The need for energy is growing in the world and the market of nuclear power is now once more expanding. Some issues of the current light-water reactors can be solved by the next generation of nuclear power, Generation IV, where sodium-cooled reactors are one of the candidates. Phénix was a French prototype sodium-cooled reactor, which is seen as a success. Although it did encounter an earlier unexperienced phenomenon, A.U.R.N., in which a negative reactivity transient followed by an oscillating behavior forced an automatic emergency shutdown of the reactor. This phenomenon lead to a lot of downtime of the reactor and is still unsolved. However, the most probable cause of the transients is radial movements of the core, referred to as core-flowering. This study has investigated the available documentation of the A.U.R.N. events. A simplified model of core-flowering was also created in order to simulate how radial expansion affects the reactivity of a sodium-cooled core. Serpent, which is a Monte-Carlo based simulation code, was chosen as calculation tool. Furthermore, a model of the Phénix core was successfully created and partly validated. The model of the core has a k_eff = 1.00298 and a neutron flux of (8.43+-0.02)!10^15 neutrons/cm^2 at normal state. The result obtained from the simulations shows that an expansion of the core radius decreases the reactivity. A linear approximation of the result gave the relation: change in k_eff/core extension = - 60 pcm/mm. This value corresponds remarkably well to the around - 60 pcm/mm that was obtained from the dedicated core-flowering experiments in Phénix made by the CEA. Core-flowering can recreate similar signals to those registered during the A.U.R.N. events, though the absence of trace of core movements in Phénix speaks against this. However, if core-flowering is the sought answer, it can be avoided by design. The equipment that registered the A.U.R.N. events have proved to be insensitive to noise. Though, the high amplitude of the transients and their rapidness have made some researcher believe that the events are a combination of interference in the equipment of Phénix and a mechanical phenomenon. Regardless, the origin of A.U.R.N. seems to be bound to some specific parameter of Phénix due to the fact that the transients only have occurred in this reactor. A safety analysis made by an expert committee, appointed by CEA, showed that the A.U.R.N. events are not a threat to the safety of Phénix. However, the origin of these negative transients has to be found before any construction of a commercial size sodium-cooled fast reactor can begin. Thus, further research is needed.

A laranjeira ,,x11\" é um mutante espontâneo de laranja doce, com seedlings florescendo a partir do primeiro ou segundo ano de cultivo e plantas adultas podendo florescer em várias épocas num mesmo ano. Estas características tornam este mutante um excelente material para estudos de genômica funcional relacionado ao florescimento e a frutificação. Os objetivos deste trabalho foram caracterizar o florescimento da laranjeira ,,x11\" em quatro épocas do ano e acompanhar o desenvolvimento do meristema apical em gemas axilares de plantas adultas, em relação às plantas de ,,Valência\". Também foi avaliado o perfil de expressão dos genes envolvidos na indução e no florescimento em plantas adultas e juvenis das duas laranjeiras. Plantas adultas de ,,x11\" enxertadas em ,,Cravo\" e ,,Swingle\" foram podadas no outono, inverno, primavera e verão e, em seguida, realizou-se a caracterização do florescimento em ramos novos e a determinação da viabilidade e germinação in vitro de grãos de pólen. O acompanhamento morfo-anatômico do meristema apical foi realizado em quatro estádios das brotações axilares das duas laranjeiras após a poda de outono. A expressão dos genes integradores das vias de indução (FT, SOC1 e LFY), genes repressores (FLC, SVP e TFL1) e os genes de identidade do meristema floral (AP1, BAM e WUS) foram analisados por RT-PCR em três estádios de desenvolvimento das brotações de plantas adultas e juvenis. A caracterização fenotípica do florescimento em ,,x11\" demonstrou que as podas de primavera e de outono induziram a formação de ramos com flores terminais, sendo que no outono ocorreu a formação de ramos vegetativos. A poda de inverno resultou em ramos multiflorais e a poda de verão flores abortadas. O número de dias até a formação de botões florais variou entre 5 e 20 dias após a poda, com ramos medindo entre 18 a 24 cm e número médio de folhas variando entre 9 e 12. A viabilidade e germinação in vitro de grãos de pólen foram maiores após a poda de inverno. Pelas análises morfo-anatômicas foi possível observar a diferenciação de botão floral em laranjeira ,,x11\" quando as brotações apresentavam 13 mm de comprimento. A análise de transcritos das plantas adultas de ,,x11\" no estádio 1 indicou maiores níveis de expressão nos genes FT e TFL1 enquanto os genes BAM e LFY foram reprimidos em relação às plantas de ,,Valência\". No estádio 2, os genes FT, LFY e BAM apresentaram um maior número de transcritos, porém o gene TFL1 teve um baixo número de transcritos quando comparado com plantas de ,,Valência\". No estádio 3, uma elevada expressão relativa foi observada no gene LFY nas plantas adultas de ,,x11\" em relação à ,,Valência\". As plantas juvenis de ,,x11\" nos três estádios não apresentaram grandes alterações de expressão dos nove genes em relação às plantas juvenis de ,,Valência\". A exceção foi para o gene BAM, que apresentou maiores expressões nos estádios 1 e 3, mas no estádio 2, sofreu repressão em relação a \"Valência\". Palavras-chave: Citrus sinensis (L.) Osbeck. Florescimento precoce. Indução. Diferenciação floral. Genes do florescimento / The ,,x11\" plant is a spontaneous mutant of sweet orange, with seedlings flowering from the first or second year of the growing and adult plants can flower several times a year. These features make this mutant into an excellent material for functional genomics studies related to flowering and fruiting. The present work aimed to characterize the flowering of ,,x11\" sweet orange in four seasons and to follow the development of the apical meristem in axillary buds of adult plants, compared to ,,Valencia\" sweet orange. In addition, the expression profile of genes involved in the induction and flowering was evaluated in adult and juvenile plants of the both sweet oranges. Adult plants of ,,x11\" grafted on \'Rangpur\' and \'Swingle\' were pruned in fall, winter, spring and summer, and then, the characterization of the flowering in new branches and the viability and in vitro germination of pollen grains were evaluated. The following morpho-anatomical apical meristem was carried out in four stages of the axillary sprouts in both sweet oranges after fall pruning. Gene expression of floral pathway integrators (FT, SOC1, and LFY), repressor genes (FLC, TFL1 and SVP) and the genes of floral meristem identity (AP1, BAM and WUS) were analyzed by RT-PCR in three stages development of sprouting from juvenile and adult plants. Phenotypic characterization of flowering in ,,x11\" showed that the spring and fall pruning induced the formation of terminal branches with flowers, and the fall pruning also presented vegetative branches. The winter pruning resulted in multifloral branches and the summer pruning produced aborted flowers. The number of days up to the arising of flower buds ranged between 5 and 20 days after pruning, with branches measuring between 18 and 24 cm and number of leaves between 9 and 12. The viability and in vitro germination of pollen grains were higher after winter pruning. It was observed the differentiation of floral bud in ,,x11\" sweet orange by the morpho-anatomical analysis when the sprouting was 13 mm in length. The analysis of transcripts of the ,,x11\" adult plants in stage 1 showed higher levels of expression in FT and TFL1 genes while the BAM and LFY genes were repressed in relation to ,,Valencia\" plants. In stage 2, FT, LFY and BAM genes had a larger number of transcripts, but the TFL1 gene had a low number of transcripts compared with ,,Valencia\" plants. In stage 3, high expression was observed in LFY gene in ,,x11\" adult plants relation to the ,,Valencia\". Juvenile plants of ,,x11\"in the three stages showed no significant changes of expression of nine genes in relation to juvenile plants of ,,Valencia\". The exception was the BAM gene, which showed higher expression in stages 1 and 3, but in stage 2, had a repression when compared to ,,Valencia\"

[ES] En los cítricos, la baja temperatura promueve la inducción floral en otoño-invierno aumentando la expresión del gen promotor CiFT3 (homólogo en los cítricos del gen FLOWERING LOCUS T). La presencia de un gran número de frutos en el árbol durante ese momento inhibe la expresión de CiFT3 y la floración, pero se desconoce la señal inhibitoria que genera el fruto. Las hipótesis mayormente aceptadas proponen que la señal puede ser hormonal o nutricional. En el primer caso, el efecto inhibidor se atribuye a las hormonas que el fruto produce y exporta durante su desarrollo. En el segundo caso, el efecto inhibidor se atribuye a la alta demanda y consumo de carbohidratos por los frutos en desarrollo. Ambas hipótesis son complementarias y no excluyentes entre sí. Además, se ha demostrado que el fruto promueve la activación epigenética del represor de la floración CcMADS19 (homólogo en los cítricos del gen FLOWERING LOCUS C), que inhibe la expresión del gen CiFT3. Con el objetivo de determinar qué señal produce el fruto para inhibir la floración, en esta Tesis se propone la siguiente hipótesis: El fruto inhibe la floración a través de la síntesis y exportación de auxinas que activa la síntesis de giberelinas y, a su vez, la expresión de CcMADS19. Mediante experimentos con tratamientos exógenos de auxinas, giberelinas, y sus antagonistas, aclareo de frutos, y la interrupción del transporte por el floema entre el fruto y las yemas, los resultados indican que ni las giberelinas ni las auxinas se relacionan de forma consistente con la activación de la expresión de CcMADS19 en las hojas. En las yemas, las giberelinas se relacionan con la activación del gen inhibidor CENTRORRADIALIS (CEN), cuando hay fruto por aumento de la síntesis de GA4, y cuando no hay fruto por su aplicación exógena. La presencia del fruto aumenta la concentración de auxinas en el tallo y la yema en el momento de la inducción, y reprime su síntesis y trasporte. Pero esto no impide que, en la yema, el gen CcMADS19 esté epigenéticamente silenciado y que el silenciamiento se transmita a los nuevos brotes vegetativos. Estos brotes florecen en el siguiente ciclo, y, en sus yemas, la diferenciación floral se relaciona con un aumento de la síntesis y trasporte de auxinas y una reducción de la síntesis de giberelinas. / [CA] Als cítrics, les baixes temperatures promouen la inducció floral a la tardor i l'hivern augmentant l'expressió del gen promotor CiFT3 (homòleg en els cítrics del gen FLOWERING LOCUS T). La presència d'un gran nombre de fruita a l'arbre en aquest moment inhibeix l'expressió de CiFT3 i la floració, però es desconeix la senyal inhibidora que genera la fruita. Les hipòtesis majoritàriament acceptades proposen que la senyal pot ser hormonal o nutricional. En el primer cas, l'efecte inhibidor s'atribueix a les hormones que la fruita produeix i exporta durant el seu desenvolupament. En el segon cas, l'efecte inhibidor s'atribueix a la alta demanda i consum de carbohidrats per part de la fruita en desenvolupament. Ambdues hipòtesis són complementàries i no es descarten mútuament. A més, s'ha demostrat que la fruita promou l'activació epigenètica del repressor de la floració CcMADS19 (homòleg en els cítrics del gen FLOWERING LOCUS C), que inhibeix l'expressió del gen CiFT3. Amb l'objectiu de determinar quina senyal produeix la fruita per inhibir la floració, en aquesta Tesi es proposa la següent hipòtesi: La fruita inhibeix la floració mitjançant la síntesi i exportació d'auxines que activa la síntesi de giberelines i, al seu torn, l'expressió de CcMADS19. Mitjançant experiments amb tractaments exògens d'auxines, giberelines i els seus antagonistes, aclarida de fruita i la interrupció del transport pel floema entre la fruita i les brots, els resultats indiquen que ni les giberelines ni les auxines es relacionen de manera consistent amb l'activació de l'expressió de CcMADS19 a les fulles. A les gemmes, les giberelines es relacionen amb l'activació del gen inhibidor CENTRORRADIALIS (CEN) quan hi ha fruita per l'augment de la síntesi de GA4 i quan no hi ha fruita per la seua aplicació exògena. La presència de la fruita augmenta la concentració d'auxines a la tija i la gemma en el moment de la inducció i reprimeix la seua síntesi i transport. Però això no impedeix que, a la gemma, el gen CcMADS19 estigui epigenèticament silenciat i que el silenciament es transmeti als nous brots vegetatius. Aquests brots floreixen al següent cicle i, a les seues gemmes, la diferenciació floral es relaciona amb un augment de la síntesi i transport d'auxines i una reducció de la síntesi de giberelines. / [EN] In citrus, low temperature promotes flower induction in autumn-winter by increasing the expression of the CiFT3 promoter gene (citrus homologue of the FLOWERING LOCUS T gene). The presence of large numbers of fruits on the tree at this time inhibits CiFT3 expression and flowering, but the inhibitory signal produced by the fruits is unknown. The most widely accepted hypotheses are that the signal is hormonal or nutritional. In the first case, the inhibitory effect is attributed to hormones produced and exported by the fruit during development. In the second case, the inhibitory effect is attributed to the high demand and consumption of carbohydrates by the developing fruit. The two hypotheses are complementary and not mutually exclusive. In addition, it has been shown that the fruit promotes the epigenetic activation of the flowering repressor CcMADS19 (citrus homolog of the FLOWERING LOCUS C gene), which inhibits the expression of the CiFT3 gene. To determine which signal is produced by the fruit to inhibit flowering, the following hypothesis is proposed in this thesis: The fruit inhibits flowering through the synthesis and export of auxins, which activates the synthesis of gibberellins and, in turn, the expression of CcMADS19. Experiments with exogenous treatments of auxins, gibberellins and their antagonists, fruit thinning, and disruption of phloem transport between fruit and buds indicate that neither gibberellins nor auxins are consistently associated with the activation of CcMADS19 expression in leaves. In buds, gibberellins are associated with the activation of the flowering inhibitor CENTRORADIALIS (CEN), in the presence of fruit by increasing GA4 synthesis, and in the absence of fruit by its exogenous application. The presence of fruit increases the concentration of auxin in the stem and bud at the time of induction and suppresses its synthesis and transport. However, this does not prevent the epigenetic silencing of the CcMADS19 gene in the bud, which is transmitted to the leaves of the new vegetative shoots. These shoots flower in the following cycle, where floral differentiation is associated with an increase in auxin synthesis and transport and a decrease in gibberellin synthesis in the bud. / Marzal Blay, A. (2024). Study of the Fruit Inhibitory Mechanism on Citrus flowering. Nutritional, Hormonal and Genetic Factors [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203155

Call number: LD2668 .T4 1985 L82 / Master of Science

Growth rate and flowering time are agriculturally important traits that are linked to fitness, productivity and reproductive success of plants. To study the genetic basis for natural variation in growth rate and flowering time between local accessions of Arabidopsis thaliana, hybrids were produced between fast growing / late flowering and slow growing / early flowering parents. F3 and F5 hybrid families were grown under a range of conditions – under a constant controlled environment, outside over the winter and outside in spring and early summer. Growth rates were estimated from repeated images of rosettes. Flowering time, as number of leaves to flower, was also recorded both in control and natural conditions for F5 lines. Damage by slugs and stress-induced production of anthocyanin pigments were also recorded for plants grown outside. Broad-sense heritability estimates were higher for F5 families than F3, in which more loci will segregate, and ranged from 48% to 89%. No significant correlation between growth rates under different environments was observed in most cases for F3 populations, however significant correlations were detected for F5 families outside and under controlled conditions, suggesting that same genes can affect growth rate in more than one environment. The genotypes of F3 families were determined at thirty-nine SSLP (simple sequence length polymorphism) loci and used in regression with phenotype data to search for quantitative trait loci (QTL). Significant QTLs were detected in F3 families for growth rate, flowering time and anthocyanin production, but not for herbivore damage. To confirm QTL detected in the F3 and to detect additional loci, bulk segregant analysis was carried out in F5 families grown under different conditions. Potentially linked markers were tested further in individual F5 plants and QTL mapped on a finer scale in F5 families that remained heterozygous for candidate regions. VIP5 and LDL1 were selected as potential candidate genes for flowering time variation. These genes were sequenced for two parental alleles. A transposon insertion and 5’ UTR deletion were found in the LDL1 allele from the late flowering parent and SNPs (single nucleotide polymorphisms) were observed throughout the gene. However both alleles appeared to be expressed at similar levels. Transgenic lines have been produced carrying the LDL1 allele from the early flowering parent (4D1) in the background of the later flowering parent (11C1). This work is on-going and will hopefully reveal whether LDL1 underlies differences in flowering behaviour seen between 11C1 and 4D1.

Thesis (MSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Species’ seasonal behaviour is of paramount importance in understanding community functioning and dynamics. Recently, plant phenology has further gained significance as a reliable indicator of climate change impacts. Despite the importance of understanding plant dynamics, there are relatively few plant phenological records for the sub-Antarctic region, and where records exist they are often not extensive. Sub-Antarctic Marion Island, typical of Southern Ocean Islands, offers a useful setting for addressing these knowledge gaps. This study documented the vegetative and reproductive phenologies (or aggregate phenological patterns) of twelve indigenous and three alien vascular plant species on the island. The phenological differences among the species and distinct seasonal groupings (e.g. early, intermediate and late species) were examined. I also investigated the phenological differences among the indigenous and alien plant species. Furthermore, the onset of selected reproductive phenophases from the current records was compared with historical records for determining the extent of climate change-related alterations in phenology. Phenological data were collected fortnightly on five, 5 m x 5 m permanent plots per species (except for a few species) for a full growing season. Thus the sample size is n = 5 for all plant species except for Crassula moschata (n = 4), Juncus effusus (n=4) and Rumex acetosella (n=1). Sites of the same species were separated by at least 500 m except for the alien plant, Juncus effusus, where all four known populations were selected despite two of these populations being < 500 m apart. This study indicated that Marion Island plants grow throughout the year with no major peaks except in Azorella selago and Acaena magellanica which showed winter dormancy. However, reproduction in most plant species predominately occurred in spring and summer months. Pringlea antiscorbutica and Poa cookii were the first two species to set flower buds in September while most species dispersed their seeds in summer except for Agrostis magellanica and Crassula moschata which dispersed in early autumn. Distinct from most temperate systems, the reproductive seasonality displayed by Marion Island plant species is explained more by daylength than by temperature, perhaps due to the region’s typical thermal aseasonality. Interestingly, many cooccurring species and/or clades across the Falkland, Kerguelen, Macquarie and South Georgia Islands also showed similar flowering onset date to the Marion Island plants, further confirming their daylength sensitivity. However, other external factors seem to come into play at later events of reproduction. Consequently, fruit maturation time of similar species across the sub-Antarctic islands varied substantially despite the plants having flowered in the same month. Although plant species showed similar reproductive seasonality, there were significant differences among species phenologies i.e. phenophase timing, duration and peak occurrence dates. However, using 95% confidence intervals of Generalized Linear Models weighted means, and/or one-way ANOVA (Tukey post hoc test), three homogenous sets of species (early, late, or intermediate onsets) were identified based on flower bud, flowering and seed dispersal phenophase onset dates. The homogenous species groupings observed for flower buds also remained unchanged during flowering onset except for Cotula plumosa and Callitriche antarctica which switched groups. As for the seed dispersal timing, the pattern was not consistent with that of the flower bud and flowering onset homogenous groupings, except for Acaena magellanica and Agrostis magellanica which remained in the early and late groups, respectively. Conversely, in the case of the timing of other phenophases (pollen release, fruit set and fruit ripening), entire phenophase durations, and peak occurrence dates, species overlapped greatly, resulting in an unbroken progression or continuum of phenology among species. Similarly, the three alien plant species investigated here (Cerastium fontanum, Juncus effusus and Rumex acetosella) showed no consistent phenological differences from the rest of the species. However, a widespread alien plant species on Marion Island, C. fontanum, reproduced for most of the year, although its reproduction peak was in summer months as was the case for the rest of the species. This study also indicated that indigenous plant species have altered their reproductive phenologies since 1965. Although the response was species-specific, the majority of plant species significantly delayed the onset of reproductive activities in 2007 by comparison with 1965. However, it is not clear if the observed species response was caused by the now drier and warmer Marion Island climate or by discrepancies in reporting in the earlier studies and/or sampling differences between the recent and historical records. Therefore, these results should be taken with caution. In conclusion, this research provided a detailed phenological dynamics record for vascular plant species on the island. Over time these records may be used as a basis for monitoring and modelling the impact of climate on plant phenology on the island. / AFRIKAANSE OPSOMMING: Spesies se seisoenale gedrag is van die allergrootste belang in die begrip van gemeenskapsfunksionering en dinamika. Meer onlangs het plant fenologie verdere betekenis verwerf as ‘n betroubare indikator vir die impakte van klimaatsverandering. Ondanks die belangrikheid om plant dinamika te verstaan, is daar relatief min plant fenologiese rekords vir die sub-Antarktiese streek en waar rekords wel bestaan is dit dikwels nie omvangryk nie. Sub- Antarktiese Marion Eiland, tipies van Suidelike Oseaan Eilande, bied ‘n nuttige ligging om hierdie kennis gapings aan te spreek. Hierdie studie het die vegetatiewe en voorplantingsfenologieë (of gesamentlike fenologiese patrone) van elf inheemse en drie uitheemse vaatplantspesies op die eiland gedokumenteer. Die fenologiese verskille tussen die spesies en duidelike seisoenale groeperings (bv. vroeë, intermediêre en laat spesies) is ondersoek. Ek het ook die betekenisvolle fenologiese verskille tussen die inheemse en uitheemse plantspesies ondersoek. Voorts, die aanvang van gekose voortplanting feno-fases van huidige rekords is vergelyk met historiese rekords om die mate van klimaatsverandering verbandhoudende veranderings in die fenologie te bepaal. Fenologiese data is twee weekliks ingesamel op vyf, 5 m x 5 m permanente plotte per spesie (behalwe vir ‘n paar spesies) vir ‘n volle groei seisoen. Dus, die insamelings grootte is n = 5 vir al die plantspesies behalwe vir C. moschata (n = 4), Juncus effusus (n=4) en Rumex acetosella (n=1). Persele vir dieselfde spesies is geskei deur ten minste 500 m, behalwe vir die uitheemse plant, Juncus effusus, waar al vier populasies wat bekend is gekies is, ten spyte daarvan dat twee van hierdie populasies < 500 m uitmekaar is. Hierdie studie het aangedui dat Marion Eiland plante regdeur die jaar groei, met geen belangrike spitstye nie, behalwe in Azorella selago en Acaena magellanica wat ‘n winter rusperiode wys. Hoe ookal, voortplanting in meeste van die plantspesies het hoofsaaklik voorgekom tussen die lente en somermaande. Pringlea antiscorbutica en Poa cookii was die eerste twee spesies om blomknoppe uit te stoot in September, terwyl die meeste spesies hulle sade versprei het gedurende die somer, behalwe vir Agrostis magellanica en Crassula moschata wat versprei het in vroeg herfs. Duidelik van meeste gematigde sisteme, word die voortplanting seisoenaliteit, getoon deur die Marion Eiland plantspesies, verduidelik meer deur daglengte as deur temperatuur, moontlik weens die streek se tipiese termiese a-seisoenaliteit. Interessant, baie spesies en/of afstameling-groeperings wat saam aangtref word dwarsoor die Falkland, Kerguelen, Macquarie en Suid Georgia Eilande wys ook soortgelyke bloei aanvangsdatums as die Marion Eiland plante, nog meer bevestigend van hulle dag-lengte sensitieweteit. Hoe ookal, ander eksterne faktore blyk betrokke te raak by latere gebeure van voortplanting. Gevolglik het vrug rypwordingstyd van dieselfde spesies oor die sub-Antarktiek noemenswaardig verskil, ten spyte daarvan dat die plante in dieselfde maand geblom het. Alhoewel plantspesies dieselfde voortplanting seisoenaliteit gewys het, was daar ‘n noemenswaardige veskil tussen spesie fenologieë, m. a. w. feno-fase tydsberekenning, tydsduur en spits voorkomsdatums. Hoe ookal, deur gebruik te maak van 95% betroubaarheid intervalle van Algemene Lineêre Modelle gewigte gemiddelde en/of een rigting ANOVA (Turkey post hoc toets), is drie homogene stelle van spesies (vroeë, laat en intermediêre aanvang) geïdentifiseer gebasseer op blomknop, bloei en saad verspreiding feno-fase aanvangsdatums. Die homogene spesie groeperings waargeneem op blomknoppe het ook onveranderd gebly gedurende bloei aanvang behalwe vir Cotula plumosa en Crassula antarctica wat groepe geruil het. Vir die saadverspreiding tydsberekenning was die patroon nie konstant met die van die blomknop en bloei aanvang homogene groepe nie, behalwe vir Acaena magellanica en Agrostis magellanica wat in die vroeë en laat groepe respektiewelik gebly het. Omgekeerd, in die geval van tydsberekenning van ander feno-fases (stuifmeel vrysetelling, vrugwerp, vrugrypwording), volledige feno-fase tydsduur en spits voorkomsdatums het spesies grootliks oorvleuel, wat ‘n ongebroke vordering of deurlopendheid van fenologie tussen die spesies tot gevolg het. Ooreenkomstig het die drie uitheemse spesies wat hier ondersoek is (Cerastium fontanum, Juncus effusus en Rumex acetosella) geen bestendige fenologiese verskille van die res van die spesies gewys nie. Hoe ookal, ‘n wydverspreide uitheemse spesie op Marion Eiland, Cerastium fontanum, het deur die meeste van die jaar voortgeplant, hoewel met ‘n voorplanting spits in die somer maande soos die res van die spesies. Hierdie studie dui ook aan dat inheemse plantspesies hulle voortplanting fenologieë verander het sedert 1965. Alhoewel die reaksie spesiespesifiek was, het die meerderheid van die plantspesies hulle voortplanting aanvang aansienlik vertraag gedurende 2007 in vergelyking met 1965. Hoe ookal, dis nie duidelik of die waargeneemde spesie reaksie was as gevolg van die nou droër en warmer Marion Eiland klimaat of deur teenstrydighede in verslagewing gedurende die vroëre studies en/of insameling verskille tussen die onlangse en historiese rekords. Daarom moet hierdie resultate met versigtigheid hanteer word. In samevatting, hierdie navorsing voorsien ‘n gedetaileerde fenologiese dinamieka rekord vir vaatplantspesies op die eiland. Oor tyd kan hierdie rekords gebruik word as basis vir monitering en modellering van die impak van klimaat.

Identification of allelic variation through quantitative trait loci (QTL) mapping offers possibilities for the improvement of quantitatively inherited traits. This requires a genetic map along with the phenotypic characterization of a mapping population. A doubled haploid (DH) Polo X Topas population consisting of 194 lines and a recombinant inbred line population of 92 lines was developed. Individual genetic maps derived from each population were integrated into a consensus map. The DH-based genetic map was used for QTL mapping. The DH-based map was comprised of 620 loci that were assembled into 19 linkage groups that were anchored to the B. napus chromosomes. The DH-based map covered 2244.1 cM genomic distance with an average marker interval of 3.7 cM. The DH population was phenotyped in four environments with each line replicated twice in a randomized complete block design. Days to flowering was recorded and oil content and fatty acid composition were determined using Near Infrared spectroscopy (NIR) and Gas Chromatography, respectively. Fourteen QTL were identified for oil content, 33 QTL for palmitic acid content, 18 QTL for stearic acid content, 21 QTL for oleic acid content, 20 QTL for linoleic acid content, 23 QTL for linolenic acid content, 16 QTL for arachidic acid content and 14 QTL for flowering time. Oil content QTL were identified on five linkage groups, A3, A10, C1, C5, and C6. An oil content QTL, qOIL-A10c appeared in all four environments, whereas qOIL-A10a appeared in only one environment but explained 26.99% variation. The oil content in the population ranged from 35% to 55.5% with the parents having values of 42% to 46%. Two genomic regions on C3, with map positions at 147.83 cM and 154.55 cM harbored QTL (rQTL) for all the fatty acids studied. The additive effects of the rQTL reveal a correlation pattern which is supported by the phenotypic correlation observed between the fatty acids. This suggests rQTL have role in the fatty acid composition and possibly determine total seed oil content. The rQTL and flanking markers of the identified QTL offer utility in further development of B. napus. / October 2015

The effects of planting date were evaluated on field establishment and flowering of ten southwestern wildflower species combined in a mix. Species tested include Baileya multiradiata, Castilleja lanata, Eschscholtzia californica, Eschscholtzia mexicana, Gaillardia pulchellum, Lesquerella gordonii, Lupinus sparsiflorus, Orthocarpus purpurascens, Penstemon eatonii, and Phacelia campanularia. Seeds of all species were combined in a mix and directly seeded into field plots. All species are native to the southwestern deserts of the United States. Treatments consisted of five planting dates, starting September 30, 1987 and continuing through November 30, 1987, with treatments planted at two week intervals during the ten week period. There were significant differences in both plant stand and flowering between planting dates. The October 15 planting had the optimum plant stand with regard to the largest spectrum of species represented by desirable numbers. Flowering was most pronounced in the September 30 and October 15 plantings.

This study was conducted to investigate the effects of four drip irrigation treatments on five fruiting characteristics of cotton (Gossypium hirsutum L.) using periodic observations to gauge the relative impact of these effects over time. The fruiting characteristics measured were: (1) number of flowers, (2) percent boll set, (3) number of bolls, (4) weight boll-1, and (5) seedcotton production. The irrigation treatments included four levels that in total season applied irrigation equaled 60, 68, 76, and 83 cm of water. Periodic observations included three, 3-week-intervals from the onset of flowering (26 June) to cutout (29 August). Results indicate that irrigation treatments had a significant effect on all characters measured, only in the later stages of development (later in the season) with higher amounts of irrigation applied producing higher levels of each character measured. Significant differences were found among periods of observation for all characters measured.

Ethylene and carbohydrate deprivation were investigated as possible causes of bud abortion in Lilium longiflorum Thunb. Silver thiosulfate (STS) was investigated as an inhibitor of ethylene-induced abortion. Fourteen days of 92.5% irradiance reduction increased bud abortion when plants were exposed to 2.07 mM ethephon. Percent bud abortion was 39% and 60% for plants grown in full irradiance and reduced irradiance, respectively. Ethephon resulted in 54% abortion, regardless of irradiance at 4.15 mM. A 70% irradiance reduction for 14 days did not increase bud abortion when plants were treated with ethephon. STS was applied to plants at visible bud +2 weeks followed by ethephon application 2 days later. Bud abortion was reduced from 69 to 13% with 2 mM STS; the STS x ethephon interaction was significant. STS inhibited ethephon-induced bud abortion when applied at visible bud, 4 weeks prior to ethephon application; However, STS application at flower bud initiation did not prevent/reduce ethephon-induced bud abortion.