Comparação entre métodos para a avaliação do vigor de lotes de sementes de couve-brócolos (Brassica oleracea L. var. italica Plenk)

Os testes de vigor e o teste de germinação são componentes essenciais no controle de qualidade das empresas de produção de sementes. Com o objetivo de verificar a eficiência de diferentes testes de vigor e de variações de suas metodologias na avaliação da qualidade de sementes de couve-brócolos visando diferenciação de lotes e previsão de emergência em bandeja, cinco lotes de sementes do híbrido Flórida foram submetidos aos seguintes testes: germinação; primeira contagem de germinação; emissão de raiz primária (após 48, 56, 72, 80 e 96 h após a instalação do teste de germinação); emergência de plântulas em substrato; envelhecimento acelerado com água (1g de sementes mantidas a 41ºC por 48 e 72 h a 100%UR); envelhecimento acelerado com solução saturada de sal (mesmo procedimento do item anterior, porém usando solução de NaCl, 40% e 76%UR); condutividade elétrica (50 sementes em 25 mL de água destilada a 25ºC e leituras após 2, 4, 6, 8 e 24 h). Todos os testes apresentaram correlação significativa com a porcentagem de emergência de plântulas em substrato, a 1% de probabilidade. Os testes de envelhecimento acelerado com solução saturada de sal por 48 h e de condutividade elétrica após 8 e 24 h de embebição foram eficientes e tiveram resultados semelhantes aos da emergência em substrato. Os testes da primeira contagem de germinação, emissão da raiz primária após 56 h e envelhecimento acelerado com solução saturada de sal por 72 h, apresentaram-se mais eficientes que a emergência de plântulas em substrato na diferenciação do vigor dos lotes.

Adequação da metodologia do teste de deterioração controlada para sementes de brócolis (Brassica oleracea L. - var. itálica)

A eficiência dos testes de vigor na avaliação da qualidade de sementes, depende da sua padronização para as diferentes espécies. Neste contexto, os objetivos deste trabalho foram elaborar as curvas de absorção de água para determinar o período necessário ao ajuste do teor de água das sementes e aprimorar o teste de deterioração controlada para sementes de brócolis. Foram utilizadas sementes de três variedades: dois lotes de Piracicaba precoce, dois lotes de Flórida e quatro lotes de Ramoso. Os lotes foram caracterizados mediante a determinação do teor de água e germinação; o vigor foi determinado pelos testes de primeira contagem, comprimento de plântula, emergência e índice de velocidade de emergência. Foram determinadas as curvas de absorção de água por 84 horas. Para averiguar a eficiência do teste de deterioração controlada para sementes de brócolis, foi feito o ajuste do conteúdo de água das sementes para: 18, 20, 21, 23 e 24%, sendo estas expostas a 45ºC em banho-maria, por 24 horas. O delineamento utilizado foi o inteiramente casualizado. As médias foram comparadas pelo teste de Tukey a 5% de probabilidade. As curvas de absorção permitiram estimar os períodos de 15, 20, 22, 32 e 48 horas para elevação do teor de água a 18, 20, 21, 23 e 24% respectivamente. O teste de deterioração controlada, para sementes de brócolis, propiciou resultados promissores, tendo sido eficiente na separação de lotes, em todos os teores de água estudados, tanto quanto os testes de emergência de plântula e índice de velocidade de emergência.

Conseqüências fisiológicas da dessecação em sementes de açaí (Euterpe oleracea Mart.)

O presente trabalho foi realizado com o objetivo de verificar os efeitos imediatos da desidratação sobre a qualidade fisiológica de sementes de açaí. Anteriormente à secagem das sementes da cultivar BRS Pará foi determinado o teor de água das mesmas e selecionado o lote daquelas que apresentavam o maior teor de água, que foi de 43,4%. As sementes foram submetidas à secagem, em equipamento com circulação forçada de ar (30±2ºC), até atingirem o teor de água de 37,4%, 30,3% 26,1%, 21,0%, 15,% e 11,9%, constituindo os demais tratamentos. O efeito da secagem sobre a qualidade das sementes foi avaliado por meio das determinações de germinação, tempo médio de germinação, velocidade de emergência, comprimento e massa da matéria seca de plântulas. A secagem até 37,4% de água não produz efeitos fisiológicos prejudiciais imediatos sobre as sementes de açaí, contudo, abaixo de 30,3% há redução progressiva da germinação e do vigor das sementes e ao atingirem 15,1% de teor de água, o desempenho fisiológico é anulado.

Conservação de sementes de açaí (Euterpe oleracea Mart.)

Sementes de Euterpe oleracea são consideradas recalcitrantes e demandam ampliação do conhecimento sobre os fatores que interferem na sua conservação. Diante disso, o presente trabalho foi realizado com o objetivo de verificar os efeitos do teor de água da semente e da temperatura do ambiente na manutenção da qualidade das mesmas. Sementes da cultivar BRS Pará, com diferentes teores de água (43,4; 37,4; 30,3; 26,1; 21,0; 15,1 e 11,9%) e acondicionadas em sacos de polietileno foram armazenadas sob temperaturas de 20, 15 e 10 ºC durante 360 dias e submetidas a avaliações periódicas do teor de água, da germinação e do vigor. A secagem parcial até 37,4% de água não produz efeitos imediatos sobre a germinação e o vigor das sementes, a partir daí a secagem favorece, progressivamente, a deterioração das sementes e, ao atingirem 15,1% as sementes não germinam. Após o armazenamento, sementes com 21,0% de água ou menos não germinam independentemente da temperatura. A associação de 43,4% de água na semente e o armazenamento em ambiente a 20 ºC favorece a conservação das sementes por até 270 dias.

Modificación en los ambientes espectrales de crecimiento y su efecto sobre el comportamiento fisiológico y productividad de lactuca sativa L. y spinacia oleracea L.

Tesis (Doctorado en Ciencias Biológicas con Especialidad en Botánica) UANL

Biochemical characterization of a novel halide/bisulfide mythyltransferase purified from Brassica oleracea L.

Thèse diffusée initialement dans le cadre d'un projet pilote des Presses de l'Université de Montréal/Centre d'édition numérique UdeM (1997-2008) avec l'autorisation de l'auteur.

Influence of pre-plant densities of Meloidogyne incognita on growth and root infestation of spinach (Spinacia oleracea L.) (Amaranthaceae) – an important dimension towards enhancing crop production

Vegetables represent a main source of micro-nutrients which can improve the health status of malnourished poor in the world. Spinach (Spinacia oleracea L.) is a popular leafy vegetable in many countries which is rich with several important micro-nutrients. Thus, consuming Spinach helps to overcome micro-nutrient deficiencies. Pests and pathogens act as major yield constraints in food production. Root-knot nematodes, Meloidogyne species, constitute a large group of highly destructive plant pests. Spinach is found to be highly susceptible for these nematode attacks. Though agricultural production has largely benefited from modern technologies and innovations, some important dimensions which can minimize the yield losses have been neglected by most of the growers. Pre-plant or initial nematode density in soil is a crucial biotic factor which is directly responsible for crop losses. Hence, information on preplant nematode densities and the corresponding damage is of vital importance to develop successful control procedures to enhance crop production. In the present study, effect of seven initial densities of M. incognita, i.e., 156, 312, 625, 1250, 2,500, 5,000 and 10,000 infective juveniles (IJs)/plant (equivalent to 1000cm3 soil) on the growth and root infestation on potted spinach plants was determined in a screen house. In order to ensure a high accuracy, root infestation was ascertained by the number of galls formed, the percentage galled-length of feeder roots and galled-feeder roots, and egg production, per plant. Fifty days post-inoculation, shoot length and weight, and root length were suppressed at the lowest IJs density. However, the pathogenic effect was pronounced at the highest density at which 43%, 46% and 45% reduction in shoot length and weight, and root length, respectively, was recorded. The highest reduction in root weight (26%) was detected at the second highest density. The Number of galls and percentage galled-length of feeder roots/per plant showed significant progressive increase across the increasing IJs density with the highest mean value of 432.3 and 54%, respectively. The two shoot growth parameters and root length showed significant inverse relationship with the increasing gall formation. Moreover, the shoot and root length were shown to be mutually dependent on each other. Suppression of shoot growth of spinach greatly affects the grower’s economy. Hence, control measures are essentially needed to ensure a better production of spinach via reducing the pre-plant density below the level of 0.156 IJs/cm3.

Análisis del cultivo de brócoli (Brassica oleracea var Italica), manejo-reducción de pesticidas y posibilidades de aplicación del método circular de estudio en la Comunidad de Gatazo Zambrano, Cantón Colta, Provincia Chimborazo - Ecuador

La investigación propuesta pretende comprobar si la educación formal, la capacitación, la asistencia técnica son fundamentales para manejar adecuadamente los pesticidas y reducir sus residuos tóxicos en los agro-ecosistemas de pequeña producción. De hecho, a través de la encuesta proporcionada por el equipo técnico del proyecto Marco de Inversión en Desarrollo Rural y Reducción de Pobreza (MIRREP) se trabajó con indicadores socio-ambientales y económicos que permitieron reconocer que miembros de la comunidad son los más perjudicados por el mal uso de pesticidas. Para el efecto, se recopiló los datos desde el mes de julio hasta el mes de octubre del 2007. Los datos se compilaron en las encuestas prediseñadas de las que se obtuvo datos porcentuales y datos estadísticos levantados a través de Análisis de Correspondencia Múltiple (MCA) y Chi-Cuadrado de Pearson. A la vez, se introdujo el Método Circular de Estudio (SCM) como metodología de capacitación para el campesinado adulto con el fin de comprobar su efectividad, y generar y transmitir conocimientos respecto al uso de pesticidas y eliminación de sus residuos. Ahora bien, para analizar cual es la situación respecto al manejo de pesticidas se hizo observación directa, entrevistas (informales, formales), conferencias grupales y comunales para finalmente por medio del SCM establecer diálogos horizontales donde tanto técnicos como campesinos tienen el mismo derecho de participar y opinar, considerando sus opiniones tan valederas como las del personal técnico con el fin de enriquecerse las partes participantes en un verdadero proceso de transmisión y generación de conocimientos in situ. De esta forma, se ha generado un trabajo de investigación-acción enmarcado en la capacitación y valoración de las condiciones socio-ambientales y económicas con el fin de implementar programas y metodologías para el manejo y reducción de pesticidas. De hecho, contextualizar la realidad del campesinado respecto al manejo de pesticidas, evidenciarlo ante las autoridades de turno y proponer una alternativa de desarrollo rural valedera donde se reduzcan las múltiples externalidades negativas (sociales, económicas, y ambientales) es el valor agregado que este trabajo con el fin de reducir la pobreza a la que el campesinado se ha visto acogido por más de 2 décadas.

Characterization and origin of infection of Rhizoctonia solani associated with Brassica oleracea crops in the UK

An extensive study was conducted to determine where in the production chain Rhizoctonia solani became associated with UK module-raised Brassica oleracea plants. In total, 2600 plants from 52 crops were sampled directly from propagators and repeat sampled from the field. Additional soil, compost and water samples were collected from propagation nurseries and screened using conventional agar isolation methods. No isolates of R. solani were recovered from any samples collected from propagation nurseries. Furthermore, nucleic acid preparations from samples of soil and compost from propagation nurseries gave negative results when tested for R. solani using real-time PCR. Conversely, R. solani was recovered from 116 of 1300 stem bases collected from field crops. All the data collected suggested R. solani became associated with B. oleracea in the field rather than during propagation. Parsimony and Bayesian phylogenetic studies of ribosomal DNA suggested the majority of further classified isolates belonged to anastomosis groups 2-1 (48/57) and AG-4HGII (8/57), groups known to be pathogenic on Brassica spp. in other countries. Many R. solani isolates were recovered from symptomless plant material and the possibilities for such an association are discussed.

Simple sequence repeats reveal uneven distribution of genetic diversity in chloroplast genomes of Brassica oleracea L. and (n=9) wild relatives

Diversity in the chloroplast genome of 171 accessions representing the Brassica 'C' (n = 9) genome, including domesticated and wild B. oleracea and nine inter-fertile related wild species, was investigated using six chloroplast SSR (microsatellite) markers. The lack of diversity detected among 105 cultivated and wild accessions of B. oleracea contrasted starkly with that found within its wild relatives. The vast majority of B. oleracea accessions shared a single haplotype, whereas as many as six haplotypes were detected in two wild species, B. villosa Biv. and B. cretica Lam.. The SSRs proved to be highly polymorphic across haplotypes, with calculated genetic diversity values (H) of 0.23-0.87. In total, 23 different haplotypes were detected in C genome species, with an additional five haplotypes detected in B. rapa L. (A genome n = 10) and another in B. nigra L. (B genome, n = 8). The low chloroplast diversity of B. oleracea is not suggestive of multiple domestication events. The predominant B. oleracea haplotype was also common in B. incana Ten. and present in low frequencies in B. villosa, B. macrocarpa Guss, B. rupestris Raf. and B. cretica. The chloroplast SSRs reveal a wealth of diversity within wild Brassica species that will facilitate further evolutionary and phylogeographic studies of this important crop genus.

Spontaneous gene flow from rapeseed (Brassica napus) to wild Brassica oleracea

Research on the environmental risks of gene flow from genetically modified ( GM) crops to wild relatives has traditionally emphasized recipients yielding most hybrids. For GM rapeseed ( Brassica napus), interest has centred on the 'frequently hybridizing' Brassica rapa over relatives such as Brassica oleracea, where spontaneous hybrids are unreported in the wild. In two sites, where rapeseed and wild B. oleracea grow together, we used flow cytometry and crop-specific microsatellite markers to identify one triploid F-1 hybrid, together with nine diploid and two near triploid introgressants. Given the newly discovered capacity for spontaneous introgression into B. oleracea, we then surveyed associated flora and fauna to evaluate the capacity of both recipients to harm cohabitant species with acknowledged conservational importance. Only B. oleracea occupies rich communities containing species afforded legislative protection; these include one rare micromoth species that feeds on B. oleracea and warrants further assessment. We conclude that increased attention should now focus on B. oleracea and similar species that yield few crop-hybrids, but possess scope to affect rare or endangered associates.

The potential to intensify sulforaphane formation in cooked broccoli (Brassica oleracea var. italica) using mustard seeds (Sinapis alba)

Sulforaphane, a naturally occurring cancer chemopreventive, is the hydrolysis product of glucoraphanin, the main glucosinolate in broccoli. The hydrolysis requires myrosinase isoenzyme to be present in sufficient activity; however processing leads to its denaturation and hence reduced hydrolysis. In this study, the effect of adding mustard seeds, which has a more resilient isoform of myrosinase, to processed broccoli was investigated with a view to intensify the formation of sulforaphane. Thermal inactivation of myrosinase from both broccoli and mustard seeds was studied. Thermal degradation of broccoli glucoraphanin was investigated in addition to the effects of thermal processing on the formation of sulforaphane and sulforaphane nitrile. Limited thermal degradation of glucoraphanin (less than 12 %) was observed when broccoli was placed in vacuum sealed bag (sous vide) and cooked in a water bath at 100 ºC for 8 and 12 min. Boiling broccoli in water prevented the formation of any significant levels of sulforaphane due to inactivated myrosinase. However, addition of powdered mustard seeds to the heat processed broccoli significantly increased the formation of sulforaphane.

Shoot calcium and magnesium concentrations differ between subtaxa, are highly heritable, and associate with potentially pleiotropic loci in Brassica oleracea

Calcium (Ca) and magnesium (Mg) are the most abundant group II elements in both plants and animals. Genetic variation in shoot Ca and shoot Mg concentration (shoot Ca and Mg) in plants can be exploited to biofortify food crops and thereby increase dietary Ca and Mg intake for humans and livestock. We present a comprehensive analysis of within-species genetic variation for shoot Ca and Mg, demonstrating that shoot mineral concentration differs significantly between subtaxa (varietas). We established a structured diversity foundation set of 376 accessions to capture a high proportion of species-wide allelic diversity within domesticated Brassica oleracea, including representation of wild relatives (C genome, 1n = 9) from natural populations. These accessions and 74 modern F-1 hybrid cultivars were grown in glasshouse and field environments. Shoot Ca and Mg varied 2- and 2.3-fold, respectively, and was typically not inversely correlated with shoot biomass, within most subtaxa. The closely related capitata (cabbage) and sabauda (Savoy cabbage) subtaxa consistently had the highest mean shoot Ca and Mg. Shoot Ca and Mg in glasshouse-grown plants was highly correlated with data from the field. To understand and dissect the genetic basis of variation in shoot Ca and Mg, we studied homozygous lines from a segregating B. oleracea mapping population. Shoot Ca and Mg was highly heritable (up to 40). Quantitative trait loci (QTL) for shoot Ca and Mg were detected on chromosomes C2, C6, C7, C8, and, in particular, C9, where QTL accounted for 14 to 55 of the total genetic variance. The presence of QTL on C9 was substantiated by scoring recurrent backcross substitution lines, derived from the same parents. This also greatly increased the map resolution, with strong evidence that a 4-cM region on C9 influences shoot Ca. This region corresponds to a 0.41-Mb region on Arabidopsis (Arabidopsis thaliana) chromosome 5 that includes 106 genes. There is also evidence that pleiotropic loci on C8 and C9 affect shoot Ca and Mg. Map-based cloning of these loci will reveal how shoot-level phenotypes relate to Ca 21 and Mg 21 uptake and homeostasis at the molecular level.

Shoot zinc (Zn) concentration varies widely within Brassica oleracea L. and is affected by soil Zn and phosphorus (P) levels

The low availability of zinc (Zn) in soils and crops affects dietary Zn intake worldwide. This study sought to determine if the natural genetic variation in shoot Zn concentrations (Zn(shoot)) is sufficient to pursue a crop improvement breeding strategy in a leafy vegetable crop. The gene-pool of Brassica oleracea L. was sampled using a large (n = 376) diversity foundation set (DFS), representing almost all species-wide common allelic variation, and 74 commercial varieties (mostly F(1)). The DFS genotypes were grown at low and high soil phosphorus (P) levels under glasshouse and field conditions, and also in a Zn-deficient soil, with or without Zn-fertilisation, in a glasshouse. Despite the large variation in Zn(shoot) among genotypes, environment had a profound effect on Zn(shoot) The heritability of Zn(shoot) was significant, but relatively low, among 90 doubled-haploid (DH) lines from a mapping population. While several quantitative trait loci (QTL) associated with Zn(shoot) occurred on chromosomes C2, C3, C5, C7, and C9, these were generally weak and conditional upon growth conditions. Breeding for Zn(shoot) in B. oleracea is therefore likely to be challenging. Shoot P concentrations increased substantially in all genotypes under low soil Zn conditions. Conversely, only some genotypes had increased Zn(shoot) at low soil P levels. Sufficient natural genetic variation may therefore exist to study some of the interactions between Zn and P nutrition.

Shoot yield drives phosphorus use efficiency in Brassica oleracea and correlates with root architecture traits

The environmental and financial costs of using inorganic phosphate fertilizers to maintain crop yield and quality are high. Breeding crops that acquire and use phosphorus (P) more efficiently could reduce these costs. The variation in shoot P concentration (shoot-P) and various measures of P use efficiency (PUE) were quantified among 355 Brassica oleracea L. accessions, 74 current commercial cultivars, and 90 doubled haploid (DH) mapping lines from a reference genetic mapping population. Accessions were grown at two or more external P concentrations in glasshouse experiments; commercial and DH accessions were also grown in replicated field experiments. Within the substantial species-wide diversity observed for shoot-P and various measures of PUE in B. oleracea, current commercial cultivars have greater PUE than would be expected by chance. This may be a consequence of breeding for increased yield, which is a significant component of most measures of PUE, or early establishment. Root development and architecture correlate with PUE; in particular, lateral root number, length, and growth rate. Significant quantitative trait loci associated with shoot-P and PUE occur on chromosomes C3 and C7. These data provide information to initiate breeding programmes to improve PUE in B. oleracea.