Search
Search Results
-
The in vitro and in vivo anatomical structure of leaves of Prunus x Davidopersica ‘Piroska' and Sorbus rotundifolia L. ‘Bükk szépe'
92-95.Views:576Immature in vitro leaves showed similar structure of the mesophyll tissue to the immature field-grown (in vivo) leaves of Prunus x davidopersica `Piroska'. Mature leaf anatomical characteristics of in vitro plantlets differ from the field-grown plants. The mesophyll tissue of in vitro plantlets were thinner than the in vivo plants and consisted of only one layer palisade parenchyma, the shape of the cells and the structure of spongy parenchyma basically differed from the field-grown plants. In the case of Sorbus rotundifolia similar anatomical differences were found both in vitro and in vivo as in the case of Prunus x davidopersica `Piroska'.
-
Prospects of mango fruit powder production at farm level and its utilisation during mango off-season in Ghana
Views:1012Mango (Mangifera indica) is an important fruit served to customers as fresh-cut fruit, juice, ice cream and yogurts in many fruit juice joints, restaurants and hotels in Ghana. However, the crop’s highly seasonal and perishable nature is a challenge for food processors and farmers. Preservation of the fruit in dry particulate form can serve as a substitute in off-seasons. The study sought to determine mango fruit powder production prospects at the farm level and explore its potential use as a substitute during the off-season. Farmer groups and food enterprises were therefore interviewed. The study showed that Keitt and Kent varieties were the most cultivated varieties because of market demand and high yield. However, an average annual fruit loss of 29.8% at the farm level was observed. Postharvest extension delivery service to farmers is inadequate, and where available, frequency of contact is irregular. A limited number of farmers received training in fruit processing; and few were engaged in transformational value addition activities but were willing to add value through processing into powder. Probit regression analysis showed that a unit increase in training would increase transformational farm level value addition into mango fruit powder by 22.9%. The majority of the food enterprises source fruits within Ghana while 79% experienced mango fruit shortage in the off-seasons. Only a few of the enterprises used mango fruit-based substitutes to serve customers in off-seasons. Probit regression analysis showed that a marginal increase in processors’ use of substitute significantly (p≤0.05) increased willingness to use mango fruit powder as a substitute by 47%. The study has revealed that local production of mango fruit powder could serve as a substitute to fill the seasonal gap in mango supply and also reduce post-harvest losses.
-
Effect of variety and cultivation technology on phenols and antioxidant activity of sweet and sour cherry
59-61.Views:1219The goal of the present work was to compare different sweet and sour cherry cultivars and cultivation methods (bio/integrated) with respect to polyphenol content and antioxidant activity. The concentration of total polyphenols ranged between 880–1050 mg kg-1 of fresh fruit, whereas antioxidant activity expressed as TEAC was found to be between 5.4 and 10.3 mmol kg-1 for the sweet cherry cultivars examined. In case of sour cherry the level of polyphenols ranged between 1283 and 3490 mg/kg fresh edible part of the fruit. Antioxidant activity was recorded between 15–32 mmol kg-1 for the different sour cherry cultivars included in this work. After one-month storage at low temperature, the total phenols and antioxidant activity decreased by 2–40% in the sour cherry cultivars studied. The anthocyanin content in cherry cultivars was less (131–312 mg kg-1) than the135–1893 mg kg-1 found in sour cherries. Anthocyanin level was higher in samples produced under organic farming conditions than in those produced with integrated cultivation.
-
Evaluation of essential oils by gas-chromatography and a new method: "electronic nose"
85-89.Views:282The chemical quality of the essential oils is determined by their composition as well as by the complex aroma features. For the evaluation of odour and aroma, sensory tests are practised, especially for applications such as aromatherapy, food industry or perfumery. In the recent studies we investigated eight Mentha origins (populations of Mentha iperita, M. spicata and M. arvensis) of our genebank collection using a new and effective instrumental sensory evaluation method parallelly with the usual GC analysis.
The results show that the examined mint clones possess different essential oil accumulation levels and special flavour characteristics, too. The GC analysis of the essential oil revealed characteristic differences at both inter- and intraspecific level in the proportion of mentol, menthon, carvon, limonene, menthyl acetate and in two not identified monoterpenes.
In the sensory tests the special complex aroma enables a reliable distinction with a single exception among the populations by the help of the "electronic nose" equipment. The distinction among the samples based on the sensor signals of the instrument — evaluated by multivariate methods — shows a close relation with the detected monoterpene components of the essential oil.
-
Shoot induction and plant regeneration from cotyledon segments of the muskmelon variety "hógolyó"
61-64.Views:333Cotyledonary segments of the casaba type muskmelon variety "Hógolyó" were used to induce organogenesis. Fifty different hormone combinations were applied to enhance the induction of shoot formation on the edge of the segments. The phases of organogenesis were followed with light- and scanning electron microscope. Shoot induction was achieved with high frequency. The shoots were transferred to hormone free media for root induction. The rooted plantlets were planted out to soil.
NAA was feasible and the method can be applied in transformation experiments.
-
Performance of sweet cherry cultivars grafted on Colt rootstock
7-10.Views:1055In this paper growing characteristics and fruit bearing parameters of ‘Lapins’, ‘Kordia’, ‘Sweetheart’ and ‘Regina’ sweet cherry cultivars grafted on vigorous Colt rootstock were evaluated at the University of Debrecen, Pallag Experimental Station. Based on our data five years old trees can be described with homogenous strong growing, but very week yielding (2.1-3.1 kg/tree), as while fruit size varies between 26.2 and 27.2 mm. Producing the examined cultivars on Colt rootstock with high plant density requires higher attention and more interventions (root pruning, sawing the trunk) during the technology.
-
Apple allergens as affected by cultivation technolog and variental factors
91-93.Views:1240Our objective was to study the effect of organic farming and area of cultivation on the allergen content of apple varieties by quantification of the major allergens (Mal d 1 and Mal d 2) using allergen-specific ELISA. The obtained results showed that except Idared IX. 29. most of examined varieties, when cultivated under organic farming conditions, contained lower level of Mal d1 allergen than those produced with integrated farming. The different varieties were found to vary substantially in theirMal d 1 allergen content. Furthermore, with some varieties the area of cultivation affected to some extent the content of Mal d 1 allergen.
-
The Effects of Some Parameters on Agrobacterium-Mediated Transformation in Muskmelon
46-49.Views:398Some parameters involved in Agrobacterium-mediated transformation in muskmelon Hales best (HBS) were studied. Cotyledon explants excised from 3.5-day-old seedlings were co-cultivated with Agrobacterium tumefaciens harbouring binary vectors which contained GUS and BAR genes. After co-cultivation on a low pH medium, explants were transferred to selective medium, with higher pH, containing Claforan and Finale. The medium was changed every two weeks till shoots were induced. All shoots rooted on MS medium supplemented with 0.3 mg/L IBA. These parameters combined as a whole led to successful transformation. The expression of the introduced gene construct was confirmed by GUS staining of shoot segments.
-
Content of mineral- and sulphur compounds in Hungarian and French garlic varieties
61-65.Views:418In our days about 2 million tons of garlic are grown in the world. Garlic was used as medicine already in ancient Egypt. It contains approx 33 sulfur compounds, several enzymes, 17 amino acids and minerals. We determined the content of diallyl sulfone, boron, calcium, copper, iron, potassium, magnesium, natrium, phosphorus and zinc in fi ve garlic varieties (3 French, 2 Hungarian). We searched if there were signiffi cant differences between the varieties.
-
The effect of modified bacterial virulence to host-pathogen relationship (Phaseolus vulgaris L. Pseudomonas savastanoi pv. phaseolicola)
53-56.Views:592The Pseudomonas savastanoi pv. phaseolicola is one of the most expressive biogen stressors of the bean (Phaseolus vulgaris L.) in Hungary. The chemical and agrotechnological defence is inefficient, so breeding is the only workable way. The conventional cultivars are susceptible to PS while most of the new industrial varieties have genetic resistance to the pathogen. The genetic background of resistance is, however, a complex system in the bean. Leaf resistance is a monogenic system, but this gene is not expressed in juvenile stage of the host. The pathogen species can be divided into different races. After inoculation with virulent strains, typical symptoms appeared on the leaves. To understand the details of host-pathogen relationships, there were carried out experiments using bacterial strains with altered virulence. Six transposon mutants of the PS were tested. Our main objective was to test these modified bacterial strains on bean cultivars of known genetic background. First we analysed the symptoms, and then the correlation between the symptoms and the multiplication of mutant bacteria. Three cultivars (Cherokee, Inka and Főnix) were tested.
The infection by the virulent PS isolate produced typical symptoms on the three cultivars tested. Mutant bacteria (except strain 756) did not cause any significant symptoms on the hosts. The mutant 756 induced visible symptoms on the cultivars Cherokee and Inka. On Cherokee there were small watersoaked lesions, and HR (hypersensitivity reaction) was detected on Inka, but this was restricted to some cells only (mikro HR). The rate of multiplication of the wild type strain was much higher than the multiplication of the mutants. Bacteria were detected in the cotyledons and primordial leaf, but there is not any substantial number of bacteria in leaves, except for strains 757, 1212 and 1213. The rate of multiplication of strain 756 was intermediate. These, and other experiments can help to understand the genetic background of resistance and the host-pathogen relationship in the Pseudomonas-bean pathosystem.
-
The effect of storage to optical properties in case of two apple fruit varieties
33-36.Views:1027The keeping quality of fruits is a very important factor in storage point of view, since it could be elongated the consumption time of fruits. In many cases the storage may be necessary, e.g. in short time it is not able to market due to the rich harvest, or all fruits could sell in markets throughout the year. The keeping quality of various fruit species is greatly different; moreover it could be observed some differences between the varieties as well. In our research, we have investigated the spectral properties of the external surface and fl esh of two ripe apple varieties – Jonagored and Granny Smith – before and after storage (about 3°C and about three weeks). The hyperspectral investigation was carried out with AvaSpec-2048 Fiber Optic Spectrometer. The experimental results represented the differences between healthy and chilling injured apple fruits. Furthermore, some indices were created to given countenance to the spectral differences.
-
Antioxidant capacity, total phenolics and mineral element contents in fruits of Hungarian sour cherry cultivars
59-64.Views:1365Several epidemiological studies revealed that the consumption of antioxidant compounds and the risk of atherosclerosis, increased blood pressure or cancer are inversely proportional. Fruits of sour cherry contain a wide range of antioxidant compounds including melatonin, perillyl alcohol, ellagic acid, several flavonoids, polyphenolics, and anthocyanins. This study was carried out to survey the antioxidant power and mineral element content of seven commercial sour cherry cultivars and three cultivar candidates and to assess the influence of some external conditions on fruits' functional properties. Our analysis revealed nearly 5- and 2-fold differences between the lowest and highest antioxidant capacities and total phenolics content, respectively. Some cultivars (`Kántorjánosi' and ‘Újfehértói fürtös') and cultivar candidates (D, 'Petri' and 'Éva') showed outstanding antioxidant capacity and total phenolic content; in addition, mineral element content in fruits of the ‘Újfehértói fürtös' cultivar was also favourable. Redox parameters of fruits were influenced by the cultivation plot or fruit positions within the canopy in about half of the cultivars tested. Genetic background of cultivars forms the decisive factor in determining fruits' antioxidant capacity, although external factors may have also sizeable modifying effects. Enhanced functional properties of the fruit may also be further increased through breeding programs since considerable variation exists within the tested germplasm.
-
Stress physiology of palm trees II. The effect of heavy metals and high irradiance on the photosynthesis of palm Trachycarpus fortunei
84-88.Views:306A study was carried out to analyse the individual and combined effects of heavy metal toxicity and high irradiance on the photosynthetic characteristics of young, fully expanded leaves of palm seedling Trachycarpus fortunei under laboratory conditions. Heavy metals were found to inhibit both the light and dark reactions of photosynthesis and the inhibition was more affected in the light than in the dark. Single photoinhibitory conditions caused a 60 % decrease in the electron transport activity after 120 min of light exposure which was completely reversible in the dark. In contrast, the combined effect of high light and heavy metal treatment resulted in a 90 % decrease in the activity, but no reversible recovery in the dark could be detected. This indicated that the simultaneous effect of these two stress factors led to irreversible damages of the photosynthetic machinery and as a consequence caused the general destruction of the plant.
Abbreviations and symbols: Fo: initial chlorophyll fluorescence; Fm: maximum total fluorescence; Fv: variable fluorescence; AFi: intermediate level of fluorescence induction; PSII: photosystem 2.
-
Change of Thiamine concentration and amino acid composition during sparkling wine base Production
62-66.Views:297It has been established, that thiamin content added in 3 mg/I concentration to musts before fermentation resulted in the enhanced storability of sparkling wine base at lower SO2 levels. Fermentation rate is not increased by this concentration and it causes no "thiamine taste" in organoleptic evaluation.
-
Determination of quality in stored pear fruits by chemical analysis and sensorial judgement
27-31.Views:994Aim of this research/project to determine the external and internal preferences of pear using descriptive sensory analysis, consumer preference. The research was performed on local consumers. Destructive measurements included fi rmness by puncture tests, soluble solids content (SSC), titrated acidity (TA). While there is a general positive trend for increasing preference with fi rmness, some consumers will prefer softer apples, and some will dislike the fi rmest pear. Sensorial judgement is able to classify the attractiveness, preference of properties specifi c for pear. Tests were performed by 13 persons on 4 pear varieties (Bosc kobak, Conference, Packham’s Triumph, Dessertnaia) checking 11 sensorial properties on a scale of 1 to 100 points. Relations of measurements and judgements were processed by correlation analysis. For analysis, the objects were furnished in 2011 from different growing sites (Csenger, Mérk and Nagykanizsa), taking from the store (in January) immediately. Among those the best notes were given to Bosc kobak and Conference coming from Mérk and to Packham’s Triumph grown at Nagykanizsa. It was stated that the success of sensorial judgement depends on the state of maturity, which is diffi cult to guarantee to be synchronous among samples of different varieties. Mature fruits are more praised as a sample of Bosc kobak taken from a chain of department store proved to be of balanced composition regarding its sugar/acid ratio (0.12) and the optimal fi rmness (5.75 N/cm2). Results of the correlation analysis suggest that the thickness of the skin is a decisive component of preference (r= 0.857), the typical pear flavour (r= 0.948), the taste as sweetness and acidity (r= 0.930 and r= 0.813). At the same time, no valuable relation could be detected between the data raised in the laboratory and the preference expressed by the sensorial tests, which should signalise that the opinion of consumers does not depend on any individual parameter obtained in the laboratory (sugar- or acid content, fi rmness) but rather on the complexity of several decisive components together (sweetness, acidity, fl avour, skin, etc.). The consumers’ preference cannot be measured objectively without the aid of adequate expertise and a prosperous surrounding, samples of optimal maturity and a thoughtfully edited judging form.
-
Investigation of the Antioxidant Effect of Hungarian White Wines and Tokaj Wine Specialities
22-26.Views:545Authors investigated the antioxidant effect of wine-phenolics, expressed as total antioxidant status (TAS-value). This property may play an important role in elimination of the harmful effects of free radicals in human body.
Independently of their polyphenol composition, special quality Tokaj wines did not show extremely high TAS-values. In Tokaj Aszu wines the total antioxidant status was independent of the "puttony" number but was influenced by the length of aging time.
-
Investigation of flowering dynamics of the basil (Ocimum basilicum L.) and its consequences in production
74-80.Views:501The flowering dynamics of Ocimum basilicum L., (a common population maintained at the UHFI) was studied with the aim to create an exact and practically applicable method for definition of phenological phases.
According to our observation the development of individual flowers of the basil can be characterized by 8 distinguishable phases, which must be considered for description of the actual phenological stage of a spike.
An accurate model was created for the unambiguous description of flowering process of different flowers within the spike and for the individual plant as a whole. The new flowering index formula is calculated from the number of flowers weighed by their phenological phases.
The time dependence of flowering is presented by functions fitted to values of the flowering index. The results reflected different patterns of the main inflorescence, the inflorescences formed on the side shoots in the first or in the second half of the flowering period. However, for description of the flowering process of the whole plant, a sigmoid function proved to be the appropriate model.
The accumulation process of the essential oil could be characterized by the flowering index values. They showed close correlation (r=0.964) at high probability.
The new method assures an exact definition of phenological phases in basil. Its application seems to be optimal during breeding procedures, seed production and even in production of high quality drugs, according to the requirements of the Good Agricultural Practice (Guidelines for GAP, 1998).
-
Importance of orchard floor management in organic fruit growing (nutritional aspects)
61-67.Views:1587Worldwide 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.
-
Growing characteristics of apple cultivars in environmentally friendly growing systems
7-10.Views:659Nowadays the condition of the good saleability of the fruit is the application of controlled environmentally friendly technologies. Success of the growing is basically influenced by the production value of the cultivars, and their flexibility to the different technologies. In our examinations the effect of the integrated and organic farming system has been evaluated on the growing characteristics of the apple cultivars. According to our results the trunk thickness of the trees both in the initial and both in the later bearing period is higher in the integratedproduction compared to the organic farming system. This differences most likely caused by the variance of the crop load.
-
Possibility of stevia (Stevia rebaudiana B.) production in Hungary
29-32.Views:511Artificial sweeteners have harmful effect on human health, so it is great interested in stevia extract. Our experiment was aimed to show the possibility of inland production of stevia. Different plastic mulches were used (black and white) on raised bed and were compared to uncovered (control) plots for yield and state of health of plants. Furthermore we evaluated the depth of cuttings (low cutting until the 6th double leaf; normal cutting until the upper ⅓ of the plant) on the yield depending on the covering method. The plants were transplanted on 9 of May, 2014 on raised bed, 3 rows on it, with 33x25 cm spacing. According to our results, the black plastic mulch produced the highest yield, which can be explained by suppressing effect on weeds, furthermore it kept the soil warm, moist and protected the lower leaves from soil wetness. But, the white sheet mulch could not eliminate weeds around the plants. The total biomass on the black plastic sheet covered plots was the highest, nearly 1000 g pro plant by low cutting. On the control plots the fungi infection reached about 25-30%, which caused leaf falling of plants, decreasing of yield by the end of vegetation period. To summarise, stevia production is possible in Hungary, but it is important to pay attention to the balanced soil moisture and low humidity in the leaf area. It is suggested to cover the soil with plastic sheet or organic materials, such as bark and chippings.
-
Antioxidant, polyphenol and sensory analysis of cherry tomato varieties and landraces
75-80.Views:607Among vegetables produced both for raw consumption and processing, tomato is one of the most important one in Europe, by production area and by yield as well. In the past years several study dealt with the investigation of the inner content of tomato, with special regards to antioxidant content. In this paper cherry tomato varieties and landraces from conventional and organic production were compared. Besides basic investigations sensory analysis were designed and Antioxidant Capacity (AOC) and Total Phenol Content (TPC) were measured. The aim of the research was to compare varieties and to study the effect of variety and production methods on antioxidant capacity and sensory profiles.
-
Seed protectant potential of Mitracarpus villosus and Phyllanthus fraternus extracts on germinative capability of stored food grains
7-10.Views:494Seed storage is an essential post-harvest operation that decides the success of seeds viability and germination in next generation. The study explored Mitracarpus villosus and Phyllanthus fraternus extracts as bio-insecticides seed treatments on stored wheat and green gram seeds viability and germination. M. villosus and P. fraternus plants powder were sequentially extracted with solvents of increasing polarity (Petroleum ether, hexane, ethyl acetate, acetone, chloroform and methanol), concentrated and tested for insecticidal activity by fumigant toxicity. The extract which showed maximum activity, was selected for seed viability and germination test. Five replications each were made for the treatment and the control. The plant extracts strengthen the non-phytotoxic nature of plant products against seed viability and germination. Seeds treated with extracts (50-400 μg seed-1) did not lose their viability as it resulted in successful and normal germination within the range of 90 – 97.67% irrespective of the extracts concentration. While, seeds in control recorded 95.55 and 100% germination which were not significantly different (P>0.05) compared to the treated seeds. Based on findings from the study, potential exploitation of M. villosus and P. fraternus as food grains protectant in insect pest management strategies is recommended for the resource poor farmers. However, further investigations are suggested on biosafety and effects of the extracts on the organoleptic contents of the grains prior to consumption.
-
Evaluation of elder (Sambucus nigra) varieties and candidates for the canning industry. Results of the composition studies
102-107.Views:292Sambucus nigra is a very common elder species in Europe. Due to its excellent composition, natural dye content and healing power it can be considered as a biological active plant. In Hungary the cultivation of Sambucus nigra started in the nineties and since that time there is a growing demand for this plant. Sambucus nigra is a special fruit due to its sole.-application for processing industry. Partly fruit products are made of it, partly it is used as a natural dye. In both cases the first step is the knowledge and evaluation of the composition of the various elder varieties and candidates. For that reason composition studies of different elder types were performed in several years at the Department of the Canning Technology of the Szent Istvan University.
The most important sample was the Haschberg variety, which is the sole elder type accepted and allowed for propagation by the government. This plant is grown in the Pilot Plant of the Szent István University in Szigetcsép. Among the studied samples there were some varieties cultivated in the Fertőd Research Station. They were the following types: No. 33, 480 and 481. Besides elder collected wild in Szigetcsep and the very promising early-ripened SZ-CS 21-23 variety originated also from Szigetcsép were investigated. One year it was possible to study the Sambu variety, too. Department of the Fruit Culture of the Szent István University helped to obtain the various elder types and candidates. Along our experimental activities, the following components and parameters were studied: the content of pectin, organic acid, carbohydrate, mineral, vitamin C, total acid, aquesoluble dry material, anthocyanin and the pH.
After having obtained a juice, a concentrate from the species has been made and — after freezing — the aquesoluble dry substance and the acid content, as well as the colour parameters were monitored. Studies were performed in two years (1997-98). On the basis of these results classes were established for all compounds, from which an overall ranking was derived.
It was found that in both years the Haschberg variety proved to have the best composition. Therefore regarding to the overall series of order the experiments performed in the second year supported the results obtained in the previous year. Results have shown that Sambucus nigra has excellent composition beside its curative effect. Its mineral content has surpassed that of the other fruits and it had advantageous acid-and carbohydrate composition. The ascorbic acid content of the Haschberg variety is striking. It can be concluded from the experiments that the Haschberg type has the most advantageous composition, therefore it is suitable for making special curative and exclusive products.
-
Improved evaluation method for reliable distinction of poppy (Papaver somniferum L.) cultivars
68-73.Views:394Investigating seven Hungarian standard cultivars (i.e. 'A1’, 'Kék Gemona', '13C-2`,'Kék Duna', `Kompolti M’, `Gödi N',
'Kozmosz) it was proved that for the reliable distinction between cultivars a complex analysis is necessitated. Because of the large morphophenological and production-biological plasticity of the species qualitative and quantitative features as well as alkaloid accumulation characters have to be evaluated simultaneously applying discriminant analysis.
It was proved by the investigations that some of the qualitative and quantitative characters included into the DUS evaluation procedure have slight importance for reliable distinction. As an example the majority of cultivars show high inhomogentity in such characters like the shape of stigmatic disc, the number of stigmatic lobes etc. Furthermore these characters never had been chosen for the goal of any practical selection and are modified by the weather conditions as well.
In the evaluation process the alkaloid accumulation characteristics (both qualitative and quantitative ones) have to be evaluated on a higher rank. For instance the high accumulation level of morphine in cv. 'A1' (10.5 %o), exceptionally high narcotine accumulation in 'Kék Gemona' (7.8 %o), or the low morphine accumulation level in cv. 'Kozmosz' (1.1 %o) proved to be proper characters for their distinction, alone. However, at the same time the weather conditions existing at the time of experiment have to be taken into consideration. From practical point of view, the years rich in precipitation and poor in sunshine are less suitable for distinction of cultivars selected for higher alkaloid accumulation, especially for production of codeine and thebaine characterized by a higher methylation level. Based on the example of 'Kék Gemona', the accumulation level of morphine decreases from 7.4 %o to 4.1 %o under such conditions, while thebaine and codeine disappear, practically.
-
Study of genetic resources for Powdery mildew resistance by biochemical and physiological parameters on peaches and nectarines in Romania
57-61.Views:257During 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.
