Resumo: Com o objetivo de avaliar o efeito de densidades populacionais e épocas de plantio na cultura da couve-flor, híbrido Verona 284, foram realizados dois experimentos no campo. O primeiro na primavera-verão (novembro a janeiro) e o segundo no outonoinverno (maio a julho). O delineamento experimental foi o de blocos casualizados completos, em esquema fatorial 4 x 4, com três repetições. Foram avaliados os fatores espaçamento entre linhas (0,6; 0,8; 1,0 e 1,2 m) e espaçamentos entre plantas (0,4; 0,5; 0,6 e 0,7 m). A segunda época proporcionou os maiores teores de N, K e B na folha diagnóstica, com relação à primeira época de plantio. Nos menores espaçamentos foram verificados os menores números de folhas, diâmetro do caule e da inflorescência e massa da inflorescência, no entanto, houve incremento na produtividade. A maior quantidade de inflorescências classificadas na classe Extra foi obtida na primaveraverão, enquanto no outono-inverno houve maior quantidade de inflorescências classificadas na classe Especial. Constatou-se que a ordem decrescente de acúmulo de nutrientes pela planta ao final do ciclo foi à mesma verificada para exportação pela inflorescência, N, K, P, e B, com os nutrientes acumulando-se preferencialmente nas folhas, seguidas da inflorescência e do caule. O plantio da couve-flor 'Verona 284', na primeira época de plantio, proporcionou a maior receita bruta, utilizando-se os espaçamentos 0,8 x 0,4 m, enquanto na segunda época maior receita bruta foi obtida com os espaçamentos 0,6 x 0,6 m. / Abstract: With the aim of evaluating the effect of population densities and planting seasons on cauliflower crop, hybrid Verona 284, two experiments were carried out in the field. The first one was conducted in the spring-summer (from November to January) and the second one in the fall-winter (from May to July). The experiments were arranged in completely randomized blocks, in a 4 x 4 factorial design, with three replications. The evaluated factors were the spacing between rows (0.6; 0.8; 1.0 and 1.2 m) and the spacing between plants (0.4; 0.5; 0.6 and 0.7 m). The second planting season yielded the highest N, K and B content in the diagnostic leaf compared with the first planting season. Smaller spacing showed smaller numbers of leaves, smaller diameter of the stem and inflorescence, and less inflorescence mass. However, an increment in yield was observed. The largest quantity of inflorescences classified as Extra was obtained in the spring-summer, whereas in the fall-winter a larger quantity of inflorescences was classified as Special. The nutrients in decreasing order of accumulation by the plant at the end of its cycle was the same as that observed for their export by the inflorescence - N, K, P, and B - and they accumulated especially in the leaves, followed by the inflorescence and stem. Cauliflower 'Verona 284' planted in the first planting season yielded the highest gross income using the 0.8 x 0.4 m spacing, whereas in the second planting season the highest gross income was obtained when the 0.6 x 0.6 m spacing was used. / Orientador: Arthur Bernardes Cecílio Filho / Coorientador: José Carlos Barbosa / Banca: Antonio Ismael Inácio Cardoso / Banca: Juliano Tadeu Vilela de Resende / Banca: Jairo Osvaldo Cazetta / Banca: Durvalina Maria Mathias dos Santos / Doutor

Orientador: Sergio Antonio De Bortoli / Banca: Robson Thomaz Thuler / Banca: Rogéria Inês Rosa Lara / Resumo: O trabalho foi desenvolvido no Laboratório de Biologia e Criação de Insetos (LBCI) da FCAV - UNESP - Jaboticabal, para avaliar os aspectos biológicos e a taxa de consumo do predador Orius insidiosus (Say, 1832) (Hemiptera: Anthocoridae), alimentando-se de ovos e lagartas de segundo ínstar de Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) e em ovos de Anagasta kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae) (considerado tratamento testemunha). Para as espécies estudadas, O. insidiosus apresentou um período ninfal maior quando alimentado com lagartas de P. xylostella. O consumo total, durante a fase ninfal, foi maior quando alimentados com ovos de A. kuehniella, ovos e lagartas de P. xylostella, respectivamente. Na fase adulta, o período de pré-oviposição foi menor para os insetos alimentados com lagartas de P. xylostella, o que resultou em um encurtamento nessa fase biológica do predador. Os ovos de P. xylostella foram nutricionalmente mais adequados ao desenvolvimento de O. insidiosus. Para os ovos de P. xylostella, O. insidiosus apresentou curva de resposta funcional tipo II e mostrou uma tendência de estabilização nas densidades mais altas. A taxa de ataque (a) foi de 0,0127 ovos/hora e 0,00233 lagartas/hora e o tempo de manipulação (Th) foi de 1,4037 horas e de 2,7903 horas, para ovos e lagartas de P. xylostella, respectivamente. / Abstract: This study was done at the Laboratório de Biologia e Criação de Insetos (LBCI) at FCAV - UNESP - Jaboticabal, to assess the biological aspects and the rate of consumption of the predator Orius insidiosus (Say, 1832) (Hemiptera: Anthocoridae), feeding on eggs and second instar larvae of Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) and on eggs of Anagasta kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae) (considered to be check treatment). For the species studied, O. insidiosus presented a longer nymph period when fed with P. xylostella caterpillars. Total consumption, during the nymph stage, was greater for A. kuehniella eggs, P. xylostella eggs and caterpillars, respectively. In the adult phase, the preoviposition period was shorter for the insects fed on P. xylostella caterpillars, demonstrating a shortening of this biological phase in the predator. The eggs of P. xylostella were nutritionally better suited to the development of O. insidiosus. For the eggs of P. xylostella, O. insidiosus presented a type II functional response curve, showing a tendency to stabilize in higher densities. The searching rate (a) was 0.0127 eggs/hour and 0.00233 caterpillars/hour and the handling time (Ht) was 1.4037 hours and 2.7903 hours, for P. xylostella eggs and caterpillars, respectively. / Mestre

Made available in DSpace on 2014-06-11T19:29:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-07-26Bitstream added on 2014-06-13T20:39:21Z : No. of bitstreams: 1 castro_mm_me_ilha.pdf: 319106 bytes, checksum: 89fc3a676e9512a3244916375bfda750 (MD5) / Universidade Estadual Paulista (UNESP) / Em sementes de hortaliças, devido ao elevado valor comercial, o potencial fisiológico apresenta alta relevância, pois a redução do vigor pode ocasionar aumento no custo de implantação da cultura. Quatro lotes de sementes de couve-flor cv. Piracicaba Precoce foram submetidos ao teste de condutividade elétrica, avaliação do grau de umidade, teste padrão de germinação, massa seca de plântulas, emergência em bandeja de isopor preliminarmente e quanto à produtividade e características agronômicas. Para avaliar a produtividade, foram instalados dois experimentos, um combinando os quatro lotes com quatro doses de nitrogênio na forma de uréia (0, 100, 200 e 300 kg ha -1 de N, o que corresponde a 0, 5, 10 e 15 g de N por cova) e outro apenas comparando o desempenho dos lotes. Os experimentos foram instalados em blocos casualizados com 16 tratamentos e quatro repetições para o primeiro e, 4 tratamentos e 4 repetições para o segundo. As parcelas constaram de 6 covas espaçadas de 0,5 m entre plantas e 1 m entre linhas no primeiro ensaio; e 24 mudas a uma distância de 0,5 m entre plantas e 1 m entre linhas no segundo ensaio. Na semeadura, todas as covas receberam 20 g da fórmula 8-28- 16 e o equivalente a 40 kg ha -1 de bórax. No experimento 2 foram feitas duas adubações em cobertura colocando-se 5 g de uréia por cova aos 15 e 30 dias após o transplante. Avaliou-se o número de folhas por planta, massa média fresca das cabeças em função das doses de nitrogênio, número e área de cabeças, produtividade e teores de macronutrientes (N, P, K, Ca, Mg, S) presentes nas cabeças em função dos níveis de vigor e doses de nitrogênio. Os resultados permitiram concluir que houve efeito do vigor no desenvolvimento e produção das plantas, sendo que a origem da semente foi um importante componente em seu desempenho e as doses de 200 e 300 kg ha -1 promoveram maior produtividade. / In seeds of vegetables, due to the high commercial value, the physiologic potential presents high relevance, because the reduction of the vigour can cause increase in the cost of implantation of the culture. Four lots of seeds of cauliflower cv. Piracicaba Precoce were submitted to the test of electric conductivity, seed water content, standard germination, dry matter of seedling, emergency in polypropylene tray, productivity and agronomic characteristics. To evaluate the productivity, two experiments were installed, a combining the four lots with four doses of nitrogen in the urea form (0, 100, 200 and 300 kg ha -1 of N, what corresponds to 0, 5, 10 and 15 g of N hole) and other just comparing the acting of the lots. The experiments were installed in randomized blocks with 16 treatments and four repetitions for the first and 4 treatments and 4 repetitions for the second. The parcels consisted of 6 spaced holes of 0,5 m between plants and 1 m among lines in the first rehearsal; and 24 seedlings the a distance of 0,5 m between plants and 1 m among lines in the second rehearsal. In the sowing all the holes received 20 g of the formula 8-28- 16 and the equivalent to 40 kg ha -1 of borax. In the experiment 2 they were made two manurings in covering being placed 5 g of urea by hole to the 15 and 30 days after the transplant. The number of levels was evaluated by plant, mass medium breeze of the heads in function of the doses of nitrogen, number and area of heads, productivity and nutrients tenors (N, P, K, Ca, Mg, S) presents in the heads in function of the vigour levels and nitrogen doses. The results allowed to end that there was effect of the vigour in the development and production of the plants, and the origin of the seed was an important component in your acting and the doses of 200 and 300 kg ha -1 they promoted larger productivity.

As brássicas compreendem diversas espécies de grande relevância comercial dentre as demais espécies olerícolas cultivadas no Brasil. A região localizada próxima à cidade de São Paulo (SP) tem se destacado no cultivo de brássicas, especialmente do repolho, da couve-flor e do brócolis. Em campos de cultivo destas espécies, tem sido observadas plantas exibindo redução de tamanho, inflorescências mal formadas, avermelhamento de folhas e necrose dos vasos condutores. Investigações tem mostrado que estas anormalidades estão associadas aos fitoplasmas e a doença tem sido denominada enfezamento. Ainda, estudos anteriores têm sugerido a ocorrência de algumas espécies de cigarrinhas potencialmente vetoras destes fitoplasmas. Considerando estas informações, o presente trabalho teve por objetivo identificar espécies transmissoras de fitoplasmas para plantas de brócolis, buscando aumentar os conhecimentos sobre os vetores de fitoplasmas envolvidos com o enfezamento desta cultura. Para isto, foram coletados insetos no interior e áreas marginais de campos cultivados. Estes insetos foram separados em grupos, identificados taxonomicamente e confinados em plantas sadias de brócolis. A avaliação da transmissão foi feita com base na detecção de fitoplasmas nos tecidos dos insetos e das plantas, usando-se a técnica de PCR duplo, com primers específicos para identificação de fitoplasmas do grupo 16SrIII. A sobrevivência dos insetos nas plantas de brócolis foi pouco duradoura, não excedendo 48 horas. A transmissão experimental foi constatada em 30% das plantas inoculadas. Dentre as 8 potenciais espécies de vetores que foram testadas, as espécies Atanus nitidus, Balclutha hebe, Agalliana sticticollis e Agallia albidula transmitiram fitoplasma para plantas de brócolis. Os resultados deste estudo confirmaram aqueles obtidos nas investigações anteriores, as quais sugeriam a ocorrência de potenciais espécies vetoras de fitoplasmas dentre aquelas presentes nos campos de cultivo. No entanto, o conhecimento de detalhes sobre a transmissão necessita de estudos com populações sadias e infectivas das espécies vetoras, sob condições controladas. Apesar desta necessidade, uma etapa importante foi cumprida no presente trabalho, o qual se constitui numa contribuição relevante tanto para o conhecimento de aspectos epidemiológicos relacionados à disseminação do agente causal do enfezamento do brócolis como para a área de conhecimento relacionada à transmissão de patógenos por insetos vetores, nas condições brasileiras. / Cole crops include several species of commercial importance among the vegetable crops cultivated in Brazil. The region located near the city of São Paulo (SP) has excelled in the cultivation of brassica, especially cabbage, cauliflower and broccoli. In cultivated fields with these species have been observed plants showing reduction of size, malformed inflorescences, reddening of leaves and necrosis of region of vessels. Previous investigations have shown that these abnormalities are associated with phytoplasmas and the disease has been called stunt. In addition, previous studies have suggested the occurrence of some species of leafhoppers potentially vectors of phytoplasmas. Considering this information, the present study aimed to identify species that transmit phytoplasmas to plants of broccoli, seeking to increase knowledge about vectors of phytoplasmas involved with this culture. Thus, insects were collected within and in marginal areas of cultivated fields. These insects were separated into groups, taxonomically identified and confined in healthy plants of broccoli. The evaluation of transmission was based on detection of phytoplasmas in the tissues of plants and insects using the technique of nested PCR with specific primers for identification of phytoplasmas group 16SrIII. The survival of insects on plants of broccoli was short-lived, not exceeding 48 hours. The experimental transmission was observed in 30% of inoculated plants. Among the 8 potential vector species that were tested, the species Atanus nitidus, Balclutha hebe, Agalliana sticticollis and Agallia albidula transmitted phytoplasma to plants of broccoli. The results of the present study confirmed those obtained in previous research, which suggested the occurrence of potential vector species of phytoplasmas among those present in crop fields. However, details about these species as vectors require the creation of healthy populations of these species and infective for broadcast demonstration in controlled conditions. Despite this need, an important step has been accomplished in this work, which constitutes a significant contribution both to the knowledge of epidemiological aspects related to the spread of causal agent of broccoli stunt and the area of knowledge related to the transmission of pathogens by insects vectors, the Brazilian conditions.

Made available in DSpace on 2014-08-20T13:42:10Z (GMT). No. of bitstreams: 1 Dissertacao_Diego_Batista_Zeni.pdf: 366485 bytes, checksum: 6607655f98dea67ee4ce2ba69cb56557 (MD5) Previous issue date: 2010-06-30 / The storage of grain for longer periods, especially those containing high content of oil to manufacture biodiesel, generated a major difficulty of the production chain in the stage of post-harvest, where there are few data on drying and storage of oilseeds with maintaining their technological characteristics. The aim of the work, we study the effects of canola grain temperature in grains dried at temperatures of 20- 25, 35-40, 55-60 and 75-80°C, were stored for periods of 1, 100, 200 and 300 days in both environments with relative humidity 55-65% and 75-85%, and temperature controlled of 21±3°C. Were analyzed moisture, bulk density and oil content of grains and also its acidity, peroxide value, saponification and iodine oil canola grain stored subjected analysis of variance (ANOVA) of data, by Tukey test (P<0,05). We conclude that: A) the drying temperature in grains causes more damage than immediate dormant grains. B) the relative humidity in the storage environment alters the equilibrium moisture content of grain density, oil content and hydrolytic and oxidative stability. C) the storage time is more important in the stability of oil in the grain mass during drying temperatures above 40°C and storage environment with relative humidity above 70%. D) drying temperature with a mass greater than 60ºC only allow oil stability of grain in storage with humidity below 70% and up to 200 days. / A armazenagem de grãos por períodos mais longos, principalmente os que contém alto teor de óleos para a fabricação de biocombustível, gerou uma maior dificuldade da cadeia produtiva na etapa de pós-colheita, onde há poucos dados referentes a secagem e armazenamento de grãos oleaginosos com manutenção de suas características tecnológicas. Objetivou-se, com o trabalho, estudar nos grãos de canola os efeitos da temperatura na massa de grãos secados as temperaturas de 20-25, 35-40, 55-60 e 75-80°C, armazenados por períodos de 1, 100, 200 e 300 dias, em ambientes com umidade relativa do ar de 55 a 65% e 75 a 85% e temperatura controlada de 21±3°C. Foram analisados umidade, massa volumétrica e teor de óleo dos grãos e também índices de acidez, peróxidos, saponificação e iodo do óleo dos grãos de canola armazenados e submetidos análise de variância (ANOVA) dos dados, pelo teste de Tukey (P<0,05). Conclui-se que: A) a temperatura de secagem na massa de grãos provoca mais danos latentes do que imediatos nos grãos. B) A umidade relativa do ar no ambiente de armazenamento altera a umidade de equilíbrio dos grãos, a massa específica, o teor de óleo e a estabilidade hidrolítica e oxidatíva. C) O tempo de armazenamento é mais influente na estabilidade do óleo dos grãos em secagens com temperaturas de massa superiores a 40ºC e armazenamento em ambiente com umidade relativa do ar superior a 70%. D) Secagens com temperatura de massa superior a 60ºC só possibilitam estabilidade do óleo dos grãos em armazenamentos com umidade menor que 70% e até 200 dias.

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Rhonda R. Janke / Petiole sap nitrate-nitrogen (NO3-N) analysis with handheld meters is a valuable tool in applying in-season nitrogen (N) for many crops. Sufficiency levels have been determined for several leafy green crops, including lettuce (Lactuca sativa L.) and cabbage (Brassica oleracea L.), but not for pac choi (Brassica rapa L.). The response of pac choi to different fertilizer rates and sources [conventional and organic] has established optimal soluble N application rates and Cardy meter sufficiency ranges. Greenhouse experiments were conducted during summer and fall of 2008 in Manhattan, KS. Conventional soluble fertilizer was formulated from inorganic salts with a 4 NO3-N: 1 ammonium ratio. Phosphorus was held at 1.72mM and K at 0.83mM for all treatment levels. The organic soluble fertilizer, fish hydrolyzate (2N:1.72P:0.83K), was diluted to provide the same N levels as with conventional treatments. Both fertilizers were applied at rates of 0, 32, 75, 150, 225, 300, and 450 mg. L-1. Seedlings were transplanted and fertilizer application began at 18 days. Plants were harvested at seven weeks (five weeks post transplanting) after receiving 15 fertilizer applications during production. Samples of the most recently matured leaves were harvested weekly and analyzed for petiole sap NO3-N and leaf blade total N concentration. Leaf count, leaf length, and chlorophyll content were also measured weekly. Fresh and dry weights were determined on whole shoots and roots. Optimum yield was achieved at the 150 mg. L-1 fertility rate with both conventional and organic fertilizers. Field and high tunnel experiments were conducted during fall 2008 to validate the sufficiency ranges obtained from the greenhouse studies. Based on field and high tunnel results, sufficiency levels of NO3-N for pac choi petiole sap during weeks 2 to 3 of production were 800-1500 mg. L-1, and then dropped to 600-1000 mg. L-1 during weeks 4 through harvest for both conventional and organic fertilizers sources. These ranges could vary based on the variety of the crop, the fertility of soil, and certain environmental factors such as photoperiod, light intensity. However, we found that petiole sap nitrate always increased to the point associated with the maximum biomass, followed by a plateau where sap nitrate remained constant. This characteristic of the Cardy meter can provide the growers with a practical methodology to generate their standard curves under specific conditions to guide in-season N applications. Total N in leaf tissue showed fewer fertilizer rate effects than petiole sap NO3-N. Chlorophyll content was not useful in evaluating pac choi N status.

To improve understanding of the effectiveness of host resistance against Leptosphaeria spp., three aspects of effectiveness of resistance were investigated. With focus on the major Rlm-mediated resistance against L. maculans, changes in effectiveness of Rlm7-mediated resistance to prevent initiation of disease epidemics at the leaf spot stage were investigated in winter oilseed rape field experiments at five sites in the UK over the period with the cropping seasons 2009/2010 - 2013/2014. L. maculans isolates virulent against Rlm7 were identified in the UK. This may be associated with observed changes in lesion phenotypes on the Rlm7 cultivars in field conditions. However, despite increased severity of phoma leaf spotting on Rlm7 cultivars, there was no associated increase in phoma stem canker severity at the end of the cropping seasons. The effectiveness of winter oilseed rape cultivars for control of phoma stem canker (caused by L. maculans or L. biglobosa) was affected by the coexistence of the two Leptosphaeria species in oilseed rape crops. Weather conditions influenced ascospore release of both species and favoured L. biglobosa ascospore release in 2011, resulting in subsequent increased L. biglobosa phoma leaf spotting and stem canker severity. However, coexistence of Leptosphaeria spp. on oilseed rape crops was affected by the cultivar resistance against L. maculans. CE experiments showed that there were interactions between the two Leptosphaeria spp. in planta. Their coexistence on B. napus was influenced by the different host responses that they trigger during host colonisation. Effects of increased temperature on effectiveness of resistance against L. maculans and on severity of symptoms by Leptosphaeria spp. on B. napus were investigated. Increased temperature affected both Rlm4- and Rlm7-mediated resistance, when assessed by phenotypic and molecular techniques. Increased temperature was associated with increased symptom severity, for both L. maculans and L. biglobosa lesions on plants. Cultivar quantitative resistance background increased effectiveness of resistance against phoma stem canker pathogens at increased temperature and should be deployed in in strategies for adaptation to climate change to avoid increased phoma stem canker epidemics in the future.

Masters of Science / Bacterial endophytes are able to improve the growth of their hosts through a number of different mechanisms such as nutrient uptake regulation, plant hormone production and regulation, siderophore production and phosphate solubilisation. They have also been shown to be able to provide protection to plants against various abiotic stressors, through various means such as oxidative stress protection. The purpose of this study was therefore to isolate endophytic bacteria from the stems of different weeds, to characterize their ability to use some of the most important growth promoting mechanisms including the ability to produce IAA, siderophores and ACC deaminase, what effect they had on the nutrient uptake in their hosts and to determine to what extent they could promote growth in the roots, stems and leaves of Brassica napus plants. In addition to this the endophytes were tested to see to what extent they could protect Brassica napus from the negative effects of vanadium stress and how this affected the plant physiologically in terms of morphology, overall biomass, the plants nutrient profile, lipid peroxidation and levels of cell death. The effect of vanadium stress on the oxidative state of Brassica napus was also monitored by determining the levels of stress induced reactive oxygen species (ROS) and the corresponding antioxidants that are responsible for regulating these reactive oxygen species. Six different endophytes (P1, P2, P3, P4, P5, P6) were isolated from different weed samples. Each endophyte was found to be able to significantly improve germination and growth in their host plant. Each isolate was able to improve the uptake of certain macronutrients and micronutrients in their respective hosts, while all of the isolates were shown to be capable of producing siderophores and ACC deaminase. One isolate had high levels of IAA production, with the remaining isolates producing small amounts of IAA. All isolates were also unable to solubilize phosphate. The five best performing endophytes (P1, P2, P3, P5, P6) in the preliminary growth trials were used in the follow up vanadium stressed growth trials, with endophyte P4 being left out of the remaining experiments. All of the endophytes showed improvements in growth promotion in comparison to the control, with endophyte treated plants showing both increased growth and biomass in both the non-stressed and vanadium stressed treatments of the vanadium stressed growth trial; however, the leaves of the vanadium stressed plants were significantly smaller than their non-stressed counterparts. When looking at the oxidative state it was found that vanadium stress caused a significant increase in the development of O2 -, H2O2 and •OH in the control and in addition to this it was shown that treatment with endophytes was able to cause a significant decrease in the levels of stress induced H2O2 and •OH in all of the treatments and O2 - for plants treated with endophyte P5. The noted change in the oxidative state of endophyte treated plants was attributed to an increase in the antioxidant activity of these plants, as it was found that endophyte treated plants showed a combination of increased activity for Superoxide dismutase, catalase and ascorbate peroxidase. This study has shown that endophytic bacteria from plant stems can be used to improve crop growth and yield, while simultaneously producing more nutrient dense crops from the same amount of land. It has also determined that endophytes P1, P2, P3, P5 and P6 are able to successfully provide protection to crop plants from the harmful effects of exposure to vanadium stress. This has great potential for improving food security locally and around the world, by allowing those who cannot gain access to large amounts of food to take in more nutrients from the same amount of food. Furthermore, it also presents the opportunity to use endophyte treatments to grow crops on land that has been previously contaminated with certain heavy metals. / 2023-12-01

>Magister Scientiae - MSc / In an ever changing environment, plants are constantly challenged by various abiotic stresses such as salinity, which limits global crop production. This directly affects food availability for the global population, which is projected to increase to 9.5 billion by 2050, which in turn places great pressure on natural resources and food security. These environmental adversities induce the accumulation of reactive oxygen species (ROS) hydrogen peroxide, hydroxyl and superoxide radicals which cause severe oxidative damage to plants. The equilibrium between the production and detoxification of ROS is then dependent on the modulation of enzymatic and non-enzymatic antioxidants to achieve plant homeostasis. / 2024

Raps wurde als Fallstudie für eine Kulturpflanze ausgewählt, die sich außerhalb des Anbaus spontan etablieren kann und so als Quelle für Neophyten dient. In einer regionalen Studie im Osnabrücker Land wurde basierend auf Kartierungen (2004-2008) und kernkodierten Mikrosatellitenmarkern die Herkunft, Persistenz und genetische Variation verwilderter Rapspopulationen untersucht. Die wichtigsten Quellen für die erhöhte genetische Variation in verwilderten Rapspopulationen waren die mehrfache Einschleppung verschiedener Sorten und Hybridisierungen zwischen diesen. Raps tritt im Osnabrücker Land mit einer Reihe nah verwandter Arten, darunter Brassica rapa und Raphanus raphanistrum, sympatrisch in verwilderten Populationen auf. Hybride zwischen Raps und diploiden Rübsen konnten nachgewiesen werden. Tetraploider Rübsen wurde als Kreuzungspartner von Raps erstmals in dieser Studie untersucht. In Kreuzungsversuchen und in einem Freilandversuch konnten interspezifische Hybridisierungen zwischen tetraploiden Rübsen und Raps nachgewiesen werden. Unter natürlichen Bestäubungsbedingungen im Freilandversuch mit tetraploiden Rübsen-Mutterpflanzen wurde eine Hybridisierungsrate von 16,2% abgeschätzt. Die Untersuchungen zeigen, dass verwilderte Rapspopulationen durchaus ein Potenzial zu evolutiven Entwicklungen besitzen. Verwilderte Rapspopulationen können als Trittsteine für intra- und interspezifischen Genfluss dienen und dadurch beim Anbau transgener Rapssorten die Koexistenz verschiedener Anbauformen erschweren. Sie können die Etablierung von Transgenen außerhalb des Anbaus ermöglichen, die Transgenausbreitung fördern und Introgression in nah verwandte Arten vermitteln. Die Wahrscheinlichkeit von Hybridisierungen zwischen Raps und Rübsen (diploid und tetraploid) könnte verringert werden, wenn vermieden würde, diese kreuzkompatiblen Arten gemeinsam in Saatgutmischungen zu verwenden.