAA and OK. butoppositely with GA and ABA. The changes in tryptophan level, IAA oxidizing enzymes, and phenol metabolism controlled the IAA level in the nodules.
The nodules developed similarly throughout the year, but they had variable hormone levels in different seasons. This indicated that the formation and growth of the nodules was controlled not only by the nodular hormones.

This paper describes the successful selection of plant cell var ants with differing secondary substance productions by means of an adsorbent filter method. The method allows a simultaneous screening of up to 100 small cell aggregates per Petri dish within short time.

The herbicide terbutryn induced up to 11.3 % chromosomal abnormalities in cells undergoing meiosis inVicia faba. The mean number of pods/plant and the mean number of seeds/pod were considerably reduced, but the average seed dry mass was not or was only slightly affected by this herbicide. In C₂ plants chromosomal abnormalities were observed in few but significant numbers of cells.

Uptake and loss of irorganic phosphate was determined in sweet potato slices 'aged' in the presence or absence of gibberellic acid. Concentrations of uptake medium were varied from 0.1 to 1.2 mM. Slices, aged in gibberellic acid, took up considerably less phosphate, at all concentrations than control, whereas efflux from GA₃ treated discs was greater than control. Whether treated or untreated, kinetics proved to be biphasic hyperbolas. The results suggested an alteration in membrane permeability induced by gibberellic acid.

Kanamycin resistance gene was introduced into tobacco and Atropa belladonna cells by binary vectors, based on Agrobacterium, by means of inoculation of seedlings. The plasmid pGA472, which carries chimaeric kanamycin resistance gene expressed in plants was introduced by transformation into A. tumefaciens Bo542, harbouring pTiBo542 plasmid and A. rhizogenes 8196, carrying pRi8196 plasmids and the resulting two strains were used as binary vectors. Tobacco tumors induced by A. tumefaciens Bo542(pGA472) grew as undifferentiated, kanamycin resistant tissues. Those induced by A. rhizogenes 8196(pGA472) differentiated into transformed plants. When cultivated in vitro on 200 μg ml^-1 kanamycin medium, they showed yellow green sectoring, which was not selected out during vegetative propagation. Atropa belladonna tissues transformed by both A. tumefaciens Bo542(pGA472) and A. rhizogenes 8196(pGA472) differentiated plants which grew well on 200 μg ml^-1 kanamycin as green, non-sectoring plants; sensitive cells obviously did not divide at all. Selection of Atropa belladonna transformed tissues on kanamycin medium is much more efficient than selection of transformed tobacco tissues with introduced kanamycin resistance gene.