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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Organizaciono-ekonomska obeležja zasnivanja i proizvodnje jagode (Fragaria x ananassa Duch.)

Galić Dragan 16 April 2015 (has links)
<p>Ba&scaron;tenska jagoda (Fragaria x ananassa Duch.), poznata po svom delikatnom mirisu, ukusu i bogastvu u vitaminima i mineralima, gaji se u svim regionima sveta. Jagode, kao voće sa visokom proizvodnom i upotrebnom vredno&scaron;ću, zahtevaju visoka ulaganja rada i metrijala po jedinici povr&scaron;ine. Imajući ovo u vidu, jagoda zahteva posebnu pažnju u svim etapama proizvodnje (gajenja) tj. od zasnivanja jagodnjaka do berbe i prodaje. Cilj ovog istraživanja je, utvrđivanje investicione vrednosti zasnivanja i ostvarenih ekonomskih efekata koji se postižu u proizvodnji jagode karatkog i neutralnog dana u uslovima jugo-zapadnog Ontarija u Kanadi. Najveća proizvodnja u svetu se ostvaruje u severnoj hemisferi (90,5%). Vodeće zemlje po proizvodnji jagode su: SAD, &Scaron;panija, Japan i Republika Koreja. Ove četiri zemlje čine 47,2% od ukupne svetske proizvodnje. Najveće povećanje kapaciteta jagode postignuto je u južnoj hemisferi. Za prikupljanje podataka o tehnologiji gajenja i investicionoj vrednosti ulaganja u proizvodnji jagode, kori&scaron;ćena je metoda anketiranja. U anketi je učestvovalo 19. proizvođača jagoda kratkog i 9. neutralnog dana u toku 2011. i 2012. godine. Upitnikom su prikupljeni podaci o tehnologije gajenja jagode po radnim operacijama, upotrebi materijala, ma&scaron;ina i radne snageTakođe, evidentirane su i strane usluge, ostvareni prosečni prinosi, prodajni kanali i procenat uče&scaron;ća u ukupnoj prodaji i postignuta prosečna cena.</p><p>Na osnovu prikupljenih podataka izračunati su tro&scaron;kovi zasnivanja jagodnjaka, redovne nege i brbe u prvoj i drugoj godini i ostvareni profit za obe grupe jagode. Jagode kratkog dana se isključivo gaje u redovima na otvorenom, a jagode neutralnog dana na bankovima obloženim belom polietilenskom folijom i instaliranim kap-po-kap sistemom za navodnjavanje. Najveći procenat (70%) jagode kratkog dana se prodaje direktno kupcima na gazdinstvu ili lokalnim pijacama, a 55% jagode neutralnog dana se prodaje kanalima veleprodaje. U proseku, proizvođači jagode kratkog dana su postigli profit $CAD 22.300/ha (29,10% od ukupnog prihoda), a proizvođači jagode neutralnog dana $CAD 37.962/ha (29,50% od ukupnog prihoda). Znači, proizvodnja obe grupe jagoda je veoma profitabilna, i postoji realna osnova za dalje povećanje profita.</p> / <p>The cultivated strawberries (Fragaria x ananassa Duch.), known for its delicate fragrance, flavour, and rich vitamin and mineral content, can be grown in most arable regions of the globe. Strawberry production, like many high-value crops, is resource and labour-intensive. Therefore, attention to detail is required at all stages of strawberry production, from establishment to harvest and marketing. The objective of this study was to determn the cost of strawberry establishment and achived economic effects of short-day and day-neutral strawberry production in south-western Ontario, Canada. The most of the production is located in the northern hemisphere (90.5%). The leading strawberry producing nations are USA, Spain, Japan and Republic of Korea. These four countries counted for 47.2% of all world&rsquo;s strawberry production. The largest increase in strawberry production capacity was recorded in the southern hemisphere. For data collection on procedure for growing a crop of strawberries and investment in strawberry production a survey technique was used. In survey participated 19 short-day and 9 day-neutral strawberry growers and was conducted in 2011 and 2012. The survey recorded strawberry production procedures, materials, equipment and labour use. Also, growers reported external<br />Mr Dragan M. Galić - Doktorska disertacija<br />vii<br />services used, achieved yields, marketing channels of sale, percent of each channel and achieved average sale prices. Based on collected information the cost of establishment, regular care, harvest in first and second year and total income were calculated for both groups of strawberries. Short-day strawberries are grown on matted-rows, while day-neutral on raised beds on white plastic with trickle irrigation installed. Most (70%) of the short-day crop was sold via direct sale (&ldquo;U-pick&rdquo;, ready-picked and farmers&rsquo; market), while 55% of day-neutral strawberries were sold in wholesale. On average, growers of short-day strawberries generated a profit of 22,300 $CAD/ha (29.10% of total income), and growers of day-neutral strawberries 37,962 $CAD/ha (29.50% of total income). Based on this study, both groups of strawberries in Ontario are highly profitable and with great potential for frofit increase.</p>
32

POLYPHENOL CONTENT AND DIFFERENTIAL EXPRESSION OF FLAVONOID BIOSYNTHETIC PATHWAY GENES OF <em>FRAGARIA</em> SPP. WITH WHITE FRUIT

Roy, Sutapa 01 January 2016 (has links)
Strawberries are a rich source of polyphenols which contribute to berry color and plant disease resistance, and have been shown to lower the risk of many chronic when consumed. While a considerable body of work exists on the polyphenolic composition of commercial strawberry (Fragaria x ananassa Duch.), less information is available concerning polyphenols in Fragaria vesca, or Alpine strawberry, considered a model system for the Rosaceae family of crop species. The study of natural and genetically-engineered F. vesca mutants with white fruit can provide unique insight into regulation of metabolic flux through the complex branched phenylpropanoid/flavonoid biosynthetic pathway. Thus, the identity and quantity of major phenolic-derived anthocyanins, flavonols, flavan-3-ols, hydroxycinnamic acids, and ellagic acid (EA)-derived compounds, of red-fruited versus white-fruited genotypes of F. vesca and F. x ananassa were compared by high performance liquid chromatography-mass spectrometry. Due to the unknown origin of all but one white-fruited mutant of F. vesca, it was assumed that each resulted from independent mutation events and would exhibit different flavonoid profiles. A total of 27 phenolic-derived compounds were identified. The white genotypes of both species had very low anthocyanin levels. Total content of free EA and its conjugated forms were generally higher in white than in red F. vesca, but were the opposite in F. x ananassa, more in red than in white berries. Differences in content of individual flavonoids and in group totals among the white F. vesca genotypes suggested that they may represent different mutations affecting flavonoid production. Polyphenol profiles of a red and a white cultivar of F. vesca during four fruit developmental stages were determined along with transcriptional analyses of key structural and regulatory genes of the phenylpropanoid/ flavonoid biosynthesis. The final concentration of polyphenolic groups in red versus white F. vesca was due to the differential expression patterns of key pathway genes, especially dihydroflavonol-4-reductase, anthocyanidin synthase, and UDP-glucose-flavonoid-3-O-glucosyltransferase. The efficacy of phenolic compounds were evaluated in an in vitro study for inhibiting growth of Colletotrichum spp. associated with anthracnose fruit rot of strawberry. Only trans-cinnamic, p-coumaric, and ferulic acid inhibited isolates of the pathogen.
33

The effect of silicon on strawberry plants and its role in reducing infection by Podosphaera aphanis

Fatema, Kaneez January 2014 (has links)
Podosphaera aphanis which causes powdery mildew of strawberry is of economic importance in strawberry production in United Kingdom as it affects yield and fruit quality. Silicon has been shown to reduce the severity of a number of plant diseases. In strawberry, the mechanism of suppression against powdery mildew remains uncertain. Therefore, it has been suggested that supplying silicon would help strawberry plants to absorb silicon and improve resistance against the pathogen. The silicon based wetter Omex SW7 was used and three different concentrations of silicon wetter were applied on the leaves of the strawberry plants (foliar application). Each treatment was applied at three different timings. Enhanced level of silicon was quantified by the Autoclave Induced Digestion (AID) method. Whilst the main study has used the variety Elsanta, other varieties have also been used. It was observed that the weekly application (total 5 sprays) of 3 different concentrations of Omex SW7 on leaves showed significantly (P&lt;0.05) higher silicon concentrations compared to application 3 times in weeks 1, 3 and 5 or twice in weeks 1 and 5. Microscopic observations showed that weekly application of standard, high and very high concentrations of Omex SW7 significantly (P&lt;0.05) increased the number and length of leaf hairs on both the upper and lower surfaces of strawberry leaves. The different varieties of strawberry used showed morphological changes in the leaves with regard to the density and length of leaf hairs. Untreated leaves from Rhapsody had no hairs on the upper leaf surface, but a low density of hairs was observed after treatment with the high concentration of Omex SW7. In this study, Omex SW7, a silicon based wetter was applied to the roots of strawberry plants (root application) and silicon accumulation and physical changes in leaves were assessed. Strawberry variety Elsanta was used in this experiment. Results revealed that weekly application (total 5 applications) of 2 different concentrations (standard and high) of Omex SW7 to roots showed significantly (P&lt;0.05) higher silicon concentrations compared to application 3 times in weeks 1, 3 and 5 or twice in weeks 1 and 5. It was found that the weekly application of two different concentrations of Omex SW7 showed significantly higher (P&lt;0.05) leaf hair numbers and significantly (P&lt;0.05) longer leaf hair length on both the upper and lower surfaces of leaves compared to application 3 times in weeks 1, 3 and 5 or twice in weeks 1 and 5. The effect of foliar application of silicon and potassium carbonate to limit P. aphanis infection was examined in a field trial under polythene tunnel at Wisbech. Treatments were arranged in a randomised block design of 3 replicates. There were a total of 18 plots. There were six treatments and all treatments were applied to the strawberry variety Sonata. Results revealed that application of silicon based wetter Omex SW7 onto the leaf surface does result in accumulation of silicon in the leaves. The application of Omex SW7 has stimulated an increase in the number and length of leaf hairs in strawberry plants. Results showed that germinating ascospores and colonies were present in all plots before the trial was sprayed. Treatments with standard and high Omex SW7 significantly (P&lt;0.05) reduced the number of germinating ascospores and colonies in this trial. However, Potassium carbonate alone gave some reduction in the number of colonies and germinating ascospores. Moreover, potassium carbonate mixed with silicon based wetter Omex SW7 significantly (P&lt;0.05) reduced the number of germinating ascospores and colonies.
34

Effect of Nitrogen Application on Growth and Photosynthetic Nitrogen use Efficiency in Two Ecotypes of Wild Strawberry, Fragaria chiloensis (L.) Duchn

Moon, J. W. Jr., Bailey, D. A., Fallahi, E., Jensen, R. G., Zhu, G. 12 1900 (has links)
The relationships between increasing nitrogen fertilization and growth, maximum CO₂ assimilation and the initial slope of the CO₂ response curve were studied in two ecotypes of wild strawberry, Fragaria chiloensis (L) Duchn. Nitrogen accumulation of CA11, an ecotype from a low -nutrient dune site, was greater at all nitrogen concentrations than that of RCP37, an ecotype from a higher- nutrient strand site. Maximum CO₂ assimilation, total Rubisco activity, dry weight, and initiation of leaves and crowns were higher in CA11 than RCP37 as nitrogen treatment was increased from 0 to 200 mg l⁻¹, whereas these parameters were lower in CA11 when fertilized at 300 mg l⁻¹, but not in RCP37. The mean leaf area of CA11 was greater than RCP37 when grown with no supplemental nitrogen, but mean leaf area of the two lines was similar under nitrogen fertilization. Maximum CO₂ assimilation and carboxylation efficiency increased with increasing leaf nitrogen in both clones. At equivalent concentrations of leaf nitrogen, RCP37 had higher CO₂ assimilation and carboxylation efficiency than CA11 and the difference between the 2 clones increased as leaf nitrogen increased. Thus, RCP37 had a higher photosynthetic nitrogen use efficiency than CA11. However, at a given applied nitrogen level, CA11 allocated more nitrogen to a unit of leaf area so that photosynthetic rates were higher than RCP37, except at the highest application of 300 mg l⁻¹. The high nitrogen accumulation capacity and resource allocation to fruiting structures (crowns) in CA11 lead us to suggest that this clone may possess genes that could increase fruit yield in cultivated strawberry.
35

Physiology of Flowering and Diurnal Net Photosynthetic Response in American Strawberry Cultivars under Controlled Environment

Garcia, Karla Patricia, Garcia, Karla Patricia January 2016 (has links)
Strawberry production in the United States is almost entirely done in open-fields. Recently, interest in off-season strawberry production using controlled environment (CE) systems such as greenhouses and soilless cultivation has increased in the US. However, strawberry production in greenhouses is relatively new in North America and available information about greenhouse strawberry production is limited. Plant physiological responses to the environment must be well understood to maximize production using CE systems. In the present research, photoperiodic and photosynthetic responses of strawberry plants in greenhouse were studied. To evaluate photoperiodic response eight cultivars of strawberry widely cultivated in North America were subjected to varied photoperiods under an average daily temperature of 17 °C. Short-day (SD) cultivars included 'Radiance', 'F-127', 'Shuksan' and 'Chandler', and day-neutral/ever-bearing (DN/EB) cultivars included 'Albion', 'Portola', 'Monterey' and 'San Andreas'. SD cultivars were subjected to treatments of 11-h, 12-h, 13-h and 14-h photoperiod for 8 weeks. DN/EB cultivars were subjected to separated treatments of 8-h, 11-h, 14-h and 17-h photoperiod for up to 10 weeks. After 8 and 10 weeks of photoperiodic treatments in SD and DN/EB cultivars respectively, shoot apical meristems (SAM) were observed under microscope and classified into one of twelve developmental stages (Indices: 0-11). All SD cultivars examined showed a critical photoperiod between 13 h and 14 h. DN/EB cultivars 'San Andreas', 'Albion' and 'Monterey' presented facultative long-day response with positive correlation between SAM developmental indices and photoperiod after 8 weeks of treatment. 'Portola' showed non-significant influences of photoperiodic treatments in flower primordial development, suggesting day neutral response. However, further experiments must be conducted to confirm cultivar responses and identify possible interactions between photoperiod and temperature. The effect of light intensity and plant sink/source balance on strawberry plant photosynthesis was also investigated. Measurements of leaf net photosynthetic rate (Pn), stomatal conductance, intercellular CO2 concentration (Ci) and transpiration rate under near-saturated photosynthetically photon flux of 1,000ï ­mol m-2 s-1 and ambient CO2 concentration in strawberry cultivars 'Albion' and 'Nyoho'; and tomato cultivar 'Speedella'(comparison purposes) were conducted monthly in greenhouse during May 2014, and monthly from September 2015 through May 2016 (winter/spring production season). Hourly measurements were recorded hourly from 9 AM to 4 PM. Potential source strength was determined by the number of leaves and the daily light integral (DLI, 400-700 nm) and sink load from flowers and fruits was represented as the number of flowers and fruits. Seasonal changes in daily maximum Pn were observed, as well as diurnal change in Pn in both strawberry cultivars. A significant positive correlation was determined between the estimated ratios of sink/source and the slopes representing diurnal linear decline of Pn. Also, Pn was negatively correlated with Ci but not significantly correlated with vapor pressure deficit (VPD) in greenhouse, suggesting diurnal decline in Pn was likely due to negative feedback of photosynthesis caused by unbalance of sink and source, and not to water stress from high VPD. The photosynthetic capacity as affected by seasonal changes in greenhouse environment and its diurnal change as affected by sink/source balance could help develop more effective practices in CE strawberry production to maximize production. Also, photoperiodic response revealed in this study for American strawberry cultivars will specify conditions to induce flowering in these economically important cultivars off-season.
36

Estudo da impregnação a vácuo de trealose como crioprotetor em morangos

Kunsler, Nicole Luíse Froehlich January 2017 (has links)
Embora o congelamento apresente vantagens em relação a outros métodos de conservação de alimentos, o mesmo causa alterações sensoriais, principalmente em produtos de origem vegetal. O morango, uma fruta muito apreciada e com formas variadas de consumo, tem comportamento sazonal e apresenta como fator limitante para o congelamento sua estrutura frágil e sensível ao processo, o que causa alterações sensoriais. Tais alterações podem ser minimizadas com a incorporação de crioprotetores, como a trealose, um dissacarídeo que vem se destacando pelo seu efeito crioprotetor em produtos congelados e desidratados. O principal objetivo deste trabalho foi verificar o efeito crioprotetor da trealose incorporada através da impregnação a vácuo em soluções de diferentes concentrações (100, 300 e 500 g/L) em morangos submetidos ao congelamento e descongelamento. As condições de impregnação foram de 5 min, aplicando pressão de -650 mmHg e 10 min de tempo de relaxamento. As alterações provocadas pelo processo de impregnação bem como a verificação do efeito crioprotetor da trealose foram identificadas através de análise de cromatografia líquida de alta eficiência (High Performance Liquid Chromatography- HPLC), análise colorimétrica, análise de textura, determinação do teor de sólidos solúveis, determinação do teor de umidade e perda de massa (perda por gotejamento). Os resultados mostraram que a concentração da solução de trealose exerce influência significativa no teor de umidade, teor de sólidos solúveis e teor de trealose. As amostras tratadas com soluções mais concentradas não sofreram desidratação após descongelamento. O teor de trealose, após descongelamento, permaneceu constante em todas as amostras tratadas. Todas as amostras tiveram a mesma perda de massa após descongelamento (perda por gotejamento), porém a composição da massa diferiu entre elas. Amostras tratadas com a solução mais concentrada perderam sólidos enquanto que as amostras tratadas com a menos concentrada, perderam água. Na análise de textura, a introdução da trealose não influenciou a força máxima de pico nas amostras impregnadas. Após descongelamento, todas as amostras, exceto a tradada com solução de 500 g/L, sofreram amolecimento. A parte externa dos morangos não sofreu alterações de cor devido à introdução da trealose nem devido ao congelamento e descongelamento. Na parte interna dos frutos, ocorreram variações no parâmetro L* devido à impregnação e no parâmetro b*, devido ao congelamento e descongelamento. / Although freezing offers advantages to others food conservations process, it causes sensorial changes, mostly in vegetables products. The strawberry, a quite appreciated fruit, shows different ways of use, has seasonal behavior and is limited to freezing due the sensorial changes caused by its fragile structure to freezing process. These sensorial changes can be minimized by the incorporation of cryoprotectors, as trehalose, that is known by its cryoprotector effect during freezing and dehydration. The aim of this work was to verify the trehalose cryoprotector effect in frozen and thawed strawberries introduced by vacuum impregnation with different solutions (100, 300 and 500 g/L). The impregnation conditions were 5 min of applying pressure of -650 mmHg and after atmospheric pressure was restored, the sample was maintained within the solution for 10 min (these conditions were obtained from previous experiments). The alterations caused by the vacuum impregnation and the verification of the cryoprotector effect of trehalose were identified by High Performance Liquid Chromatography (HPLC), color analysis, texture analysis, soluble solids content, moisture content and drip loss. The results have shown that concentration of the trehalose solution had a significant influence on the moisture content, soluble solids and trehalose content of impregnated strawberries. The samples treated with more concentration solutions did not dehydrated after thawing. The trehalose content was the same in all treated samples after thawing. All the samples showed the same drip loss due to thawing although the composition of the mass was different among the samples. Samples treated with the most concentration solution lost trehalose while the sample treated with the least concentration solutions lost water. The introduction of trehalose did not affect the maximum peak force of the impregnated samples. The freezing and the thawing process caused the softening of the samples. This effect was not observed on the sample treated with solution of 500 g/L. The introduction of trehalose did not cause significant differences in all color parameters measured on the outside of the strawberries after impregnation and thawing. In the inside of the samples, there were variation in the L* parameter caused by the vacuum impregnations and in the b* parameter caused by the freezing and thawing process.
37

Phenotypic Differences in Populations of Euonymus Americanus L. from the Central United States & Autecological Studies of this Species in a Deciduous Forest of Kentucky

Bayer, Paul 01 May 1984 (has links)
The concentrations of sodium and potassium in the leaves of Euonymus americanus collected from a relict hardwood forest during a four month period showed a possible winter conditioning pattern. Seeds collected from this same relict stand would not germinate, even though they were subjected to a wide variety of germination experiments. Phenotypic differentiation in fully developed leaves was not found; however, differences related to the length of the growing season were noted. Autecological studies of Euonymus americanus should be continued to investigate the role of this plant in relict hardwood stands.
38

Evaluation of Post Harvest Technologies for Improving Strawberry Fruit Quality

Misran, Azizah 17 May 2013 (has links)
Fragaria ananassa, generally known as strawberry is a nutritious fruit that is rich in polyphenols and widely consumed as part of a healthy diet. Anthocyanins have been found to be the main group of phenolic components present in strawberry with pelargonidin-3-glucoside as the major component in all strawberry cultivars studied. The main volatile component has been identified as caryophyllene oxide, a sesquiterpene compound that was present abundantly in all cultivars. The effect of preharvest spray applications of a formulation containing hexanal which is known to enhance membrane preservation, was evaluated using two strawberry cultivars, ‘Jewel’ and ‘Mira’. Our results suggest that preharvest spray application of hexanal formulation results in biochemical changes that alter the profile of phenolic compounds and the volatiles of the fruit. An osmotic infusion treatment was implemented to generate an intermediate moisture food product with high quality and enhanced storage life that can be potentially used in processed food. Infusing strawberry with other functional ingredients such as fructoligosaccharides, lecithin, and ascorbic acid showed that the infused strawberry produced by this technique was structurally and organoleptically similar to fresh strawberry, and visually similar to the intial fruits. Drying of infused fruits could extend their shelf life up to several months, while providing fruit products with superior nutritional qualities. Subjecting strawberry fruit extract to a simulated in vitro digestion of strawberry greatly affected the polyphenol composition and concentrations during different stages of digestion. The concentrations of most polyphenols increased during gastric digestion suggesting that the acidic environment of the stomach may help to release polyphenols that are bound to the strawberry matrix. Following incubation of the IN and the OUT fractions with colonic bacteria, the presence of urolithin B glucunoride in the IN fraction and the increase of ellagic acid deoxyhexoside in both the IN and OUT fractions after fermentation process, suggest that the polyphenols are catabolized into simple phenolic compounds in the colon. The remaining polyphenols as well as the catabolites in the gut, could potentially have a beneficial effect in enhancing colonial health. / Ministry of Higher Education Malaysia, Universiti Putra Malaysia
39

Braškių užsigrūdinimo ir atsparumo šalčiui charakterizavimas in vitro ir in vivo / Characterization of cold acclimation and cold hardiness of strawberry in vitro and in vivo

Lukoševičiūtė, Vanda 02 January 2014 (has links)
Atsparumas šalčiui ir ištvermingumas žiemą – pagrindiniai veiksniai, lemiantys augalų geografinį pasiskirstymą. Be to, šie veiksniai turi didžiulę įtaką kultūrinių augalų derlingumui. Braškės, kurios yra tarp svarbiausių uoginių augalų pasaulyje ir Lietuvoje, stipriai pašąla esant nepastoviai sniego dangai, vis dažniau pasitaikančiomis permainingomis žiemojimo sąlygomis. Nepakankamas braškių ištvermingumas žiemą, aiškių kriterijų, kurie leistų per trumpesnį nei kelių metų laikotarpį atrinkti ištvermingas veisles nebuvimas, apsunkina naujų, adaptyvių, derlingų, kokybiškomis uogomis, braškių veislių sukūrimą ir introdukciją. Atsparumo šalčiui mechanizmai intensyviai tirti naudojant modelinius augalus, tačiau žinių apie žiemojančių kultūrinių augalų, kurių įvairovė labai didelė, ištvermingumo žiemą mechanizmus ir jo genetinį reguliavimą labai trūksta. Atsparių šalčiui augalų atrankai vykdyti reikalingos žinios apie augalų užsigrūdinimą, apie atsparumą šalčiui lemiančius veiksnius ir juos kontroliuojančius genus. Tiriant augalus kontroliuojamomis sąlygomis in vitro, galima ištirti atskirų veiksnių įtaką užsigrūdinimui ir atsparumui šalčiui, atsiribojant nuo, neišvengiamo natūraliomis sąlygomis, daugelio įvairių veiksnių poveikio. Braškių užsigrūdinimas ir atsparumas šalčiui svarbūs ne vien tik atrankai. Genetinių išteklių išsaugojimas ateities kartoms - svarbus šiuolaikinės biologijos uždavinys. Didelių kolekcijų išsaugojimą palengvina ir sąnaudas sumažina, augalų laikymas... [toliau žr. visą tekstą] / Cold hardiness and resistance in winter are key factors determining the geographical distribution of plants. In addition, these factors have a huge impact on harvest of cultural plants. Strawberries, which are among the most important berry plants in the world and in Lithuania, are vulnerable to cold because of unstable snow cover, which is more and more often occurring during variable wintering conditions. Insufficient resistance of strawberries in winter, absence of clear criteria, which enable to select the most resistant varieties during a shorter time than the few year period, impedes the development and introduction of new, adaptive, fertile, and of high-quality berries strawberry cultivars. The mechanisms of cold hardiness were intensively investigated using model plants. However, there is a lack of knowledge about the genetic regulation mechanisms of winterhardiness of cultural plants. For the selection of resistant to cold plants, the knowledge about plants cold acclimation and factors determining cold resistance and controlling genes is necessary. Investigating the plants under controlled conditions in vitro, it is possible to investigate the influence of individual factors on acclimation and cold hardiness by disassociating from the influence of many different factors, which is unavoidable under natural conditions. The cold acclimation and cold hardiness of strawberries are important not only for breeding. Preservation of plant genetic resources for future... [to full text]
40

BIOSYNTHESIS OF trans-2-HEXENAL IN RESPONSE TO WOUNDING IN STRAWBERRY FRUIT AND INTERACTION OF trans-2-HEXENAL WITH BOTRYTIS CINEREA

Myung, Kyung 01 January 2005 (has links)
Intact strawberry fruit did not produce detectable t-2-H which is derived from -linolenic acid (18:3). However, in response to wounding by gentle bruising, strawberry fruit emitted t-2-H with the largest quantity produced within 10 min following injury. The level of total lipid 18:3 in the fruit increased two-fold in response to wounding whereas free 18:3 declined slightly (about 30%). At 10 min following wounding, fruit exhibited a 25% increase in 13-lipoxygenase (LOX) activity, which leads to the production of 13-hydroperoxyoctadecatrienoic acid (13-HPOT) from 18:3. The activity of hydroperoxide lyase (HPL), which catalyzes formation of cis-3-hexenal (c-3-H), the precursor of t-2-H, from 13-HPOT, increased two-fold at 10 min after wounding. Thus, within 15 min after wounding, free 18:3 substrate availability and the activity of two key enzymes, LOX and HPL, changed in a manner consistent with increased t-2-H biosynthesis. The site and mode of interaction of C6 aldehydes with Botrytis cinerea, a common pathogen of many plant species, was characterized using radiolabeled six carbon (C6) aldehydes, including c-3-H and t-2-H. An approximately 25% molar conversion of 18:3 to C6 aldehydes was obtained by enzymatic manipulation with LOX and HPL extracts. Following exposure of Botrytis cultures to radiolabeled aldehydes, radiolabeled aldehydes were recovered in protein fractions, but not in the lipid fraction. They were incorporated into conidia at a 20-fold higher level than mycelia (per mg fresh weight). About 95% of the radiolabeled aldehyde was recovered in proteins on the surface (wash protein) of the fungal tissue, while 5% was from protein in internal tissue (cell wall and membrane and cytosol). Supplementing radiolabeled aldehydes with nonradiolabled C6 aldehydes to increase the vapor phase concentration affected distribution of radiolabel in each protein fraction. The t-2-H at both 5.4 and 85.6 mol affected protein expression patterns, changing the intensity of expression in over one third of all proteins. Both up- and down-regulation of specific proteins were observed. Though five proteins of interest were analyzed, their identities were not determined. However, the data indicate a clear effect of t-2-H on protein expression in Botrytis cinerea.

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