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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.
161

Identificação molecular de fitoplasmas associados ao enfezamento do repolho e análise epidemiológica da doença / Molecular identification of phytoplasmas associated to cabbage stunt and epidemiological analysis of disease

Mello, Ana Paula de Oliveira Amaral 28 November 2007 (has links)
Uma doença, denominada de enfezamento, de etiologia desconhecida, tem sido observada nos campos de cultivo de repolho da região do cinturão verde de São Paulo. A doença tem causado sérios danos à cultura nos últimos anos. A sintomatologia apresentada pelas plantas afetadas tem sido caracterizada por clorose foliar, avermelhamento das nervuras e do limbo, enfezamento generalizado, proliferação de brotos e má formação da cabeça, de folhas e órgãos florais. A presença destes sintomas levou à suspeita da ocorrência de fitoplasma associado à doença. Com o objetivo de investigar o possível agente etiológico, plantas de repolho naturalmente infectadas foram coletadas em São Paulo e também nos Estados do Paraná e Rio Grande do Sul, onde a doença, recentemente, tem ocorrido com alta intensidade. Cigarrinhas que ocorrem em cultivos comerciais também foram amostradas em campos de Ibiúna/SP. Após a extração, o DNA total foi submetido ao teste de duplo PCR empregando-se os pares de primers universais P1/Tint e R16F2n/R2 e os pares específicos para identificação de fitoplasmas. Análises de PCR mostraram a amplificação consistente de fragmentos de DNA de 1,2 kb, evidenciando a associação constante de fitoplasma com tecidos das plantas sintomáticas e de insetos. O uso de primers específicos para identificação demonstrou a ocorrência de fitoplasmas afiliados ao grupos 16SrI e 16SrIII, tanto em repolho como nas cigarrinhas. Análises de RFLP, usando as enzimas de restrição AluI, Bsh 12361, HhaI HpaII, KpnI, MboI, MseI e RsaI confirmaram a ocorrência de fitoplasmas pertencentes aos referidos grupos no material vegetal e nos insetos. O padrão espacial de plantas sintomáticas no campo foi do tipo agregado e não houve evidência da disseminação planta a planta, indicando um papel mais importante do comportamento do vetor no arranjo espacial da doença do que de influências do patógeno ou do hospedeiro. / A disease called stunt, of unknown etiology, has occurred in cabbage crops located in the green belt region of the São Paulo State (Brazil). The disease has caused serious yield losses in the last years. The symptomatology exhibited by the affected plants has been characterized by foliar chlorosis, intense red coloration of leafs, general stunt, shoot proliferation and malformation of heads, leaves and floral parts. The presence of those symptoms suggested the occurrence of phytoplasma associated with the disease. In order to investigate the possible agent of the disease, naturally infected cabbage plants were collected from the States of São Paulo, and also from Paraná and Rio Grande do Sul, where the disease has occurred recently with level of intensity. Leafhoppers present in cabbage fields were sampled from Ibiúna, in São Paulo State. Total DNA was extracted and submitted to nested PCR with the universal primer pairs P1/Tint and R16 F2n/R2 and specific primers for phytoplasmas identification. PCR assays revealed the amplification of DNA fragments of 1.2kb, demonstrating consistently the presence of phytoplasma in the tissues from symptomatic plants and insects. Specific primers revealed the occurrence of phytoplasmas affiliated with the groups 16SrI and 16SrIII, both cabbage plants and leafhoppers. RFLP analyses using the restriction enzymes AluI, Bsh 12361, HhaI, HpaII, KpnI, MboI, MseI and RsaI confirmed the occurrence of phytoplasmas belonging to the same groups in plants and insects. Spatial pattern of symptomatic plants in the field was aggregated and there was no evidence of the spread plant-to-plant. This indicates a more important role of the vector behavior on spatial pattern than influences of the pathogen or host.
162

Atividade antiproliferativa \"in vitro\" em diferentes estádios de maturação do brócolis (Brassica oleracea L. var. itálica) biofortificados ou não com selênio / Antiproliferative activity \"in vitro\" in different broccoli (Brassica oleracea L. var. itálica) maturation stages biofortified or not with selenium

Bachiega, Patricia 02 July 2014 (has links)
O câncer é a segunda causa de morte da população mundial e constitui-se em sério problema de saúde pública no mundo. Seu tratamento acarreta além de elevados gastos, diversos efeitos colaterais aos pacientes. Dessa forma, alternativas que possam minimizar esses fatos são extremamente viáveis. Diversos estudos já comprovaram o efeito sinérgico dos isotiocianatos e do selênio e a sua contribuição como agentes protetores contra danos oxidativos e aumentam a expressão de enzimas responsáveis pela desintoxicação de compostos cancerígenos. Com base nisso, o objetivo desta pesquisa foi avaliar a influência da suplementação com selênio, durante o processo de maturação do brócolis, em parâmetros das atividades antioxidantes e antiproliferativo. No presente estudo foi constatado que a biofortificação do brócolis com selênio é possível uma vez que, as amostras tratadas foram capazes de absorver este mineral. Além disso, a biofortificação acarretou o aumento tanto da atividade antioxidante como dos compostos fenólicos em todas as amostras testadas. A avaliação do potencial antiproliferativo do brócolis demonstrou que os extratos brutos diclorometânicos apresentaram tal potencial. Os extratos brutos diclorometânicos das mudas de brócolis biofortificadas com selênio se destacaram perante os demais extratos quanto a atividade antiproliferativa. Concluindo, a biofortificação com selênio constitui-se uma técnica viável para o aumento do potencial antioxidante do brócolis e os estudos iniciais sobre a atividade antiproliferativa demonstram que as mudas de brócolis biofortificadas com selênio são as amostras mais promissoras para realização de estudos futuro. / Worldwide cancer is the second leading cause of death and constitutes a serious public health problem. The traditional treatment beyond expensive has several side effect, thus alternatives that can minimize these realities are extremely viable. Isothiocyanates and selenium have synergic effect, contributes as protective agents against oxidative damage and increase the expression of detoxification enzymes responsible for eliminate carcinogenic compounds. Therefore, the aim of this research was to evaluate the influence of selenium supplementation during the broccoli maturation in antioxidant and antiproliferative parameters. In the present study it was found that broccoli biofortification with selenium is possible since plants were able to absorb this mineral. Furthermore, an increase of both antioxidant activity and phenolic compounds was observed in all samples supplemented. All dichloromethanic crude extracts showed better antiproliferative activity when compared with ethanolic extracts being seedlings supplemented with selenium the best antiproliferative agent among the extracts tested. In conclusion, biofortification with selenium constitutes a viable technique for increasing the antioxidant potential of broccoli. Initial studies with antiproliferative activity showed that the broccoli seedlings biofortified with selenium are the most promising samples for future studies.
163

Óleos essenciais para controle da podridão mole em couve-chinesa

GUERRA, Myrzânia de Lira 26 July 2011 (has links)
Submitted by (lucia.rodrigues@ufrpe.br) on 2017-03-22T15:55:30Z No. of bitstreams: 1 Myrzania de Lira Guerra.pdf: 865300 bytes, checksum: 159f62ad074b37facb2aca234031d937 (MD5) / Made available in DSpace on 2017-03-22T15:55:30Z (GMT). No. of bitstreams: 1 Myrzania de Lira Guerra.pdf: 865300 bytes, checksum: 159f62ad074b37facb2aca234031d937 (MD5) Previous issue date: 2011-07-26 / Chinese cabbage (Brassica pekinensis L.) is very important in the Brazilian horticulture due to its nutritional value and increasing yielding. In the Zona da Mata and Agreste of Pernambuco State, Brazil, this vegetable is intensely cultivated in the conventional system although its production is limited by several factors including the soft rot disease. It was evaluated the action of essential oils in controlling soft rot in Chinese cabbage and their influence in colorimetry and physicochemical characteristics of this vegetable. Preliminary fitotoxicity tests selected 11 oils. In the greenhouse, plants of cv. Natsume were sprayed with the oils of bergamot, lemon grass, copaiba, eucalyptus citriodora, eucalyptus globulus, fennel, ginger, mint, sweet orange, lemon and clary sage (0.5%) and the antibiotic Mycoshield® (3 g L-1), and inoculated with P. carotovorum subsp. carotovorum (Pcc-c) after 72 h. The disease severity was evaluated every six hours until 48 h, and the final severity (SEV) and area under the disease progress curve (AUDPC) were determined. The 11 oils and Mycoshield® reduced similarly SEV and AUDPreduced SEV in 53.1 and 38.8% and AUDPC in 37.0 and 27.5%, respectively. The oils of bergamot, copaiba, eucalyptus citriodora, mint and sweet orange were selected for further studies and tested for stability of the effectiveness of disease control in relation to three strains of Pcc. The interaction oils x strains was not significant (P≤0.05). The five oils reduced the SEV and AUDPC without differences between themselves or from Mycoshield®, except for copaiba oil that was less effective than the antibiotic in reducing the AUDPC. In the in vitro tests, filter paper discs were soaked in those five oils (0.5%) and Mycoshield® and deposited on culture medium containing Pcc-c. The pathogen was inhibited in vitro only by Mycoshield®. The technique of overlapping plates was used for detection of antibacterial activity of volatile substances at different pHs. Pcc-c growth was inhibited only by the oils of mint and bergamot at pH 7.0, and by the oil of copaiba at pH 8.0. The colorimetry of Chinese cabbage leaves, the ascorbic acid content and the pH of the plants treated with those five oils have not changed compared to the control without Pcc-c. The acidity was elevated by mint oil and total soluble solids (˚Brix) by the oils of sweet orange, eucalyptus citriodora and bergamot. / A couve-chinesa (Brassica pekinensis L.) destaca-se na olericultura brasileira pelo valor nutricional e aumento da produtividade. Nas regiões da Zona da Mata e do Agreste Pernambucano esta hortaliça é intensamente cultivada no sistema convencional tendo sua produção limitada entre outros fatores pela ocorrência da podridão mole. Avaliou-se a ação de óleos essenciais no controle da podridão mole em couve-chinesa e sua influência na colorimetria e características físico-químicas da hortaliça. Em testes preliminares de fitotoxidez foram selecionados 11 óleos. Em casa de vegetação, plantas da cv. Natsume foram pulverizadas com os óleos de bergamota, capim limão, copaíba, eucalipto citriodora, eucalipto globulus, funcho de erva-doce, gengibre, hortelã, laranja doce, limão e sálvia esclaréia (0,5%) e o antibiótico agrícola Mycoshield® (3g L-1), sendo inoculadas com Pectobacterium carotovorum subsp. carotovorum (Pcc-c) após 72 h. Avaliou-se a severidade da doença a cada seis horas até 48 h, determinando-se a severidade final (SEV) e área abaixo da curva de progresso da doença (AACPD). Os 11 óleos e o Mycoshield® reduziram similarmente a SEV e a AACPD em relação à testemunha. O óleo de hortelã e o Mycoshield® reduziram a SEV em 53,1 e 38,8% e a AACPD em 37,0 e 27,5%, respectivamente. Os óleos de bergamota, copaíba, eucalipto citriodora, hortelã e laranja doce foram selecionados para a continuidade dos estudos e testados quanto à estabilidade da eficácia de controle da doença em relação a três isolados de Pcc. A interação óleos x isolados não foi significativa (P≤0,05). Os cinco óleos reduziram a SEV e AACPD sem diferirem entre si ou do Mycoshield® exceto o óleo de copaíba que se mostrou menos eficiente do que o antibiótico na redução da AACPD. Nos testes in vitro, discos de papel de filtro foram embebidos nos cinco óleos (0,5%) e Mycoshield® e depositados sobre meio de cultura contendo Pcc-c. O patógeno foi inibido in vitro apenas pelo Mycoshield®. Para detecção da atividade antibacteriana das substâncias voláteis em diferentes pHs foi utilizada a técnica da placa sobreposta. O crescimento de Pcc-c foi inibido apenas pelos óleos de hortelã e bergamota no pH 7,0, e pelo óleo de copaíba no pH 8,0. A colorimetria das folhas da couve-chinesa, o teor de ácido ascórbico e o pH das plantas tratadas com os cinco óleos não foram alterados, considerando a testemunha sem Pcc-c. A acidez titulável foi elevada pelo óleo de hortelã e o ˚Brix pelos óleos de laranja doce, eucalipto citriodora e bergamota.
164

Effect of temperature and photoperiod on broccoli development, yield and quality in south-east Queensland

Tan, Daniel Kean Yuen January 1999 (has links)
Broccoli is a vegetable crop of increasing importance in Australia, particularly in south-east Queensland and farmers need to maintain a regular supply of good quality broccoli to meet the expanding market. However, harvest maturity date, head yield and quality are all affected by climatic variations during the production cycle, particularly low temperature episodes. There are also interactions between genotype and climatic variability. A predictive model of ontogeny, incorporating climatic data including frost risk, would enable farmers to predict harvest maturity date and select appropriate cultivar - sowing date combinations. The first stage of this research was to define floral initiation, which is fundamental to predicting ontogeny. Scanning electron micrographs of the apical meristem were made for the transition from the vegetative to advanced reproductive stage. During the early vegetative stage (stage 1), the apical meristem was a small, pointed shoot tip surrounded by leaf primordia. The transitional stage (stage 2) was marked by a widening and flattening to form a dome-shaped apical meristem. In the floral initiation stage (stage 3), the first-order floral primordia were observed in the axils of the developing bracts. Under field conditions, the shoot apex has an average diameter of 500 micro m at floral initiation and floral primordia can be observed under a light microscope. Sub-zero temperatures can result in freezing injury and thereby reduce head yield and quality. In order to predict the effects of frosts, it is desirable to know the stages of development at which plants are most susceptible. Therefore, the effects of sub-zero temperatures on leaf and shoot mortality, head yield and quality were determined after exposure of plants to a range of temperatures for short periods, at different stages of development (vegetative, floral initiation and buttoning). Plants in pots and in the field were subjected to sub-zero temperature regimes from -1 C to -19 C. Extracellular ice formation was achieved by reducing temperatures slowly, at a rate of -2 C per hour. The floral initiation stage was most sensitive to freezing injury, as yields were significantly reduced at -1 C and -3 C, and shoot apices were killed at -5 C. There was no significant yield reduction when the inflorescence buttoning stage was subjected to -1 C and -3 C. Although shoot apices at buttoning survived the -5 C treatment, very poor quality heads of uneven bud size were produced as a result of arrested development. The lethal temperature for pot-grown broccoli was between -3 C and -5 C, whereas the lethal temperature for field-grown broccoli was between -7 C and -9 C. The difference was presumably due to variation in cold acclimation. Freezing injury can reduce broccoli head yield and quality, and retard plant growth. Crop development models based only on simple thermal time without restrictions will not predict yield or maturity if broccoli crops are frost-damaged. Field studies were conducted to develop procedures for predicting ontogeny, yield and quality. Three cultivars, (Fiesta, Greenbelt and Marathon) were sown on eight dates from 11 March to 22 May 1997, and grown under natural and extended (16 h) photoperiods in a sub-tropical environment at Gatton College, south-east Queensland, under non-limiting conditions of water and nutrient supply. Daily climatic data, and dates of emergence, floral initiation, harvest maturity, together with yield and quality were obtained. Yield and quality responses to temperature and photoperiod were quantified. As growing season mean minimum temperatures decreased, fresh weight of tops decreased while fresh weight harvest index increased linearly. There was no definite relationship between fresh weight of tops or fresh weight harvest index and growing season minimum temperatures greater than 10 C. Genotype, rather than the environment, mainly determined head quality attributes. Fiesta had the best head quality, with higher head shape and branching angle ratings than Greenbelt or Marathon. Bud colour and cluster separation of Marathon were only acceptable for export when growing season mean minimum temperatures were less than 8 C. Photoperiod did not influence yield or quality in any of the three cultivars. A better understanding of genotype and environmental interactions will help farmers optimise yield and quality, by matching cultivars with time of sowing. Crop developmental responses to temperature and photoperiod were quantified from emergence to harvest maturity (Model 1), from emergence to floral initiation (Model 2), from floral initiation to harvest maturity (Model 3), and in a combination of Models 2 and 3 (Model 4). These thermal time models were based on optimised base and optimum temperatures of 0 and 20 C, respectively. These optimised temperatures were determined using an iterative optimisation routine (simplex). Cardinal temperatures were consistent across cultivars but thermal time of phenological intervals were cultivar specific. Sensitivity to photoperiod and solar radiation was low in the three cultivars used. Thermal time models tested on independent data for five cultivars (Fiesta, Greenbelt, Marathon, CMS Liberty and Triathlon) grown as commercial crops on the Darling Downs over two years, adequately predicted floral initiation and harvest maturity. Model 4 provided the best prediction for the chronological duration from emergence to harvest maturity. Model 1 was useful when floral initiation data were not available, and it predicted harvest maturity almost as well as Model 4 since the same base and optimum temperatures of 0 C and 20 C, respectively, were used for both phenological intervals. Model 1 was also generated using data from 1979-80 sowings of three cultivars (Premium Crop, Selection 160 and Selection 165A). When Model 1 was tested with independent data from 1983-84, it predicted harvest maturity well. Where floral initiation data were available, predictions of harvest maturity were most precise using Model 3, since the variation, which occurred from emergence to floral initiation, was removed. Prediction of floral initiation using Model 2 can be useful for timing cultural practices, and for avoiding frost and high temperature periods. This research has produced models to assist broccoli farmers in crop scheduling and cultivar selection in south-east Queensland. Using the models as a guide, farmers can optimise yield and quality, by matching cultivars with sowing date. By accurately predicting floral initiation, the risk of frost damage during floral initiation can be reduced by adjusting sowing dates or crop management options. The simple and robust thermal time models will improve production and marketing arrangements, which have to be made in advance. The thermal time models in this study, incorporating frost risk using conditional statements, provide a foundation for a decision support system to manage the sequence of sowings on commercial broccoli farms.
165

From QTLs to Genes: Flowering Time Variation and CONSTANS-LIKE Genes in the Black Mustard (Brassica nigra)

Kruskopf Österberg, Marita January 2007 (has links)
The transition to flowering is a major developmental switch in angiosperms, the timing of which is expected to be important for fitness. In this thesis the focus has been on identification of genes affecting natural variation in flowering time in Brassica nigra. The background for this thesis is an earlier QTL-mapping study in B. nigra. The genomic area with the greatest effect on flowering time in that study contained a homolog to the CONSTANS gene, which is known to affect flowering time in A. thaliana. When studied more closely this gene did not seem to affect flowering time variation in B. nigra. Near the B.nigra CO gene (BniCOa), however, we identified a homolog to the related CONSTANS LIKE 1 (COL1) gene. In A. thaliana COL1 has not been shown to be associated with induction of flowering but since the B. nigra homolog (BniCOL1) in the QTL area showed surprising amounts of variation between early and late flowering plants we set out to test if this variation was associated with flowering time variation. In the first paper we found a significant association between flowering time and one indel (Ind2) in the coding region. Motivated by the results in paper one, we searched for evidence of selection at the BniCOL1(paper two). In paper three the aim was to validate the results from the first paper in a larger sample of populations, and to check whether the association found in paper I could reflect linkage disequilibrium with areas outside of the gene. Finally, in paper four we investigate the general evolution of three CONSTANS-LIKE genes in B. nigra, namely BniCOL1, BniCOa and BniCOb.
166

The nutritive value of high fiber canola meal for ruminants

Mustafa, Arif Fouad 01 January 1996 (has links)
Five trials were conducted to assess the nutritive value of high fiber canola meal (HFCM) as a protein supplement for ruminants. Trial one determined the chemical composition of HFCM relative to low fiber canola meal (LFCM) and canola meal in a completely randomized design using samples obtained from five different crushers. In the second trial, the in situ nylon bag technique was used to determine disappearance of dry matter (DMD), crude protein (CPD), neutral (NDFD) and acid (ADFD) detergent fiber from canola meal, LFCM and HFCM samples derived from five different crushers following 24 h of nunen incubation. The effect of crushing plant of origin on in situ nutrient disappearance in the three meals was also determined. In the third trial, rumen nutrient kinetic parameters and effective degradabilities were determined for the blended canola meal, LFCM and HFCM. In situ disappearance of different amino acids canola meal, LFCM and HFCM following 12 h of rumen incubation was determined in the fourth study. The fifth trial was designed to determine nutrient digestibility coefficients by growing lambs of seven diets containing dehydrated alfalfa and 0, 25, 50 and 75% HFCM or canola meal in a randomized complete block design. Milk yield and composition responses of early to mid lactation dairy cows to diets supplemented with HFCM, canola meal or soybean meal were also determined. Results of the first trial indicated that tail-end dehulling of canola meal resulted in more fractionation of fiber than protein between HFCM and LFCM. Results of the second trial showed differences in CPD and DMD within LFCM and HFCM but not within canola meal samples. However, no meal by crusher interaction was observed indicating that in situ nutrient disappearances in the three meals were consistent across crushers. At 5% h<sup>-1</sup> rumen flow rate, effective DM degradability (trial three) was higher (P $<$ 0.05) in LFCM than in canola meal and was higher in canola meal than in HFCM while effective CP degradability was higher in LFCM and canola meal than in HFCM. Effective NDF degradability was higher (P $<$ 0.05) in LFCM than in canola meal and MFCM. However, effective ADF degradability was higher in LFCM than in canola meal and was higher in canola meal than in HFCM. Tail-end dehulling had little effect on in situ disappearance of amino acids from canola meal, LFCM and HFCM following 12 h of rumen incubation. Results from the fifth trial indicated that at 75% inclusion rate, the diet containing HFCM had lower (P $<$ 0.05) DM, CP and gross energy digestibility coefficients relative to canala meal diet. Results of the dairy trial showed no treatment effect on feed intake. (Abstract shortened by UMI.)
167

Genome analysis and genetic mapping of restorer loci in raphanus

Bett, Kirstin Elizabeth 01 January 2001 (has links)
Genetic variation exists in <i>Raphanus</i> that could be of use to <i>Brassica</i> breeders. Of particular interest is the Ogura system of cytoplasmic male sterility (CMS) which has been worked on extensively in a <i>Brassica napus</i> background. Problems have been experienced in <i>B. napus</i>restorer lines due to the inheritance of a large segment of <i>Raphanus</i> chromosome containing the fertility restoring locus. This restorer introgression is located on the <i>Brassica</i> C genome making it only of use for <i>B. napus</i> and not for <i>B. rapa</i> or <i>B. juncea</i>. This thesis describes the development of the materials necessary for the introgression into the <i>Brassica</i> A genome of a defined segment of <i>Raphanus</i> chromosome containing a restorer locus. Defined genetic stocks of <i>Raphanus</i> were developed that contained specific loci controlling restoration of Ogura CMS. This material was used to develop populations segregating for specific restorer loci. Extensive RFLP maps of three <i>Raphanus</i> populations were developed and aligned, resulting in a robust consensus map of the entire <i>Raphanus</i> genome. Three restorer loci were accurately mapped on three separate linkage groups. The segment of <i>Raphanus</i> that is implicated in the restoration of Ogura CMS in a <i>B. napus</i> restorer line developed by INRA was identified and it did not correspond to any of the regions containing the three mapped restorer loci, suggesting the presence of more restorer loci in <i>Raphanus</i>. Comparative mapping between the <i>Raphanus</i> genome map and previously generated <i>Brassica</i> A genome RFLP maps demonstrated large regions of collinearity between segments of chromosomes of the two species. Preliminary examination of the two genome maps suggest they contain essentially the same overall genetic content but with large segments of the genomes rearranged with respect to each other. Likely sites of <i>Raphanus</i> restorer introgression into the <i>Brassica</i> A genome were predicted. Trigenomic tetraploids were developed in which pairing and recombination between homoeologous segments of <i>Raphanus</i> and <i>Brassica</i> A chromosomes should result. Progeny of these individuals will allow an assessment of the pattern and extent of recombination that occurs between the chromosomes of the <i>Raphanus</i> and <i>Brassica</i> A genomes and should lead to the development of 'B. napus' lines carrying Ogura CMS restorer alleles from <i>Raphanus</i>.
168

Chemical interactions between Verticillium longisporum and oilseed rape Brassica napus

Ibrahem Aroud, Husam 03 July 2013 (has links)
No description available.
169

DIRVOS BIOAKTYVUMO IR PIKTŽOLIŲ PLITIMO TYRIMAI SKIRTINGO TANKUMO VASARINIŲ RAPSŲ AGROCENOZĖSE / Investigation of soil bioactivity and weed infestation in spring oilseed rape agrocoenosis of different density

Grybaitė, Aušra 09 June 2006 (has links)
Investigation of soil bioactivity and weed infestation in spring oilseed rape agrocoenosis of different density Aušra Grybaitė Field experiments were carried out in 2004 and 2005 at the Experimental Station of Lithuanian University of Agriculture to study the influence of different spring oilseed rape (Brassica napus L.) ‘Sponsor’ densities (50.1-100, 100.1-150, 150.1-200, 200.1-250, 250.1-300, 300.1-350, 350.1-400, 400.1-450 plants m-2) on soil bioactivity and weed infestation. Soil - Calc(ar)i-Endohypogleyic Luvisol. By increasing of spring oilseed rape crop urease activity in the soil didn’t chage significantly. The saccharase activity in the rape agrocoenosis with density more than 150.1 plants m-2 significantly increased in comparison with saccharase activity in the thinest rape agrocoenosis. The content of humus (r = 0.73, P < 0.05) and available phosphorus (r = 0.71, P < 0.05) influenced the saccharase activity. Spring oilseed rape crop density had no influence on number of weed species, weed sprouts and weed density before harvest. Efficiency of weed suppressing increased when weed density in crop at 3-4 leaves stage increased. This proved the small similarity indexes of weed density in crop at 3-4 leaves stage and before harvest. Rape crop density had no influence on weed species change. Significant negative relationship was found between weed air-dry biomass and rape crop density (r = -0.82, P < 0.01). Most of weeds in rape crop were therophytes. Most of them... [to full text]
170

Selection response to global change of Brassica juncea (L.) czern

Tousignant, Denise January 1993 (has links)
The potential for an adaptive response to global climatic change was evaluated for an annual C$ sb3$ weed, Brassica juncea, by performing a selection on fecundity for eight generations. During the selection, atmospheric carbon dioxide and temperature were gradually increased from current levels (370 $ rm mu L cdot L sp{-1}$ CO$ sb2$, 20$ sp circ$C) to conditions predicted during the next century by climate models (650 $ rm mu L cdot L sp{-1}$ CO$ sb2$, 23.6$ sp circ$C) including heat stress events at 32$ sp circ$C/26$ sp circ$C day/night), At the end of the selection, a reciprocal transplant experiment was conducted to identify genetic differences between control selection lines of plants and those selected under increasing CO$ sb2$ and temperature. I observed a genetic adaptation of early vegetative growth elevated CO$ sb2$ and temperature, which resulted in to 63% more biomass and 11% higher photosynthetic rates. Reproductive biomass, however, was decreased during the selection, mainly due to temperature stress, which disrupted flower development and induced strong maternal effects, counteracting the selection on fecundity.

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