A low reproducibility of some characteristics in the life cycle of the volvocal algaChlamydomonas geitleri was observed in repeated experiments. The sets of the cultures were very similar in the number of the studied characteristics, but some of them differed significantly in one or several characteristics whereas the others agreed in a whole set. This is documented by the growth in a nitrogenless medium, the formation of zygotes, and their maturation and germination. The results of a small representative set of experiments were treated by an analysis of variance. Some possible explanations are discussed.

The occurrence of polysomaty was noted in a diploid cytotype ofUrginea indica with B chromosomes. These accessories could be clearly distinguished from the other chromosomes in their stainability, very small size, morphology, variability and irregular behaviour. The variant nuclei were hyperdiploid, hypertriploid and hypertetraploid. B chromosomes were noted only in diploid cells and no accessories could be recorded in cells showing higher chromosome number.
The amount of DNA content as indicated by the absorbance is rather low as compared to the diploid without accessories which may be due to the shorter size of the chromosomes. Under ultrastructural study subterminal centromeric region of B chromosome show low electron dense appearance.

On rooting the poplar stem cutting, the growth processes are coordinated so as to ensure optimum development of the new, vegetatively acquired individual. At first, adventitious roots develop on the cutting from latent root primordia. A part of them is short-lived, but in the meantime other, the so-called wound adventitious roots initiate from the callus on the lower cut surface of the cutting, which complement the permanent root system. In this way, conditions are prepared for a rapid growth and development of the stem, which forms from the upper bud on the cutting. The action of apical meristems providing the elongation of the stem and root, is followed by the action of vascular cambium. By the radial growth of organs controlled by cambium, the capacity of substance transport increases relatively to progressing development of the new plant. In the buried stem cutting cambium is the first to start functioning. Its reactivation is slow, discontinuous, and at the beginning it depends on local stimulating sources of the cutting itself. It was observed for the first time that, in addition to expanding buds, activated root primordia are also such sources of stimuli. The overall induction of cambial activity in the cutting occurs only in the period of rapid growth and development of the new stem, which thus becomes the main source of factors controlling the cambial activity of the cutting. In comparison with the growth of stem and cutting, the radial growth of adventitious roots is limited and there are considerable differences in the thickness of radial increments between individual roots.

Salinity caused a consistent reduction in the growth of cowpea plants and water content in their leaves. The total as well as the pigment fractions, except carotenoids, exhibited lower values than those of control plants at almost all salinity levels. With the rise of salinization, the total nitrogen and potassium contents in the leaves were decreased but the sodium content was increased and phosphorus content was not significantly affected as compared with the controls.
The application of IAA to salt-treated plants increased the water content in the leaves but it had no effect on the number of leaves and the stem length. The pigment contents in the leaves were either promoted or inhibited with the application of IAA, depending upon the level of salinization. The application of IAA to plants irrigated with water of the highest salinity level was effective in increasing the potassium content in the leaves as compared with the control, but it had no effect on the other mineral elements.

Supply of 0.01 to 5.0 mM salicylic, caffeic and gallic acids, either during imbibition of seeds for 24 to 48 h or during seedling growth increased anthocyanin production in maize (Zea mays L. cv. Ganga safed-2) roots. While tyrosine had no effect, phenylalanine either in the presence or absence of the phenolic acids increased anthocyanin content. Glucose in a concentration range of 1 to 20 mM and shikimic acid in 0.01 to 5.0 mM range also increased pigment level, which was higher in the presence of salicylic acid than in it.s absence. The experiments demonstrate the possibility of some indirect effects of salicylic acid and other phenolic acids on anthocyanin synthesis.

The flag and second leaves of wheat showed physiological and biochemical differences in the normal and water stressed plants. Although the flag leaf had lower enzyme activities in the control plants, in stressed plants it could continue nitrate assimilation better than the second and other leaves. The flag leaf also exhibited a higher tendency to resume normal metabolic activity after the release of stress as is indicated by higher NRA, NiRa, lower r_ad and r_ab.

The effect of sodium humate on phosphorus uptake by maize seedlings devoid of the endosperm was studied. Short-term experiments have shown that a suppression of phosphate ion absorption occurs under the described conditions in the presence of humate without decreasing the weight of experimental plants. The effect reported is delayed and is enhanced by prolonging the preliminary phase of starvation. It varies with the pH of the medium and reduces under extreme conditions the phosphate release from the root to the medium.

Lupin aleurone grains from dry cotyledons contain about 87% of globulin including 57% of proteins solubilized by NaCl solution and 30% by NaOH extractions, and also about 12% of albumin. Activity of acid protease with the optimum at pH 3.6-3.8 was associated with albumin. Albumin was separated by gel filtration on Ultrogel AcA 22 into 3 fractions with mol. m. 179 000, 113 000, and below 100 000, respectively. The component with mol. m. 113 000 prevailed and comprised about 60% of albumin. Globulin was composed mainly of two major components with mol. m. above 364 000 and about 280 000. These correspond to α-and β-conglutin fractions, respectively.
γ-conglutin minor globulin fraction of lupin aleurone grains was composed of about 66% glycoprotein. In contrast, about 82% of albumin lack glycosylation. Essentially, globulins in lupin aleurone grains are glycoprotein.

Four strains of the phytopathogenic bacteriumCorynebacterium fascians (Tilford)Dowson were selected from our isolates and deposited in the Czechoslovak National Collection of Type Cultures (CNCTC) of the Institute of Hygiene and Epidemiology in Prague. Two very virulent (Cor 83/82 "UPR" and Cor 82/81 "UP") and one avirulent (Cor 81/80 "CP1b") pelargonium strains, producing acid from rhamnose, were isolated from fasciations onPelargonium zonale W. One avirulent celery strain ofC. fascians (Cor 80/80 "CF4a") was isolated from a root expiant ofApium graveolens L. growing on a nutrient mediumin vitro. Morphological, cultural, physiological and biochemical characteristics of these selected Czechoslovak isolates were compared with the American patented strain cotype ATCC 12974.

A closed gas exchange system has been designed for connection to the Hewlett-Packard programmable calculator controlled data acquisition system to provide a complete process of measuring and control. The system enables routine measurements of photosynthetic and dark respiration rates at different irradiances and different carbon dioxide and oxygen concentrations and leaf temperatures, and also a simple and rapid automatic control of irradiance according to the actual photosynthetic rate.

Willows were rapidly propagated by repeated division of cultured rooted shoots into a larger number of nodal segments. Rapid clonal propagation of mountain-ash and black locust was achieved by induction of shoots from axillary buds and a multiple shoot culture was used for rapid multiplication. Excised shoots were rooted in an agar medium with a low concentration of auxin and rooted plantlets were transplanted to soil.

Net CO₂ exchange rates, stomatal and internal resistances for CO₂-transport were followed on fully expanded Witloof chicory leaves (Cichorium intybus L. cv. Foliosum) for several months during vegetative growth. Maximum net CO₂ exchange rate (P_max) stayed high with a sudden drastic drop at the end of the growing season largely due to an increase in internal diffusion resistance.
During an analogous growth period the H₂O vapour diffusion resistances of leaves for four selections were measured. The adaxial stomatal resistance was always higher than the abaxial one. Stomatal densities calculated for those selections showed higher values at the abaxial leaf side.

The effect of several plant growth regulators on the number of tumors developing on potato tuber discs (Solatium tuberosum L. cv. Radka) inoculated withAgrobacterium tumefaciens, strain C 58 was studied. The plant growth regulators used in appropriate range of concentrations stimulated the formation of tumors byA. tumefaciens.
Naphthaleneacetic acid (NAA) was most active in concentration of 10^-4 mg ml^-1. Kinetin gave a biphasic response with optimal promotions of tumor initiation at 10^-4 - 2 × 10^-3 mg ml^-1. High kinetin concentration (10^-1 mg ml^-1) inhibited the formation of tumors completely. Indoleacetic acid (IAA) stimulated the initiation of tumors in the same range of concentrations as kinetin, except that very high concentrations did not inhibit but enhanced tumor formation. 2,4-diehlorphenoxyacetic acid (2,4-D) showed a biphasic response with maxima in 10^-4 mg ml^-1 and 10^-1 mg ml^-1. All the tumors scored for nopaline production showed nopaline synthase activity independently whether their formation was stimulated by l0^-1 mg ml^-1 IAA or they were initiated without any treatment by plant growth regulators.

Three different treatments by calcium (10²M), namely seed treatment, foliar spraying and their combination were applied on field-grown rice (Oryza sativa L. cv. Ratna) under both water stressed and non-stressed conditions in the course of plant development. The relative water content and leaf water potential decreased with increase in age of stressed and non-stressed plants. Pretreatment of seeds with Ca improved the water status of the plants most prominently at the vegetative stage but the effect gradually faded away with plant development. The foliar spraying by Ca was more effective in improving the water status of the plants at the reproductive stage. The combined Ca treatment significantly improved water status of the plants both at the vegetative and reproductive stages. The contents of chlorophyll and protein decreased and the activities of protease and RNase increased in the course of plant development in both non-stressed and even more in stressed plants. Ca treatments of seeds or plants or their combination inhibited the decline in chlorophyll and protein contents and the rising trends of protease and RNase activities, the combined treatment being most effective. During plant development free proline content increased significantly more in water stressed plants. In non-stressed plants there was a marked increase in the free proline content at the mature fruit stage. Ca treatment inhibited the rise of free proline in stressed plants. A significant reduction in yield components and yield of the crop in water stressed plants was increased by Ca treatment.

Plants were regenerated from mesophyll protoplasts of axenically growing plants of four dihaploid clones and five tetraploid cultivars ofSolanum tuberosum L. andSolanum phureja Juz. etBuk.

The effect of herbicides N-(phosphonomethyl)glycine (glyphosate), 2-methyl-4-chlorophenoxyacetic acid (MCPA), 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine (atrazine) and the respective commercial preparations "Round-up", "Aminex", and "Zeazin", on the activity of lactate dehydrogenase isolated from germinating soybean seeds and beef heart were compared. The main aim of the work was to compare the effect of the herbicides on lactate dehydrogenase isolated from animal and plant material. Simultaneously the effect of herbicides and the respective commercial preparations was compared. Substantial differences resulting from the two comparisons indicate differences in the structure of active centres of lactate dehydrogenase isolated from animal and plant material, and also a considerable effect of additives and surfactants in commercial preparations.

The lectins from the seeds of two species of the genusArtocarpus (A. integrifolia L. andA. incisa L.) were isolated by affinity chromatography on an AB (+) human stoma column, and compared by physicochemical and immunochemical methods. Although with marked differences in the hemagglutinating activity, the elution pattern of the albummic and globulinic fractions from both seeds were comparable by affinity chromatography on a human-stroma column. The two isolectin families presented many similarities. All the lectins presented the same subunit pattern by SDS-polyacrylamide gel electrpphoresia, were recognised by both rabbit antisera prepared against the crude extracts from the two seeds, and presented fused rockets when electrophoresed in agarose gel containing one or the other antiserum.