On squash preparations of anthers from pollen fertile and sterile plants of sweet pepper (Capsicum annuum L. cv. Severka) callose envelopes of microsporocytes, stained specifically with resorcin blue, were investigated microscopically. During normal course of microsporogenesis in fertile plants the envelopes remained intact up to the stage of microspore tetrads. Then callose begins to dissolve, and that from individual microspores towards the envelope periphery. In sterile analogues of the same cultivar the callose breakdown occurred precociously, usually in the course of the second, but sometimes as early as the first meiotic division of PMCs. Having completed meiosis sporadic microsporocytes formed microspore tetrads. Most PMCs contained an undivided four-nucleate protoplast rimmed with a narrow or wider unstained zone of dissolved callose. In certain cases more condensed callose septa pointing to the furrows on the surface of the PMC protoplast were well-observable in this lytic zone, as a residuum of normal mechanism of tetradogenesis.

Acid-soluble chromosomal proteins were extracted from purified nuclei, isolated from 3 - 4 h, 12 -14 h and 24 -26 h maize embryos, as well as from nuclei isolated from meris-tematic, elongating and differentiated cells, from 2 and 3-day-oldZea mays seedlings primary roots.
Using polyacrylamide gel electrophoresis (urea-acetic acid in the cylindrical gels and slab-SDS-electrophoresis), it was established that germination and root cell differentiation induced changes in some nuclear acid-soluble chromosomal proteins, especially in histone H1.
The results of proteins belonging to the high-mobility group proteins (HMG) and some other acid-soluble proteins with unknown nature for the plants, based on the electrophoretic mobility, were discussed.

Germination was increasingly inhibited at concentrations above 5 and 20 mM and stopped altogether at 80 and 50 mM NaF in rice and jute respectively, whereas the inhibition of seedling growth began at much lower concentrations. Of the enzymes, RNase activity was increased by fluoride, while α-amylase, protease, phytase and ATPase activities exhibited distinct inhibition from the control.

A simple model was developed to characterize the daily water potential dynamics (Ψ_x of sun and shade leaves of three forest tree species (Quercus cerris, Acer campestre andCarpinus betulus) under anticyclonic weather types. Input data used for this-model were the vapour pressure deficit (d) and the soil moisture content (w.). The model is usable for the calculation of the actual Ψ_x-values with a probable error 0.18 -0.28 MPa and limits the maximum and minimum Ψ_x-values which may occur with the particular tree species. The model makes it possible to establish for each species the regime, determined byd andw, at which the water potential of the leaves reacts most sensitively to the changes of the environmental parameters.

GA₃, cyclic AMP as well as 3'-AMP and 5'-AMP induced the formation of floral buds inImpatiens balsamina under strictly non-inductive photoperiods. While photoperiods and treatments with GA₃ or AMPs did not much affect acid phosphatase activity, AMPs increased the activity of alkaline phosphatase both in the stem and the leaves under both photoperiods. The phosphatase activity of the water- and GA₃-treated plants under inductive photoperiods was higher than that of the plants of the respective treatments under non-inductive photoperiods. GA₃ as well as all the three AMPs induced both in the stem and the leaves the formation of new isoenzymes of both these enzymes under both photoperiods.

The effect of Ethephon preparations upon stomatal openings in detached epidermal strips of tobacco leaves floated on 0.1 M KC1 was measured microscopically after different times of exposure. Addition of 0.01 v/v % or 0.1 v/v % Camposan, Ethrel, or E-BOH resulted in the opening or closing of the stomata depending upon the time of exposure and the concentration of Ethephon. It is evident from the results obtained in these studies that an increase in stomatal opening was induced by the acidity of the preparations and the released ethylene too. Prolonged times of action resulted in decreased stomatal openings or in stomata being closed, respectively. High concentrations of Ethephon also resulted in major damage being caused to guard cells after having been permitted to act upon them for an extended period of time.

Using the statistical analysis of leaf wator potential (ψ daily course of forest tree species (Quercus cerris, Acer campestre andCarpinus betulus) we have determined the optimal times of ψ measurement (i.e. at 08.00, 10.00 and 16.00) making possible the calculation of the ψ daily course resp. ψ-value at any time. The accuracy of the calculation does not deviate much from the errors of ψ measurement. The probable error of a single ψ-measurement was forQ. cerris 0.06 MPa and for bothA. campestre andC. betulus it was 0.05 MPa.

Detailed karyological analyses have been made of the five biotypes ofPennisetum pedicellatum Trin. These biotypes not only differ in some morphological traits but also in their chromosomal characteristics. Biotype-B with 2n = 48 chromosomes shows constancy, while in the other four 2n = 36 and 64 are found to be "floating". Other numerical variations include 2n = 42 and 18 chromosomes. Minute karyological differences are not only noted amongst the biotypes, but also there are variations in the complements within a biotype. Such variations are presumed to be buffered through the apomictic mode of reproduction. From the morphological and cytological studies, the possibility of separation of biotype-B from the complex in future has been envisaged.

The morphoregulatory effect of FeEDTA chelating complex was verified in an androgenically more productive cultivar of tobacco White Burley and inDatura innoxia Mill. The presence of EDTA in Nitsch (1969) medium (N medium) was sufficient for the conversion of isolated embryoids and embryoids in anthers into complete plants. The androgenic development was most rapid in N medium with FeEDTA. In N medium with EDTA, the cultures developed more slowly and remained vital for a long time. In the medium without EDTA, new embryoids developed continuously. The embryoids arose and developed also in closed anthers. All embryoids which arose in anthers cultured on N medium were capable of forming complete plants. The threshold morphoregulatory concentration of FeEDTA was 40 μM FeEDTA per 1 litre of medium for embryoids in anthers and 30 μM FeEDTA per 1 litre for isolated embryoids. The dark brown colour of the anthers of tobacco andD. innoxia was due to the presence of iron (FeEDTA) in the culture medium. The morphoregulatory effect of EDTA in N medium is explained by the formation of a complex with iron present in the form of pollution of chemicals and agar. This amount of iron in complex with EDTA is sufficient for the conversion of embryoids into plants, but it is insufficient for the browning of anthers.

Developmental changes in poly(A)-bearing RNA in male tobacco gametophyte were examined by sedimentation analysis and by hybridization with³H-poly(U). The results indicate that the transition of microspore undergoing postmeiotic division to mature pollen is accompanied by characteristic changes in RNA and poly(A) content and the size of poly(A)⁺RNA.
The volume of pollen grain increases about 2times, total RNA per grain from 34 to 230 pg and poly(A) from 22 to 450 fg, which together with the estimated increase in the number average size of poly(A)⁺RNA from 700 to 2 100 nucleotides suggests an approx. rise of RNA containing poly(A) from 0.3 to 2.7% of total RNA. Size distribution of the populations of polyadenylated RNAs shows progressive formation of species with a higher molecular mass and differentiation of the pollen-characteristic pattern with main sedimentation maxima close to 12S, 19S and 26S. This pattern remains almost unchanged during 8 h of pollen tube growth and is also found in polysomes formed at the beginning of germination. The amount of poly(A) decreases gradually after the onset of soaking at a rate of slightly more than 1 % per h within 24 h of pollen cultivation.
As a whole, the results demonstrate that in the course of pollen maturation a specific population of polyadenylated mRNAs is formed which persists as stored mRNA in quiescent pollen and is used as template during-pollen tube formation.

ADPglucose pyrophosphorylase level and mechanisms regulating its activity were studied in cucumber plants infected with the cucumber mosaic virus at the stage of chronic infection. Studies carried out with partially purified preparations of the enzyme have shown that there was no substantial difference in the regulatory influence of the ratio 3-PGA/P₁, or in the number of binding sites of the effectors on the enzyme, but that the virus infection reduced the level of the enzyme in the tissues to 74% of the control and the 3-PGA/P₁ ratio to one half which resulted in a further decrease in ADPglucose pyrophosphorylase activity. In crude homogenate prepared from diseased plants, activity of the enzyme was reduced to 42% of the healthy control.
The level of UDPglucose pyrophosphorylase was three times higher in cucumber leaf tissues than the level of ADPglucose pyrophosphorylase which was inhibited by both 3-PGA and P₁. Inhibitory effects of both these effectors were cumulated. The enzyme isolated from healthy plants was inhibited by inorganic phosphate more strongly than the enzyme isolated from diseased plants. UDPglucose pyrophosphorylase activity was increased in crude homogenate of diseased plants to 127% of the healthy control when the level of the enzyme was the same in the tissues of both healthy and diseased plants which was presumably connected with the enhanced rate of sucrose catabolism.

Individual specimen trees (or replicated clonal material) of 33 species and hybrids in theCupressaceae andTaxodiaceae were injected with gibberellic acid (GA₃) solutions, to test the general applicability of cone induction techniques developed forThuja plicata. Reproductive material for taxonomic study was subsequently available in 82% of treated taxa, compared with 39% of untreated. The latter generally produced small numbers of male or female cones, but both were formed in abundance in half the hormone-treated taxa. Eleven species and hybrids are reported for the first time as responding to GA₃.

Salinity had a varying effect on stomatal frequency, size and pore in barley (Hordeum vulgare L.). This variation in stomatal frequency, size and pore under salinity offers a scope of selecting cultivars with lesser increase in stomatal number to avoid excessive loss of water due to transpiration without effecting photosynthetic efficiency.

Nitrate reductase (NR) activity estimated byin vivo andin vitro methods in 17 days old pea seedlings is the highest in young fully expanded leaves (4th leaf from the stem base). NO₃-N content is parallel to the NR activity being also highest in the 4th leaf. On the other hand the activity of glutamine synthetase (GS) is the highest in the youngest leaves which had not yet reached their maximum size (5th leaf). Equilibrium between NO₃-N content and activity of enzymes involved in assimilation of nitrogen containing compounds in individual leaves is discussed in relation to their insertion.

α-N-Benzoyl-DL-arginine-p-nitroanilide (BAPA) hydrolytic enzyme was partially purified from cotyledons of mature dry seeds ofVigna unguiculata (L.) Walp, cv. Seridó. Extracts of a finely ground meal ofVigna seeds were obtained with 0.02 M phosphate buffer (KH₂PO₄/ /Na₂HPO₄) pH 7.6. A protein fraction was obtained from the extracts by ammonium sulfate precipitation (25 to 50% saturation). This protein fraction was subjected to chromatography on DEAE-cellulose. A separated fraction of the cellulose column presented one main component and two minor bands as seen on polyacrylamide gels. The main component of the separated fraction gave a positive reaction with BAPA and acetyl-DL-phenylalanine-β-naphthyl ester (APNE). This fraction shows a molecular mass of 60 000 by gel filtration on Sephadex G-100, pH 7.6.
The BAPA-ase activity was stable at pH values of 7.0 to 9.0 and no decrease in activity was observed by heating at 40 °C up to 40 min. The activity was not affected by PMSF, EDTA, cysteine,p- CMB, and IAC but was inhibited by NEM and strongly inhibited by TLCK.
Leucine-p-nitroanilide (LPA) hydrolytic enzyme properties were also determined. This activity was inhibited by PMSF,p- CMB, and NEM.

Coumarin-caused stimulation of rooting of cuttings ofImpatiens balsamina L. is associated with an increase in the endogenous contents of carbohydrates, total phenols and proteins. Peroxidase, IAA oxidase and polyphenol oxidase activities also increased in coumarin treated cuttings at the time of cell division preceding primordia formation (6-12 h after treatment). Coumarin effect on rooting as well as on related biochemical changes resembles the effect of auxins in some ways.

An investigation has been carried out to find out in what compounds carbon is radially transported from stele to the cortex and to study sucrose metabolism in the root. These tissues were fed with¹⁴C-sucrose either directly or through the mesocotyle. In the latter case, the bulk of radioactivity, both in the stele and cortex, was concentrated in sucrose rather than in mono saccharides. This corresponds to the radial transport of carbon from stele to cortex predominantly in the form of sucrose. In the case of a direct exposure of stele and cortex,¹⁴C-sucrose was utilized for respiration, amino acid biosynthesis, and accumulation of carbon in the form of glucose. The hydrolysis of sucrose to the monosaccharides and subsequent utilization of the latter in respiration was more intensive in the stele. In the cortex, the sucrose carbon was more actively used for amino acid synthesis, owing to a high concentration of nitrate reductase, glutamate dehydrogenase and glutamine synthetase. It was concluded that the cortex is the main issue zone providing nitrogen assimilation in the root.