Both quantitative and qualitative immunochemical methods were used for studying the mutual relationships of several spocies and the subspecies of the genusPhaseolus: Ph. vulgaris L. ssp.vulgaris, Ph. vulgaris L. ssp.aborigineus Burk.,Ph. coccineus L.,Ph. acutifolius A. Gray,Ph. lunatus L. (American endemites) andPh. aureus L. (a typical Asian bean). Protein characters of cotyledons (i.e., "storage" proteins) of the above species were compared with the aid of antisera prepared against seed (cotyledon) proteins ofPh. vulgaris L. ssp.vulgaris, cv. Veltruská Saxa, using
(a) the whole complex of cotyledon protein,
(b) the albumin fraction of this complex,
(c) the globulin fraction,
(d) crystaline phaseolin.
Our results are in agreement with the morphological and genetic data ofBurkart andBrücher on the close relationship betweenPh. vulgaris L. ssp.vulgaris andPh. vulgaris L. ssp.aborigineus (both contain a character designated asPh. vulgaris protein 1 which is lacking in the others, both contain an identical phaseolin and exhibit only negligible differences in the specificity of proteins). The closest to these two species isPh. coccineus (almost identical phaseolin, small differences in the albumin and globulin fractions, a greater quantitative difference in protein specificity).Ph. acutifolius contains a somewhat different phaseolin, exhibits greater deviations in the albumin and globulin fractions and a greater quantitative difference in protein specificity.Ph. lunatus andPh. aureus are quite different in all the above respects. These data are in good agreement with genetic data (crossability).

In both types of crosses (3n C.G.×4n D 154 and 4n D 154×3n C.G.) pods were found to set. In the first case pods shed within 4 days. In the second case pods were found to persist till maturity. Only a few uppermost ovules were found to be fertilized. Pollen tubes were seen to reach the ovules within 24 hours.
In 4n D 154×3n C.G. fusion of sperm with the egg was not noted to be complete till 3 days but the secondary nucleus is fertilized by other sperm. In 3n C.G.×D 154 fusion of sperm with egg or with polars was not complete within 3 days. Signs of degeneration of ovules were noted on the 5th day in both cases.

Mosaic disease ofAnchusa officinalis found at a ruderal association in Prague-Holešovice in the close proximity of TMV infected cruciferous weedsCardaria draba andSisymbrium loeselii, was identified to be caused by the same agent-the necrotic TMV-strain.

The effects of various cultural factors on the secretion of three pectic enzymes (PP, PG and PE) byAlternaria tenuis on synthetic media were studied. The results can be summarised as follow:
1. No definite correlation between the secretion of pectic enzymes, pH of the medium and the growth of the fungus was observed.
2. The secretion of the enzyme was dependent on the presence of pectin in the medium.
3. While various sugars were found to be equally effective, production of the enzymes was better on a medium without any sugar.
4. After varying the various concentrations and constituents of the medium, the following medium was found to be the best for the enzyme secretion: 1% pectin, 0.2% asparagine, 0.05% magnesium sulphate and 0.3% potassium dihydrogen phosphate.
5. It was established that on the above medium the fungus required four days of incubation at 25°C for the secretion of most active pectic enzymes.

Substances inhibiting local infection with virus X were isolated from leaves of potato cultivars Saphir, Saco, and Blaník by means of ultracentifugation and were concentrated with ammonium sulphate. These inhibitors were effective if rubbed into leaves of some host plants at least 2-4 days prior to infection without using any abrasives.

The calculation and construction of a simple nomogram to be used instead of a set of two equations in a two-wavelength spectrophotometric determination of chlorophyllsa, b, their total amount and ratio is are described. Any pair of equations can be represented nomographically by this construction.

In unseren Versuchen haben wir die Wirkung der 3 isomeren Styrylpyridine und des bekannten Herbizidstoffes 3-Amino-1,2,4-triazols (AT) in der Konzentration 10^-3 m auf die Succinat-dehydrogenase und Succinoxydase-aktivität der Wurzel vonSinapis alba untersucht. Styrylpyridine hommten das SDH-Enzymsystem vollständig, falls sie zum Pflanzenhomogenat noch vor der Messung der Aktivität hinzugefügt wurden. Diese Stoffe zeigten die gleiche Hemmwirkung wie Malonat. In den Versuchen, wo die Pflanzen direkt in den Versuchslösungen kultiviert wurden, zeigte sich 3-Styrylpyridin als das wirksamste; weniger wirksam war 4-Styrylpyridin und am wenigsten wirkte 2-Styrylpyridin. Die gleiche Abstufung der Wirksamkeit lieferten auch die Wachstumsteste und die Untersuchungen der SO-Aktivität. Die Succinoxydase-aktivität war nur wenig beeinflust, falls die Substanzen dem Pflanzenhomogenat beigefügt wurden. Bei den Pflanzen, die in den Versuchslösungen kultiviert wurden, zeigte sich die gleiche Abstufung der Hemmwirkung der SO-Aktivität wie bei dem SDH-System. AT beeinflusste das SO-Enzymsystem überhaupt nicht und das SDH-Enzymsystem wurde im Gegenteil noch stimuliert.

In experiments with fodder cabbage and sugar beet the influences were tested which restrict the finding of a uniform linear dependence between the chlorophyll content and photosynthetic rate. The main factor is most probably the irradiation during the growth of plants and the measuring of photosynthetic rate. Changes in the density and length of irradiation with the proceeding spring season are reflected in the decrease of unit chlorophyll activity in all leaves of the plant. Such differences were not observed in plants grown in winter months at a low greenhouse irradiation density. High irradiation density during the measurement of photosynthesis ensures the finding of high correlation of photosynthetic rate with the chlorophyll amount per unit area of leaf. With a low irradiation density, or in thick leaves, the lower layers of chloroplasts are not saturated with radiation, and hence a higher correlation coefficient is found by relating photosynthetic rate to the percentage of chlorophyll in dry weight than to the quantity of chlorophyll per unit area of leaf blade. In some experiments higher activity of chlorophylls was found in young leaves before they have reached the state of "photosynthetic maturity" than after this turning point. This difference diminished by relating the photosynthetic rate to chlorophylla content instead of the total amount of chlorophylls (a+b). High activity of chlorophylls in very young leaves and great individual variability within the experimental plant groups caused by uneven cultivation conditions are the basis of apparent sigmoid character of average curves for the chlorophyll-photosynthesis relation.

Comparison with the findings in the cells of other plants and animals showed that the endoplasmic reticulum in the root apex ofFagopyrum has the same general character and function as in other biological objects, i.e. in secretory processes and especially in this case in the transport of the substances produced. Detailed studies of the morphology and activity of the endoplasmic reticulum showed some functional differences which are characteristic for this object. The endoplasmic reticulum participates apparently in the transport of the mass of known but functionally and nomenclatorically controversial formations which here are called dense bodies. Dense bodies exist inFagopyrum in a considerable amount as compared to other objects. Frequent contact of the dense bodies with the ends of the endoplasmic reticulum, contact with the endoplasmic retieulum passing through the plasmodesm, accumulation of the dense bodies along the cell wall and in proximal distance of the plasmodesms and intensive staining of some plasmodesms was observed. The dense vacuoles in this object represent dilated spaces of the endoplasmic reticulum which apparently have the function of reservoirs of the dense mass. The endoplasmic reticulum in the calyptra cells appears to participate in the formation of the cell walls. This object differs hereby from others, where the participation of the Golgi apparatus has been observed in this function.

Stimulation and inhibition of photosynthesis inHydrilla verticillata Presl. with quinine sulphate and quinine alkaloid with concentrations ranging between 0.001 and 100 ppm was observed. Quantitative measurements of photosynthesis were done by a microburette (Audus 1940) and qualitative estimations by the modified apparatus byZutshi (1965a). Maximum inhibition of 50% and 34% is obtained with 100 ppm of quinine sulphate and quinine alkaloid respectively. The inhibition is due to the adverse effect on the pigment system particularly on carotene (Zutshi 1963). Forty percent stimulation of photosynthesis is obtained with 0.01 ppm quinine sulphate and 12.5% with 0.001 ppm quinine alkaloid. Difference in the biological activity of these two alkaloids is due to their different chemical structure and purity.

Mycelium of white-rot fungi secretes laccase into the medium. It was found by cultivation on malt-agar plates that the mycelium does not produce laccase equally in all its parts. The youngest hyphae at the margins of the colony represent usually the maximum producers, whereas older hyphae produce less or none at all. An exception here isCollybia velutipes which is the weakest producer of laccase of all the fungi studied and where only the older hyphae begin to secrete it. Manometric estimation of laccase showed that maximum specific activity of laccase is achieved at the boundary between the phases of initial and linear growth and i₁₁ some cases during the first half of linear growth. Ageing of the mycelium characterized by certain changes in its metabolism is reflected in changes of enzyme production by fungal hypha of different age.

The inhibitor of the X virus (Jermoljev, Albrechtová 1965) can be separated from other proteins by 60 min centrifugation at 40000 r.p.m. in the Spinco L centrifuge and by subsequent gel filtration of the supernatant on a Sephadex G-50 column. For the elution it is best to use Tris-maleate buffers and 0.2M Tris-HCl of pH 7.2. The inhibitor is present in the first fractions containing proteins, between 30 and 45 ml. It is most suitable to concentrate the inhibitor by salting out with ammonium sulphate to 30-50% saturation. The inhibitor can be preserved by adding ammonium sulphate to the sap. At 3°C it can be kept in this manner for 2 months. If the pH of the sap drops below 5.5, the inhibitor is inactivated. Complete inactivation of the inhibitor takes place after a 10 min heating at 67.5°C. No substantial difference in the amount of inhibitor in the sap from apical leaves and leaves from middle levels has been found. Keeping the plants in the dark has no effect on the inhibitor level.

The action of zinc on the growth of barley and the biosynthesis of indol compounds and gibberellin-like substances was investigated in a number of concentrations of zinc from doses stimulating growth to toxic doses. The seeds were soaked before sowing in solutions of zinc sulphate (5.10^-5 to 5.10^-1% Zn), and the plants cultivated for 7 days in water. Lower concentrations of zinc increased both plant growth and the biosynthesis of tryptophan and auxins. At the optimum concentration of 5.10^-3% Zn this increase in tryptophan amounted to 241% of the variant without zinc; in substances with an R_F corresponding to indolyacetic acid, the increase determined by the biological test, was 207% as against the variant without zinc. Higher concentrations of zinc inhibited growth, the tryptophan content was decreased to below that of the control without zinc and the auxin content also fell to below the control values. Zinc also influenced the content of gibberellin-like substances in the plants. At a concentration of 5.10^-3% Zn the increase in the growth activity in the gibberellic acid area of the chromatogram was 294% of the variant without zinc. At toxic concentrations of zinc, the content of gibberellin-like substances fell to below that of the controls. The finding that zinc acts simultaneously on the biosynthesis of auxins and gibberellins is also evidence for the common action of growth substances of various chemical types on plant growth.

The author intended here to present a classification of discontinuous, particulate membraneous structures of the plant cell, including (1) dense bodies, (2) vacuoles, (3) vesicles in plastids and mitochondria, (4) vesicles outside the protoplast and (5) vesicles surrounded by a compound (double) membrane. Three types of dense bodies (1) are distinguished: (a)Mühlethaler's spherosomes, including phragmosomes (b) lipoid bodies and (c) classical spherosomes. Type (a) is characterized in particular by being clearly bounded by the unit membrane; the matrix of these structures after ordinary treatment is grey in the positive and shows a more or less visible internal structure, the bodies are round in shape. Types (b) and (c), on the other hand, are frequently described as membrane-less structures, their matrix being very dark in the positive, frequently with a dark fringe and a lighter central part. They show no other structure and are mostly irregular in shape which is apparently an artifact. Bodies of type (a) are undoubtedly the immediate component of active living matter which cannot be said about types (b) and (c).Frey-Wyssling's interpretation of spherosomes need not be generally valid for all dense bodies, other explanations being acceptable. It is thus possible to interprot spherosomes as promitochondria and "preproplastids".
The present manuscript is a torso where only the dense bodies have been treated in greater detail A chronological review of the literature opens the manuscript, dealing mainly with the descriptive morphology of these structures. This section is published in extenso. In the other section-unfinished-the functional morphology of the dense bodies was to be presente d. From this section only the conclusions concerningMühlethaler's spherosomes are published.

1. Protein synthesis in pollen tubes ofNicotiana alata Link etOtto estimated by the incorporation of leucine-¹⁴C is linear over six hours of artificial cultivation after a short lag phase. 2-Thiouracil and other growth-stimulating antimetabolites of natural pyrimidines and purines, such as 6-azauracil, 5-nitrouracil, 8-azaguanine and 8-azaadenine, stimulate the incorporation of leucine-¹⁴C into protein. The intensity of stimulation of protein synthesis is associated with the intensity of growth stimulation by antimetabolite.
2. Synthesis of RNA is inhibited by 2-thiouracil (according to the incorporation of uracil-¹⁴C, orotic acid-¹⁴C and³²PO₄ ^3- ).
3. Chloramphenicol (25 and 250 ppm) decreases during a one-hour treatment of pollen tubes the incorporation of leucine-¹⁴C by 12 and 24%, respectively. The same inhibition is found in pollen tubes stimulated with 2-thiouracil.
4. Pollen tubes incorporated 2-thiouracil into RNA. Stimulation of growth by 2-thiouracil can be reversed with uracil or uridylic acid.
These findings are related to the present views on protein synthesis and the mechanism of the chloramphenicol effect especially with respect to the possible explanation of the stimulation of protein synthesis during a simultaneous inhibition of RNA formation.
Physiological resistance of pollen tubes toward RNA antimetabolites, the relatively low sensitivity toward chloramphenicol, the contradictory change in RNA and protein synthesis due to 2-thiouracil and, further, resistance toward actinomycin D (Tupý, Süss 1965) point to the stability of the complex of messenger RNA with ribosomes in pollen tubes.

Exogenous RNA is degraded under sterile conditions in solution to fragments greater than tetranucleotides which can be taken up by the tomato. The degradation and uptake are not equilibre at first. Equilibrium is established only after 20 hours. Fragments of high-molecular RNA are taken up more readily than those of artificially degraded RNA.
Isolated roots take up RNA fragments in the same manner as the whole tomato.

Changes in water uptake immediately following the application of high concentrations of 2-methyl-4-chlorophenoxyacetic acid (MCPA) into the root medium of whole plants ofPisum sativum andVicia faba were investigated potometrically under controlled conditions. It was found that concentrations between 10^-2 and 10^-5 m bring about a sudden, pronounced and lasting inhibition of water uptake. Its rate depends directly on MCPA concentration. At 10^-2 m, sudden inhibition of water uptake becomes apparent as early as 10 min after application. With decreasing concentrations the appearance of inhibition is retarded but the inhibition is still sudden and well-pronounced. The inhibition of water uptake observed after MCPA application to the root medium of whole plants agrees with the sudden striking reduction in transpiration intensity observed byAllerup (1964) after the application of similar concentrations of 2,4-dichlorophenoxyacetic acid. The presence of MCPA in the nutrient medium causes inhibition of water uptake even in cut plants. Its rate again depends on the concentration of the growth substance. The inhibition does not appear here as quickly and is not as sudden and pronounced. High concentrations of MCPA during application to over-ground plant organs do not bring about immediate inhibition of water uptake by the root.

1. Wasserextrakt aus zerriebenen BlattläusenBrachycaudus napeli Schrk. verursachte in Verdünnungen von 1∶9 und 1∶25 an abgeschnittenen und in die Extrakte gestellten Tomatensprossen Welkeerscheinungen, d. h. das Welken und Einrollen der Fiederblätter, das Welken der Blattstiele und der Gipfelblätter. Die Wirkung stärker verdünnter Extrakte und solcher, die durch den Bakterialfilter filtriert wurden, war schwächer.
2. Durch Versuche unter normalen und konstanten Bedingungen wurde festgestellt, dass Wasserextrakte aus derselben Blattlausart in Verdünnungen 1∶9 und 1∶25 eine wesentliche Hemmung der Wasseraufnahme und Transpiration der abgeschnittenen und in die Extrakte gestellten Tomatenpflanzensprosse hervorrufen.

The transmission of the carrot mosaic virus (CMV) by the aphidsAcyrtJiosiphon pisum HARRÍS,Cavariela aegopodii SCOP, andMyzus persicae SULZ was proved experimentally. It was observed simultaneously that CMV has a non-persistent character. CMV can be transmitted already 2 min after acquisition feeding by the aphidsMyzus persicae SDLZ andCavariella aego-podii Scop. When the time of acquisition feeding is prolonged to 4 min, CMV is transmitted also by aphidAcyrthosiphon pisum HAREÍs. The host range of the investigated virus wasalso determined and its transmission to 8 plant species, belonging to 4 families, was achieved. On the basis of studies of the vector virus relationship and of the host range, further proof was given for the different character of the Australian Carrot motley dwarf virus, theApivm virus 1 Roland and CMV. The experiments showed that preliminary starving of the aphids for 1 h increases their ability to transmit the virus by 3-3%.

Durch die Erforschung des Verlaufes der Winterruhe im Zeitabschnitt von 1954 bis 1959 konnten wir Ergebnisse erzielen, auf Grund derer man behaupten kann, dass die Aprikose unter den Bedingungen der Südslowakei im Verlauf des Monates August ins Stadium der echten Winterruhe eintritt und diese im Verlauf des Monates Dezember beendet. Unter diesen Bedingungen braucht die Aprikose 1200-1300 Stunden Temperaturen unter 6°C, um die echte Winterruhe zu überwinden. Von zwölf Aprikosensorten, die wir durch Abschneiden und Versetzen der Äste in Zimmertemperatur auf die Dauer der Winterruhe geprüft haben, trieb die Sorte "Ananas" im Vergleich mit den übrigen Sorten regelmässig um 6-10 Tage später aus. Diese Tatsache ist auch mit den praktischen Erfahrungen im Einklang, die bei der Haltung von Aprikosenbäumen unter den normalen ökologischen Bedingungen der gemässigten Zone gesammelt wurden, unter denen die angeführte Sorte im Vergleich mit den übrigen Sorten um 3-6 Tage später blüht. Nach der Ansicht des Verfassers kann man nicht von einer direkten Abhängigkeit zwischen der Dauer der echten Winterruhe und der Frostfestigkeit der Aprikose sprechen. Die Pflanze ist nach Beendigung der echten Winterruhe von Temperaturbedingungen in starkem Masse abhängig. Unter günstigen Temperaturbedingungen (ohne Temperaturschwankungen) sind die Apriklsenbäume fähig, Frösten bis zu -20°C zu widerstehen.

Mit Hilfe eines volumetrischen Mikrorespirometers (nachZurzycki) wurde die Atmungsintensität an Vegetationskegoln von Winterweizen in drei, den Übergang vom vegetativen zum generativen Zustand bezeichnenden Etappen der Organogenese bestimmt. Die Atmungsintensität bezogen auf einen Vegetationskegel, das Trockengewicht oder den Proteinstickstoff war in der 2. und 3. Etappe der Organogenese niedrig, in der 4. Etappe höher. Die festgestellten Unterschiede sind wahrscheinlich mit den anatomischen Veränderungen, die in den Vegetationskegeln im Laufe des Differenzierungsprozesses stattfinden, verbunden. Dies betrifft besonders den steigenden Anteil der sich streckenden zentralen Markzellen und die mit dem Beginn der 4. Etappe verbundene Differenzierung der Ährchenprimordien. Man kann annehmen, dass die Änderungen der Atmungsintensität mit der Induktion der Blühreife nur indirekt zusammenhängen und eher mit dem anatomischen Umbau des Apikalmeristems im Laufe der Ontogenese verbunden sind.

Antiserum against the X virus inhibitor was prepared by immunizing rabbits with the inhibitor antigen obtained in two ways: (1) ultracentrifugation of potato leaf sap in a Spinco L for 1 h at 40000 r.p.m., (2) ultracentrifugation and fractionation of the sap on a Sephadex G-50 column.
The antiserum is specific against the inhibitor protein and does not react with other proteins of the plant or with the X virus. Direct serological analysis makes it possible to determine in the potato leaf sap either the presence or the absence of the X virus inhibitor, to follow the degree of inactivation of the inhibitor due to various factors and finally to determine the relative amount of inhibitor in various cultivars and hybrids of the potato plant.
A detailed description of the method for determining the amount of the X virus inhibitor in the leaf sap from various potato cultivars and hybrids is given. The amount of sap required for analysis is very small (1-2 ml) which makes it possible to carry out analyses on individual plants. The duration of analysis is about 1 h.
The determination of the inhibitor amount in the potato leaf sap agrees with that of the inhibitory potency of the cell sap in 87.7% cases.

Investigations were made on the effect of exposing barley seeds to gamma-radiation (5-40 kR), alone and in combination with the application of zinc (soaking the seeds in solutions containing 5.10^-5-5.10^-1% Zn for 12 hours before sowing) on growth and on the content of tryptophan, indole auxins and gibberellin-like substances in seven-day plants. Radiation decreased both growth and the content of tryptophan (e.g. by about 53% at 30 kR), of indole auxins (by about 60% auxin in the zone of IAA on the chromatogram at 30 kR), and also the content of gibberellin-like substances (by about 67% gibberellin content in the zone of GA₃ on the chromatogram) of plants. The irradiation of standard samples of tryptophan, indolyl-acetic acid and gibberellic acid alone with many times greater doses (up to 1000 kR) did not lead to marked radiochemical degradation of these substances. It can be assumed that radiation damages the enzyme systems "synthesizing" natural growth substances in plants. The damaging effect of radiation on auxins is already displayed in the synthesis of tryptophan, which is inhibited.
Zinc interacts with the damaging effect of radiation on growth. Optimum concentrations of zinc (5.10^-3% Zn) counteract the effect of radiation, up to doses of about 12 kR, on the growth in height in 7-day plants so that it is equal to the controls. Normal content of tryptophan and auxin in the position of indolecetic acid on chromatograms can only be reached by the addition of zinc when the dose of radiation was not greater than about 8 kR, which is less than the influence exerted by zinc on the restitution of growth. On the other hand, the biosynthesis of gibberellin-like substances at the position of gibberellic acid on chromatograms can be restored by zinc to their original level to doses of up to 30 kR. The increased biosynthesis of auxins and gibberellins caused by zinc in irradiated plants is explained by the activation of the remaining and non-damaged enzyme systems carrying out this biosynthesis. The activation of the biosynthesis of growth substances by zinc will also contribute to the restitution effect of zinc on the growth of plants from irradiated seeds.

The influence of penicillin in concontrations of 8.3-10,000 IU/ml on algaChlorella pyrenoidosa was studied. Depending on temperature, the concentrations of 14 to 6,000 IU/ml have a stimulating influence on algal growth which may go as far as 1572% as against the control. The differences in temperature (15° to 18°C or 25° to 28° C) and in the concentration of mineral substances in the Knop solution employed do not affect the mode of action of penicillin, but affect the absolute production of algae whose maximum lies between 2,500 and 3,000 IU penicillin/ml.

The paper presents results obtained from studying the linkages of the Rf₁ gene causing the restoration of fertility of pollen in the T type of cytoplasmic sterility of maize with signal genes of the 3rd chromosome in the F₂ and B₁ hybrid generations. Crossing of the fertility-restorer lines obtained on the basis of T cytoplasm with signal lines carrying recessive genes of the 3rd linkage group was carried out during the coupling phase.
The data obtained on the linkage of genes indicates that the Rf₁ gene is located at the proximal end of the long arm of the 3rd chromosome between loci d₁ and ba₁. The linear sequence of genes and the map of their distances were determined on the basis of experimental recombined values as follows: d₁-26-Rf₁-16(?)-ba₁-42-sh₂.

Application of a 1% aqueous solution of 2-methyl-4-chlorophenoxyacetic acid at the three-leaf phase brings about abnormalities in the development of barley ovule. The most typical abnormality is the complete or partial abortion of the embryonal sac, disturbances in the orientation of the embryonal sac (associated with the development of an integumental excrescence) and concrescences of two or more ovules. The abnormal ovules remain mostly unfertilized, which can have a negative influence on the crop.

Senf- und Zuckerrübenpflanzen wurden in der Phase des ersten echten Blattes mit dem Herbizid Pyrazon (= 1-Phenyl-4-amino-5-chlorpyridazon-6) in der Form eines Suspensionspräparates Pyramin in 0,4% Konzentration besprüht. Nach 1, 4, 7 und 14 Tagen nach der Besprühung wurde die Respiration der oberirdischen Pflanzenteile mit Hilfe von Warburgs Respirometer bestimmt. Der Stoffwechselquotient (in μl des verbrauchten O₂ pro 1 mg Trockenmasse in 1 Std. ausgedrückt) war beim Weissen Senf, der gegen Pyrazon sensitiven Pflanze, im Vergleich zu den Kontrollpflanzen gesenkt. Die Senkung der Respiration war desto grösser, je grösser die Zeitspanne zwischen Besprühung und Respirationsbestimmung war. Bei der Zuckerrübe, der gegen Pyrazon resistenten Pflanze, sank die Respiration nur den ersten Tag nach der Besprühung, wogegen sie zu den weiteren untersuchten Terminen nur unbedeutend herabgesetzt war. Bei der Anwendung von schwach subletalen Aufwandmengen war der Stoffwechselquotient der Zuckerrübe 7 und 14 Tage nach der Besprühung sogar höher als bei den Kontrollpflanzen. Diese Unterschiede waren jedoch nicht signifikant.