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.

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.

An improved system of plant cultivation at stable and specific levels of polyethyleneglycol (PEG, mol. mass 1400-1600) - induced water stress has been described. To set up this system a perforated tubular glass vessel containing soil to support seedling growth was wrapped externally first with a layer of macroporous silica gel-G and then with three layers of a dialysis membrane of a lower exclusion limit (2000 mol. mass). Effects of 8 days of PEG - induced stress have been studied on uptake and translocation of N and P and growth of barley (Hordeum vulgare L. cv. KN 16) seedlings. Some of the noteworthy improvements of the system were exelusion of PEG from the plant consequent upon use of silica gel-membrane combination, shorter time (2 days) for the soil-plant-air continuum to attain steady state, and stability of the plant water potential over a period of a few days.

The addition of Na₂EDTA to a minimal medium (agar, sucrose) deprived of cations produces no morphoregulatory effect. This effect is induced only by the addition of iron. Traces of iron present in the agar are sufficient for the development of globular embryoid into a complete plant. The traces of iron in distilled water and sucrose (p. a.) are insufficient for the morphoregulation. The marked difference between the necessary limiting amount of chelate and necessary limiting amount of iron in non-modified media is explained by the presence of other cations, which saturate and thereby inactivate a greater part of Na₂EDTA. It is recommended to decrease the amount of iron and leave the commonly used amount of chelate in the prepared media. Simultaneously with optimal morphoregulatory effect in androgenesis and somatic embryogenesis, vitality of tissue culture will be lengthened and ageing as well as necrosis of the cultures be decreased.

This paper deals with some morphological and histological changes observed during regular intervals inMatricaria inodora L. tissue cultures derived from leaf expiants. The expiants were cultivated on Murashige-Skoog's culture medium supplemented with 1.0 mg 1^-1 2,4-dichlorophenoxyacetic acid. The callus formation started about a week after isolation. During the second week the meristematic centers were differentiated from which root and shoot apices were later formed. During long term cultivation under the same culture conditions the inhibition of development of shoot apices took place. Only roots of unorganized growth have been regenerated. The influence of culture conditions on morphogenetic potential is discussed.

Water-stress for 10d at different developmental stages, affected relative water content and leaf water potential of plants. Subsequent rewatering removed these effects. Water stress lowered the contents of chlorophyll, protein, RNA and the activity of catalase, while it increased free proline accumulation and activities of protease, RNase and peroxidase. An overall improvement in biochemical parameters was achieved as soon as the stress was withdrawn by watering and this was reflected in subsequent developmental stages. Water-stress at the reproductive stages induced similar changes as in the vegetative stage but the removal of stress could not improve these parameters to the same extent as at the vegetative stage. In consequence, stress applied at the vegetative stage augmented yield parameters but when applied at the reproductive stage it significantly reduced the yield.

The fluctuation of free IAA under 16 h dark period in shoots (receptor organs of photoperiodic induction) and roots of the short-day plant (SDP)Chenopodium rubrum and in shoots of the long-day plant (LDP)Chenopodium murale is very similar. The data reflect the general adjustment of auxin level to day-length rather than changes due to floral induction. However, the shift in phasing of the circadian rhythm of flowering was accompanied by a change in the position of the' troughs' of free IAA levels indicating a possible relationship between the two processes. Periods of higher sensitivity to application of IAA (3. 10^-4M) inhibitory to flowering have been observed both during the endogenous rhythm of flowering in the SDPC. rubrum and during induction by days of continuous illumination in the LDPC. murale. There exist common traits in the response of LDP and of SDPChenopodium to auxin treatment. Aminoethoxyvinylglycine (AVG), an inhibitor of ethylene biosynthesis, counteracted some flowering inhibitory effects of IAA when applied simultaneously with it. This suggests that auxin effects in modifying flowering might in fact be due to ethylene.

In an experiment with native maize roots depending on different phosphorus concentration in the external solution (0.001 … 50 mM P), the multiphasic character of the kinetics of phosphate uptake has been stated. The single phases are characterized by the different values of K_m and V_max. In the wide range of concentrations the isotherm of the phosphate uptake has five evident phases. The character of kinetics for the uptake of phosphate is analogical to the kinetics of the enzymatic reactions described by the Michaelis-Menten equation. On the other hand the linear dependence for the inactivated root was determined,i.e. the uptake of phosphate versus different phosphorus concentration in the external solution.
The graphic representation of the logarithmic values for the phosphorus taken up versus the different phosphorus concentration in the external solution gives the biphasic course including concentration less than 1.0 mM P and more than 1.0 mM P. Within the framework of the concentration range the following values of V_max, K_m and ϕ_in were calculated under the conditions if the concentration of phosphorus is less than 1.0mMP: V_max = 1.705 μmol P × g^-1h^-1, K_m = 0.057 mM P and ϕ_in = 0.83,i.e. if the concentration of phosphorus is more than 1.0mM P: V_max = 40 μmol P × g^-1 h^-1, K_m = 16.66 mM and ϕ_in = 20.
According to these results, the phosphate concentration in the external solution influences the activity of the transport mechanisms concerning their conformative changes which discretely change their working regime of membrane transport. This is also demonstrated in the change of values V_max, K_m and ϕ_in.

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.

Starch, lipids and proteins are localized histochemically in fusiform and ray initials ofTectona grandis andGmelina arborea during the periodicity of cambium in the year 1978. The histochemical variations are correlated with the seasonal activity and dormancy of the cambium and phenology. Starch grains appear in the cambial cells with the development of young leaves after defoliation. Lipid and protein bodies are significantly high in dormant cambial cells and scarce in active ones.

Roots obtained from 4-day maize seedlings were allowed to absorb uniformly labelled¹⁴C-suorose only with their middle part while the apical and basal parts did not contact the medium. The amino acids and their amides produced in the cortex at the expense of nitrates and the¹⁴C-sucrose carbon moved radially to the stele where they were selectively distributed in the polar directions of transport. "Primary" amino acids moved predominantly in the apical direction while amides and basic amino acids were transported mainly in the opposite direction. When the nutrient medium was devoid of nitrogen sources, the amino acids entering the stele from the cortex were transported mostly to the root tip, indicating a significant role of young tissues in consuming organic nitrogen compounds when they are in short supply in the root.

Dependence of the growth of this alga culture on temperature displays a wide interval of temperatures (from 4 °C to 30 °C) and the dependence of the sexual reproduction only a narrow one (from 18 °C to 25 °C). The optimum temperatures for both the processes are not so different (round 23 °C). Dependence of both the processes on irradiance displays a wide interval of irradiances in both eases (from 4 W m^t-2 to 80 W m^t-2 PhAR and higher). The optimum irradiances for these processes are very different (approx. 50 W m^t-2 PhAR for the growth and approx. 10 W m^t-2 PhAR for the sexual reproduction) under the experimental conditions used.

In partly purified protein complexes obtained from 22 species of theAllium genus and 6 cultivars ofAllium cepa the activity of cholinesterases was detected and measured using the method of Ellman et al. The degree of its inhibition with 10^-4 M neostigmine was also tested. It was found that the activity of cholinesterase differed in individual species up to two hundred times, while the differences in the inhibitory activity of 10^-4 M neostigmine occurred only in a few cases. Individual sections and cultivars could not be characterized on the basis of the differences in the activities of the cholinesterases. Of all the sections that ofPhyllodolon shows the highest average activity. In the case of the tested cultivars distinctly the lowest activity was observed in cv. Kastická. The values of the enzymatic activity measured by Ellman's method in this plant material include the activity of specific and unspecific cholinesterases and the part uninhibitable by neostigmine.

Red light (660 nm) break which cancels the floral inductive effect of the dark period brought about a transitional rise in the level of free IAA in the shoot ofChenopodium rubrum. The higher content of IAA was then found in treated plants at the beginning of the following photoperiod, too. The red light treatment did not change the phase of endogenous rhythm fluctuations of free IAA.