Studies on seeds of 40 arid zone plant species have revealed that seeds exhibit differential specificity in water inhibition percentage. Most of these seeds show very poor imbibition capacity and that takes place within the first three hours, after which this uptake becomes very slow. This low hydrature and quick water uptake wherever it takes place is correlated with the erratic rainfall in the Indian arid zone. Most of the leguminous seeds are impermeable to water because of hard seed coatedness. However, those seeds which imbibed showed a very high percentage of water uptake.

A simple bioassay of gibberellic acid (GA₃) based on the GA₃-induced reduction of anthocyanin contents in young seedlings of tomato is described and compared with the amaranthin reduction test. It was found that GA₃-induced reduction of anthocyanin in tomato seedlings was linear from 10^-5 to 10 mg 1^-1 GA₃ whereas the reduction of amaranthin inAn aranthus caudatus seedlings was linear from 10^-3 to 10 mg 1^-1 GA₃. From these results, it is concluded that the anthocyanin reduction test for GA₃ is more sensitive at lower concentrations of GA₃ than the amaranthin reduction test.

The changes in the levels of growth regulating substances using the wheat coleoptile straight growth test were determined in the leaves of vernalized (flowering) and non-vernalized (non-flowering) plants of sugar-beet, cv. Poly-AG-Poland at two stages; the end of vernalization treatment (210 days from planting) and full-flowering stage. IAA was detected only in the extracts of the leaves of non-vernalized plants after210 days from planting. No inhibitory activity was detected, except in the case of the concentrated extract of the leaves of non-vernalized plants. This growth promoting zone was found at R_f 0.5-0.8 in the leaves of flowering plants after cold treatment and at flowering time. This zone of growth promoting action was suggested to have a major role in the flowering of sugar-beet.

A description is presented of a simplified procedure for the serological diagnosis of plant viruses which utilizes the high sensitivity of the latex test. Small pieces of the plant examined are soaked in a drop of water, buffer, or directly in the sensibilized antiserum. Following the reaction with the antiserum the virus is evidenced by visual evaluation of the presence of agglutination. The procedure is applicable for routine serological diagnosis; it demonstrates even small virus concentrations and is as reliable as the normal procedure of the latex test. Using this simplified procedure the following viruses were demonstrated in various host plants: X-, Y-, S-, and M-virus of potato, the carnation mottle virus, and the tomato bushy stunt virus.

Callus culture was derived from haploid barley embryos after crossing withHordeum bulbosum. The callus tissue is cytologically heterogeneous, containing haploid, diploid and polyploid cells. Aneuploidy and karyokinetic irregularities were also observed. Some problems of chromosomal instabilities in plant tissue cultures are discussed.

Seeds of mung bean (Phaseolus aureus Roxb.) cv. Pusa Baisakhi were surface sterilized and sown both in Petri dishes and sand culture containing aqueous solutions of four different saltsviz. NaCl, KC1, Na₂SO₄ and K₂SO₄ each at 5 and 10 m ώ^-1 cm^-1. Malate dehydrogenase (MDH) isoenzymes were studied in different plant parts of mung bean at suitable intervals during germination under four different salts. In cotyledons, 96 h after sowing only one isoenzyme was left in control as compared to three under salt treatment. In the embryo axis, 96 h after sowing, sulphate salts resulted in the disappearance of isoenzymes with R₁ 0.43 and 0.62, whereas isoenzyme with R₁ 0.62 was missing only at a higher concentration of chloride salts. Chloride salts also resulted in the disappearance of band with R₁ 0.15, both in the embryo axis and leaves. However, in the roots the isoenzymic pattern remains the same with all the salt treatments.

The growth changes of cotyledons, leaves, hypocotyls and roots due to photoperiodic induction in short day plantChenopodium rubrum were investigated in relation to flowering. Six-day old plants were induced by photoperiods with a different number of dark hours. We found that the degree of inhibition which occurred during induction in the growth of leaves, cotyledons and roots similarly as the stimulation of hypocotyl is proportional to the length of dark period. The photoperiods with 12, 16 and 20 dark hours bring about marked inhibition of growth and at the same time induce flowering in terminal and axillary meristems. The inhibitory effect of critical period for flowering,i.e. 8 dark hours, is not apparent in all criteria used and even the flower differentiation is retarded. The photoperiods of 4 and 6 dark hours did not affect growth and were ineffective in inducing flowering even if their number has been increased. The experiments with inductive photoperiod interrupted by light break have clearly shown that growth pattern characteristic for induced plants can be evoked in purely vegetative ones. Such statement did not exclude the possible importance of growth inhibition as a modifying factor of flower differentiation. We demonstrated that the early events of flower bud differentiation are accompanied by stimulation of leaf growth. The evaluation of growth and development of axillary buds at different nodes of insertion enabled us to quantify the photoperiodic effect and to detect the effects due to differences in dark period length not exceeding 2 hours.

The plants of two herbaceous species, namelyPulmonaria officinalis L. andSymphytum tuberosum L., growing in two deciduous forests in SW. Slovakia, were used for analysis of anatomicphysiological gradients along the insertion level of individual leaves. The gradients were established for six leaf characteristics. Specific leaf area and development of leaf area increased, while leaf tissue hydration, degrees of succulence and consistency decreased with height of insertion of leaves upon the stems. The gradients indicate the decreasing of the leaf water content and dry mass with height of the leaf on the stem. Stomatal resistance was usually the lowest in basal leaves and the highest in apical leaves of the plant. The anatomic-physiological heterogeneity of leaves of a plant is large and cannot be neglected in any anatomical or physiological investigations.

Among different populations of monogerm sugarbeet fruits, those characterized by the lowest percentages of germination exhibited the lowest percentages of mechanical deoperculation (removal of the fruit cap under the sole imbitition pressure). X-ray radiography of dry fruits allowed a classification based on the space occupied by seeds inside the fruit cavity and further established a correlation between the fruit type (filled, semi-filled, empty), passive deoperculation and germination. The degree of correlation depended on the amount of bedding water which further conditioned the fruit surrounding water film.

During high altitude acclimatization both the number of stomata and their pore width decreased. The number of open stomata per unit leaf area in the morning and evening hours was higher as compared to that in plants grown at a lower altitude. Thickness of leaves also decreased at high altitudes but the effect on the size of epidermal, mesophyll and spongy parenchymatous cells varied from species to species. Adaptational significance of these changes are discussed.

Using the enzyme-linked immunosorbent assay (ELISA) beet yellows virus (BYV) could be detected reliably in the leaves of sugar beet andTetragonia expansa Pall. and in the roots of sugar beet. Specifio γ-globulin of BYV antiserum was coupled to horse radish peroxidase by periodate oxidation. Optimum dilutions of antigen (extract from infected leaves) were1: 50 to 1: 200 for BYV detection in sugar beet andT. expansa leaves and1: 2 to 1: 5 for detection in sugar beet roots. Extracts from beet roots are not to be purified by ultracentrifugation, however, by the described method virus can be demonstrated only in 80-90% of naturally infected sugar beet roots. The method is specific, no increase of extinction values was found in healthy or beet western yellows virus infected plants. Presence of virus can be demonstrated by visual as well as photometric evaluation. Results confirmed the suitability of peroxidase application for detection of plant viruses by ELISA.

Cell division contributing to longitudinal growth of the shoot apex was investigated inChenopodium rubrum in segments marked by the axils of leaf primordia. Plants treated with two short days (16h of darkness and 8h of light) were compared with two non-induced controls (cultivated in continuous light or treated by alternations of 8 h of darkness and 4 h of light for two days). During the short-day treatments the rate of cell division contributing to the longitudinal growth decreases in all segments of the shoot apex irrespective of whether the darkness was given in inductive or non-inductive photoperiods. The rate of cell division contributing to longitudinal growth increases in the upper internodes of the shoot apex after the termination of the photoperiodic treatment and transfer of the plants to continuous light. However, cell division remains inhibited in the lowest segment of the shoot apex. This inhibition in the differentiating parts of the shoot apical meristem is a direct consequence of photoperiodic induction. It is supposed that this inhibition is related to evocation similarly as the well-known phenomenon of stimulation of cell division in the apical dome.

A time course study of changes in the pattern of peroxidase isoenzymes shows that two new isoenzymesa andb appeared in hypocotyl cuttings cultured either in indolyl-3 acetic acid (IAA) + sucrose or in water but not in maleic hydrazide (MH). Roots were also initiated in the former two cases but not in the last case. That these isoenzymes may be associated with root initiation is also evident from the fact that these appeared when hypocotyl cuttings were transferred from MH to IAA + sucrose. The time of appearance of these isoenzymes in different cultures also synchronized with the time of microscopic root initiation. While the isoenzymea disappeared,b persisted in cuttings transferred from IAA + sucrose to MH. The number of roots produced on cuttings transferred to MH was very low, though their development was normal. It is suggested that isoenzymesa andb may be associated with root initiation andc andd with root development.

Protoplasts isolated from cell suspension cultures of potato were cultured as far as the level of regeneration of substrains. The influence of various factors (age of the cell culture, mode of precultivation, composition of the enzymatic mixture, incubation period) on the efficiency of isolation as well as the viability of protoplasts, has been studied. Various cultivation procedures have been screened and the effect of especially the hormonal composition of the medium on different phases of the regeneration of cell colonies (regeneration of the cell wall, growth and elongation, cell division) evaluated.

The reaction: Chlorophyll + Enzyme → Chlorophyllide + Phytol follows a first order kinetics with regard to the quantity of enzyme, when it is saturated by substrate. K_m and V_m were determined from the average reaction rates for the substrates: Chlorophylla andb, pheophytina andb, methylchlorophyllidea and methylpheophorbide a: The lowest K_m corresponded to chlorophylla and the highest V_m to methylpheophorbidea. For a substrate of chlorophyll (a + b), K_m and V_m were determined also using the initial reaction rates. "Enzyme efficiency" was calculated using both methods of determination. The reaction products partially inhibit the hydrolytic process.

Wheat seedlings were cultivated in nutrient solutions containing 10^-3 M CCC, 10^-3 M CEPA or 5 × 10^-4 M CCO and CEPA, respectively. CCC applied alone or mixed with CEPA increased chlorophyll content per unit fresh matter but had no influence on the epinastio response of the primary leaf. In contrast, CEPA had no influence on chlorophyll content but greatly increased the epinastic response. The different response to the application of these substances with regard to chlorophyll content ha been claimed in a previous paper to be due to their different effect on cell extension and cell division. The epinastic response of the primary leaf suggests that ethylene participates in the reaction chain of CEPA effect on plant tissues.

The investigation of the substrate specificity of the anionic peroxidase isoenzymes, isolated from the zone of differentiation of the primary roots ofZea mays, for some representatives of phenolic compounds and aromatic amines, as hydrogen donors, is reported. The investigation was carried out electrophoretically with peroxidase isoenzymes partially purified by a combination of gel filtration by Sephadex G-25 and Sephadex G-100. A difference in the substrate specificity of the individual isoenzymes is observed. It was established that the anionic peroxidase isoenzymes showed a similarity in total number and relative activity on staining with bivalent phenols and difference on staining with trivalent phenols, as hydrogen donors. A greater number of isoenzymes was stained with benzidine ando-dianisidine and a lesser number witho- andp-phenylendiamine. The substrate specificity of the peroxidase isoenzymes was compared for guaiacol and benzidine. The substrate specificity of peroxidase soenzymes was discussed as regards their diverse role in the plant metabolism.

Conductance of abaxial epidermis was measured in leaves ofAcer campeatre, Carpinus betulus, Quercus cerris andQ. petraea sample trees growing in an oak-hornbeam forest. Measurements were performed on several summer days during morning and midday hours. Stomata tended to oscillations only inQ. cerris. The occurrence of stomatal oscillations was controlled by environmental conditions,e.g. weather.

Radioactive phosphate was applied to the roots of intact alfalfa plants (Medicago sativa L.) on the 49th day after inoculation withCorynebacterium insidiosum (Me Culloch) Jensen and the³²P contents in different fractions of phosphoric compounds were determined. In inoculated plants, susceptible to bacterial wilt, the inorganio phosphate contents (³²Pinorg) was increased markedly and the³²P bound in organic compounds soluble in acids (³²Porg) decreased as compared with control. In roots of the same plants the³²P contents in phospholipid fraction and DNA were decreased. In tolerant inoculated plants the³²Pinorg increase and³²Porg decrease as compared with those changes in susceptible plants were less expressive. No expressive changes in determined³²P fractions have been proved in resistant plants without any visible disease symptoms.

Net photosynthetic (P_N) and dark respiration (R_D) rate, stomatal (rs') and internal (ri') resistances to carbon dioxide were measured by gas exchange methods on leaves of different ages, expressed in leaf plastochron index units (LPI) for a fast growing poplar cultivar Unal 2. Although the optimal leaf age differs slightly for the different gas exchange parameters, leaf ontogeny is reflected in the same way in these different parameters. MaximalP_N and minimalrs' and ri' values were found at LPI between 6 and 10. Chlorophyll concentrations were lowest at LPI lower than 10 although an increase in two steps was found, when leaf age increases up to maturity.

Levels of ferricyanide reduction, cyclic and non-cyclic photophosphorylation were measured in chloroplasts of two cultivars of pea and a comparison of their P/2e⁺ ratios were made. No differences were observed in cyclic photophosphorylation or ferricyanide reduction but non-cyclic photophosphorylation was lower in chloroplasts from the dwarf than the normal cultivar. Thus the P/2e⁺ ratio of the dwarf was lower than the normal. Dwarf seedlings treated with gibberellic acid (GA₃) had similar rates of cyclic photophosphorylation as the untreated dwarf but non-cyclic photophosphorylation was lower as was ferricyanide reduction. This resulted in P/2e⁺ ratios that were higher in chloroplasts from the GA₃ treated dwarf seedlings than the untreated, and were the same as the untreated normal. Addition of GA₃ directly to the chloroplasts did not alter the activity in any way. Hence gibberellins do not directly affect changes in chloroplastic activity but may conceivably be involved in a feed-back control system.

Extirped barley embryos were pre-cultivated in aerated liquid nutrient solution for 24 h and then cultivated for 6 h in nutrient solution containing either³H-DNA fromBacillus subtilis or³H-thymidine. After this treatment the embryos were thoroughly washed and transferred to the fresh nutrient medium. Samples were fixed at different intervals up to 24 h. Feulgen squashes were made and covered with autoradiographic emulsion. Microautodiagrams of different parts of the embryos (root meristem, shoot apex plus meristem of the third leaf, second leaf meristem, coleoptile, scutelum) were observed. Labelling of the nuclei after the application of both³H-DNA and³H-thymidine was found in the proliferating parts of the embryos but no label was found in the scutelum. The labelling index values were almost similar in different embryo organs after the treatment with³H-DNA and³H-thymidine. Labelling index and the fraction of labelled mitoses at different intervals after the application of the labelled substances were almost similar after treatment with³H-DNA and³H-thymidine, except some variations due to irrelevant differences in the kinetics of the mitotic cycle. No disappearance of the activity of³H-DNA was observed at different intervals after removal from the labelled solutions during cultivation for other 24 h in non-labelled nutrient medium either containing DNA fromBacillus subtilis or without it. The embryos which were immersed into 0.2% NaCl solution with either one of the labelled compounds did not show any initiation of the S phase nor uptake of³H-DNA. All these results demonstrate that the label from³H-DNA is localized in those cell nuclei which were in the S phase during treatment but they do not yet distinguish unambiguously between the adsorbtion of polymerous DNA or its degradation and reutilization of low-molecular weight products.

The major trypsin inhibitor ofVigna sinensis cv. seridó was isolated and shown to be devoid of chymotrypsin inhibiting activity. It has a molecular weight of 9800 as determined by gel electrophoresis and a pI of 5.0. The activity of the inhibitor was decreased by treatment with trinitrobenzenesulfonic acid, suggesting that it isa LYS-X type trypsin inhibitor. Selfassociation of the molecule was demonstrated both in 1% sodium dodecylsulfate and inacidic (pH 2.4) conditions.