The influence of light, particularly blue and red light, on the cytokinin content of seedlings ofAmaranthus caudatus was studied. Cytokinin content was determined by two different bio-assays (amaranthin accumulation byAmaranthus seedlings and mtrate-reductase activity ofAgrostemma embryos). In both bio-assays similar results were obtained. Oytokinin content is increased, especially by blue light. It is suggested that especially blue light promotes amaranthin accumulation inAmaranthus seedlingsvia the increase of cytokinin content of tissues. The results support our hypothesis on cytokinin action.

The localization was studied of α- and β-galactosidases in frozen sections of Ca-formol fixed root tips using simultaneous azocoupling reaction. In all species studied (Allium cepa,Cucurbita maxima, Lupinus albus, Pisum sativum, Vicia faba, Zea mays) positive results were obtained, the localization being ubiquitous (according to localization typology given here).
InVicia faba andZea mays the isoenzymes of α- and β-galactosidases were revealed by means of acrylamide gel electrophoresis, using authors' modification of Reisfeld method, in whole root tips, particular growth zones and separately in cortex and central cylinder. No differences were observed comparing stele and cortex. Whereas characteristic isoenzyme patterns were found in individual growth zones in maize, no differences appeared in broad bean.
A comparison was made of thein situ localization and of the isoenzyme patterns of α- and β-galactosidases with α- and β-glucosidases. In the case of galactosidases, positive results appear with both α- and β-galactoside. The rising of pH to neutrality leads to considerable decrease in the activity of both galactosidases.

Excised barley embryos were cultivated in a liquid complete medium for 48 h and then 5-fluordeoxyuridine was added. The concentrations of 5-fluordeoxyuridine differed in the range of 6 orders of magnitude (10^-8 to 10^-3 M). All concentrations, except 10^-8 M led to a total inhibition of mitosis during 24 h. 5-fluordeoxyuridine induced chromosomal aberrations of the non-exchange type in all concentrations used. The frequencies of induced breaks increased during the interval of 12 h in whích they were followed and, in samples fixed at later intervals after the beginning of the treatment, there was a tendency to clustering of the induced fragments in some mitotic figures. The most striking feature of the effects oliowed is the relatively small dependence on the concentration used.

A study was made of the changes in the the content of camomile essential oil and its components [(-)-α-bisabolol, (-)-α-bisabololoxide A, (-)-α-bisabololoxide B and spathulenol, and chamazulene] in dependence on the time of day under field conditions. The essential oil, distilled immediately after sampling, was analysed by means of gas chromatography at 3-h intervals in the course of 51 h. A 24-h period rhythm of (-)-α-bisabolol with maximum content in the scotoperiod, was demonstrated in 1976 using periodogram and cosinor tests. The other substances investigated exhibit a rhythm with a 12-h period. The latter test did not reveal any rhythm in the total content of essential oil.

Decapitation induced an additional formation of secondary shoots and anomalous spikes in all the species. The moan numbers of nodes, spikelets per spike, seeds per spikelet and spike, and the mean length of the stem and spike were reduced on secondary shoots of decapitated plants, while the mean and peak numbers of flowers per spikelet and the peak number of seeds per spikelet increased. The increase in the number of flowers per spikelet was the most striking on spike base; the seeds regularly occurred even in spikelets with an expressively increased number of flowers. The post-decapitation changes of the spike could be well expressed quantitatively according to the increased mean number of the flowers per one seed. Morphological ohanges in anomalous spikes of all the wheat species resemble phylogenetic reversions described in literature. Moreover, the peak numbers of flowers and seeds per spikelet were recorded in 52 varieties belonging to 21 wheat species. As compared with the decapitation trial, the greatest variability and the greatest differences between the speoies were also reoorded in the tetraploid group, and the smallest variability and differences between the species in the diploid group. We suppose that the striking morphological differences in post-decapitation spikes take place because the apical dominance was interrupted before differentiation of the recent form had been controlled in meristems on the decapitated stem base. Ancestral forms were morphologically realized with the help of an assimilating part of the decapitated stem.

Sucrose gradient analyses were made on free ribosomes extracted from Azuki bean seedling leaves subjected to mannitol induced water stress. Comparisons were made of the effect of duration of stress and the effect of urea on the free ribosomes. The capacities of the ribosomal fractions to incorporate amino-acids were also studied. Water stress reduced total free ribosomes and proportion of polysomes in the ribosomes as well as the capacity of the ribosomes to incorporate amino-acids into proteins. Polysomes which were broken down by the water stress also appeared to be more susceptible to denaturation and synthesized different proteins than polysomes which remained in the leaves after water stress.

A virus transmissible toChenopodium quinoa was isolated from leaves of sugar beet showing large chlorotic ring spots and line pattern. The virus was serologically unrelated to tobacco necrosis virus and tomato black ring virus or to its beet ringspot strain either. A positive result was obtained with antiserum against tomato bushy stunt virus. Reactions of herbaceous indicators and properties of the virus in crude sap were in accordance with the serological diagnosis. A survey of natural hosts of tomato bushy stunt virus demonstrated recently by the authors is given.

The stomatal density, dimension and conductances to water vapour diffusion of sevenHevea species were studied. It was found that these parameters were significantly different between the species. However, no distinct relationship between stomatal density or dimension and stomatal conductances could be discerned.

Dimethyl sulfoxide present in the agar medium at concentration 0.2 % (v/v) and lower does not inhibit cytokinin-induced betacyanin synthesis in theAmaranthus caudatus seedlings. The activity of kinetin, N⁶-(Δ²-isopentenyl)adenine andtrans- zeatin is the same when these cytokinins are dissolved in either water or dimethyl sulfoxide and incorporated into the medium after autoclaving. A simple method is described which allows the cytokinin activity of slightly water-soluble and thermolabile compounds,e.g. aromatic urea and thiourea derivatives, to be determined in theAmaranthus bioassay.

Sap flow rate (Q_w) and leaf water potential (Ψ_w.leaf) in adult specimens of birch (Betula) and oak (Quercus) were measured under contrasting soil moisture conditions (Ψ_w.sofl). With sufficient soil moisture Q_w reached about 250 cm³h^-1 calculated per unit tree-trunk segment as given by 1 cm length of its circumference. In soil water-stress conditions (when Ψ_w.leaf = = -15 × 10⁵Pa), birch stopped transpiration and wilted. Oak transpired even when Ψ_w.leaf fell below -20 × 10⁵Pa. The relation between Q_w and Ψ_w.leaf was always linear and with various Ψ_w.soil differed in the slopes of regression lines only. Hydraulic conductance (K_wcu) with nonlimiting moisture conditions reached about 6 × 10^-9m³ 10^-5Pa^-1s^-1 and "conductivity" ("k_wa") when calculated per leaf area unit reached about 23 m 10^-5Pa^-1s^-1. K_wcu and "k_wa" were of about one half to nine times greater in birch than in oak. On the basis of relations between Ψ_w.soil at various depths, Ψ_w.leaf and Q_w (resp. K_w) it is possible to assess the maximal rooting depth and the effective depth where the maximum of absorption of roots occurs. It is to be seen that the root system macrostructure substantially participates in the drought avoidance of adult trees in a forest stand.

Cytokinin activity was demonstrated in the Baltic sea waters. This activity was always higher in the near-bottom water, taken from theFucus vesiculosuszone, than in the superficial zone. A cytokinin-like substance showing properties typical of 6-(3-methyl-2-butenylamino)purine (2iP) was also present in extracts from the thallus ofFucus. It was found that exogenously applied cytokinins, in some concentration ranges, markedly increased the number of adventitious branches formed on the cut surface of the thallus fragments. The growth responses of the investigated plant tissues to the different cytokinins varied according to season and kind of cytokinin applied. The possibility of exudation of some cytokinin like substances by the algal cells into the surrounding waters was considered.

Barley plants were grown until day 21 under conditions which were different in relation to photon flux density, carbon dioxide concentration and temperature. Dry weight and leaf area increase from day 7 until day 21, shoot apex development between day 15 and day 47, and yield of each treatment group were considered. Photon flux density was demonstrated to have a greater influence on net assimilation rate (NAR) of young plants than has carbon dioxide enrichment. High temperature treatment seems to influence NAR less than growth and developmental processes. Grain yield of high temperature treated plants was significantly lower than that of the other treatment groups. Significant correlations have been found between growth analysis values of young plants and some yield components of each treatment.

This paper describes a procedure for isolation and preservation of mesophyll cells, adapted toValerianella olitoria. We have tested the best conditions of temperature, pH, enzyme concentration, plasmolysis and the action of several adjuvants, dithioerythritol and mineral nutrients. The method described gives a high yield of viable cells. The ability of isolated cells and cellsin situ to take up methyl-glucose is compared.

Studies on seeds of 40 arid zone plant species have revealed that seeds exhibit differential specificity in water inhibition percentage. Most of these seeds show very poor imbibition capacity and that takes place within the first three hours, after which this uptake becomes very slow. This low hydrature and quick water uptake wherever it takes place is correlated with the erratic rainfall in the Indian arid zone. Most of the leguminous seeds are impermeable to water because of hard seed coatedness. However, those seeds which imbibed showed a very high percentage of water uptake.

A simple bioassay of gibberellic acid (GA₃) based on the GA₃-induced reduction of anthocyanin contents in young seedlings of tomato is described and compared with the amaranthin reduction test. It was found that GA₃-induced reduction of anthocyanin in tomato seedlings was linear from 10^-5 to 10 mg 1^-1 GA₃ whereas the reduction of amaranthin inAn aranthus caudatus seedlings was linear from 10^-3 to 10 mg 1^-1 GA₃. From these results, it is concluded that the anthocyanin reduction test for GA₃ is more sensitive at lower concentrations of GA₃ than the amaranthin reduction test.

The changes in the levels of growth regulating substances using the wheat coleoptile straight growth test were determined in the leaves of vernalized (flowering) and non-vernalized (non-flowering) plants of sugar-beet, cv. Poly-AG-Poland at two stages; the end of vernalization treatment (210 days from planting) and full-flowering stage. IAA was detected only in the extracts of the leaves of non-vernalized plants after210 days from planting. No inhibitory activity was detected, except in the case of the concentrated extract of the leaves of non-vernalized plants. This growth promoting zone was found at R_f 0.5-0.8 in the leaves of flowering plants after cold treatment and at flowering time. This zone of growth promoting action was suggested to have a major role in the flowering of sugar-beet.

A description is presented of a simplified procedure for the serological diagnosis of plant viruses which utilizes the high sensitivity of the latex test. Small pieces of the plant examined are soaked in a drop of water, buffer, or directly in the sensibilized antiserum. Following the reaction with the antiserum the virus is evidenced by visual evaluation of the presence of agglutination. The procedure is applicable for routine serological diagnosis; it demonstrates even small virus concentrations and is as reliable as the normal procedure of the latex test. Using this simplified procedure the following viruses were demonstrated in various host plants: X-, Y-, S-, and M-virus of potato, the carnation mottle virus, and the tomato bushy stunt virus.