A haemagglutinating material was isolated and purified from the phosphate buffered saline extract of the seeds of the jack fruit using an immobilized N-aeetyl-D-galactosamine column. This material was composed of two iso-lectins of molecular masses 11 500 and 15 000. The lectins agglutinated native washed red blood cells of the human A, B and 0 groups and sheep, rabbit and mouse erythrocytes. The lectins were found to be composed of single polypeptide chains and they contained no covalently linked sugars. The lower molecular mass material was present in considerably greater quantity than the higher molecular mass component. On isoelectric focussing on PAG the lectins gave a spread of components with calculated pI between 6.0 and 8.3.

The content of ATP, ADP, AMP, P_i, the activity of the enzymes involved in the glycolytic pathway, some problems of their regulation by adenine nucleotides and some basic problems connected with tissue energy balance were studied in tobacco plants infected with the potato virus Y (PVY). The contents of ATP and ΣAdN were increased in virus-infected tissues when compared with healthy tissues and correlated with the PVY reproduction curve. ADP and AMP contents decreased just after the inoculation and increased at the end of the experimental period, P_i content was not influenced by the infection.
The activities of the key enzymes of the glycolytic pathway (6-phosphofructokinase, hexosediphosphatase, and pyruvate kinase), determined both in crude homogenates and after partial purification, did not differ during the entire experimental period from the values found in healthy control tissues, similarly as the activities of glucosephosphate isomerase, glyceraldehydephosphate dehydrogenase, phosphoglyceromutase and enolase observed in crude homogenates. The unchanging AEC value in virus-infected tissues simultaneously indicated that no change in the rate of the glycolytic pathway occurred even under "invivo" conditions at the period of the acute stage of infection.

The rice is important in plant science for its ability to germinate and grow with restricted or without oxygen availability. In this work we have investigated the variation of growth substances when anoxia was imposed to rice seedlings previously grown in air. An increase, in all the organs of a seedling and in particular in the fraction released in the medium, was observed for ABA (abscisic acid), PA (phaseic acid) and DPA (dihydrophaseic acid) quantities.Vice versa a reduction of total IAA (indol-3-ylacetic acid) was observed in seedlings. This was accompanied by its accumulation in roots. IAA was poorly released in aerobic conditions and anoxia has not changed this pattern.

Isolated uninucleate microspores of tomato,Lycopersicon esculentum Mill, were cultured in defined, liquid nutritive media. The microspores developed to haploid embryoids with or without an attached suspensor or into calli with compactly or loosely arranged cells.

Diphenylamine (DPA), 2-hydroxybiphenyl (OHBP) and 9-fluorenone (9-F), known inhibitors of carotenoids (car) synthesis, altered the pattern of incorporation of 2-¹⁴C-mevalonate into car in ripening fruits ofCapsicum annuum. OHBP was the most powerful inhibitor of the whole process of biosynthesis, followed by DPA and 9-F. The most sensitive step was the dehydrogenation of phytofluene. Cyclization of β-carotene and isomerizations yielding the structure of hydroxy-cyclopentane were also affected, although to a lesser extent.

The effect of phosphorus deficiency on acid phosphatase activity in the apical, middle and basal parts of the root of maize plants was followed. The supernatant obtained by centrifuging the homogenate of plant tissue at 1500 ×g was further centrifuged at 18 000 ×g, the sediment being marked as fraction II and the supernatant as fraction III. The results obtained document the fact that acid phosphatase activity of the two fractions of all analyzed root segments was higher in plants cultured in nutrient medium without phosphate than in those containing phosphorus in nutrient medium. In most cases this difference was significant to highly significant. The results of experiments proved unambiguously a higher enzymatic activity in all root segments in fraction III than in fraction II. In fraction III the highest acid phosphatase activity was found in the apical part, in fraction II in the basal part of the root.

The level of gibberellin-like substances was determined in the cotyledons and axis of developing seedlings of dwarf (Little Marvel) and normal (Tall Telephone) cultivars of pea (Pisum sativum L.). The effect of cotyledon removal with GA₃ application on growth was also examined. Greater levels of gibberellin-like substances were observed in the cotyledons of the normal cultivar than the dwarf. This was particularly evident in the cotyledons during the early stages of seedling growth. Subsequently there was a decline in GA levels in the cotyledons. This was coincidental with a rise in GA content in the axis with markedly greater levels in the normal than the dwarf cultivar.
Decotyledonated dwarf and normal plants supplied with GA were much taller than the decotyledonated controls. This observation along with those of the gibberellin levels in the cotyledons and axis, provided circumstantial evidence that there may be translocation of gibberellins from the cotyledons to the axis.

This paper describes the differentiation of karyotypically stable callus strains ofCrepis capillaris (with modal chromosome numbers 7, 8 -11 and ≧ 12, in particular) during 12 years' subculturing on an identical M-S medium with supplements, including 2,4-D (1 mg 1^-1) and adenine (1 mg 1^-1). The possible modes and factors of karyotypic adaptationin vitro are discussed.

Two phases of radish ontogenesis (I-when the plant had produced 3 -5 nodes and II-when the plant had produced 8 -10 nodes) were established on the basis of axillary, meristem localization. Flowering of the plants in response to GA treatment depends on the phases in which they were treated and on growth correlations in the apical meristem. The results obtained suggest that the reaction ofRaphanus sativus (LDP) to GA treatment is parallel to that ofChenopodium rubrum (SDP), and that the response of radish plants also depends on changes in growth correlations in the shoot apical meristem at the time of treatment.

Capsicum annuum L. cv. Ramillete fruits grown in the field were covered 60 d after flowering with "white", yellow, red and blue cellophane filters. Two other sets were left in full sunlight and under cover, respectively. After 30 d of treatment, during the ripening period, the contents of individual carotenoids were analyzed.
The red radiation was the most effective to increase the carotenoid biosynthesis, but the green and blue radiations inhibited their production. Either class of filters inhibited the formation of capsanthin, the most important carotenoid in the production of red colour of the maturation, but capsorubin, the other carotenoid responsible for the maturation colour, was more enhanced in the shade and under red radiation. Neither type of radiation was so efficient in increasing the total carotenoids content as the full sun radiation.

In addition to the primary seminal primordium, the so-called secondary seminal root primordia are also initiated in a barley embryo. The primary root primordium is developmentally most advanced. It is formed by root meristem covered with the root cap, and by a histologically determined region with completed cell division. On germination, the restoration of growth processes begins in this non-meristematic region of root primordium by cell elongation, with the exception of the zone adjacent to the scutellar node, the cells of which do not elongate but continue differentiating. In the root primordia initiated later, the zone with completed cell division is relatively shorter, in the youngest primordia the non-meristematic cells may be lacking. The root meristem is reactivated after the primary root primordium has broken through the sheath-like coleorrhiza and emerges from the caryopsis as the primary root. The character of root meristem indicates a reduced water content at the embryonic development of root primordium. With progressing growth the root apex becomes thinner, the meristematic region becomes longer, and the differences in the extent of cell division between individual cell types increase. - The primary root base is formed of cells pre-existing in the seminal root primordium. Upon desiccation of caryopsis in maturation, and subsequent quiescent period, their development was temporarily broken, proceeding with the onset of germination. The length of this postembryonically non-dividing basal zone is different in individual cell types. The column of central metaxylem characteristic of the smallest number of cell cycles, has, under the given conditions, a mean length of about 22 mm, whereas the pericycle, as the tissue with most prolonged cell division, has a mean length of about 6 mm. In the seminal root primordia initiated later the non-dividing areas are relatively shorter. The basal region of seminal roots thus differs in its ontogenesis from the increase which is formed "de novo" by the action of root meristem upon seed germination.

The occurrence of browning in protoplast cultures ofCyamopsis tetragonoloba completely inhibited the growth of protoplast derived colonies. Of the various additives employed to counteract the problem of browning and subsequent necrosis, polyvinylpolypyrrolidone (PVPP) was found most effective. Simultaneous addition of polyvinylpyrrolidone (PVP) to the protoplast culture medium accentuated the effect of PVPP and also improved the frequency of protoplast division.

Sublethal doses of metribuzin applied to wheat plants at the stage of ear emergence increased endogenous gibberellin levels in the ears. The activation of hormonal systems in connection with "chemical stress" is briefly discussed.

The level of endogenous gibberellin-like and cytokinin-like substances was estimated in the plumule and the root of 2-to 3-day-old intact pea seedlings, in the plumule of seedlings from which the radicle was cut off, and in the root of seedlings from which the plumule was removed.
An increase in the level of gibberellin-like substances and a decrease in the level of cytokininlike substances in the plumule as a consequence of radicle amputation were observed within 48 h. Plumule amputation resulted in a decreased level of both gibberellin-like and cytokinin-like substances in the root in the same period.

Ethylene induces the flower formation and stimulates the flower-bud development of some bulbous plants exposed to the gas when the apex is in the vegetative state. For iris bulbs cv. Ideal maximum responses have been found after exposure to 5 ppm for 8 h; lower concentrations, shorter exposure periods and, depending on seasonal conditions, low temperatures during gas treatment, gave intermediate responses. The effects are opposite to the ethylene induced flower-bud blasting which occurs when bulbous plants are exposed to the gas after completion of the flower formation.
Dry storage of the bulbs in atmospheres containing 5% CO₂ reduces the temperature-enhanced flower formation, suggesting a possible effect of endogenous ethylene.

Exogenous³H-thymidine is absorbed by the primary root of young plants ofDatura stramonium L. and gradually translocated into shoots: following a 3 to 72-h application of³H-thymidine the radioactivity was revealed, using the autoradiographic technique, especially in the region of primary and secondary meristems and in proximity to vascular bundles of the primary root, stem, hypocotyl and leaves. These regions may be considered as the sites of active DNA synthesis. The intensity of incorporation was dependent on the time of plant incubation in labelled thymidine.

Pigeon pea cultivars AL 15 (early-) and T₂₁ (late-maturing) were compared for dry matter accumulation in fruit parts pod wall (PW), seed coats (SC) and seed at various seed developmental stages. Significant water loss and dry matter accumulation in the fruit parts commenced much earlier in cv. AL 15 as compared with cv. T₂₁. The pod wall accumulated starch, reducing sugars and N-substances up to 21 and 28 days after anthesis (DAA) in cultivars AL 15 and T₂₁, respectively, which was later distributed to the seed. Growth of pod wall and seed was sequential, not concurrent, as the pod wall lost significant dry matter when the seeds within them reached their maximum dry matter. The fruit parts of cv. AL 15 accumulated more photosynthates than cv. T₂₁ at all comparable stages.

Flours prepared from seeds of two non-agglutinating and one agglutinating cultivar ofPhaseolus vulgaris ssp.vulgaris (tested against human A, B, O, and rabbit erythrocytes) were stored in a refrigerator for eight months. Extracts from aliquot portions of these flours were prepared in one-month intervals, their agglutinating activity was tested against rabbit erythrocytes, and their immunoelectrophoretic patterns and protein contents were determined. Agglutinating activity occurred during storage in ageing flours of originally non-agglutinating cultivars and a typical lectin zone which was absent in extracts of freshly prepared flours appeared in their immunoelectrophoretic patterns. This newly formed agglutinating activity in some cases again disappeared during further storage.

The influence of IAA in two concentrations (10^-8M and 10^-5M) on relations between growth, water absorption and cation uptake and accumulation was tested.IAA in a higher concentration retarded growth remarkably. First of all, potassium uptake and water absorption were significantly decreased while the uptake of divalent cations was affected later and less remarkably. 10^-8 M IAA accelerated the growth rate slightly together with acceleration of water absorption and cation uptake.

Under strictly non-inductive photoperiods (24-h photoperiods) floral buds were initiated on plants receiving 25 treatments with Reso (resorcinol) or 8 treatments with GA₃ (gibberellic acid) or GA₃ + Reso, while water treated control plants did not flower at all. Although a single treatment of plants with GA₃ or GA₃ + Reso is not adequate to cause induction under LD conditions, its effect is added to the sub-threshold induction caused by one SD (short day: 8-h photoperiod) cycle. The initiation of floral buds was hastened with an increasing number of SD cycles accompanying respective number of treatments, the effect of GA₃ alone or together with Reso being more pronounced than that of Reso alone. GA₃ increased the number of floral buds more than Reso, the number being the highest in plants receiving the respective number of treatments with the combination GA₃ + Reso under both inductive as well as non-inductive photoperiods.

The effects of salicylate on stomatal resistance (a measure of stomatal opening) were compared with those produced by 2,4-dinitrophenol and abscisic acid. Salicylate and dinitrophenol had the same minimum effective concentration and comparable kinetics, and induced stomatal closure persisting for a long time in the absence of further supply. However, a K and Ca solution prevented the salicylate-induced, but not dinitrophenol-induced, stomatal closure. The effects of salicylate and abscisic acid had very different characteristics. Cytokinins had no relevant effects on the stomatal closure induced by the three compounds. A close correlation was found between stomatal closure and K⁺ leakage from the treated leaves, suggesting that damage to the cell membrane may be involved.

A rapid method is presented for the determination of ribonuclease activity in coloured extracts from citrus leaves. At the same time, the influence exercised by several precipitating reagents and the storage time at 4 °c on the activity of the enzymatic system are studied. In addition the enzyme stability against heat is studied.

As the dynamics of changes in phytohormones may be involved in photoperiodic regulation of the rates of growth and flowering, fluctuation of cytokinins was followed in long-day and short-day tobacco. Zeatin (Z) and zeatin riboside (ZR) were identified in leaves and roots using a GC-MSC system. In plants of the long-day tobaccoNicotiana silvestris increasing the number of long-day inductive for flowering (10, 20, 30, 40 LD) resulted in a rise in ZR activity. Half the plants reached a reproductive stage on the 40th day of induction. In short-day Mam moth tobacco plants, short-day floral induction (10, 20, 30, 40 SD) caused similar but less marked changes in ZR.

An attempt is made to characterize the functional activity of the protein moleculo possessing both peroxidase and IAA oxidase activity by comparing the kinetic parameters for the two types of enzyme activity with regard to the following substrates: H₂O₂, benzidine, guaiacol and IAA. The curves expressing the dependence of the enzyme reaction velocity on the concentration of the enzyme or the substrate are different depending on the enzyme extract origin and the type of the substrate. It is established that the K_m of peroxidase for IAA decreases while its K_m for H₂O₂ increases during cell development. Both types of enzyme activity show similar pH and temperature dependence. The presented data show that IAA oxidase activity of the peroxidase develops as extension and differentiation of the root cells proceed. This is one of the possible mechanisms through which peroxidase may participate in the regulation of growth and differentiation of the primary root cells of maize (Zea mays L.)