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  • Path analysis and correlation coefficient of environmental factors influencing foraging behaviour of four honeybee species pollinating litchi flowers (Litchi chinensis Sonn.)
    77-82.
    Views:
    118

    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.

  • Studies on the effects of growing substrates and physical factors in sweet pepper forcing in context with the generation of calcium deficiency symptoms
    61-65.
    Views:
    180

    In the publications available for us, exact levels of physical factors and those of the growing technology determining Ca2+ deficiency are rarely detailed. Although the influencing role of the various environmental factors (humidity, light, temperature) is known, we had only little information about their exact values which could be presented for the growing practice. Sweet pepper varieties of the same type grown in various substrates responded to the environmental factors in different ways. Our results revealed that increasing temperature of the root zone had the most significant effect on the incidence of Ca2+ -deficient fruits. Their amount, however, gave different results depending on the growing substrate. In forced sweet pepper grown in soil the proportion of Ca2+ - deficient fruits were significantly lower compared to the plants grown on rockwool. Fruits derived from forcing on perlite, in container were damaged the least by the blossom end rot deficiency symptoms. Our experimental results and technological suggestions are based on measurement results of three years.

  • Path coefficient analysis of environmental factors influencing flight activity of Apis florea F. and seed yield in carrot (Daucus carota L.)
    87-92.
    Views:
    117

    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.

  • Factors affecting apricot fruit antioxidant capacity and mineral element contents
    95-99.
    Views:
    199

    Several epidemiological studies revealed that the consumption of antioxidant compounds and the risk of atherosclerosis, increased blood pressure or cancer are inversely proportional. The individual amounts and relative proportions of macro- and micro elements present in food is also of great consideration since these are involved in a wide range of physiological processes including the influence of the redox homeostasis. The antioxidant power and mineral nutrient content of fruits might be affected by several factors including genotype, ripening stage, year-effects or a wide range of environmental conditions. This study was carried out to survey the antioxidant power and mineral element content in fresh fruits of apricot and analyse some genetic and environmental factors that may have important contribution to the inner content of apricot fruits. In addition, the influencing effect of the extraction procedure used for antioxidant analyses was also tested. Our analyses indicate that a considerable fraction of antioxidant capacity is attributable to the hydrophilic antioxidants. The genetic background has crucial importance in determining apricot fruit antioxidant capacity and mineral nutrient content; however, the growing season and the ripening time of fruits may have also important effects.

  • The brown rot fungi of fruit crops (Monilinia spp.): II. Important features of their epidemiology (Review paper)
    17-33.
    Views:
    205

    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.

  • Fruit drop: The role of inner agents and environmental factors in the drop of flowers and fruits
    13-23.
    Views:
    382

    The basic conditions of fruit set (synchronic bloom, transfer of pollen, etc.) still do decide definitely the fate of the flower (Cano-Medrano & Darnell, 1998) in spite of the best weather conditions (Stösser, 2002). Beyond a set quantity of fruits, the tree is unable to bring up larger load. A system of autoregulation works in the background and causes the drop of a fraction of fruits in spite of the accomplished fertilisation and the equality of physiological precedents (Soltész, 1997). There are also basically genetic agents in action. The further development of fruits maintained on the tree depends mainly on the growing conditions (e.g. water, supply of nutrients, weather adversities, pruning, fruit thinning, biotic damages, etc.), which may cause on their own turn fruit drop especially at the time of approaching maturity.

  • Relationship between flowering, fruit setting and environmental factors on consecutive clusters in greenhouse tomato (Lycopersicon lycopersicum (L) Karsten)
    111-116.
    Views:
    124

    The main season of greenhouse tomato begins late winter or early spring in the northern Temperate Zone. During this period decisive environmental factors affect flowering and fruit setting.

    In the present experiments, progress and dynamics of greenhouse tomato flowering and fruit set were examined in 1999 and 2001 spring. The beginning and the end of flowering and fruit set, the number of flowers and fruits set in each cluster were recorded. Flowering and fruit set characteristics were analysed with respect to the accumulated PAR and temperature were calculated for each cluster. One flower required 31.3 mol M-2 of accumulated PAR and 38 °C of sum temperature as an average for anthesis. One fruit required 27.9 mol m-2 of accumulated PAR and 33.3 °C of sum temperature as an average for fruit setting.

  • Importance of orchard floor management in organic fruit growing (nutritional aspects)
    61-67.
    Views:
    264

    Worldwide research goals and concerns are to soil conservation and improve. This conception is mostly actual in horticulture where the numbers of high-density plantings are continuously increasing. High-density orchards cause more intensive nutrient and water uptake. So that the preservation of soil moisture and nutrient level are key factors in qualified fruit growing. On the other hand due to the climatic changes the water supply of trees will be satisfied among worse conditions than some decades ago. Appearance of water supply problems and water stress is increased in organic growing, where the number of corrections is limited anyway. Furthermore, floor management is a successful tool in weed management which causes many problems for organic growers due to the prohibition of synthetic herbicides. This paper will mainly focus on the nutritional aspects of methods of orchard floor management for growers adopting organic fruit management to make their production profitable.

  • Relationship between several meteorological factors and phenological features of pear cultivars
    67-73.
    Views:
    194

    The aim of this paper was to investigate the fl owering characteristic of apples and their relationship to meteorological parameters. The trees observed are grown at Újfehértó, Eastern Hungary in the plantation of an assortment (gene bank) with 586 apple varieties. Each of the varieties were observed as for their dates of subsequent phenophases, the beginning of bloom, main bloom and the end of bloom over a period between 1984 and 2001 during this period the meteorological data-base keeps the following variables: daily means of temperature (°C), daily maximum temperature (°C), daily minimum temperature (°C), daily precipitation sums (mm), daily sums of sunny hours, daily means of the differences between the day-time and night-time temperatures (°C), average differences between temperatures of successive daily means (°C). Between the 90th and 147th day of the year over the 18 years of observation. The early blooming varieties start blooming at 10–21April. The varieties of intermediate bloom start at the interval 20 April to 3 May, whereas the late blooming group start at 2–10 May. Among the meteorological variables of the former autumnal and hibernal periods, the hibernal maxima were the most active factor infl uencing the start of bloom in the subsequent spring.

  • Luminescence variations in cucumber (Cucumis sativus L.) leaves derived from different regeneration systems
    50-52.
    Views:
    151

    Plants obtained from in vitro culture can show increased susceptibility to environmental stress conditions. In the process of their adaptation to natural conditions it requires monitoring of their physiological state. The methods used to check this phenomenon should estimate quickly and exactly the tolerance to suboptimal environmental factors. Such requirements are satisfied by the methods of measuring chlorophyll luminescence in vivo, e.g. fluorescence induction and delayed luminescence. The objects of our studies were cucumber plants regenerated from cultures of callus and embryogenic cell suspension, as well as the plants obtained from seeds. The plants derived from in vitro cultures displayed a poor physiological condition at the early phase of adaptation characterised by higher susceptibility both to stress caused by increased density of the light flux and low temperature (4 °C) in comparison with the plants obtained from seeds.

     

  • Evaluation of cauliflower genotypes by different growing method
    11-14.
    Views:
    225

    Cauliflower is currently cultivated on 350-400 thousand hectares in the world and around 1500 ha in Hungary. Its cultivation requires considerable expertise as it is sensitive to environmental factors and adequate nutrient supply. The aim of our experiment was to compare three genotypes (Abeni, SV5777 AC and Telergy F1) by different growing method – under plastic tunnel and on open field. On open field the planting was on 19th of March, 2018, the row and plant distances were 45 and 35 cm. Under plastic tunnel the transplants were set out on the same day with the same genotypes as on open field, with 55x45 cm arrangement. The results have proved that cauliflower curds from plastic tunnel was two times bigger than on open field. The more protected environment had a positive effect not only on the mass of the curd, but also on the biomass production. Among the examined genotypes Abeni showed the highest yield (about 1 kg/plant) under plastic tunnel. The shape of the head is important for the market. According to our data, we measured the width and height of the curd. Open field conditions induced wider curd with longer stem and caused lower product quality and weaker correlation between the parameters than plastic tunnel.

  • Storability of some apricot varieties as affected by storage period
    39-42.
    Views:
    238

    The aim of this study was the estimation of storability of 10 apricot varieties in regard to percentage fruit weight loss, firmness, acidity and T.S.S in fruit during storage periods from one week to 4 weeks. All the variety gave the same trend as all of them loss weight, firmness decreased, acidity and T.S.S decreased but the differences were not the same in all varieties. in case of some varieties the percentage of fruit weight loss reached to about 9 % after 28 days also the differences between varieties in two seasons refer that this character is determined by genetic factors beside effect of environmental and agriculture factors.

  • The Role of Human Factor in the Innovation of Apricot Production-Empirical Study in a Disadvantage Area of East-Central European Country
    131-134.
    Views:
    202

    Hungary is a traditional fruit growing country for ages. As fruit sector has a very high hand work request and value added, it has an important role to decrease the elimination of unemployment and the lack of income in the disadvantage rural areas. The study was made in the year of 2009, the studied population consisted of the members of the fruit-grower marketing organization (Gyümölcsért Ltd.), that organizes growing and sales of stone fruits in Hungary. The number of studied population were 95 capita, the number of fi lled out and evaluated questionnaires was 35. By the composition of the questions both qualitative and quantitative methods have been used. We tried to get answers to the following questions: Are the studied human factors (age, educational level, sex etc.) of growers, determined the extension of innovation of apricot production?

  • Foliar Nutrition and Post-Harvest of Onion Seed: Effects of storage temperatures, storage period and foliar nutrition
    29-47.
    Views:
    200

    The aim of onion bulb storage is to meet consumer demand for extended availability of onions whilst maintaining product quality. The principal biological factors leading to onion bulb deterioration are respiration, resumption of growth and pathogen attack. In onion bulbs a dormant period, when sprouting and rooting cannot be induced, is followed by a period of internal changes that prepare the bulb for breaking of dormancy and subsequent growth. Out of storage, the bulb then proceeds towards flowering and seed production. Two successive winter seasons of 2008/2009 and 2009/2010 were conducted under sandy soil conditions to study the effect of spraying with 12 commercial compounds on yield and yield components of onion seeds and storage The seed yield of each commercial compounds plot from previous experiment was divided into two groups, storage under room temperature and 5°C. Seeds transferred immediately after drying to Increasing Export Competition of Some Vegetable Crops Project Laboratory located in Faculty of Agriculture, Cairo University. The effects of storage temperature, storage period and foliar with some commercial compounds on onion seed quality were considered. Storage in 5°C had the higher germination percentage than storage in room temperature. Results indicated that as storage period increased the germination percent decreased. The treatment with boron or amica in the first season had the highest germination percentage. While, the treatment with union Zn, union feer, union Mn, boron, elga 600, caboron, amica, hummer or amino X had the highest germination percentage in the second season. Storage in 5°C resulted in higher moisture content than storage in room temperature. Regarding the effect of storage period on moisture content, the water content was significantly increased with prolongation of storage period. The lowest values of water content were recorded for treatments with union feer, shams K or boron in the first season, and union feer, shams K, boron, magnesium, shetocare or hummer in the second one. Catalase activity was significantly decreased as storage period increased. The treatment with shams K, boron, shetocare or amino X had the highest catalase activity in both seasons. Peroxidase activity was significantly decreased as storage period increased. Foliar application with boron had the highest peroxidase activity in both seasons. Seed stored in room temperature had the higher malondialdehyde content than those stored in 5°C in the second season. The malondialdehyde content increased as storage period increased. The treatment with magnesium, caboron and the control in the first season, and the treatment with magnesium and the control in the second season had the highest malondialdehyde content.

  • Propagation of plum rootstocks by hardwood cuttings
    23-28.
    Views:
    124

    Vegetative propagation by hardwood cuttings is a very simple and cheap method for production of plum rootstocks. The aim of this study was to examine if this propagation technique is suitable for practice of three plum rootstocks and find the time or period when the percent of rooted cuttings is maximal. Based on our results, hardwood cuttings of the rootstocks tested have the rooting potential acceptable for practice, however, for Fehér besztercei in the previous literature leafy cuttings are recommended. Fehér besztercei reached 74.0% rooting, cuttings of Sainte Julien GF 655/2 rooted in as high percentage as 78.3%, and Marianna GF 8-1 had 88.3% rooted cuttings. Rooting potential of hardwood cuttings depends on more factors, one of them can be their dissimilar sensitivity for the diverse environmental circumstances at the different propagating dates, affecting through the internal biochemical changes that can be in relation with the differences in their dormancy.

    The cuttings of Marianna GF 8-1 take root easily, but in some years the conditions were less favourable for reaching maximal rooting. For taking cuttings the period from the beginning of October until December was optimal. For Fehér besztercei the optimal date of cutting collection was around the end of October, but in some years the rooting in the middle of December was also high. Sainte Julien GF 655/2 definitely rooted best in October. The treatments with different IBA concentrations in two years affected differently the rooting percentage. The rooting of Marianna GF 8-1 and Sainte Julien GF 655/2 is barely influenced by the different hormone dose in both years. Hardwood cuttings of Fehér besztercei rooted definitely better when treated with 2000 ppm IBA in comparison to untreated ones, while in 2001-2002 there was no difference between 2000 and 4000 ppm.

     


     

  • Review on rain induced fruit cracking of sweet cherries (Prunus avium L.), its causes and the possibilities of prevention
    27-35.
    Views:
    705

    The rain induced fruit cracking is a big, serious and costly problem for cherry growers. Cracked fruits lose their value and they are not marketable because of the poor fruit quality. Cracked fruits have different storage diseases and shorter storage and shelf life.

    There are many influencing factors of the cherry fruit cracking such as: water uptake; fruit characteristics (fruit size, fruit firmness; anatomy and strength of the fruit skin, stomata in fruit skin, cuticular properties, osmotic concentration, water capacity of the fruit pulp, growth stage of the fruit,); orchard temperature and other environmental conditions;

    The most effective protection technique is the plastic rain cover over the tree rows. The installation of these equipments is too expensive for the cherry growers. That is the reason why researchers tried to find other less expensive and sufficiently effective ways against the Lim induced fruit cracking.

    Several calcium formulas: calcium chloride (CaC1,), calcium hydroxide (Ca (OH)2) and calcium nitrate (Ca(NO3)2 ) can be sprayed in appropriate concentration. Spraying with other mineral salts (aluminium and copper salts, borax) and PBRs (Plant Bioregulators) may be also effective to reduce fruit cracking.

  • Effects of environmental factors on morphological and quality parameters of table beet root
    139-146.
    Views:
    259

    In our trial morphological and quality parameters of 15 table root varieties were tested at 3 different sowing dates: 15 April, 9 July and 19 August 2010. In the trials the root shape of the varieties form the April sowing date approached most the regular spherical shape (diameter/length –1.0) which is favoured both by fresh market and the processing industry. In the July and August sowings the roots were elongated with reduced proportions. The highest red pigment content (betacyanin) was observed in the second sowing of July (>80 mg/100 g). In the late sowing (August, under plastic tent) a further 10–20 mg/100 g pigment increase was measured in relation to the earlier sowing dates of the same varieties. A similar trend could be observed in yellow pigments (vulgaxanthis) which proves a close correlation between the quantities of the 2 pigments (r=0.823). The highest vulgaxanthin content (103.3–124.18 mg/100 g) was obtained form roots of the late sowing harvested in December. Varieties reacted differently to temperature and so to sugar accumulation in the different sowing periods. In the July sowing higher water soluble solids content was measured on the mean of varieties (10.12 %) as compared to the April sowing (7.76%). Sensory evaluations included inner colour intensity (1–5), with ring (1–3) and taste (1–5) of the raw material evaluated by scoring. According to laboratory measurements better inner colour intensity was observed in the July and August sowing dates. In these samples uniformly coloured, almost with, ring-free roots were obtained. In our trial varieties from the spring sowing had superior taste. Early sowing is recommended for fresh market sale while the second crop (July) harvested in autumn can satisfy processing requirements. In the late sowing (under unheated plastic tent) fresh beet root can be grown at the end of autumn or beginning of winter, thus prolonging the usability of plastic tents.

  • Some relationships between soil and nutrient requirements and nutrient supply of pepper (Capsicum annuum L.) with respect to types grown in Hungary
    93-105.
    Views:
    155

    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.

  • Evaluation of vermicompost application and stress of dehydration on mullein medicinal plants
    69-77.
    Views:
    82

    The use of organic fertilizers is one of the suitable solutions in the organic production of medicinal plants due to its good effect in improving soil properties, reducing environmental effects, and better plant growth. To investigate the effect of vermicompost organic fertilizer application and water stress on some morphological and physiological traits of the Mullein medicinal plant, research was conducted at Isfahan Azad University in the form of split plots in the form of a randomized complete block design with 4 replications. The test factors included the application of vermicompost organic fertilizer at three levels of 0, 4, and 8 kg per square meter of soil and water stress at two levels of normal irrigation and irrigation at the time of 50% of the soil's agricultural capacity as the main treatment in research farm conditions. The results of the experiment showed that the application of vermicompost organic fertilizer and water stress improved the morphological and physiological characteristics of the Mullein medicinal plant compared to the control, i.e. no application of organic fertilizers. The results showed that the highest number of secondary branches, number of flowers of the secondary stem, diameter of flowering stem, the diameter of flower, and fresh weight of shoot in the Mullein medicinal plant were obtained by applying vermicompost organic fertilizer at the rate of 4 and 8 kg of soil. The application of vermicompost organic fertilizer at the rate of 8 kg in the soil increased flavonoids compared to the non-use of vermicompost treatment. However, to improve the vegetative growth and increase the reproductive efficiency of the Mullein plant and reduce production costs, the use of vermicompost organic fertilizer is recommended at the rate of 4 and 8 kg of soil, respectively.

  • Genetic variation in the rose pathogen Marssonina rosae estimated by RAPD
    63-67.
    Views:
    150

    Blackspot, caused by the fungus Marssonina rosae (Diplocarpon msae), is one of the most devastating and widespread diseases in garden roses, and it has as yet not been fully characterized in molecular terms. In this initial study we used RAPD analysis to investigate the genetic diversity among and within a few geographically diverse groups of single-spore isolates of M. rosae. DNA was extracted from in vitro­grown mycelia of 1 I single spore isolates grown on PDA medium. High levels of polymorphism were detected among the isolates. They clustered into three distinct groups: Group !consisted of isolates from eastern North America plus a European isolate (Germany), Group 2 included isolates from southern Sweden, and Group 3 included the isolates from Manitoba, Canada. The greater similarity of the environmental conditions in eastern North America and Europe as compared to the Canadian prairies suggest that. climate and weather could be key factors in influencing the potential race structure of M. rosae. However, variations among closely situated sites, e.g. southern Sweden, also occurred.

  • The increasing importance of grapevine trunk diseases
    21-30.
    Views:
    303

    Grapevine trunk diseases (GTDs) are destroying the woody parts of the plants, resulting decline or dieback of the grapevine. More detailed research of the GTD began in 1950s, when Hewitt et al. (1957) observed that specific symptoms cannot be detected on the diseased trunks every year. Latest results have also proved that abiotic factors affect the appearance and the severity of the disease. Moreover several pathogenic fungi may play role as causative agents (Bertsch et al., 2013). Eutypa, Botryosphaeria, Phomopsis dieback, esca disease complex, and Petri disease are considered the major GTDs, where a variety of pathogens attack the woody perennial organs of the vine and ultimately lead to the death of the plant (Lehoczky, 1974; Larignon & Dubos, 1997; Rolshausen et al. 2010; Kotze et al., 2011; Bertsch et al., 2013; Fontaine et al., 2015).
    The GTD incidence has been reported to be increased during the last decades (Úrbez-Torres et al., 2014). The esca incidence has reached 60% to 80% in some old vineyards in southern Italy (Pollastro et al., 2000; Surico et al., 2000; Calzarano & Di Marco, 2007). The disease incidence of the esca was reported to be increased from 1.83% to almost 13%, between 2003 and 2007 in Hungary (Dula, 2011). There was detected a five times increase in the GTD disease incidence in the Tokaj Wine Region, Hungary between 2014 and 2016 (Bihari et al,
    2016).

  • Prediction infection risk on the basis of weather-related factors and Erwinia amylovora colonization in apple and pear flowers
    39-54.
    Views:
    153

    Current infection risk prediction models utilize environmental parameters and field records, but do not take into account the estimated inoculum potential within the orchard. The object of this study was to survey the accuracy of three simple prediction methods under Hungarian climatic conditions, which could easily be used by the farmers. We also tested whether the accuracy of infection risk predictions can be improved by taking into consideration the incidence and/or rate of flower colonization by Erwinia amylovora.

    After preliminary investigations in 1999-2001, data concerning the weather-related infection risk were recorded in 5 apple and 1 pear orchards in 2002, and in 12 apple and I pear orchards in 2003. The weather data were processed by the easy-to-use risk assessment models of the mean temperature prediction line (MTL), Smith's Cougarblight 98C and Billing's integrated system (BIS), and by the MaryblytTM 4.3 computer-assisted model for reference. The population size of E. amylovora in the flower samples was estimated within an order of magnitude by PCR.

    For all years and orchards tested, Maryblyt indicated 35 days on which there was an acute infection risk. The same days were indicated by all 3 methods in 23 cases (66%), 8 days were indicated by 2 methods (23%) and 4 days were indicated by 1 method only. A similarly good correlation was found for prediction of the date of the first massive infection risk: in 2003, for instance, there was a perfectly consistent prediction by all 4 models in 9 of the 13 participating orchards. A coincidental forecast was provided by 3 of the 4 models in the other 4 orchards.

    The results indicate that any of the risk assessment models could provide an increased accuracy of the actual infection risk prediction if combined with an estimation of the incidence of Erwinia amylovora colonization in the open flowers. We found no convincing differences in the size of the epiphytic population in flowers of cultivars possessing high or low susceptibility to Erwinia amylovora.

    We conclude that the easy-to-use methods tested could be used by the fanners to recognize weather-related risks, especially when coupled with an estimation of the proportion of the pathogen-infested flowers. This local prediction would provide rapid information (faster than the regional forecast systems) specifically for a given orchard.

  • Abnormalities of the stigma of sour cherry cultivar
    31-33.
    Views:
    229

    The objective of this study was to evaluate the ratio of blackness of the surface of stigma of sour cherry cultivars. At the full bloom time of sour cherry 100 new opened flowers were marked in the internal (Inside), external (outside), bottom and upper parts of the crown of each cultivars including sour cherry cultivars ‘Érdi bőtermő', `Debreceni bőtermő', `Kántorjánosi', 'R. clone', 'Petri', Pándy', and 'D. clone'. The trees were replicated four times. The numbers of flowers with black stigma were counted and the percentage of dead stigma was calculated. In addition, tissues of black stigmata were investigated for blossom pathogens by microscopy. After flowering time the fruit set of the marked flowers counted and then percentage fruit set was calculated. Numbers of counted flowers were between 300 and 980 depending on the four position of the tree. Black color of stigma could be seen only on three cultivars (`Debreceni bőtermő', Érdi bőtermő' and 'Petri') out of seven assessed cultivars. The highest numbers of black colored stigma were found on cultivar ‘Érdi bőtermő' which ranged between incidences of 12 and 21%. Black stigma was never able to produce a fruit set. Microscopic examination revealed no pathogens associated with black stigma. Different part of the tree resulted different amount of black stigma. Black stigma was the largest on the outer part of the tree on cv. 'Érdi bőtermő' but also bottom part of the tree also produced larger number of black stigma on cvs. `Debreceni bőtermő' and ‘Érdi bőtermő'. Though symptoms were not typical to frost damage, we believe that black stigma is probably due to environmental factors during flowering. This might be associated with late spring cold coming from the soil surface as the bottom and outer part of the tree was more suffered from the disease.