Application of kinetin to four interspecific crosses in Brassica, either singly or in combination with NAA, resulted in larger length and retention time of ovaries, increased frequency of ovules with embryos and aided embryo development.

The cross B. campestris ssp. japonica x B. oleracea var. botrytis fails due to incompatibility barrier at the stigma. To realize this cross, irradiated compatible pollen (mentor pollen) was used before the incompatible pollination. The presence of mentor pollen stimulated the incompatible pollen to germinate and effect fertilization and seed set. One hybrid was thus obtained. Most of the seeds were inviable. Of the 5 plants raised one was a hybrid and 4 resembled the female parent.

The quantitative changes of chlorogenic acid in shoots and leaves of two groups of grape vines differing in their flower- and fruit-formation have been studied. It was established that in most cases the acid level was lower in both shoots and leaves of grape vines with suppressed growth and intensified generative processes. The results obtained suggest that the lower content of chlorogenic acid is related to the reduced growth of shoots and acceleration of generative processes.

In negatively photoblastic seeds of Cucumis anguria L. the scarification of micropyle overcame the inhibitory effect of "white light ", although far-red radiation inhibited the germination in both intact and scarified seeds. The moistened testa powder transmitted more far-red than red radiation. Thus the testa could act as a filter of radiation and maintain a high far-red/red ratio at the photosensitive site of the embryo, which must be localized near the micropyle.

The effect of potassium administration in early germination of wheat (Triticum durum L., cv. Appulo) was studied by incubating isolated embryos at different viability levels with 1 mM KC1. The stimulation of germination and growth in aged embryos by K⁺ was accompanied by a significant increase in (³H) leucine incorporation into protein and in phospholipid synthesis as evidenced by TLC analysis of embryo phospholipids extracted after 24 h of imbibition. The metabolic improvement mediated by the cation would in turn repair aging damage occurring at subcellular sites including membranes.

Vitrification of stem explants of carnation was brought about by culturing in liquid medium. Cellulose and lignin levels were decreased in vitrified stems and leaves. Isolated cell walls of vitrified tissues were also characterized by low calcium content, low Ca²⁺/uronic acids ratio, low ratio of uronic acids to neutral sugars due to higher amounts of the latters. All these characteristics may account for the high wall plastic potential previously measured in vitrifying internodes.

Different species of yam tubers were examined for the presence of pyruvate kinase and phosphatase activities, Pyruvate kinase was purified 25 fold with a yield of 50 %. using ammonium sulphate precipitation and ion exchange chromatography on DEAE-Sephadex. Partially purified enzyme showed normal Michaelis-Menten kinetics. However, pyruvate kinase from crude extract of dormant yam tuber showed slight sigmoid response towards phosphoenol-pyruvate and magnesium and to a certain extent ADP. The enzyme is activated by AMP and inhibited by ATP and citrate in both crude and partially purified preparations. Further studies on the effect of energy charge on the enzyme strongly suggest that pyruvate kinase from D. alata is a regulatory enzyme. No evidence was found for the presence of more than one pyruvate kinase in germinating D. alata tuber. With the exception of D. dumentorum, all the other three species of yams studied contain very little or no detectable phosphatase activity during dormancy. However, phosphatase activity increased during germination in all the species, thus excluding the use of sprouting yam tubers for kinetic study of pyruvate kinase.

Uptake of³⁵S-sulphate by bundle sheath strands (BSC) from leaves of maize plants (Zea mays L. ev. Dekalb L 72 A) was higher than that by isolated mesophyll protoplasts (MC) of maize. Ion uptake followed the Michaelis-Menten kinetic satuiation curves. SO² ₄-uptake increased after addition of malate, NADPH, malate + NADP+ to BSC suspensions, but not to MC susp: nsions.

The season of collection of shoot tips from field-grown plants ofChrysanthemum morifolium cv. Birbal Salmi was found to be crucial for their proliferation and establishment of plants in vitro. Shoot tips collected only during the period of March to April proliferated and survived. Shoot apices and segments of leaf, stem (nodal und internodal) and root, excised from aseptically established plants, were cultured on Murashige and Skoog's medium supplemented with different concentrations and combinations of Kn, BAP, IAA and NAA. A maximum number of 9 off-shoots differentiated, without intervening callus formation, from a shoot tip in a treatment containing 1.5 mg l^-1 BAP and 0.1 mg^-1 NAA in 60 days. A single-node stem segment produced less shoots in the same treatment. Other kinds of expiants produced only callus. About 2-cm-long shoots, excised from cultures of proliferating shoots, were rooted 100 %, acclimatized and grown in soil. They grew normally and flowered true-to-type.

The change in protein composition of whole cotyledons and cotyledon aleurone grains ofLupinus luteus L. during seed germination was studied. SDS-polyacrylamide gel electro-phoresis showed a clear change in composition of cotyledon proteins as well as in composition of the aleurone grains during 5 days of seed germination. At this time, both in whole cotyledons as well as in aleurone grains, two subunits of β-conglutin with mol. m. 53 000 and 39 000 were rapidly hydrolyzed. After 5 days of germination traces of α-conglutin subunits could be detected in the cotyledons, whereas in aleurone grains this globulin fraction disappeared. In whole cotyledons and in cotyledon aleurone grains the γ-conglutin subunits with mol. m. 28 000 and 17 000 were not mobilized during the study period. These results indicate that the protein components with lower mol. m. were degraded later than those withhigher mol. m. during seed germination.

The effect of choline, acetylcholine, carbamylcholine and of the acetylcholinesterase inhibitors, eserine and neostigmine, on the germination of seeds exhibiting different photosenitivities was studied in two light variants. Both in the darkness and in continuous white light the substances in question had no effect or only slightly modified germination of photoblastically neutral seeds. On the other hand, the above substances, particularly aeetylcholine and carbamylcholine, stimulated germination of photoblastically positive seeds, and inhibited germination of photoblastically negative seeds in continuous white light.

High rates of oak shoot multiplication were achieved on low salt nutrient media (BTM, WPM) supplemented with adenine type cytokinin or BAP. Low concentration of (0.2-0.6 mg 1^-1) stimulated formation of a large number of axillary shoots and their elongation. Thidiazuron in very low concentration (0.001 - 0.002 mg 1^-1) promoted shoot proliferation, in high concentration stimulated formation of large callus. More than twelve thousand micropropagated shoots were rooted in low salt agar media supplemented with low concentration of auxin (IBA or NAA 0.2 - 0.5 mg 1^-1). High rooting percentages (81 %) were obtained. Survival of the mieropropagated plantlets transplanted into soil was high (78 %). Micropropagated trees planted in the field withstood severe winter frosts without significant losses. At the end of the fifth growing season trees attained considerable size.

The rooting ability of 2 cm long shoots ofPisum sativum L., derived from differentin vitro shoot-tip cultures in two pea cultivars Bohatýr and Kleine Rheinländerin was evaluated. In three mutually independent experiments the full and half-strength Murashige-Skoog medium (containing full or half concentration of macro and microelements), with sucrose concentrations 10-30 g l-¹, and with various NAA and IAA combinations, was tested. The variant with half concentration of macro- and microelements, supplemented with 30 g l¹ sucrose, and with growth regulators in the quantity of 1 μM proved optimum.

Response of stomata in epidermal strips from green leaves ofTradescantia sillamontana and anthocyanin-rich purple leaves ofT. virginiana and from green and pigmented regions ofPedilanthus tithymaloides leaves, to ABA have been compared. Stomata from anthocyanin-rich leaves or leaf parts appeared to be relatively insensitive to ABA as compared to those from green leaves or leaf parts. Observations indicate the possibility of the involvement of endogenous anthocyanins in antagonising ABA in preventing the stomatal opening.

In hexaploid triticale, cultivar UPT 72142 having highly shrivelled grains, there were only five pairs of rye chromosomes, whereas cultivars UPT 78268 and UPT 79245 having medium grains had six and five pairs, respectively. Plump grained cultivars UPT 79347 and UPT 79339 had 2 pairs of rye chromosomes. A decrease in the number of rye chromosomes in triticales is con-elated with grain improvement.

Second and third leaves of 25-day old wheat (Triticum aestivum L.) planta, cultivar WL-711, were inoculated with three races of the brown rust pathogen,Puccinia recondita f. sp.tritici. The host reflected a differential interaction response towards these races, viz., susceptible reaction to race 77 (reaction type 4) intermediate reaction to race 104 (reaction type 1 - 3) and resistant reaction to race 63 (reaction type 0). Post-inoculation mutual interaction brought about observable changes in peroxidase activity along with leakage of electrolytes and phenolic constituents indicating altered permeability of host tissue. Differential increase in leakage of electrolytes and phenols occurred with increase of peroxidase activity during 12 h and 24 h post-inoculation, however, during 36 h, 48 h and 72 h post-inoculation, electrolyte leakage increased continuously with corresponding increases in peroxidase activity in all three interactions, while leakage of phenols showed a differential pattern. The differential changes in isoenzymic pattern of peroxidase activity were also noted during the progressive infection process which may also be an indication of altered permeability of the host issue at the very onset of brown rust infection.

Uncoupling of oxidative phosphorylation by 2,4 dinitrophenol stimulated leaf respiration rate measured as CO₂ production or O₂ uptake after low temperature treatment.

Vertical projections of nutation movements in the epicotyls of sessile oak, Turkey oak, horse chestnut and hypocotyls of European beech were recorded by means of photography and time-lapse cinematography at the early stages of their ontogeny. Attention was paid to the kinetics of growth rate, diameter of the lower part of the elongating zone, and the form, amplitude and frequency of nutation turns. At the beginning of ontogeny the vertical projection of the movements of all woody species under study was represented by irregular curves, followed by elliptical trajectories, particularly when reaching the maximum growth rate. The highest average growth rate was recorded in horse chestnut, followed by oak, and the lowest values were exhibited by beech. As to the size of amplitudes opposite results were obtained. The frequency of turns proved to be a less sensitive parameter characterizing the movement. It is suggested that the geocontrol system of horse chestnut is more effective than that of oak and, especially, of beech.

Growth, carbon uptake and carbon utilization in leaves of various growing phase shoots (GPS) on beech trees(Fagus sylvatica L.) growing under different light conditions were compared. The values of photosynthetic capacity (maximum daily net photosynthetic rate, Pn max) were used as comparable parameters.
Daily time and irradiance (I, PhAR), when PN max was attained, were investigated similarly. Statistically significant differences were found in growth, Pn max and SLM (specific leaf mass) between different GPS and within the same stand, as well as within the same GPS and different stands. Pn max and SLM increased in the leaves of GPS I (spring - plagiotropic shoots) on trees from a sun stand from May till September. At the end of the growing season, the spring leaves exhibited, in comparison with the summer ones, intensive senescence, but leaves of the GPS II and III (summer -orthotropic shoots) evidently attained higher values of Px max and SLM at higher I (PhAR).
The correlation of growth, PN max and SLM in relation to environmental conditions, as well as the importance of transport, distribution and utilization of assimilates for annual carbon gain and biomass production are discussed in detail.

Transpiration and water absorption rates, stomatal and cuticular resistances to water vapour diffusion, were measured onPlantago maritima (halophyte) andPlantago lanceolata (glycophyte) grown in the presence of NaCl or Na₂SO₄. Water absorption was reduced in the presence of Na₂SO₄ and transpiration rate was increased when NaCl was added to the nutrient solution. The glycophyte daily water balance was more disturbed than that of the halophyte in the presence of Na₂SO₄.

Pollen embryogenesis occurred in anther cultures of two genotypes ofBrassica carinata A. Braun. Pretreatment of anthers at 35°C for 3 or 6 days was essential for the induction of androgenesis on growth regulator-free culture medium. A combination of sucrose and glucose was better than sucrose alone. None of the pollen embryos germinated normally. Full plants were raised through adventitious bud differentiation from their hypocotyl.