Hieracium lepidulum is an invasive weed in New Zealand. It colonises a wide range of habitats including pine plantations, scrubland, native Nothofagus forest, and mid-altitude to alpine tussock grassland, where it is competing with indigenous species. Understanding the breeding systems and population genetic structure of H. lepidulum is important for biocontrol, and aids in the understanding of evolutionary colonisation processes. H. lepidulum is a triploid, diplosporous, obligate apomict. This type of reproduction through clonal seed does not involve meiosis or fertilisation, and theoretically populations should contain very low levels of genetic variation, the only source being somatic mutation. Common garden experiments and microsatellite markers were used to determine the population genetic structure of H. lepidulum populations in the Craigieburn Range, Canterbury. Both experiments revealed that populations, sampled from three replicate altitudes within three geographically-separated locations, contained no genetic variation; individuals all possessed the same microsatellite genotype. These results strongly suggest that the Craigieburn Range H. lepidulum individuals reproduce solely by apomixis and populations belong to the same clonal lineage. Populations were also examined for their response to two abiotic environmental ‘stresses’, drought and shade. H. lepidulum populations’ exhibited high drought tolerance, yet appeared to be shade-intolerant. Low levels of reproduction in light-limiting habitats will prevent the invasion of H. lepidulum into closed-canopy forest habitats. H. lepidulum appears to have overcome the reduction in fitness associated with apomictic reproduction by phenotypic plasticity, fixed heterozygosity and polyploidy – all associated with increased vigour, fitness, and the ability to occupy broader ecological niches. This study’s results are hopeful for the development of biocontrol programs involving genotype-specific pathogens but suggest that grazing management may not succeed. The data will be useful for future comparisons of genetic structure during the course of H. lepidulum invasions and will contribute to the management of this invasive weed.

This thesis aimed to study three main aspects: (i) the mechanisms underlying unreduced pollen gamete formation in the diploid `CSO¿ tangor hybrid used as male parent in 4x x 2x triploid breeding programs, (ii) the frequencies and mechanisms involved in the unreduced 2n female gametes production for `Eureka Frost¿ and `Fino¿ lemon genotypes, and (iii) the interspecific recombination and the resulting diploid gamete structures of doubled-diploid `Mexican¿ lime to evaluate the possibility that natural interploid hybridization maybe the origin of C. latifolia (`Tahiti¿ lime type) and C. aurantifolia (`Tanepao¿ lime type) triploid varieties. The production of 54 tetraploid hybrids from 4x x 2x sexual hybridizations allowed the analysis of the mechanisms underlying unreduced pollen gamete formation. SSR and SNP molecular markers revealed that the majority of these plants were obtained from 2n pollen of the diploid tangor parent. Then, the maximum-likelihood method based on parental heterozygosity restitution (PHR) of centromeric loci revealed that both FDR (First Division Restitution ) with predominant occurrence and to a lower extend SDR (Second Division Restitution) were the mechanisms leading to unreduced male gamete formation in the tangor studied. These observations were confirmed by the analysis of PHR pattern along the linkage group (LG) 2. To our knowledge, this is the first report of tetraploid citrus progenies arising from unreduced pollen and the first description of the coexistence of two meiotic restitution mechanisms (SDR and FDR) producing unreduced pollen in citrus. In order to study the frequencies and the mechanisms involved in the unreduced 2n female gametes production in two different genotypes of lemon, we produced 43 triploid and tetraploid hybrids from 2x x 2x and 2x x 4x sexual hybridizations using `Eureka Frost¿ and `Fino¿ as female parents. The frequencies of 2n gamete production were respectively 4.9% and 8.3%. The maximum-likelihood analysis and pattern of PHR along LG1 revealed that SDR is the main mechanism of unreduced female lemon gametes (88%), followed by FDR or pre-meiotic doubling (PRD) (7%) and post-meiotic genome doubling (PMD) mechanisms (5%). This is the first report of the production of a large number of lemon progenies from 2n gametes and the first identification of a new mechanism, PMD that has never been observed in citrus and has rarely been described in other herbaceous or woody species. Across both studies, we demonstrated at the methodological level the effectiveness of using two complementary approaches, the analysis of the PHR pattern in one LG and the maximum-likelihood method based on centromeric loci for distinguishing between the different mechanisms of unreduced gamete production. We analyzed the meiotic mechanisms of a doubled diploid `Mexican¿ lime, the interspecific recombination and the resulting diploid gamete structures combining a segregation analysis of SSR and SNPs markers, a cytogenetic study and pollen viability evaluation. We concluded that the doubled-diploid `Mexican¿ lime had a predominantly disomic segregation for three LGs, intermediate inheritance with disomic tendency was found for five LGs and intermediate models for one LG. The resulting interspecific diploid gamete structures displayed high C. medica / C. micrantha heterozygosity. The revealed genetic structures of the diploid gametes produced by the doubled-diploid `Mexican¿ lime are compatible with the hypothesis that `Tahiti¿ and `Tanepao¿ triploid varieties results from interploid hybridization involving a doubled-diploid `Mexican¿ like lime. This disomic tendency limits the recombination and the diversity of the diploid gamete population; however the observed pollen viability restoration at tetraploid level could be advantageous for intensive breeding projects. / Esta tesis estudia tres aspectos principales: (i) los mecanismos de la formación de gametos 2n de polen originados por un híbrido diploide (tangor `CSO¿) utilizado como parental masculino en hibridaciones sexuales 4x x 2x, (ii) las frecuencias y los mecanismos de la producción de gametos 2n femeninos en dos genotipos de limón, `Eureka Frost¿ y `Fino¿, y (iii) el análisis de la recombinación interespecífica y las estructuras de los gametos diploides originados por la lima `Mejicana¿ doble diploide para evaluar el origen de las las variedades triploides de lima C. latifolia (`Tahiti¿) y C. aurantifolia (`Tanepao¿). La obtención de 54 híbridos tetraploides a partir de hibridaciones 4x x 2x permitió analizar los mecanismos de la formación de gametos 2n de polen. El análisis molecular reveló que la mayoría de estas plantas se obtuvieron a partir de gametos 2n de polen del parental `CSO¿. A continuación, el análisis mediante el método de máxima verosimilitud indicó que FDR (Restitución de la Primera División meiótica) y SDR (Restitución de la Segunda División meiótica) son los mecanismos implicados con una mayor dominancia de FDR respecto SDR. Estos resultados se confirmaron mediante el análisis de la restitución de la heterocigosidad en el grupo de ligamiento (LG) 2. Con los datos publicados hasta la fecha, es la primera vez que se han obtenido progenies tetraploides de cítricos mediante gametos 2n de polen y es la primera descripción en cítricos de la coexistencia de dos mecanismos SDR y FDR. Para estudiar las frecuencias y los mecanismos de la producción de gametos 2n en dos genotipos de limón, se obtuvieron 43 híbridos triploides y tetraploides a partir de hibridaciones sexuales 2x x 2x y 2x x 4x utilizando los limones `Eureka Frost¿ y `Fino¿ como parentales femeninos. Las frecuencias de producción de gametos 2n fueron respectivamente 4,9% y 8,3%. El análisis de máxima verosimilitud y el patrón de PHR a lo largo del LG1 reveló que SDR es el mecanismo principal de formación de gametos 2n femeninos (88%), seguido por FDR o duplicación del genoma pre-meiosis (PRD) (7%) y se identificó un nuevo mecanismo originado a partir de la duplicación del genoma post-meiosis (PMD) (5%). En este trabajo se describe por primera vez en cítricos la producción de un elevado número de híbridos de limón a partir de gametos 2n y es la primera vez que se identifica un nuevo mecanismo PMD que nunca se ha observado en cítricos. En ambos estudios se demostró la efectividad del uso de dos métodos complementarios, el análisis del patrón de PHR a lo largo de un LG y el método de máxima verosimilitud para distinguir entre los diferentes mecanismos implicados en la formación de gametos 2n. También se ha analizado el modelo de segregación cromosómica de la lima `Mejicana¿ doble diploide (DD) así como la recombinación interespecífica y las estructuras de los gametos diploides resultantes. Se ha realizado análisis de la viabilidad del polen junto con un análisis citogenético y con marcadores SSRs y SNPs. Estos trabajos nos han permitido concluir que la lima `Mejicana¿ DD presenta una segregación predominantemente disómica para tres LGs, herencia intermedia con tendencia disómica para cinco LGs y un tipo de segregación intermedia para un LG. Las estructuras de los gametos diploides mostraron una alta heterocigosis en C. medica/C. micrantha, parentales de la lima `Mejicana¿. Las estructuras genéticas de los gametos diploides de la lima `Mejicana¿ DD son compatibles con la hipótesis de que las variedades triploides `Tahiti¿ y `Tanepao¿ se obtuvieran a partir de una hibridación interploide a partir de la lima `Mejicana¿ DD. El tipo de segregación disómico conlleva una limitación de la recombinación y la diversidad genética de la población de gametos 2n. Sin embargo la viabilidad del polen de la lima `Mejicana¿ DD en comparación con la lima `Mejicana¿ diploide permite / Aquesta tesi ha tingut com a objectius l'estudi de (i) els mecanismes subjacents a la formació de pol·len de gàmetes 2n al tangor híbrid diploide `CSO', utilitzat com a progenitor masculí en els programes de millora de triploides 4x x 2x (ii) les freqüències i els mecanismes implicats en la producció gàmetes 2n en la femella als genotips de llimona `Eureka Frost¿ i Fina' (iii) la recombinació interespecífica i les estructures resultants de gàmetes diploides del doble-diploide (DD) de `llima Mèxicana' per avaluar la possibilitat que la hibridació interploid natural potser l'origen de les varietats triploides C. latifolia (llima tipus `Tahiti') i C. aurantifolia (llima tipus `Tanepao'). La producció de 54 híbrids tetraploides obtinguts d¿hibridacions sexuals 4x x 2x va permetre l'anàlisi dels mecanismes de formació de gàmetes 2n de pol·len. Els marcadors moleculars SSR i SNP van revelar que la majoria d'aquestes plantes es van obtenir de pol·len 2n del parental diploide tangor. Llavors, el mètode de màxima probabilitat va revelar que tant FDR (Restitució en la Primera Divisió), amb ocurrència predominant, com SDR (Restitució en la Segona Divisió) van ser els mecanismes que condueixen a la formació de gàmetes masculins 2n en aquest tangor. Aquestes observacions van ser confirmades per l'anàlisi de patró de RHP al llarg del cromosoma 2. Des del nostre coneixement, aquest és el primer estudi de progènies de cítrics tetraploides derivats de pol·len no reduït i la primera descripció de la coexistència de dos mecanismes de restitució meiòtiques (FDR i SDR) produint pol·len no reduït en els cítrics. Per tal d'estudiar les freqüències i els mecanismes implicats en la producció de gàmetes 2n sense reduir de la femella, en dos genotips diferents de llimona, vam obtenir 43 híbrids triploides i tetraploides d¿hibridacions sexuals 2x x 2x i 4x x 2x utilitzant `Eureka Frost ' i `Fino' com progenitors femenins. Les freqüències de la producció de gàmetes 2n van ser, respectivament, 4,9% i 8,3%. L'anàlisi de màxima probabilitat i el patró de RHP al llarg del cromosoma 1 van revelar que SDR és el principal mecanisme de gàmetes 2n en la llimona utilitzada com parent femení (88%), seguit pels mecanismes FDR o duplicació pre-meiòtica (PRD) (7%) i la duplicació del genoma post-meiòtica (PMD) (5%). Per primera volta en els cítrics s¿ha obtingut un gran nombre de progènie de llimona a partir de gàmetes 2n i s¿ha identificat un nou mecanisme, el PMD que poques vegades s'ha descrit en altres espècies herbàcies o llenyoses. A través dels dos treballs, hem demostrat, a nivell metodològic, l'eficàcia d'utilitzar dos enfocaments complementaris, és a dir, l'anàlisi del patró de RHP en un cromosoma amb el mètode de màxima probabilitat basat en loci centromèrics per distingir entre els diferents mecanismes de la producció de gàmetes 2n . Es van analitzar els mecanismes meiòtics d'un DD `llima Mèxicana', la recombinació interespecífica i les estructures resultants de gàmetes diploides combinant una anàlisi de segregació de marcadors SSR i SNP, un estudi citogenètic i l'avaluació de la viabilitat del pol·len. Hem arribat a la conclusió que el DD de `llima Mèxicana' tenia una segregació predominantment disómica en tres cromosomes, herència intermèdia amb tendència disómica en cinc cromosomes i els models intermedis per a un altre. Les estructures resultants de gàmetes diploides interespecífiques mostren alta heterozigositat C. medica / C. micrantha. Les estructures genètiques revelades dels gàmetes diploides produïts pel DD de `llima Mèxicana' són compatibles amb la hipòtesi que les varietats triploides `Tahiti¿ i `Tanepao¿ resulten de la hibridació interploide que impliquen un DD de tipus `llima Mèxicana'. Aquesta tendència disómica limita la recombinació i la diversitat de la població de gàmetes diploides, però, la restauració de la viabilitat / Houssem, R. (2017). Genetic Structure of Diploid Gametes for the Production of Triploid Citrus Hybrids [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90634 / TESIS

Several species‐specific proteins have been identified by polyacrylamide gel electrophoresis (PAGE) of skeletal muscle extracts from the diploid gynogen, Poecilia formosa, its related triploid unisexuals, and their sympatric, bisexual species, P. mexicana and P. latipinna. These water‐soluble, low molecular weight proteins (7,000‐13,000) comigrate with a fraction of purified rabbit parvalbumin on nondenaturing gels and show staining properties similar to rabbit parvalbumins. The electrophoretic patterns of these muscle proteins provide a set of distinctive phenotypic markers for each of the host species involved in naturally occurring breeding complexes with P. mexicana × P. latipinna show no evidence of sexual dimorphisms. Furthermore, the hybrid phenotypes are those that would be predicted from appropriate combinations of parental alleles at three gene loci. The patterns found by PAGE for several generations of pedigreed stocks of P. formosa show strictly matroclinous inheritance of a characteristic muscle protein phenotype and coupled with the electrophoretic patterns of several enzymic proteins reflect the probable hybrid origin of this diploid unisexual. Finally, paternal contributions by P. mexicana to the hybrid genome of triploid unisexuals are clearly demonstrated by comparative analyses of muscle protein phenotypes for P. formosa and its contemporary host species. Our identification of distinctive phenotypic markers in the muscle proteins of several poeciliid species involved in unisexual‐bisexual breeding complexes provides an important new tool for further studies on the adaptive significance of unisexuality, hybridization, and fixed heterozygosity in the evolutionary biology of these fishes.

No description available.

Thesis (MScAgric)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Abalone production is the largest financial contributor to aquaculture in South Africa and practically all of the abalone produced is exported to Asia. This means that the product must be globally competitive and many technologies have been applied to this cause. One that specifically shows great promise for bivalve mollusc production is triploidy; more precisely, sterility due to the induction of aneuploidy. Under normal maturation, energy is diverted from somatic growth through sexual maturation, therefore inhibiting or retarding gametogenesis through a process such as aneuploidy is expected to increase growth and decrease the time to marketing. Two studies preceding this one investigated the induction of triploidy through hydrostatic shock (De Beer, 2004) and the comparative growth rate of triploid genotypes from 8 to 24 months, prior to the onset of sexual maturation (Schoonbee, 2008). During this comparative growth stage, no convincing statistical evidence of faster growth or of seasonal environmental effects could be obtained. It was recommended that growth between triploid and diploid variants be compared during the age period when sexual maturity becomes a factor to determine whether triploidy in Haliotis midae is a useful biotechnological tool to improve biological productivity and global competiveness of the abalone industry. The growth measured as shell length and wet weight in the period from 29 to 62 months showed a statistically significant difference in mean weight and mean length with diploids showing a superior growth rate compared to their triploid siblings. This difference of 1.99 mm and 5.13 g was however not perceived as being commercially significant. Important production parameters including canning yield percentage and gonadosomatic index were also measured during this trial. For both these parameters, the triploid genotype showed statistically and commercially significant improvement of 10.68% increased canning yield and 28.42% reduction in gonadosomatic index when compared to their diploid counterparts. Triploid abalone was found to be not completely sterile; gametes and even mature gonads were observed in some instances. Even though complete sterility was not achieved there appeared to be a retarded gonadosomatic development in triploid variants. The delay in sexual maturation, together with the improvement in canning yield, may justify triploidy’s commercial application, despite its reduced growth rate. / AFRIKAANSE OPSOMMING: Perlemoen produksie lewer die grootste finansiële bydra tot akwakultuur in Suid Afrika en feitlik al die Perlemoen word uitgevoer na Asië. Dit beteken dat die produk moet kompeteer op die wêreld mark en verskeie tegnologieë word reeds aangewend vir die spesifieke doel. Een so tegnologie wat potensiaal toon ten opsigte van akwakultuur produksie is triploïedie; meer spesifiek, sterieliteit veroorsaak deur aneuploïedie induksie. Onder normale volwassewording, word energie weggeneem van somatiese groei wanneer geslagsrypheid intree en daarom kan groeitempo verhoog word deur gametogenese te inhibeer of te vertraag deur ‘n proses soos aneuploïedie en, word korter tydperk benodig om bemarkingsgrootte te bereik. Twee voorafgaande studies het gehandel oor die induksie van triploïedie deur hidrostatiese druk skok (De Beer, 2004) en die vergelykende groeitempo van triploïede genotipes vanaf ouderdom 8 tot 24 maande (Schoonbee, 2008) alvorens geslagsrypheid intree. Tydens hierdie vergelykende groeifase kon geen statisties betekenisvolle aanduidings van vinniger groei of seisoenale omgewingseffekte aangetoon word nie. Die studie handel vervolgens oor die uitbreiding van die vergelykende groeistudies tussen triploïede en diploïede genotipes tot ouderdom van 62 maande wat die intrede van geslagsrypheid insluit, ten einde te bepaal of die induksie van triploïedie in Haliotis midae voordele inhou ten opsigte van produksiedoeltreffendheid en mededingendheid op wêreldmarkte. Groei gemeet in terme van skulplengte en lewende massa oor die tydperk van 29 tot 62 maande het statisties betekenisvolle verskille getoon in gemiddelde massa en lengte van diploïede genotipes bo die van triploïede verwante individue. Die verskille van 1.99 mm en 5.13 g kan egter nie as kommersieel betekenisvol beskou word nie. Belangrike produksie eienskappe waaronder persentasie opbrengs van eindproduk en die gonadosomatiese indeks is ook bepaal. Vir beide die produksie eienskappe het die triploïede genotipe statisties sowel as kommersieel betekenisvolle verbetering van 10.68% getoon vir opbrengs en 28.42% verlaging in gonadosomatiese indeks in vergelyking met die diploïede genotipe. Triploïede genotipes was nie volledig steriel nie, gegewe die aanwesigheid van gonades en gamete in sommige individue. Selfs al is totale steriliteit nie bereik nie, het dit wel voorgekom asof daar vertraging in gonadosomatiese ontwikkeling plaasgevind het in triploïede genotipes. Die vertraging in geslagsrypheid tesame met die verhoogde persentasie opbrengs van die eindproduk hou voordele in bo die andersins effense stadiger groei van triploïede genotipes.

Submitted by Deyse Queiroz (deysequeirozz@hotmail.com) on 2018-05-23T13:54:28Z No. of bitstreams: 1 JOYCE EMANUELE DE MEDEIROS - DISSERTAÇÃO PPGSA PROFISSIONAL 2013..pdf: 1718564 bytes, checksum: 08bf95bc06f72832fe2269039eb98219 (MD5) / Made available in DSpace on 2018-05-23T13:54:28Z (GMT). No. of bitstreams: 1 JOYCE EMANUELE DE MEDEIROS - DISSERTAÇÃO PPGSA PROFISSIONAL 2013..pdf: 1718564 bytes, checksum: 08bf95bc06f72832fe2269039eb98219 (MD5) Previous issue date: 2013 / A partenocarpia em melancia agrega valor aos frutos, entretanto, para seu cultivo, o produtor poderá encontrar dificuldades, como: adaptação dos híbridos às condições regionais, alto preço das sementes, baixa germinação e baixo vigor das plântulas, além da necessidade de cultivar na mesma área uma variedade diploide como fonte de pólen para as triploides. Assim, objetivou-se avaliar o efeito da aplicação da citocinina CPPU, em diferentes concentrações, na indução da frutificação partenocárpica em melancieiras diploide e triploide. A pesquisa foi constituída por dois experimentos conduzidos em campo no Câmpus da UFCG, em PombalPB, no período de 15/12/2012 a 02/03/2013 utilizando-se o híbrido triploide ‘Extasy’ e a variedade diploide ‘Crimson Sweet’. Para ambos os experimentos, os tratamentos foram compostos por cinco concentrações do regulador de crescimento CPPU (0,75; 1,0; 1,5; 2,5 e 3,5 mg L-1 ) mais testemunha (polinização natural). O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições. A aplicação do CPPU ocorreu de forma exógena no ovário das flores na antese por dois dias consecutivos. As características avaliadas foram: taxa fotossintética (A), condutância estomática (gs), transpiração (E), concentração intercelular de CO2 (Ci), eficiência no uso da água (EUA), clorofilas, carotenoides, número de folhas, área foliar, massa seca das folhas, do caule e dos frutos e massa seca total, produção total e comercial, massa média dos frutos comercializáveis, número de frutos por planta, número de frutos comercializáveis por planta, índice de formato do fruto, espessura da casca e da polpa, sólidos solúveis, acidez titulável, pH, SS/AT e ácido ascórbico. O CPPU foi eficiente na indução da frutificação em melancieiras diploide ‘Crimson Sweet’ e triploide ‘Extasy’, independentemente da concentração utilizada. A concentração 2,5 mg L-1 de CPPU aplicada nas melancieiras diploides proporcionou o maior número de frutos comercializáveis por planta, maior produção total e produção comercial comparada à testemunha, já nas triploides possibilitou maior número de frutos por planta, número de frutos comercializáveis por planta, produção total e produção comercial em relação à testemunha. A indução da frutificação com CPPU na melancieira ‘Crimson Sweet’ não interferiu no acúmulo de massa seca, no crescimento e nas características fisiológicas da planta comparada à testemunha. Na ‘Extasy’, proporcionou maior acúmulo de massa seca no fruto, redução na massa seca das folhas, do caule e crescimento da planta, incremento na condutância estomática e na assimilação de CO2 quando comparada à testemunha. Nas melancieiras ‘Crimson Sweet’, a concentração de CPPU 2,5 mg L-1 proporcionou maior condutância estomática, taxa fotossintética e acúmulo de massa seca no fruto. Na melancieira ‘Extasy’, as concentrações de CPPU foram indiferente nas trocas gasosas e no crescimento da planta. / Parthenocarpy in watermelon adds value to fruits, however, for its cultivation, the producer may encounter difficulties such as: adaptation of hybrid to regional conditions, high seed prices, low germination and seedling vigor, beyond the need to cultivate, in the same area, a diploid variety as source of pollen for triploids. Thus, the objective was to evaluate the effect of application of cytokinin CPPU at different concentrations, in the induction of fruiting partenocarpic in diploid and triploid watermelon plants. The study comprised two field experiments conducted in the field in Campus of UFCG in Pombal -PB, from 12/15/2012 to 03/02/2013 using the triploid hybrid 'Extasy' and diploid variety 'Crimson Sweet'. For both experiments, treatments consisted of five concentrations of growth regulator CPPU (0.75, 1.0, 1.5, 2.5 and 3.5 mg L- 1 ) and the control (natural pollination). The experimental design was a complete randomized block designed with four replications. The application of CPPU occurred exogenously in the ovary of flowers for two consecutive days at anthesis. The variables evaluated were: photosynthetic rate (A), stomatal conductance (gs), transpiration (E), intercellular CO2 concentration (Ci), water use efficiency (EUA), chlorophylls, carotenoids, number of leaves, leaf area, dry mass of leaves, stem and fruit and total dry matter, total and marketable yield, average weight of marketable fruit , number of fruits per plant, number of marketable fruits per plant, fruit shape index, shell thickness and pulp, soluble solids, titratable acidity, pH, SS/TA and ascorbic acid. The CPPU was efficient in inducing fruiting of diploid watermelon 'Crimson Sweet' and triploid 'Extasy’, regardless of the concentration used. The concentration 2.5 mg L- 1 of CPPU applied in diploid watermelon provided the greatest number of marketable fruits per plant, higher total and marketable yield production compared to control, and in the triploid plants in increased the number of fruits per plant, number of fruits marketable per plant, total production and commercial production compared to control. Induction of fruiting with CPPU in watermelon ‘Crimson Sweet’ had no effect on dry matter accumulation, growth and physiological characteristics of the plant compared to the control. In 'Extasy', CPPU provided a greater accumulation of dry matter in the fruit decreased dry mass of leaves, stem and plant growth, increase in stomatal conductance and CO2 assimilation compared to the control. In watermelon 'Crimson Sweet' the concentration of 2.5 mg L- 1 yielded higher stomatal conductance, photosynthetic rate and dry matter accumulation in the fruit. In watermelon 'Extasy', concentrations of CPPU were indifferent gas exchange and plant growth.

The objectives of this project were to measure changes in frequency of occurrence of submerged macrophytes over the first two growing seasons following stocking with triploid grass carp at two fish per acre and to measure differences in macrophyte biomass between areas excluded from herbivory and adjacent control sites after 16 months following establishment of exclosures. The project also seeks to measure concentrations of fluridone following the herbicide treatment, and to compare two methods of aquatic vegetation sampling.

No description available.