Mechanical scarification of seeds ofPhaseolus mungo L. resulted in 100 per cent gormination in comparison to 90 per cent dormant control. Seeds treated with concentrated sulphuric acid for 8 min led to 85 per cent germination. Heat treatment at 70 °C for 24 h exhibited 75 per cent gormination, while boiled water treatment for 7 min caused 65 per cent germination.

Gibberellic acid GA₃ (50 ppm) decreases the photosynthetic rate and increases respiration rate of rye leaves (Secale cereale L., cv. Dankowskie Zlote). The effect of GA₃ on transpiration rate is not distinctly marked.

In a greenhouse pot oulture experiment, a dinitrogen (N2) fixing - acetylene reduction activity profile was examined in detail as affected by plant age. Total [μmol C2H4 root-1 h-1] and speoifio nitrogenase [nmol C2H4 (mg nodule d. wt.)-1 min-1] activities peaked 63 days after sowing, near the end of flowering. The nitrogenase activities, nodule dry matter accumulation, top dry matter accumulation, and total nitrogen yield in the top dry matter were found to be highly correlated.

Nitrate reductase (NR) induction is enhanced by exogenously supplied sucrose in excised pea roots exposed to both exogenous nitrate and exogenous nitrite. NR synthesis is preferentially supported by sugars transported to the cells at the moment, however NR induction can take place for some time without exogenous sugar influx if roots are saturated with sugars during precultivation. Steady high NR levels are dependent on steady sugar and nitrate influxes. NR induction is low in roots precultivated for 20 h without sucrose although sugar content is still high in them. This suggests that compartmentation of sugars in the cells is of major importance during NR induction. Total nitrate content in roots exposed to nitrate is not influenced by sucrose supplied together with nitrate. Some nitrite is oxidized to nitrate in roots exposed to exogenous nitrite ; we assume that this nitrate is responsible for NR induction. Our results indicate that sugars, besides many indirect effects on NR induction, may also directly influence NR synthesis either as coinducers or as derepressors of NR synthesis. Our results further show that NR is not a product-inducible enzyme.

The effects of foliar application of morphactin (0, 10, 50 and 100 ppm) onPennisetum typhoides (cv. HB3) have been studied under different soil moisture conditions (0.3, 3 and 9 x 10Pa tension). Morphactin application reduced the plant height, increased the tillering and leaf number of the main shoot and adversely affected the growth characters associated with the grain production. The overall performance of plants was not improved by morphactin treatment under low moisture regime and it did not impart any efficiency of water use for grain production. Findings on the phosphorus and potassium levels of the shoot tissue suggested a possibility of its interference in the nutrient uptake process.

Storage proteins of the seeds (cotyledons) of the South-American speciesPhaseolus caracalla were compared by means of immunoelectrophoretic methods with other representatives of the genusPhaseolus. These proteins most resemble the proteins of the co-called tropical group (i.e. Ph. atropurpureus, Ph. geophilus, Ph. bracteatus, Ph. semierectus) and least the so-called American endemites (Ph. vulgaris, Ph. coccineus, Ph. acutifolius, Ph. lunatus), the main globulin of which is of a completely different specificity. The proteins ofPh. caracalla are less similar to the group of the so-called Asiatic species (Ph. aureus, Ph. calcaratus, Ph. angularis, Ph. aconitifolius, Ph. trilobus) including the analyzed representatives ofVigna sinensis; their main globulin is only partly similar to that ofPh. caracalla. Some considerations on the relationship ofPh. caracalla with the so-called tropical species is presented.

Excised tomato cotyledonswere subjected to mannitol induced water stress solutions for three days. Extracts of proteins and the enzyme peroxidase were made and separated with polyacrylamide gel electrophoresis. The water stress injury caused increases in bigger protein molecules but decreases in smaller protein molecules. The small fastest moving peroxidase isozyme was almost completely eliminated. Applications of growth regulators to the stress solutions indicated that the protein and peroxidase changes could be explained on the basis of reduction in endogenous cytokinin activities by the water stress.

Carbohydrate requirement for the growth of the cells and accumulation of polyphenols in culturedCassia fistula L. andDatura metel L. tissues were examined. Superiority of suerose over other carbohydrates was observed both for the growth of the cells and for the maximum production of phenolic compounds; and its availability was found to be a limiting factor for the synthesis of phenolic compounds.
Progressive changes in the pattern of peroxidase and phenylalanine ammonia-lyase (PAL) activities were followed and the relationship between the development of the enzyme activities and synthesis of polyphenols was further examined. The significance of peroxidase and PAL in the regulation of phenolic production is discussed in the light of recent findings.

The elongation of primary roots of pedunculated oak (Quercus robur L.), which is associated with nutation oscillations, was registered by a time lapse cinematography. The following characteristics were expressed graphically: relative growth rate [mm h-¹], frequency [rev. h-¹] and amplitudes [mm] of nutation oscillations, their direction and location of nutation curvatures. The growth-oscillation mechanism is interpreted as a part of the geocontrol system of the root and was evaluated on the basis of its physiological efficiency. Comparison of nutation periods showed that the control system of pedunculated oak is three times more and two times less efficient than that of pea and maize, respectively. Comparison of the oscillation amplitudes of growing roots gives similar results.

The analysis of growth and movements of seedling organs of kidney bean (Phaseolus vulgaris L.) provides a pattern of periodic phases of activity and relaxation. The existence of a central organ which would control the phase relationships, is not anticipated in the integrity of the plant. The cyclic activity of individual organs shows itself by growth associated with oscillation movements. One and the same organ may simultaneously accomplish oscillatory movements with a diurnal and ultradiurnal frequency. These rhythms originate during the organ development; the first pair of kidney bean leaves at first executes oscillation movements with a diurnal frequency and only after it is fully developed it exhibits a diurnal cycle with the photophil phase upwards and the scotophil downwards, the oscillations with an ultradiurnal oycle being maintained. The movements of the two leaves are synchronous, but there occur short sections with a desynchronous cycle. Simultaneously with these oscillations, in which the leaf petiole takes part, the adult leaf performs oscillatory movements perpendicular to the longitudinal leaf axis, the so-called side swings, controlled by periodical changes of the joint attaching the leaf blade. Their frequency is practically identical with that of the ultradiurnal cycle. Thus the periodic growth activity of the kidney bean results in growth oscillations passing in the diurnal cycle with a frequency of 0.043 rev.h^-1, their ascending and descending phases consisting of periodical ultradiurnal oscillations in cycles of 0.73-0.59 rev.h^-1. The epicotyl growth shows a similar pattern: into the basic diurnal nutation cycle with a frequency of 0.042 rev.h^-1 ultradiurnal oscillation cycles are incorporated having a similar frequency to that revealed in leaves (0.69-0.64 rev.h^-1). The diurnal oscillatory cycles belong to a system established on the basis of periodicity of day and night and other geophysical cycles. The ultradiurnal rhythmic oscillations are presumed to be an expression of the geocontrol system of root and shoot growth direction and orientation of the organ in space. The shape of their trajectories in bean leaves is contradictory to this; they are not spatial helices, as the kybernetic model would presuppose, but have a vertical, upwards and downwards course in one plane. Since these oscillatory movements with an ultradiurnal cycle cease after petiole excision from the stem and after shoot apex amputation, one may presume that they are coupled with the low-frequency oscillatory system of the epicotyl.

Effect of water stress at -1, -3, and -5xl0⁵Pa osmotic potential on some properties of acid phosphatase has been studied in two wheat cultivars. Acid phosphatase from S-308 cultivar, which is less drought resistant than C-306, was less susceptible under varying conditions of pH and temperature treatments.

The growth of callus tissue cultures and the infectivity of twenty fiveSolanum laciniatum Ait. plants and of sixteenNicotiana tabacum L. cv. Samsun plants were investigated. The plants were obtained from callus tissue cultures derived from stem pieces of the respective plants infected with a mycoplasma-like organism (MLO) evoking potato witches' broom. The tissues were cultivated on synthetic nutrient medium with kinetin and IAA. Allde novo obtainedS. laciniatum plants were healthy. On the contrary twelve of the sixteen reconstituted tobacco plants showed MLO presence.
Summarizing these and previous results, the authors suppose that the most important factor influencing MLO persistence in callus tissues cultivated on the applied nutrient medium may be the callus growth rate and the organogenesis set. Both these conditions are determined by the metabolism of the investigated plant species.

For the detection of starch in paraffin sections of FAA fixed root tipa of pea and maize the Lugol's solution of suitable constitution and proper dilution was tried. JJK containing solution of arabic gum was proved as a mounting medium preserving the resulting colour. A procedure is given combining the application of JJK with alcian blue staining.

Application of hydroxyurea to intact seeds ofAgrostemma githago as well asVaccaria pyramidata causes a strong inhibition of radicular³H-thymidine incorporation into DNA, but germination rate is only insignificantly reduced. The seedling development, however, is strongly affected. Consequently, DNA synthesis is not a prerequisite for the radicle protrusion.

A study was made on the mitotic cycle times in meristematic cells of Vicia faba root tips and on the relationship between their duration and the position of a certain cell in the column of proliferating cells. For the demonstration of the sequence and duration of mitotic oycles a single-column model was used. The results of experiments show that the great variability in the duration of mitotic cycles (from 12 to l20 h)is the result of a different program of the apical meristem cells. The long duration of the cycle of initials corresponds to the sum of cycle times of their descendants.

Various herbicides are applied on seventeen-day-old cucumber seedlings growing in a nutrient solution.
After 1 and 3 days, acid and alkaline pyrophosphatase activities are measured in the leaves and the roots of seedlings treated with lethale dosis of atrazine, chlortoluron, ioxynil, MCPA, dicamba, alachlor. The same enzymes are determined after 5 h in seedlings on which previously paraquat and DNOC were pulverised. In the leaves, acid pyrophosphatase activity is stimulated by almost all the herbicides, especially by ioxynil, paraquat and DNOC while alkaline pyrophosphatase remains similar to the controls. The alkaline and acid pyrophosphatase activity in the roots is either unchanged or stimulated or inhibited without any correlation with the various modes of action of the herbicides.

Colchicine treatment (0.05 % for 12 h) to 15 day old seedlings in the 1st generation after X-ray or gamma-ray exposure was lethal. In contrast the same colchicine treatment to 15 day old seedlings in the 2nd generation was effective in inducing polyploids.

The variability of some seed proteins ofPhaseolus vulgaris was followed in individual seeds of 26cultivars of this species. Polymorphism was established with two proteins showing completely different immunochemical specificities which have previously been classified as the protein I and the protein II of the specificity Veltruská Saxa and Krupnaya sakhamaya respectively. Various combinations of these proteins occur in several cultivars. It was further found that the protein II of the specificity Veltruská Saxa had phytohaemagglutinating activity.

In this report, B₉ treatment had no effect on the growing of rosette biennialScrophularia vernalis L.; it inhibited or slowed stem elongation. Applications of GA₃ to B₉ treated plants produced a significant increase of stem elongation, in relation to GA₃ treated plants. Plants treated with only GA3 failed to flower; otherwise, the flowering of vernalized plants was not altered by GA₃. Thus, B₉ effect on flowering was tested by using GA₃. B₉ by itself induced flowering, it increased inflorescence formation in vernalized plants without altering stem growth pattern in the most of cases. The induction or the stimulation of flowering brought about by B₉ was not reversed by GA₃; we may thus hypothesize that flowering by B₉ oannot be traced back to gibberellin biosynthesis.

The supply of nitrate nitrogen caused a marked increase in the rate of respiration of Japanese mint. Sodium azide strongly inhibited the rate of respiration at all the nitrate levels, but the inhibition was more marked at higher levels. Besides this, inhibition caused by azide treatment was less marked in older and nitrogen deficient tissues than in younger ones at higher nitrogen levels. The addition of sodium diethyl dithio-carbamate (DIECA), an inhibitor of copper containing enzymes resulted in an increase in the respiration of mint leaves which increased further with an increase in the nitrate supply. The same concentration of DIECA which stimulate the respiration of leaves caused an inhibition in the respiration of roots. The inhibition was greater at lower levels and decreased consistently as the supply of nitrate increased. The sensitivity of root respiration to DIECA observed with varying levels of nitrate indicated that unlike the leaf, the roots contain copper-containing enzymes which get decreased as the nitrate supply is increased. An increased supply of nitrogen up to 16 me NO₃^- -N was associated with an increase in respiratory quotient.