Embryos ofAgrostemma githago seeds blocked by higher temperature are suitable objects for the study of the regulation of gen expression independent of transeriptional processes. Germination of afterripened seeds can be prevented by imbibing at 30°C, whereas at 20°C germination will be completed after 30 h of soaking (BORRISS 1956). In temperature-blocked embryos RNA is synthesized with undiminished intensity, whereas DNA and protein syntheses are remarkably reduced. Equal amounts of poly(A)-RNA (probably mRNA), enriched by affinity chromatography on oligo(dT)-ceIlulose columns, are detected in blocked and activated embryos.
We suggest that in blocked embryos not synthesis itself, but the availability of mRNA to polysomal fraction is reduced. Benzylaminopurine is able to break secondary dormancy ofAgrostemma githago seeds. In benzylaminopurine-treated seeds there is only a slight increase of the incorporation of¹⁴C-L-leu-cine in protein.

Three-leaf pea (Pisum sativum L. cv. 'Alaska') seedlings were oriented horizontally and³²P was applied to leaf-2 for 6 h period, at the end of which the distribution of isotopes in the seedlings was determined. It was found that (i) isotope accumulation in the apices of the vertical and horizontal seedlings remained almost the same; (ii) on decapitation almost all the isotopes in the apex diverted to the roots in the vertical seedlings; (iii) among the horizontal seedlings³²P was retained in the hanging treated leaf and the rest moved to the roots via shoots; (iv) the dry weight of the hanging treated leaf was slightly greater than the above-axis one; (v) the position of buds on the axis had no effect on the initial³²P accumulation in them, however, a trend of greater isotope accumulation was noted in the above-axis basal buds; (vi) geo.stimulation had no effect on the total dry weight of the seedlings; and (vii) in geo-stimulated seedlings decrease in the dry weights of shoots and its concomittant increase in roots was primarily the result of the movement of substances.

The inhibitor-A, isolated from the leaves of a saline soil tolerant plantSuaeda fructicosaFoRsk., is phenolic in nature, inhibits the IAA-induced growth, and is resistant towards higher temperature.

Threadlike particles from mosaic freesia aggregate during and shortly after the purification which is followed by full degradation into insoluble amorphous precipitate. This irreversible process is caused predominantly by host plant proteases. Such degradation can be completely inhibited if the virus complex is purified and stored in the presence of 0.1 mM phenyl-methylsulfonylfluoride. A modified purification method which gives a higher yield and the virua preparation of greater purity is described.

Some diagnostic methods devised for the demonstration of the presence of plum pox virus in plum (Prunus domestica L.) and apricot (Armeniaca vulgarisLam.) leaves were examined. The method of radial diffusion in agar can be recommended as the simplest and the least time consuming method which can be used during the entire vegetation period. In order to obtain antisera, some preparation methods of PPV antigen were verified. The best preparation method was a modification of Van Oosten's method in which HEPES buffer pH 6.7 was used for the homogenization-of leaves from infectedNicotiana clevelandiiGray plants and for the solution of sediments after ultracentrifugation. In this way, antigens with titre up to 1: 2048 and during the immunization of rabbit antisera with titre 1: 512 to 1: 1024 were obtained. After the saturation of antisera according to Uyemoto, the titre of the antisera was 1: 64 to 1: 256. Antisera were used for agar preparation in transparent plastic boxes. 0.2 to 1 g portions of leaf material were homogenized with 0.05 M Tris-HCl buffer pH 7.2, 3% pyrrolidine and 1 % polyvinylpyrrolidone in the ratio of 1: 3 for the determination of PPV in plum and apricot leaves.

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.

A protease activity was detected in rice (Oryza sativa L. cv. Ratna) leaves that hydrolysed hemoglobin more efficiently than bovine serum albumin. The activity was high when the enzyme was extracted and assayed with tris-maleate buffer [tris (hydroxymethyl) methyl amino-maleate] pH 7.0 rather than with water or with citrate-phosphate buffer pH 7.0. The enzyme had a strong dependence on sulfhydryl groups for its activity without which it was inaotive. The pH optimum was 7.0 and the temperature optimum was 40 °C. Protease activity expressed per unit leaf fresh weight (absolute activity) increased only little during senescence of detached rice leaves while the same activity expressed per unit soluble protein content (specific activity) increased by a greater factor (about 5 times) than absolute activity. Total and soluble protein content decreased during the senescence of detached leaves. Benzimidazole (10-3M) and kinetin (0.5xl0-5M) treatment arrested the increase of the protease activity and the deorease in the protein content during detached leaf senescence. It was indicative that protease protein was more stable than the bulk of other proteins in senescing leaves.

¹⁴CO₂ assimilation, RuBP earboxylase and PEP carboxylase activities show cyclic changes during the development of barley leaves. Cyclic changes, but in phase opposition with respect to carboxylating enzymes, are shown by RuBP oxygenase, phosphoglycolate phosphatase, glycolate oxidase and nitrate reductase activities. The oxygenase function of RuBP carboxylase appears to be the primary source of glycolate in young leaves, whereas in old ones glycolate could be supplied from some source in addition to RuBP oxygenase activity.

Applications of various amounts of GA₃ onto the shoot apex of biennial rosette-plantHyoscyamus niger L., exposed to long days and non vernalized, caused internodes formation and stem elongation. The stem length was proportional to the amount of GA₃ applied. Number and length of developed internodes and the whole length of the shoot were maximal in plants treated with a greater amount of GA₃. In the end, stem elongation stopped and plants formed perchedrosettes without flowering. Hence, gibberellic acid participates in mechanisms of flowering only by indirect effect on stem elongation and not directly on flower formation itself.

During the period of the highest multiplication of TMV in tobacco tissues (on the 6th to l0th daya after inoeulation) the activities of NADP-glyceraldehyde-3-phosphate dehydrogenase, fructose diphosphatase, and phosphoglucoisomerase increase,i.e. the 3-phospho-glycerate is broken down more intensely, being the primer of photosynthesis via glycolysis. Products of this metabolic pathway, which are not employed directly for virus synthesis, are stored during this period as free saccharides and starch. The breaking-down rate of these substances increases during this period as well, as shown by increased activities of amylophosphorylase, phosphoglucomutase and saccharase. The increased aetivity of glucose-6-phosphate dehydrogenase is proportional to the rate of TMV multiplication; its high value (more than twice as with the control) insinuates that the virus reproduction deereases contents of some intermediates of the Calvin cycle (especiaily NADPH and ribulose-l,5-diphosphate) which act as inhibitors of the photosynthetic regulative system.

Stomata on the cotyledons of Morphactin EMD 7301 and EMD 7311 treated seedlings may be anisocytic, anomocytic, paracytic, diacytio, transitional forms and haplocytic. In spite of this diversity, the most frequent type is anisocytic on both surfaces. The stomatal ontogeny may bo perigenous, mesogenous and mesoperigenous. Morphactin EMD 7301 and EMD 7311 increase the size of cotyledons in all concentrations accompanied by an increase in the number of stomata on the adaxial surface in 100, 150, 250 ppm of EMD 7301. The effect of morphactin is promotive to the size of stomata in all concentrations, but it retards the stomatal density and number of epidermal cells. This may be due to an increase in the size of the epidermal cells. The substrates, however, have no effect on the morphology and ontogeny of the stomata; probably they are inherent chracters.

Studies performed on winter rape plants(Brassica nnpus var.oleifera, cv. 'Gór-czański') revealed that cold treatment affected the cell membranes and led to the temporary increase in electrolytic leakage from a tissue. This was followed by the marked decrease of the electrolytic leakage in the course of hardening. Changes in membrane properties were accompanied by the promotion of soluble protein accumulation. Inhibition of protein accumulation by the cycloheximide treatment brought about wilting of plants under cold conditions. Possible role of soluble protein in protection of cells against secondary water stress caused by the coldinduced changes in membrane properties is suggested. Cold-induced changes in the electrophoretic pattern of soluble protein are described and discussed.

The rise in soil salinity level tended to decrease shoot dry weight, and, grain yield per plant and, to some extent, weight of I grain. This effect was usually more pronounced in the presence of CCC. On the other hand, the shoot dry weight was increased by CCC in salinity absence but the reverse at 0.8 % salinization degree. The grain yield per plant was raised by CCC in the presence or absence of salinity, particularly in the latter case. The dry matter accumulation in the shoot system (at earing stage) rather than grain yield tended to be much more affected, whether regarding the negative response to salinity or the positive one to CCC.

This paper reports experiments performed to investigate the influence of various concentrations of streptomycin sulphate on a few parameters of importance in the metabolism of rice (Oryza sativa L.) seedlings. It was shown that respiration rate was accelerated by streptomycin. The specific activities of catalase and peroxidase decreased whereas IAA oxidase increased with increasing streptomycin concentrations. Increased activities of all these enzymes were apparent on a dry weight basis suggesting increased succulence caused by streptomycin treatment. There was a considerable rise in the water soluble protein content following streptomycin application. It may be suggested that growth inhibition by streptomycin results from reduction in the auxin level owing to enhanced auxin destruction.

The fruit pitting symptoms on cherries, plums and prunes were investigated from the standpoint of their etiology. Tomato bushy stunt virus (TBSV) was isolated from pitted fruits of these plants and from their leaves and identified by means of biological and serological methods. Both isolates reacted with antisera againstPetunia and artichoke strain of this virus. In addition, the etiology of pseudopox disease of plum and that of cherry detrimental canker is discussed.

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.

Starch was determined by means of IKI reaction in shoot apices ofChenopodium rubrum plants induced to flowering by two short days and in non-induced plants. Small starch grains were already observed in the meristematic cells at an age of four days after sowing. Larger grains were found in the subapical region of the apex. Heterogeneity increases during further growth of the plants in induced, as well as in non-induced vegetative plants. Starch disappears from the cells potentially giving rise to axillary buds, while the number and size of starch grains increase in cells from which leaf primordia will be formed. This metabolic specifity of leaf and bud primordia is preserved during morphological differentiation and applies to vegetative, as well as to prefloral apices of photoperiodically induced plants. The amount of starch in the different regions of the apex is linked rather with organogenesis than with the quantitative growth in the apex.

During the first 24 h of germination of wheat seeds, starch is hydrolysed by free β-amylase. In the next 24 h, some amount of inactive form of β-amylase is converted into active form and this together with α-amylase synthesizedde novo brings about the hydrolysis of starch. The amount of α-amylase is greater in seeds with embryo intact than with embryo excised after 24 h hydration. However, at later stages of seed germination α-amylase becomes predominant and the activity of β-amylase steadily diminishes.

0.25 % ammonium oxalate in a mixture of ethyl alcohol, chloroform, formaldehyde, acetic acid and hydrochloric acid works as a very fast and efficient macerating fixative for the root meristems ofAllium cepa, Allium sativum, Ornithogalum thyrsoides, Pisum sativum andVicia faba. Slicing the tip region of excised meristems hastens spindle poison pretreatment, fixation and staining. Owing to the dissolution of the middle lamella and eliminating a physical barrier to permeability an extremely rapid fixation and staining schedule involving several stains has thus been developed.

The content of endogenous auxins was examined in apical buds ofChenopodium rubrum plants induced by a photoperiodic cycle of 16h darkness and 8h light followed by a dark period of various duration so as to correspond with either maximal or minimal flowering response in the endogenous rhythm in capacity to flower initiated by the photoperiodic treatment. Apical buds of potentially generative plants contained less auxins than apical buds of plants which remained in the vegetative state. Apical buds from plants treated with kinetin (1. 10^-3 M) and therefore remaining in the vegetative state showed an auxin level comparable to that of untreated plants exhibiting minimal flowering response irrespective of the duration of the second dark period. Plants cultivated on a sucrose solution (0.6 M) during the second dark period became generative even at the normal minimum of flowering. The auxin content of the apical buds was low, similarly as in untreated plants induced for a period leading to maximal flowering response. On the other hand, apical buds from plants grown on sucrose solution during a dark period leading to the manifestation of maximal flowering response showed a relatively high auxin content comparable to that found in untreated plants which had obtained a more extended induction by three photoperiodic cycles. The results are discussed with respect to the possible role of endogenous auxins in the regulation of the changes in growth correlations occurring in the shoot apex during photoperiodic induction and in the expression of the competence to flower.