Made available in DSpace on 2016-12-08T16:44:44Z (GMT). No. of bitstreams: 1 PGPV13MA109.pdf: 557511 bytes, checksum: d2cb3e9e50b7e2f27e43a1b3f1a189c1 (MD5) Previous issue date: 2013-02-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The family of Brassicaceae plays an important role in Brazilian horticulture, having the species of cabbage, broccoli, and cauliflower the higher at consumption by the population. The aim of this study was to evaluate the use of high dilutions preparation for production under organic system of cabbage, broccoli, and cauliflower. Experiments were conducted in the greenhouse and under fields conditions. For greenhouse, the experimental design was completely randomized. For field experiments the experiment design were randomized complete block design. Both designs were with four replications and nine treatments. For greenhouse, trays had of 64 plants from with 20 plant were taken as experiment plot. Each plot consisted of 20 plants for each specie and repetition. Ten plants distributed in double line was the plot in the field experiment. The treatments consisted of homeopathic preparations of Arnica montana, Silicea terra, Carbo vegetabilis, and Sulphur at 6CH and 30CH. For control water was used. The experiments were conducted separately for each species. In greenhouse, the treatments were applied every four days until transplanting (seven applications). Under field conditions, the treatments were applied every fifteen days until harvest (four applications). Shoot fresh mass, root fresh mass, shoot dry mass, root dry mass, plant height, root length, and stem diameter for seedlings were evaluated. For field, shape index, rate of the length of the heart and longitudinal diameter (C / D) for cabbage field crop were evaluated. Plant height and stem diameter for broccoli were evaluated. Fresh mass and dry mass of cabbage heads and broccoli inflorescences were also evaluated. The disease incidence of black-rot and alternaria and the occurrence of cabbage aphid and damage caused by diamondback moth were evaluated. The preparations of Sulphur at 6CH increased the shoot dry mass, root dry mass for seedlings and production of cabbage heads. The preparations of Sulphur at 6CH increased the plant height, root length, and stem diameter for broccoli. Silicea terra at 30CH increased the fresh mass and dry mass of broccoli inflorescences. Sulphur at 6CH reduced the aphid occurrence for cabbage and diamondback moth damage percentage for broccoli. Sulphur at 30CH increased the shoot dry mass, root dry mass, and height for cabbage seedlings. Sulphur at 30CH increased the shoot dry mass, root dry mass, and stem diameter. Aphid occurrence, alternaria; and black rot incidence were decreased when broccoli was treated by Sulphur at 30CH. Silicea terra at 30CH increased the shoot dry mass, root dry mass, height plant, stem diameter, and root length for broccoli seedlings. Silicea terra at 30CH also increased the shoot dry mass, root dry mass, and stem diameter of cauliflower seedlings. The preparations of Silicea terra at 30CH increased the production of cabbage heads and reduced the black rot incidence for broccoli. The high dilution preparations have influence on the yield and management of pests and diseases of cabbage, broccoli, and cauliflower growth under organic production system / A família Brassicaceae ocupa papel destacado na olericultura brasileira, sendo as espécies de repolho, brócolis e couve-flor de maior consumo pela população. O objetivo deste trabalho foi avaliar o uso de preparados em altas diluições na produção em sistemas orgânicos de repolho, brócolis e couve-flor. Os experimentos com repolho, brócolis e couve-flor foram realizados em casa de vegetação e a campo na Epagri e na comunidade de Pedras Brancas, Lages, SC. O delineamento foi inteiramente casualizado em casa de vegetação e de blocos ao acaso, a campo. Ambos os delineamentos foram com quatro repetições e nove tratamentos. Em casa de vegetação, as bandejas foram constituídas por 64 plantas por parcela para cada hortaliça. A parcela útil foi composta por 20 plantas centrais das 64 plantas da parcela. A campo, cada parcela de repolho e brócolis foi constituída por 10 plantas distribuídas em dupla linha. Os tratamentos utilizados, tanto para casa de vegetação como para campo, foram os preparados homeopáticos de Arnica montana, Silicea terra, Carbo vegetabilis e Sulphur na 6CH e 30CH; e água como testemunha. Os experimentos foram delineados em separado para cada uma das hortaliças e conduzidos em duplo cego. Em casa de vegetação, os tratamentos foram aplicados a cada quatro dias, sobre as mudas até seu transplante, totalizando sete aplicações. No campo, após o transplante das mudas, os tratamentos foram aplicados a cada quinze dias, sobre as plantas até sua colheita, totalizando quatro aplicações. Foram avaliadas, em mudas, características de massa fresca e seca da parte aérea e radicular, altura da planta, comprimento de raiz e diâmetro do caule. A campo, no momento da colheita, foram avaliadas as características de índice de formato, a relação do comprimento do coração e do diâmetro longitudinal (C/D) para repolho; para o brócolis, altura da planta e diâmetro do caule. Massa fresca e seca das cabeças em repolho e das inflorescências de brócolis também foram avaliadas. A incidência de alternariose e podridão-negra, bem como, a ocorrência do pulgão e dos danos da traça-das-crucíferas foram avaliadas em repolho e brócolis. O preparado de Sulphur na 6CH aumentou a massa seca da parte aérea e radicular em mudas e a produção de cabeças de repolho, bem como o incremento da massa fresca e seca das inflorescências em brócolis. O preparado de Sulphur na 6CH reduziu também a ocorrência do pulgão em plantas de repolho e brócolis e o percentual de danos da traça-das-crucíferas em brócolis.O preparado de Sulphur na 30CH aumentou a massa seca da parte aérea e radicular e altura da plântula em mudas de repolho, bem como o incremento da massa seca da parte aérea e radicular e diâmetro do caule em mudas de couve-flor. A ocorrência do pulgão, a incidência da alternariose e a podridão-negra foram reduzidas quando tratadas como o preparado de Sulphur na 30CH em plantas de brócolis. O preparado de Silicea terra na 30CH incrementou a massa seca da parte aérea e radicular, altura da plântula, comprimento de raiz e diâmetro do caule, em mudas de brócolis, bem como a massa seca da parte aérea e radicular e diâmetro do caule em mudas de couve-flor. O preparado de Silicea terra na 30CH aumentou a produção de cabeças de repolho e reduziu a incidência da podridão-negra em plantas de brócolis. Conclui- se que preparados em altas diluições influenciam na produção e no manejo de insetos-praga e doenças de plantas de repolho, brócolis e couve-flor, sob sistema orgânico

The yield of UK’s commercial oilseed rape (Brassica napus) crops has not increased over the last three decades, while a significant increase in yield has been found in trials that test new varieties before they enter the market. It has been suggested that oilseed rape is susceptible to drought and that this may contribute to the poor yield of some commercial crops. A thorough literature review revealed that there is little information on the water relations of oilseed rape crops and in particular on root growth and function and thus no strong evidence to support the above hypothesis. The aim of this thesis was to investigate root function and water relations of oilseed rape to determine whether it is more sensitive to drought than wheat, a crop species grown in rotation with oilseed rape. The water relations of wheat (Triticum aestivum L. cv. Tybalt) and oilseed rape (Brassica napus L. cv. SW Landmark) were compared in a lysimeter experiment conducted in an open sided glass house to test the hypothesis that oilseed rape was more sensitive to drying soil than wheat. Plants were grown with or without irrigation at a population density equivalent to that of commercial field crops. Irrigated oilseed rape crops transpired more water than wheat crops and oilseed rape showed a greater reduction in growth when water was withheld. The onset of drought also occurred slightly earlier in oilseed rape. In a separate experiment the root hydraulic conductance of oilseed rape, measured on a root surface area basis, was about twice that of wheat (113.1 ± 20.0 mlNm-2Nh-1NMPa-1 for oilseed rape and 53. 5 ± 10.6 for wheat). These results suggest that oilseed rape needs a less dense root system for water extraction than wheat. In the above experiment plants were grown in relatively loose soil repacked into the lysimeters. It has been suggested that oilseed rape is particularly sensitive to soil compaction, which may be a common occurrence in commercial fields. Therefore the sensitivity of oilseed rape and wheat growth to compaction was compared in an experiment under well-watered conditions. Plants were grown in a controlled environment chamber in pots packed with soil at four different bulk densities. Although the root length, shoot mass, leaf area and stomatal conductance of oilseed rape were all reduced by soil compaction, oilseed rape was no more sensitive to soil compaction than wheat under these well-watered conditions. When soil dries it also hardens and high soil strength is known to impede root growth and alter plant-water relations. The hypothesis that oilseed rape is more sensitive to increasing soil strength than wheat was tested in an experiment in which soil bulk density and soil water content were varied to create a range of soil strengths. At low soil strength oilseed rape had a greater stomatal conductance than wheat, but as soil strength increased, stomatal conductance decreased to a greater extent in oilseed rape, indicating a more sensitive response. In dense or strong soil, plants often rely on pores created by earthworms or roots of the previous crop to explore the soil volume. The ability of oilseed rape and wheat to exploit soil pores to penetrate hard soil layers was compared in a pot experiment. A hard layer, comparable to a hard–pan in a cultivated field, was created at twelve centimetre depth of each pot by packing the soil to a bulk density of 1.5 g·cm-3 relatively loose soil at a bulk density of 1.1 g·cm-3 was present above and below the layer. In one treatment seven pores were drilled through the hard layer; controls had none. Presence of pores in the hard layer led to a significant increase in number of roots in the deeper soil, of 29% for wheat and 54% for oilseed rape. This project has shown that the physiological response to drought occurred earlier in oilseed rape than in wheat and that stomatal conductance and biomass production of oilseed rape reacted more sensitively to soil drying. However, water use by oilseed rape does not seem to be limited by the ability of its roots to explore the soil and transport water compared to wheat. The growth and distribution of roots under a range of soil conditions was as good as, if not better than, that of wheat. The implications of these findings for the commercial production of oilseed rape in the UK are discussed.

In this study the growth and yield response of Solanum retroflexum Dun. (nightshade) and Brassica rapa L. subsp. chinensis (non-heading Chinese cabbage) to N, P and K availability in the soil and the interaction effects of these three nutrients were determined by means of pot experiments in a greenhouse. S. retroflexum was most sensitive to the availability of nitrogen in the soil. Sufficient nitrogen needed to be available to achieve optimum growth but adding too much adversely affected biomass production, suggesting a fairly narrow optimum range for nitrogen availability. The production of the crop was also dependent on the adequate availability of phosphorus and potassium but any adverse effects due to excess availability were less distinct than for nitrogen. In the case of B. rapa subsp. chinensis, an optimum availability range was identified for N and K and a critical level of availability for P. The decline in biomass production caused by adding N in excess of the optimum was reversed by applying both P and K at rates that were in excess of the respective optima.

The worldwide occurrence of sites contaminated with toxic metals and the associated high costs of remediating them using chemical and mechanical methods have led to calls to develop inexpensive and sustainable approaches based on the use of plants that naturally accumulate large amounts of metals in their tissues. The ability of plants to remediate metals has been rigorously studied and some species have been identified as excellent phytoremediators. However, the growth of phytoremediators is often retarded under high soil metal concentrations, rendering them ineffective. Meanwhile, some plants do not have remediating abilities but are capable of growing in contaminated environments with little or no sign of stress. Despite the volume of research dedicated to the screening and evaluation of phytoremediators, major questions remain about why some plants survive but do not remediate while the growth of phytoremediators is mostly hindered. The growth and metal-remediating efficiency of plants exposed to toxic concentrations of metals can be enhanced by inoculating phytoremediating plants with certain bacteria but the mechanisms behind this process remain unclear. Furthermore, the use of leguminous plants to improve the growth of a target plant under a mixed planting system has long been recognised as an effective yield-enhancing cropping system. However, the possibility of a non-remediating but tolerant leguminous plant conferring metal tolerance to a phytoremediator has not been explored. This thesis reports results from repeated glasshouse and lab-based growth experiments on the phytoremediating plant Brassica juncea exposed to 400 – 600 mg Zn kg-1. The aim was to investigate the abilities of two plant growth promoting bacteria (PGPB) species Pseudomonas brassicacearum and Rhizobium leguminosarum, and a leguminous plant Vicia sativa to promote B. juncea growth and enhance remediation of Zn-contaminated soil. B. juncea plant roots were analysed using synchrotron based micro-focus X-ray Fluorescence (μXRF) imaging and X-ray Absorption Near Edge Structure (μXANES) analysis to probe Zn speciation. P. brassicacearum exhibited the poorest plant growth promoting ability, while R. leguminosarum alone and in combination with P. brassicacearum significantly enhanced B. juncea growth and Zn bioaccumulation. X-ray Absorption Spectroscopy (XAS) analysis showed that reduced plant growth was due to root accumulation of Zn as Zn sulphate, Zn oxalate and Zn polygalacturonic acids. The better growth and increased metal accumulation observed in plants inoculated with R. leguminosarum and its combination with P. brassicacearum was attributed to root storage of Zn in the chelated forms of Zn phytate and Zn cysteine. A subcellular analysis of plant root also showed that the PGPB enhanced tolerance to Zn contamination by enhancing epidermal Zn compartmentalisation depending on the nature of root colonization, and induced changes in Zn speciation to less toxic Zn species in the epidermis and endodermis of plant root. The thesis therefore identifies enhanced Zn compartmentalization at the root epidermis and bacterial mediated changes in Zn toxicity through changes in Zn speciation as key complimentary mechanisms of plant growth promotion and enhanced Zn accumulation in plants by PGPB. Further experiments investigating alternative phytoremediation strategies showed that the use of the leguminous plant V. sativa in a mixed planting system with B. juncea plants completely out performed the effects of bacteria in promoting the growth and remediation potential of B. juncea under Zn contamination. By combining PGPB with mixed planting, B. juncea recovered full growth while also achieving maximum phytoremediation efficiency. The novel legume assistedmicrobial phytoremediation method that is reported in this thesis is the first to demonstrate complete plant growth recovery in plants exposed to 400 – 450 mg kg-1 soil Zn contamination for 5 weeks. Survival of V. sativa was attributed to its root storage of Zn in the chelated forms of Zn histidine and cysteine whereas in the roots of stunted B. juncea plants the majority of Zn was present as Zn oxalate and toxic Zn sulphate. Although the use of natural and synthetic chelates has been reported to enhance phytoremediation, this thesis recommends a legume-assisted-microbialphytoremediation system as a more sustainable method for Zn bioremediation.

Excessive metal deposition in soil is of major concern to the environment due to the toxicity of metals to animals and plants. Since metals do not degrade, reducing risk of exposure relies in either removing the metals from soil, or changing their speciation which leads to changes in bioavailability, mobility and toxicity. Plants have been shown to provide a cheap alternative to chemical methods for both removing and changing metal speciation, particularly when augmented with plant growth promoting bacteria. The focus of this thesis was to investigate whether the form (speciation) in which a metal contaminant is introduced to soil affects both plant health and the efficiency of metal remediation by the plant, using the well-known hyperaccumulator Brassica juncea (L.) Czern and zinc (Zn) as the metal contaminant. This study also examined the role of plant growth promoting bacteria in changing metal speciation, impact on metal toxicity and phytoremediation efficiency. Brassica juncea was grown in pots containing soil spiked with equal amounts (600 mg Zn kg-1) of soluble Zn (ZnSO4) and nanoparticulate ZnS and ZnO. Plant height, number of leaves, root length, plant biomass and chlorophyll content of Brassica juncea were used to assess Zn toxicity. Zn localisation and speciation in soil and plant tissues was studied using transmission electron microscopy (TEM), synchrotron micro-X-ray fluorescence elemental mapping (μXRF) and synchrotron X-ray absorption spectroscopy (XAS). Growth parameters showed that ZnSO4 was the most toxic form of Zn whilst ZnS and ZnO effects were not statistically different. These differences were linked to differences in Zn content in root and shoot biomass, which was higher in ZnSO4 treatments. Inoculation with Rhizobium leguminosarum and Pseudomonas brassicacearum enhanced plant growth, Zn concentration in plant biomass and translocation of Zn in all Zn treatments. XAS analysis showed that Zn speciation was altered in roots of plants inoculated with bacteria, with Zn cysteine as the most dominant form of Zn in all inoculated Zn treatments, suggesting a role for cysteine in ameliorating Zn toxicity. By also assessing Zn speciation changes across the soilrhizosphere- plant interface, this study established that Rhizobium leguminosarum modified Zn speciation at the rhizosphere. Through this thesis work, metal speciation is a major factor in determining the efficiency of metal phytoremediation and plant tolerance. Hence, this research provides useful information on Zn speciation which will contribute to effective implementation of Zn phytoremediation.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-09-06T18:21:23Z No. of bitstreams: 1 2017 - Carlos Ant?nio dos Santos.pdf: 1589290 bytes, checksum: fbf16019cb63898c65e615c045d17094 (MD5) / Made available in DSpace on 2018-09-06T18:21:23Z (GMT). No. of bitstreams: 1 2017 - Carlos Ant?nio dos Santos.pdf: 1589290 bytes, checksum: fbf16019cb63898c65e615c045d17094 (MD5) Previous issue date: 2017-02-17 / CAPES / CNPq / FAPERJ / The search for efficient strategies to reduce the losses caused by clubroot (Plasmodiophora brassicae) in cauliflower is essential due to the economic and social importance of this culture. Thus, the present study was developed with the objective of evaluating the effect of different treatments in the control of the disease, root development, biomass and inflorescences production under field and greenhouse conditions. The study consisted of three trials carried out in a family farmer's area in the municipality of Nova Friburgo, RJ, Brazil. In the first trial, it was tested the residual effect of four doses of calcined limestone (0, 1.0, 2.0 and 4.0 Mg.ha-1) associated to the application of Trichoderma harzianum biofungicide under field conditions. In the second trial, it was tested the effect of the liming associated to the application of T. harzianum and cyazofamid, under greenhouse conditions. In the third one, two ways of applying limestone were tested, in the planting pit, and applied by hand. The use of gypsum was evaluated in the field. The increase of the limestone doses promoted higher pH levels, and Ca+2 contents, and reduction of the toxic Al + 3 contents in the soil. There was also a reduction of root volume with galls, greater root development, and productivity in cauliflower. The use of T. harzianum was not effective to control the disease and did not favor the root development, either in field or in greenhouse conditions. The fungicide cyazofamid reduced the volume roots with galls, the severity, and the progression of the disease. The third rial revealed a discrete reduction in the severity of the disease when using limestone and gypsum combined. Although there was no effect of the treatments on the root system, limestone applied to the pit and by hand resulted in greater accumulations of fresh mass of inflorescence and productivity. The application of limestone by hand, in the pit, and combined with gypsum favored the accumulation of calcium in the plants. The application of limestone in the pit was equivalent to the hand application in terms of soil chemical attributes improvement, reduction of disease severity, and increase of productivity and accumulation of nutrients. / A busca por estrat?gias eficientes na redu??o das perdas causadas pela h?rnia das cruc?feras (Plasmodiophora brassicae) em couve-flor ? essencial devido ? import?ncia econ?mica e social dessa cultura. Com isso, desenvolveu-se o presente estudo com o objetivo de avaliar, em condi??es de campo e casa de vegeta??o, o efeito de diferentes tratamentos no controle da doen?a, desenvolvimento das ra?zes e produ??o de biomassa e infloresc?ncias em couve-flor. O trabalho foi constitu?do de tr?s ensaios realizados em ?rea de produtor familiar no munic?pio de Nova Friburgo, RJ. No primeiro ensaio, avaliou-se o efeito residual de quatro doses de calc?rio calcinado (0; 1,0; 2,0 e 4,0 Mg.ha-1), associado ? aplica??o de biofungicida a base de Trichoderma harzianum, em condi??es de campo. No segundo, avaliou-se o efeito da calagem associada ? aplica??o de T. harzianum e ciazofamida, em casa de vegeta??o. No terceiro, avaliou-se em campo duas formas de aplica??o de calc?rio, na cova e ? lan?o, e o uso de gesso agr?cola. O aumento das doses de calc?rio promoveu eleva??o do pH e dos teores de Ca+2 e redu??o do teor de Al+3 t?xico no solo. Ainda, houve redu??o do volume de ra?zes com h?rnias e maior desenvolvimento radicular e produtividade em couve-flor. O uso de T. harzianum n?o foi eficaz no controle da doen?a e n?o favoreceu o desenvolvimento radicular das plantas, seja nas condi??es de campo ou de casa de vegeta??o. O fungicida ciazofamida reduziu o volume de ra?zes doentes, a severidade e a progress?o da doen?a. Constatou-se no terceiro ensaio discreta redu??o da severidade da doen?a com o uso de calc?rio combinado com gesso. N?o houve efeito dos tratamentos sobre o sistema radicular, entretanto, calc?rio aplicado na cova e ? lan?o resultaram em maiores ac?mulos de massa fresca de infloresc?ncia e produtividade. A aplica??o de calc?rio ? lan?o, na cova, e calc?rio combinado com gesso favoreceram o ac?mulo de c?lcio nas plantas. O uso de calc?rio na cova foi equivalente ? sua aplica??o ? lan?o quanto a melhorias dos atributos qu?micos do solo, redu??o da severidade da doen?a, aumento da produtividade e ac?mulo de nutrientes.

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Title from first page of PDF file (viewed Febrary 1, 2010). Includes bibliographical references (p. 140-143). Issued in print and online. Available via ProQuest Digital Dissertations.

published_or_final_version / Botany / Master / Master of Philosophy

While breeding for increased oil yield has generated new lines of spring canola (Brassica napus L.) for biodiesel production, emissions of N2O from fertilized canola fields threaten to undermine the climate change mitigation benefits of canola as a biodiesel alternative to conventional diesel. This study determined the response of N2O emissions to canola line and N treatment in a maritime setting (Truro, Nova Scotia). Tissue N uptake was measured to determine whether differences in N uptake between the lines could explain any observed effect of canola line. Nitrate Exposure (the summation of daily soil NO3- concentrations over a growing season, serving as an integrated measure of the exposure of soil biomass to nitrate over the growing season) was determined to investigate its potential as a predictor of N2O emissions. Four spring canola lines (‘Topaz’, ‘Sentry’, ‘Polo’, and 04C204, in order of increasing seed oil content) were paired with five N treatments (40, 60, 80, 100, and 120 kg N ha-1) in an incomplete two-factor factorial design over two growing seasons (2008 and 2009). N2O emissions were determined using a non-steady state vented chamber method. N2O emissions peaks closely followed increases in soil water content in both years, indicating that limited aerobicity was the trigger for N2O emissions events, and suggesting that denitrification was the predominant microbial process responsible for N2O emissions. The magnitude of average N2O emissions both years was considerably low when compared to other studies (0.55 and 0.56 kg N2O ha-1 in 2008 and 2009 respectively). Increasing N treatment resulted in significantly increased N2O emissions in 2008. Though the same trend was observed in 2009, it was not found to be significant. Differences in weed cover, soil C, soil N supplying capacity, and elevation between the sites may have contributed to the inability to detect an N2O emissions response to N treatment in 2009. Canola line had no effect on N2O emissions in either study year, though heavy competition by weeds significantly affected canola plant health and survival in 2009. Tissue N uptake increased with increasing N treatment, but did not change with choice of line, which is consistent with the observation of no N2O emissions response to line. Nitrate Exposure was found to be strongly correlated with N2O emissions in a linear relationship, supporting the conclusion that Nitrate Exposure can be a promising indicator of N2O emissions when they are limited by soil N. Finally, FluxPerOil, the ratio of N2O emissions per unit oil yield (kg N2O kg-1 oil) was found to decrease with decreased N treatment in 2008, though only very little, indicating a marginal abatement of N2O emissions at a significant cost of oil. FluxPerOil was unreliable in 2009 due to weeds compromising the line effect and therefore oil yield.

The overall aim of the study was to assess the risk of gene flow from Brassica crops by insectmediated pollen transport. I measured the viability of pollen in Brassica flowers throughout crop development and compared this with the viability of pollen transported by insects inside and outside one early- and one late-season crop. In order to evaluate the relative importance of different species in pollen transport, I measured abundance of flower visitors during crop development, and measured the foraging behaviour of five key pollinator species throughout the growing season, in relation to variation in microclimate, crop phenology and the relative abundance of other pollinator species competing for flower resources. Flower visiting insects of Brassica rapa crops were highly diverse, and their abundance and diversity changed with crop phenology. I found similar abundances at the family level for both crops studied, although capture rates were greater in the early- than in the late-season crop. Across flowering development, the greatest numbers of insects were captured at the peak of flowering for both crops. During the flowering period, Diptera was the most abundant order collected, followed by Hymenoptera. The most abundant family in Hymenoptera was Apidae which tracked crop development in both fields, with greater numbers of insects captured inside than outside the field. Standardized-count pollen loads were smaller in Diptera than in Hymenoptera. Of the five key pollinator species sampled, Lasioglossum sordidum (Hymenoptera: Halictidae), Apis mellifera (Hymenoptera: Apidae) and Bombus terrestris (Hymenoptera: Apidae) transported similar pollen loads, which were much greater than those carried by Eristalis tenax (Diptera: Syrphidae) and Melangyna novae-zealandiae (Diptera: Syrphidae). The numbers of insects captured outside of the crop were 10% and 33% of the totals captured inside for the early- and the late-season crop, respectively. The proportion of insects entering versus leaving the crop varied considerably across species, crops and trap location (i.e., whether traps were inside or 50 m outside the border of the crop). However, it is worth noting that not uncommonly more insects were attracted into the crop early in the season, staying there rather than leaving, and then when flowers started to disappear there was a massive escape of insects leaving. This research provides evidence for the influence of crop age on the foraging behaviour of key pollinators and for species-specific variation in the foraging behaviour of Brassica visitors with crop development. Temporal variation in the rate and variability of movement between flowers, and the duration and variability in time spent on each flower, throughout the growing season differed markedly between pollinator species. Flower density, plant density, and the abundance of other insects contributed to the observed variation in pollinator behavioural activity for A. mellifera, E. tenax, M. novae-zelandiae and L. sordidum. Bombus terrestris had the greatest rates and variability of movement, and the greatest rates of flower visitation among all key pollinators studied. Therefore B. terrestris might contribute to gene flow to a greater extent than other key pollinators. Additionally B. terrestris had the greatest variability in the rate of movement, increasing the risk of pollen movement over long distances. In summary, I found that (i) insect abundance and diversity changed with crop phenology and Diptera was the most abundant order collected, (ii) flower density, plant density, and the abundance of other insect pollinators were important factors explaining pollinator behaviour for all key pollinators, except B. terrestris, (iii) B. terrestris might contribute to gene flow to a greater extent than other key pollinators, because it has a greater rate of flower visitation and a greater flight distance between flowers than other pollinators, and (iv) pollen viability tended to decrease with crop development and declined sharply even just 50 m outside the edge of the crop.