Vol 8, No 3-4 (2002)

Published October 16, 2002



Microsporogenesis of peach (Prunus persica L. Batsch) varieties

Bud dormancy during winter is a critical factor in peach production in Hungary. The yield is determined basically by the survival rate of flower buds during winter frosts and by their ability to develop normal floral organs. It is important to investigate the genetic basis of slow floral development during dormancy for the purpose of breeding p...each varieties with better winter hardiness. The aim of the present research was to examine microsporogenesis in 14 peach varieties during three successive winters in a Hungarian germplasm collection and to study the effectiveness of this method in variety evaluation. There were significant differences in the dynamics of microsporogenesis both between the varieties and between the years. Of the varieties, ‘Mayfire', bred in California, possessed the quickest pollen development rate. The microsporogenesis of `Piroska', a Hungarian local variety, was the slowest. Rapid floral bud development was observed in `Aranycsillag', `Springcrest' and 'Venus'. A medium developmental rate was characteristic of `Babygold 6', Fairlane', `Michelini' and `Red June', while development was slow in 'Champion', 'Early Redhaven', `Redhaven', `Harko' and `Mariska'. Based on these results, the study of microsporogenesis represents a reliable method for the phenological description of peach varieties during dormancy. The application of this method makes it possible to identify varieties and landraces with slow flower bud development, suggesting better winter hardiness.

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Molecular diversity of Hungarian melon varieties revealed by RAPD markers

RAPD markers were used to reveal genetic diversity between nine varieties of Cucumis melo L. and to identify the studied varieties. Of the 60 primers tested 12 primers produced polymorph patterns. A set of 4 primers was sufficient for distinction the nine investigated melon varieties.

Study of genetic transformation efficiency via organogenesis and embryogenesis in eggplant (Solanum melongena L. cv. Embti): effects of co-culture, temperature and kanamycin and hygromycin-based selection procedures

The effects of kanamycin and hygromycin-based selection and co-culture temperature ranging from 22 to 28 °C upon eggplant transformation efficiency were evaluated. Both morphogenic pathways, somatic embryogenesis and organogenesis, were adopted using cotiledonary and hypocotyl explants, respectively. Somatic embryos were recovered in the prese...nce of both antibiotics, although lesser escapes were observed in hygromycin-supplemented medium. Indeed, selection provided by this antibiotic was more efficient compared to kanamycin, nevertheless, shoot regeneration was not observed with hygromycin. Significant difference on the frequency of cotiledonary explants displaying callus (FEC) was observed as embryogenesis was concerned, although a higher number of embryos was observed in hygromycin selective media. The frequency of explants presenting callus (FEC), embryos (FEE) and shoots or buds (FERG) did not differ statistically for the tested co-culture temperatures, although higher regenerant number was observed at 24 °C.

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Effects of indole-3-butyric acid levels and activated charcoal on rooting of in vitro shoots of apple rootstocks

Rooting responses of rootstocks cvs. JTE-F1, M. 26 and MM. 106 were studied to different concentration of IBA in root induction media and to presence of activated charcoal in root elongation media. High rooting rate (>90%) could be achieved in cvs. JTE-H and M. 26, while cv. MM. 106 showed weak rooting ability at each IBA level tested. Incre...asing IBA content depressed the rooting only in cv. M. 26. Presence of activated charcoal decreased considerable the rooting rate in cv. M. 26 and decreased the number of roots in cvs. JTE-H and M. 26. These cultivars developed longer roots on media containing activated charcoal, while cv. MM. 106 did not showed any reaction for it.

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Effect of 1-MCP (1-methylcyclopropene) on the vase life of Chrysanthemum and Carnation cut flowers

The effect of 1-MCP on extending the vase life of chrysanthemum and carnation cut flowers was studied. The flowering stems of both flowers were terminated to 50 cm. in height. Then, the flowers were pre-treated with 1-MCP at 0.3, 0.5 and 0.7g/m3 for 3 hours or 6 hours. The control flowers were placed in ambient air during the treatment. After t...he period of treatments the flowers were aerated then put in glass vials contained tap water. The vase life determination was conducted in a vase life evaluation room at 22 ± 1°C. Fresh weight determinations of the flowers were made just before the immersion of the flowers into the glasses of water and were repeated on the day when the vase life of the control flowers was terminated. The treatment of 1-MCP at 0.5g/m3 for 6 hours was the most effective treatment of chrysanthemum and carnation cut flowers.

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How to produce large sized microtubers of potato cv. Desiree

In vitro tuberization was induced on explants with different number of nodes layered on a medium with high sucrose (8%) content: 30, 15, 10, 7 and 6 explants per jar were cultured containing 1, 2, 3, 4 or 5 nodes, respectively. Microtubers developed were graded by their smallest diameter, and the number of tubers per jar, thei...r size distribution, their fresh weight and the multiplication rate were recorded. The highest multiplication rate (1.98) was obtained for explants with 5 nodes. The size distribution of tubers was markedly affected by treatments. The majority of microtubers (49.4%) were 6-8 mm in the case of the smallest explants (with I node). When explants with 2 to 5 nodes were used, the most microtubers were 8-10 mm but with an increase of explant size, more and more microtubers were produced with larger diameter up to 16 mm and average fresh weight of tubers also increased with the increase of explant size. For the microtuber production of Desiree the use of explants with two nodes can be suggested because in this treatment the average fresh weight of microtubers was high enough (250 mg) and the number of large sized microtubers was very high (79% was larger than 6 mm and 53% was larger than 8 mm).

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Peach latent mosaic viroid in naturally infected sweet cherry trees in southern Italy

Peach latent mosaic viroid (PLMVd) was found in naturally infected sweet cherry trees grown in commercial orchards in southern Italy. The viroid was detected in nucleic acid extracts of symptomless leaves by molecular hybridization with a PLMVd cRNA probe. The viroid was transmitted by grafting from sweet cherry to peach seedlings and identifie...d in peach by molecular hybridization.

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Certification programme for production of virus-free propagating material of grapevine and its results in Hungary

In Hungary, detection of virus and virus-like diseases of grapevine began in 1960's at the Research Institute for Viticulture and Enology by János Lehoczky and his colleagues. At present, sixteen virus and virus-like diseases of Vitis vinifera are known to occur in Hungary.

Regular virological screening of grapevine varieties ...started in 1972. The present system of screening (visual selection, indexing, ELISA) has been established using methods with continuous improvement according to recommendations of international organizations.

In the first year symptomless grapevine plants are selected and marked during surveys carried out twice in the vegetation period: at about flowering and in the second half of September. At the first selection time plants are sampled for ELISA.

In the spring of the second year, overwintered canes are checked by woody indexing on 8 indicator species in the field.

In the third and fourth years the nursery is evaluated twice again. At the end, the marked grapevine plants, giving negative results on all indicators in every case, are considered virus-free.

In autumn of the fourth year, the virus-free material is planted out under screenhouse and also in a special mother block (nuclear stock) for maintenance and propagation.

Mother blocks of virus-free scion varieties have been established on 2 ha and those of rootstock varieties on 0.5 ha planted with the following number of varieties included in the national list: 71 European scion — and 12 rootstock varieties or variety candidates/clones. It is necessary to increase the area of Pre-base, Base and Certified stocks exclusively with tested virus-free (clean) material.

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General defense system in the plant kingdom III.

Our observations regarding the symptoms not fitting into, significantly differing from the hypersensitive defense system, which we noticed during the judgment of several plant species, symptoms provoked on several million plants have constituted a unified entity. They have provided evidence for the existence of a different plant defense system.... We called this so far unknown basic response of plants to biotic effects as general defense system. This system defends them from the attack of numerous microbe species in the environment.

The evolutionary intermediate phase between the general and the specific, the two defense systems is the susceptible host—pathogen relation. The vertical resistance system of plants escaping from the susceptible host—pathogen relation, based on specific hypersensitive reaction also suggested the existence of a more original, general defense system and the susceptible host—pathogen relation developed as a result of the collapse of that system.

The evolutionary relation of the two defense systems is proved by the only recessive inheritance of the older general defense system and in the majority of cases dominant hereditary course of the specific defense system. In our experiences, the modifying genes of the recessive general defense system, in most cases, are behind the specific defense systems, which are known to have monogenic dominant hereditary course and react with hypersensitive tissue destruction. This seemingly striking genetic fact is explained by the following: the general defense system less dependent on environmental effects regulates much faster pathophysiological reaction than the specific resistance genes strongly dependant on environmental effects coding dominant hypersensitive reaction.

The general and specific defense reactions, the processes excluding the microbes attacking plants with compacting of cell growth and tissue destruction, which mean two opposite strategies, building on and regulating each other constitute the entity of resistance to plant disease.

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Study on the viruses of Petunia in Hungary

Virus susceptibility of 11 varieties of vegetatively propagated petunia against 2 virus strains (TMV-C/U1 and PVYNTN) were examined. Neither resistant nor tolerant varieties of petunia were found. The virus infection of the Petunia genus was examined in Hungary. The most common pathogens were the Tobacco mosaic tobamovirus (TM...V) and the Tomato mosaic tobamovirus (ToMV), but the samples also contained Alfalfa mosaic alfamovirus (AMV), Cucumber mosaic ClIC11171014171S (CMV) and Potato Y potyvirus (PVY). Potato X potexvirus (PVX) was isolated in the varieties of trailing petunia for the first time.

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Study on the yeast and mould biota of the botrytized grapes in Tokaj region in two years

The famous wine Tokaji Aszú is produced from "noble rotted" grapes infected and modified by Botrytis cinerea under special condition. The objective of this study was quantitative and qualitative characterisation of saprophytic fungi present on the surface of aszú­berries, with special regard to yeasts. There were considerable differ...ences in these populations depending on the origin of noble rotted berries, notably between berries taken from the vine or the ones taken from the winery. Beside Botrytis, other mould species like Penicillium, Aspergillus were commonly found, in widely varying population. Yeast counts were detected between 104 and 107 cfu/g berry. In the samples taken from the vineyard Candida pulcherrima predominated followed by some aerobic basidiomycetous species, but Hanseniaspora species were also present in relatively high population. After transport and storage of the grape in the wineries, population of aerobic yeasts and C. pulcherrima quickly declined and Candida stellata followed by other sugar tolerant species became dominant. This autoselection process directs attention to the importance of storage conditions.

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Fungicide resistant Trichoderma strains causing compost infection in shiitake production

Trichoderma infection represents the major problem of shiitake production in the growing house of the Research Institute at Kecskemet. Heavy infections occur mainly on the compost before spawn run. All the isolated strain belongs to the species Trichoderma harzianurn, but morphology of the colony indicates that there are more ...strains liable for the infection. Source of infection remained unclear but the Trichoderma strains can be considered as weed moulds rather than true pathogens of shiitake. All the Trichoderma isolates showed unusual high degree of resistance to fungicides.

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Examination of valuable ingredients of some wild fruits

A possible way of the development of Hungarian agriculture is the selection and growing of new fruit species and varieties featuring special qualities, with high biological nutritive and health protecting properties due to their natural composition. A reserve for such new fruits is the native dendroflora, e.g. those wild-growing trees and shrub...s of Hungary, which bear edible fruits. The publication is giving a summary of chemical analyses done on the fruits of the plants listed below. The research team on the project started the work in 2001 with

woody species (genera) as follows:

  • common elder (Sambucus nigra) clone named Szcs-1, Szcs-2, Szcs-3, Szcs-4, Szcs-5, SzcsK-1, SzcsK-2
  • dog rose (Rosa canina) types: clones named Sz-1, Sz-2, Sz-3, Sz-4 and Sz-5 .
  • native rowans: Sorbus dacica, S.rotundifolia, S. degenu, S.bakonyensis cv. Fánivölgy
  • hawthorns: Crataegus monogyna, C. orientalis,C..v lavallei.
  • cornel cherry: Cornus mas cv. Császló.

The present paper is reporting on the content of the following compounds in the fruits: dry matter (refractometric values), total acid content, ascorbic acid, 13-carotene, pectin, minerals and carbohydrates. The results have shown that these wild fruits have excellent composition. Besides their curative effects, their content of minerals, ascorbic acid and 13-carotene has surpassed that of the traditional fruits. These fruits are rich in ascorbic acid, 13-carotene and pectin. The high content of the above-listed, biologically active compounds makes the new wild fruits studied suitable for the preparation (and later: mass-production) of special curative and exclusive products.

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Mathematical and Statistical Modelling of Impact Symptoms and Application to Tomato

Drop tests were performed with different tomato cultivars. „Rupture" and „no rupture" conditions were determined as results. The proportion of „rupture" was shown versus the drop height and the relationships were described by a logistic function. The different cultivars are compared on this basis. The tests and results are suitable for th...e evaluation of stress sensitivity of tomatoes.

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Field Vegetable Production in Hungary

Hungary is a country with excellent ecological potentials and with rich traditions in vegetable production. The total vegetable production area comprises about 100 000 ha and annual production amounts to 1.4-1.8 million tons, 75-80% comes from fields and the rest from forcing. Approximately 40 species are produced, but only 20 of them play a do...minant role. The most important ones arc: sweet corn, peas, peppers, watermelon, onions, tomatoes, gherkin, carrots, beans, white cabbage.

40-45% of the total production is processed, 20-30% sold on the fresh market and 30% exported.

Vegetable production is based on rural farms of 1-5 ha average acreage. It provides living for about 70-100 000 families. The low number of producers' organisations is a major setback.

Profitability of vegetable production is rather low. Production costs are high, wholesale prices are depressed.

Vegetables are produced for the industry by contract. Fresh vegetables are sold through local markets (15-20%), the wholesale market (decreasing importance) and direct marketing (35-40%).

Against the self-sufficiency of the country there is a seasonal import of vegetables mainly in winter and early springtime.

Hungarian legal regulations are harmonized with the EU directives, EU standards are accepted and applied, traditionally good market connections and cooperation with several EU countries enable the country to be a partner of EU vegetable growers.

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