Vitamin C (L-ascorbic acid) being essential for many living organisms, including man, became once more into the focus of interests because of its numerous physiological effects. Its anti-scurvy and anti-oxidant properties have already been recognised since long in the human body, but it turned out gradually that it has many other functions. In plants, its primary importance is defense against the photo-oxidative stress.

The present review is intended to reveal some details of the artificial synthesis of vitamin C. Emphasis is put on the metabolism of L-ascorbic acid in higher plants. Biosynthetic processes, translocation and accumulation are discussed in detail on the basis of recent results published in the scientific literature.

Plant disease epidemiology provides the key to both a better understanding of the nature of a disease and the most effective approach to disease control. Brown rot fungi (Monilinia spp.) cause mainly fruit rot, blossom blight and stem canker which results in considerable yield losses both in the field and in the storage place. In order to provide a better disease control strategy, all aspects of brown rot fungi epidemiology are discribed and discussed in the second part of this review. The general disease cycle of Monilinia fructigena„M. laxa, M. fructicola and Monilia polystroma is described. After such environmental and biological factors are presented which influence the development of hyphae, mycelium, conidia, stroma and apothecial formation. Factors affecting the ability of brown rot fungi to survive are also demonstrated. Then spatio-temporal dynamics of brown rot fungi are discussed. In the last two parts, the epidemiology of brown rot fungi was related to disease warning models and some aspects of disease management.

Information concerning the blooming time of stone fruit varieties is, first of all, an important condition of finding suitable pollinisers securing adequate fruit set. For that purpose, varieties are assigned to blooming-time-groups. Depending on the number (3 or 5) of the groups, i.e. the length of intervals separating the groups established, pollenisers are to be chosen for self-incompatible and partially self-fertile varieties belonging to the same blooming-time-group. The mutually most overlapping blooming periods of the respective varieties should be found by raising data of their blooming phenology, i.e. dynamics, which is compared by drawing their phenograms and calculating blooming (V) indices. Variety combinations have to be checked, however, concerning mutual fertility relations of the respective pairs of varieties. That is most important in the case of Japanese plums because of the abundant incompatible combinations. Synchronous blooming has been determined by assigning the varieties to blooming-time-groups, or comparing overlaps of blooming phenograms, or by blooming (V) indices. Synchronous blooming phenology has been studied in European plum varieties (111 varietiy combinations) Japanese plums (156 variety combinations) and apricots (153 variety combinations) under Hungarian conditions, over several seasons. In determining overlaps, the less favourable season has been considered as decisive. Polliniser combinations have been chosen with at least 70% synchronous blooming. Blooming time of varieties is an important part of the variety descriptions. Blooming dates may serve also for the estimations of frost risk or security of yield.

Cross-incompatibility is a common phenomenon between various sweet cherry (Prunus avium L.) cultivars. Traditionally, choosing cross-compatible cultivar pairs is based on test crossings in the field.

There is a lack of information about fertility relations of novel Hungarian sweet cherry cultivars and selections. We have studied cross-incompatibility in 42 sweet cherry cultivar pairs by test-crossings in the field. Out of those, 3 combinations showed incompatibility and 15 pairs were compatible.

Test-crossing results proved that with the knowledge of S-allele constitution of Hungarian cultivars incompatible cultivar pairs are recognised in practice reliably. However, we assume that in sterility not only the S-gene system, but other factors (e.g. abnormal development of pollen or flower) also occur, therefore, their examination would be needed.

The black elder (Sambucus nigra L.) is a native plant in Hungary represented by extended and very variable populations. Cultivation of elderberry started during the late 90-ies because of the growing interests of the processing industry. High anthocyanin content, nutritive value of the berries and aromatic compounds of the flowers have been the esteemed constituents.

At the moment, there are about 3000 hectares elder plantations in Hungary, which is more than of any of the other European countries. Unfortunately, the cultures are planted to the Austrian selections of Haschberg, in spite of the fact that about 10-15 other selections of other foreign countries have been registered and planted elsewhere. In addition to that, the wild population of Hungary may offer a precious opportunity of further selection. Since 1970, Aladár Porpáczy at Fertőd and the Department of Fruit Growing of the former University of Horticulture in the 1980-ies started the selection in Hungary too.

The present study deals with 7 genotypes, their morphology of berries and inflorescences. Results are concentrated on four genotypes: Szcs­1, Szcs-2, Szcs-3 and Szcs-5, which are all earlier ripening than the Haschberg varieties, and are superior in characters of fruit and inflorescence.

In the recent years, several disease-resistant apple varieties appeared through the modern breeding technologies. These varieties can be grown with low usage of pesticides, which mean not only environment friendly fruit growing, but the production costs are also lower. In Eastern-Hungary — it is one of the main apple growing regions — a new apple growing structure started to form by the investment of the German Wink Ltd. — several resistant apple varieties were brought from Germany. 'Resistant' refers genetic resistance that usually transferred from the genome of wild apple species. But the fruit of these apple species is not only resistant to diseases, but its quality is poorer, too. In Germany the Re-apples are grown only for the processing industry. Due to climatic circumstances in Eastern Hungary, the first experiences showed better parameters during laboratory measurement, the fruits have more beautiful view, shape and inner characters than usual industrial apples.

In our paper we discuss the results of sensory (consumer) tests, carried out in Eastern Hungary and in the Budapest-region the data analysis of systematic storing experiments (refraction, flesh firmness, weight loss, etc.) and profile analysis of fresh and stored Re-apples. (In the profile analysis the ProfiSens software [4,5] has been used.)

During 1997-2002, studies on the physiological and biochemical changes due to powdery mildew attack in peach and nectarine cultivars and hybrids belonging to different classes of resistance had been performed at the Research Station for Fruit Tree Growing (RSFTG) Baneasa Bucharest, located in the southern part of Romania. The study was based on disease assessments in the field and on other diagnosis criteria.

The southern part of Romania has favourable ecological conditions for growing peach and nectarine but trees have been attacked by various pathogens such as Sphaerotheca pannosa (Wallr.: Fr.) Lev. var. persicae Woronichin fungus for a long time. The presence of the pathogen causes important changes in the quantity and quality of fruits and affects the metabolism of trees.

This study was focused on several physiological and biochemical parameters such as photosynthesis and respiration intensity along with catalase activity; and changes in some biochemical compounds such as free, total and linked water content, dry matter, nitrogen and protein content, tannin levels. The aim was to find possible correlation among the above parameters and the biotic stress induced by the powdery mildew fungus calculated as attack degree (AD%).

Results showed that photosynthesis diminished significantly in the case of the attacked phenotypes, the respiration was more intense in the infected cultivars and catalase proved to be less intense in the affected plants. The total water content significantly increased in contrast to the dry matter and tannin contents, which greatly reduced in the case of resistant cultivars such as 'Victoria', Vectared 7', 'KB 11-40'. The total nitrogen and protein levels showed less influence on resistance to powdery mildew on all cultivars. All genetic material found resistant to powdery mildew is currently used in peach and nectarine breeding programs in Romania.

Further studies focused on isolation and characterization of resistance genes for powdery mildew resistance will be done in the future based on data collected during several years.

The effect of acidity (pH) ranges on the mycelial growth and stroma formation of Monilia fructigena Pers: Fr. and of M. polystroma van Leeuwen was determined on agar plates and apple fruits. Four isolates of each of the brown rot fungi and two apple cultivars, `James Grieve' and 'Cox's Orange Pippin', were used for the study. For the agar plate study, a range of the initial pH was prepared from 2.5 to 6.5. The dishes were inoculated with a 4 mm plug of each isolate and incubated at 23 °C in darkness. The mycelial growth was measured after 1.5, 4, 7, 10 and 20 days of incubation. After a 30-day incubation, stroma formation was determined by image analysis and weighing of mature stroma. In the fruit experiment, both cultivars were inoculated with one isolate of M. fructigena and of M. polystroma. The pH changes were determined after 7, 14, 28 and 35 days of incubation in both healthy and inoculated fruits. The fastest mycelial growth was at pH 4.5 for M. polystroma and at pH 3.5 for M. fructigena. After a 30-day incubation, M. polystroma isolates produced twice or three times more stroma compared to M. fructigena isolates. For both brown rot fungi, the amount of mature stroma increased from pH 3.5 to 5.5, and then decreased at pH 6.5. Results of the.fruit experiment showed that healthy fruits were quite acidic (pH < 3.5), but pH rapidly increased in the inoculated fruits for both cultivars, reaching pH 4.6-5.4 depending on cultivar and fungus isolate. On both cultivars, the stroma developed at a significantly higher pH for M. polystroma than for M. fructigena. Biological and practical implications of the results are discussed.

The effects of different types of cytokinins on the shoot regeneration from leaf explants of apple scion 'Royal Gala' and apple rootstock 'M.26' were evaluated. Regeneration media contained either thidiazuron, or 6-benzylaminopurine, or meta-topolin, or zeatin, or kinetin, or their N⁹-ribosides, respectively, in the concentration range 0.5 to 8.0 mg 1^-1. Effects of 'these cytokinins were evaluated on the percentage of regeneration (R%) and that of vitrification (V%) and on the number of regenerated shoots per explant (SN). Organogenetic index (0I) calculated from these data was used for the evaluation of efficacy of cytokinins. The course of shoot organogenesis also was followed using stereomicroscope. Types and concentrations of cytokinins applied in the regeneration media influenced each parameter significantly and the regeneration answer was strongly genotype-dependent. The best regeneration (SN: 11.08, 01: 7.5) was achieved in `Royal Gala' by using TDZ in concentration of 0.5 mg 1<sup>-1</sup> (2.271,1M). There was a clear relationship between the effect on the regeneration efficacy and the chemical structure of cytokinins considering classical cytokinins, namely N<sup>9</sup>-ribosides applied in less concentration than non­ribosides have the same or best regeneration effects except for 6-benzylaminopurine riboside. However, similar relationship could not be detected in the case of 'M.26'. SN was the highest (3.22) using 6.5 mg 1<sup>-1</sup> (18.2011M) 6-benzylaminopurine riboside or 8.0 mg 1<sup>-1</sup> (21.44 µM) meta-topolin riboside (3.18). SN was not significantly lower (3.12) by using 2.0 mg 1<sup>-1</sup> (9.08 1M) TDZ, however, OI was about half as big (0.63 compared to 1.29 or 1.74 with 6-benzylaminopurine riboside or meta-topolin riboside, respectively). 'Royal Gala' had higher organogenetic ability, than `M.26': 3.5-fold higher shoot number per explant and more than 4-fold higher organogenetic index was reached with this cultivar than with 'M.26'. Moreover, the similar developmental stage of shoots could be observed 3-5 days earlier than in 'M.26' and if explants of 'Royal Gala' were further cultured with 3 weeks, SN increased from 11.08 to 24.42 on TDZ-containing regeneration medium, which might suggest higher organogenetic ability, too.

Honeybee species Apis dorsata F; A. mellifera L; A. cerana F. and A.florea F. were the most important and efficient pollinators of litchi flowers (Litchi chinensis Sonn.) in India. They constituted more than 65% of the total pollinating insects. The ecological threshold for commencement and cessation of flight activity of each honeybee species varied from one another. In general, 15.5-18.5°C temperature, 600-1700 lx light intensity, 9-20 mW/cm² solar radiation appeared to be the minimum ecological conditions for commencement of flight activity in Apis species. Cessation of activities in all the honeybee species was governed mainly by decline in values of light intensity and solar radiation irrespective of other factors.

In between commencement and cessation, the activity of all honeybee species followed the same general pattern as temperature (T), light intensity (LI). Solar radiation (SR). Nectar sugar concentration (NSC) and inversely with relative humidity (RH). Path analysis revealed that all the honeybee species differed in their responses to environmental factors prevailing under similar set of conditions depending upon physiological adaptation of each honeybee species. Of all the factors studied; temperature, light intensity and solar radiation were the three important factors whose influence on foraging population was more pronounced.

Hungarian spice pepper powder is a unique product, a real hungaricum with its flavour and aroma compounds and seasoning effect. Its competitiveness with foreign spice peppers is ensured by its high biological value deriving from the specially Hungarian production and processing technology. Besides the traditional and highly manual labour intensive processing technology, there are some modern industrial technologies as well, where high quality can be guaranteed only by producing excellent base material (raw pepper pods). This is the reason which necessitates the rational development of the elements of the production technology, such as nutrient supply. Our objective was to offer a contribution to this aim by our trials in plant nutrition.

Experiments on the nutrient supply of spice pepper were set up in the 2003 growing season in order to decide whether yields and fruit composition parameters of pepper could be increased by means of increased K fertiliser doses with lower N:K ratios. Several forms of potassium were used, as well as applying microelement top dressings in the single treatments. It was found that the increase of N:K ratio from I:1 to 1:6 did not increase yields, but resulted in higher pigment and dry matter content. Microelement top dressing had a yield increasing effect at each N:K ratio. Higher potassium doses did not accelerate ripening.

Foraging ecology of insect pollinators visiting carrot flowers (Daucus carota L.) was studied in relation to five environmental variables. The dwarf honeybee, Apis florea L., was the most abundant flower visitors and comprised more than 94% of the total flower visiting insects. Commencement of flight activity occurred when a minimum threshold of environmental variables was surpassed while the cessation was governed mainly by decline in values of light intensity and radiation. In between the commencement and cessation, the foraging population correlated significantly and positively with air temperature, light intensity, solar radiation and nectar-sugar concentration and negatively with relative humidity. Path coefficient analysis, however, revealed that direct effect of temperature was high and positive followed by light intensity and solar radiation while the direct effect of relative humidity was high and negative. The direct effect of nectar-sugar concentration was negative and negligible. Evidently, path coefficient analysis gave a more clear picture of effects than did the simple correlation analysis. Apis florea on an average visited 1.14+0.23 and 22.78+2.57 umbels and flowers/min, respectively during different hours of the day. Furthermore, the insect pollinated plots produced significantly more seeds with heavier weights than those isolated from insect visits.

Exports and local marketability of both pepper protected cultivation and open field pepper production depend on whether we succeed in the near future achieving developments capable of bringing about significant improvement of yield and quality, as well as enhanced yield security. Results from experiments and surveys carried out on farms involved in production suggest that nutrient management is one of the factors whose development could considerably improve the marketability of pepper. Technological improvements in the field of nutrient supply are also urged by the more and more demanding environmental regulations, so it is inevitable to introduce a balanced system of nutrient supply system for pepper as well. The article is a collection and summary of the relevant results of 30-year experimental work in Hungary.

Experiments are going on all over the world assisting the joint effort of researchers and practicing specialists to identify the methods which can help either in the reduction of production costs or in the increase of yields.

The task of the growers is to make profitable use of the forcing facilities and to satisfy market demands at an acceptable price by means of improving production technology and applying new scientific, technological and technical information.

For the last few years, rockwool based forcing has been gaining in importance. The subject of our scientific work was the analysis of an important question of this technological variant, the selection of the variety. Besides, we also tried to identify the most suitable pruning technology for the varieties studied.

In Hungary, the highest demand is commonly known to be for the light yellow fleshed varieties which are suitable for stuffed dishes. In the future, due to their special quality and appearance, as well as to the Hungaricum character, they could become important export goods on the European Union market. It was within this variety type that comparison between varieties already common in production (HO F₁, HRF F₁, Danubia F₁) was carried out, trying to get an answer to the question which of the three varieties could be produced with the greatest success. Considering the quantitative and qualitative indicators, it was H6 F₁ that proved the best out of the three varieties tested under unheated forcing on rockwool. It excelled the other two varieties both in quality and in average fruit weight, preserving this advantage until the end of the growing period.

20% of the cucumber crop of the world belongs to the parthenocarp type. Parthenocarp cucumber forcing has a great importance in Hungary, too. In our country the whole area of parthenocarp cucumber forcing was approximately 500 ha of the last years (2000-2002) and 75-85000 tons of yield has been harvested (MGYSZT, 2003). It means 15 — 17 kg/m² as an average yield. In European forcing systems, parthenocarp cucumber is usually planted in January or February and it is harvested in spring or early summer. In Hungary cucumber forcing is the most profitable in two separate periods: spring and autumn, the reason for it is the changes of the average prices of fresh market cucumber, but spring forcing is still the most profitable. Forced cucumber cultivars are mostly parthenocarp; non-parthenocarp cultivars are grown in summer preferably. Cucumber cultivars, forced in our country, are hybrids, and 90% of them are offered by foreign seed companies (KristOfne, 1998.). The productivity of these hybrids is high and the productive period is quite short. All the mentioned details give the reason why it is important to know everything about the productivity, the dynamics of growth, and the possibilities of timing of parthenocarp cultivars, and it is also important to learn how to control all these parameters. Our spring cucumber-forcing experiment aimed to characterize of those parameters mentioned.

The use of an adequate medium is very much emphasised in growing transplants. Due to their favourable characteristics, peats have long been used in production. With the depletion of peat resources the research of peat substitutes has come in the foreground. In the experiments cucumber transplants were grown using baked, expanded clay granules. Results have indicated that by mixing them to peat in a 50 % rate they could be suitable mineral material as a component for soil mixtures.

In spite of the several good properties of peat, recently, some experiments were carried out with the aim of finding natural materials which can substitute for peat. According to the results, several inorganic and organic materials were proved to be suitable for this purpose. This study examines the effect of different organic materials (example: pine bark, composts, peats) on the growth and yield of green pepper (Capsicum annuum L., variety Danubia). We found that the most developed plants were grown in peat-mixtures and pine bark. The average fruit weight was the highest at those plants which were planted also in these media. The plants which were grown in composts fell short of our expectations in development and in yield, too.

Aim of the present investigations was the optimalization of the production of the annual cultivar `Napfény' of Verlxiscum phlomoides L. Quantitative data on morphology (growth, leaf and flower size, branching) yield and content of active materials (mucilages, flavonoids) were studied at six sowing times.

We established, that sowing time may be one basic factor in the production of the annual variety. The major yield was obtained by sowing either late autumn (end of October) or early spring (middle March). At these plots the fresh mass of the flowers was 257-288 g/plant, the drug mass 28-29 g/plant, by 45-70% more than that of the mean of other treatments.

It was established, that under optimal cultivation conditions the annual form of mullein may reach higher individual yields than the plants of the indigenous wild growing population.

Cut flowers of Chrysanthemum morifolium RAM cv. Suny Reagan were treated with different concentrations of 8- hydroxyquinoline sulfate (8-HQS), silver thiosulfate (STS) and 1-methylcyclopropene (1-MCP) in order to improve the post production quality. 8-HQS was used at 200 and 400 ppm with or without sucrose at 50 O. STS was used at 0.2, and 0.4 mM with or without sucrose at 50 g/1 1-MCP was used at 0.3, 0.5 and 0.7 g/m³ for 6h.

All the treatments of 8-HQS prolonged the vase life and minimized the percentage of weight loss of chrysanthemum cut flowers compared to the control. The vase life was larger when sucrose not combined with 8-HQS. The best treatment of 8-1-IQS was 400 ppm 8-HQS without sucrose. STS treatment led to prolong the vase life and minimized the percentage of weight loss comparing to the control. In addition, the effect was better when sucroseas was added to STS. The treatment of STS at 0.4 mM + 50 g/I sucrose was the best one. 1-MCP treatment increased the vase life and lowered the percentage of weight loss at any level comparing with untreated control. The best treatment in this concern was 1-MCP at 0.5 g/m³ for 6h. The chlorophyll content (chl.a and chl.b) of the leaves for the best treatment of each chemical was higher than that of the control. The treatment of 1-MCP at 0.5 g/m³ 6h gave the best results in this respect.

Phaeodactylum tricornutum UTEX 640 strain of microalgae was screened under different culture conditions for their capacity to produce eicosapentaenoic acid (EPA) the most abundant polyunsaturated fatty acid (PUFA). In our experiments, the effect of sodium chlorid, nitrogen source, phosphate, initial pH, as well as the CO₂ content of the medium on production of the eicosapentaenoic acid (EPA) by P. tricornutum were investigated. The EPA content of biomass was enhanced by the low pH of the medium, with increased concentrations of B₁₇ vitamin and nitrate, and also with decreasing concentrations of sodium chlorid. The EPA is most likely associated with polar (membran) lipids and the role of EPA appears to be involved with membran permeability in microalge. The synthesis of phospholipids, enhances the EPA content of the cells, as expected. The maximum EPA yields were observed under optimum culture condition 43 — 48 mg/g of dry cell weight.