Master of Science / Department of Grain Science and Industry / Jeffrey A. Gwirtz / Variation in wheat kernel hardness is influenced by several factors including genetic expression and environmental conditions. However, these factors explain only a portion of the observed variation. Thus, there are unknown contributors to this important physical property. The following experiments investigated growing locations between farms and within the spike as a source of variation. Four commercial varieties of Hard Red Winter (HRW) wheat were chosen for evaluation; Jagger, Jagalene, Overley, and 2137. In total, 374 wheat spikes were collected from three farms participating in the Kansas State University Research and Extension- 2007 Crop Performance Tests (KSCPT). For analyses, each kernel was removed and cataloged by spikelet and floret position. A total of 10,240 kernels were uniquely identified by variety, farm, plot, spike, spikelet and floret position. Using the single kernel characterization system (SKCS), kernels were crushed to determine the hardness, diameter, weight, and moisture content. The variability of each measured attribute was greatest between spikes of a given variety. Measured attributes exist in gradients along the spike, with the top and bottom portions being most variable. This research broadens our knowledge of wheat kernel variation, and results from this experiment may contribute to improved methods for single kernel analysis.

No description available.

The purpose of this research was to increase understanding of ecology and control of cogongrass (Imperata cylindrica (L.) Beauv.) to assist with management of this invasive grass. To address different aspects of cogongrass management, I examined factors that affect spread of cogongrass, effects of cogongrass on native plant communities, and use of three native species to suppress cogongrass. Relative susceptibility of pine-bluestem and pine-shrub vegetation associations to vegetative encroachment and seed dispersal of cogongrass were evaluated. Vegetative encroachment into burned and unburned areas of these two vegetation associations also was measured. Effects of infestation size on vegetative growth of cogongrass and relationships between military activity and establishment and growth of cogongrass on military firing points were investigated. I also compared frequency of cogongrass infestation and vegetative growth rates for unpaved roads with different levels of traffic and maintenance. Native plant richness, diversity, and abundance were compared between cogongrass infestations and in uninfested adjacent areas for longleaf pine-bluestem and ruderal, cleared areas. Morella cerifera (L.) Small, Chamaecrista fasciculata (Michx.) Greene, and Panicum virgatum L. were tested for their ability to suppress cogongrass re-growth after treatment with a herbicide. Mean vegetative encroachment of cogongrass was < 2 m/yr for both habitat types regardless of burning. Vegetative encroachment was more than double in burned plots compared to unburned plots. Spikelets of cogongrass consistently dispersed farther into pine-bluestem (x¯ =17.3 m) forests compared to pine-shrub forests (x¯ = 9.4 m). Vegetative encroachment was not affected by size of infestation for cogongrass patches on firing points (x¯ < 1 m/yr) (P > 0.643). In areas of soil disturbance from military equipment, vegetative expansion rates of 7-10 m/yr were recorded. There was a positive relationship between military troop use and cogongrass establishment for one of the 2 years of the study (P = 0.023). Growth and establishment of cogongrass did not vary for unpaved roads with differing levels of maintenance and traffic (P > 0.173). Species diversity and abundance of herbaceous vegetation was less in cogongrass infestations compared to uninfested adjacent areas. Complete suppression of cogongrass was not evident for any of three native species tested.

Les inflorescences de riz sont sensibles au froid et à la chaleur ce qui se traduit par une stérilité des épillets à floraison. Ce n'est cependant pas directement la température de l'air qui est en cause mais la température des tissus à des stades de développement précis. Les stratégies pour faire face au stress thermique sont : 1) la tolérance physiologique d'une variété particulière; 2) l'échappement temporel au stress par l'ajustement de la phénologie et de l'heure de l'anthèse (TOA); 3) l'évitement du stress par le microclimat généré par la culture. Cette thèse a pour but de caractériser l'effet des composantes climatiques sur 2) et 3), et pour ce, le même essai a été mené au champ sur quatre variétés de riz irrigué cultivées dans quatre environnements climatiques contrastés (Philippines, 2 saisons aux Sénégal, France). Bien que peu de différences variétales aient été observées au sein de chaque site, il existe une grande variabilité de l'heure de l'anthèse et de la différence de température (TD) entre panicule (Tp) et air (Tair) en réponse à l'environnement. La durée de l'anthèse est stable et limitée à environ 2 heures par jour, alors que l'heure de l'anthèse varie de 3.4 à 6.75 heure solaire. Au moment de l'anthèse, TD observée varie entre +2 et -9.5°C. TOA et TD sont principalement caractérisés par Tair et VPD (Vapour Pressure Deficit) observés antérieurement (TOA) ou pendant (TD) l'anthèse. De plus, il existe une corrélation significative entre la stérilité (chaud ou froid) observée à maturité et Tp aux stades sensibles. Ces résultats montrent qu'en termes de risque de stérilité paniculaire pour le riz irrigué à floraison, un climat moyennement chaud et humide est plus dangereux qu'un climat très chaud mais sec car un fort VPD favorise la transpiration de la canopée et des panicules. TOA et TD ont ensuite été intégrés au modèle de culture RIDEV V.2 (qui prédit la stérilité) et les simulations de TD ont été comparées aux résultats d'un autre modèle de Tp (IM2PACT) développé indépendamment au Japon. Ces deux modèles s'avèrent robustes, et de futures collaborations mèneront à une validation complète de chaque modèle voire une intégration de ceux-ci à un nouvel outil en vues d'étudier l'impact des changements climatiques sur les cultures.Les résultats de cette étude permettront dans un futur proche 1) d'aider les sélectionneurs en apportant de nouveaux traits d'intérêts, et 2) de définir un zonage des territoires à haut risque de stress thermique pour le riz irrigué, pour des scénarios climatiques actuels et anticipés. Des études complémentaires seront nécessaires pour permettre l'application de cette approche aux systèmes non irrigués. / At the reproductive stage, rice spikelets are sensitive to cold and to heat which can lead to spikelet sterility. However, it is not the air temperature but the temperature of the sensitive organ itself during some specific sensitive stages that is involved. There are three different strategies to cope with thermal stress: 1) physiological tolerance of a particular variety; 2) temporal escape of the stress thanks to phenology and time of day of anthesis (TOA) adjustments; 3) stress avoidance through microclimate generated by crop architecture and transpiration. This PhD aims to characterize the effect of environment on 2) and 3) and to attain this goal, the same experiment was conducted with four rice varieties irrigated and grown in four different climatic environments (Philippines, Senegal two seasons, France). Even though few varietal differences were observed within a site, a great variability of TOA and difference of temperature (TD) between panicle (Tp) and air (Tair) exists in response to the environment. Anthesis duration is stable and limited to 2 hours per day, whereas time of onset of anthesis varied between 3.4 to 6.75 hours after sunrise. During anthesis, observed TD varied between +2.5 and -9.5°C. TOA and TD are mostly explained with Tair and VPD (Vapour Pressure Deficit) observed before (TOA) or during (TD) anthesis. A significant correlation between spikelet sterility (due to cold or heat) and Tp at sensitive stages was established across sites and varieties. Those results showed that for irrigated rice, humid and moderately hot environments are more subject to heat stress sterility than very hot but dry environments, because panicle and canopy transpiration are favored by high VPD. Ultimately, RIDEV V.2 crop model (predicting spikelet sterility) was developed to integrate the previous results and Tp simulations were compared to another Tp model (IM2PACT) simulations, developed independently with a different approach in Japan. Those two models are robust and future collaborations will lead to complete model validations and maybe integration in a new modeling tool to answer the need in evaluating the impact of different climate change scenarios and the adaptation of crop response to those changes.In a short term, the results of this study will enable to 1) help breeders providing them new interest traits for thermal tolerance, and 2) define geographic zoning for high heat stress risk for irrigated rice, for present and future climate change scenarios. Complementary studies are needed to apply this approach to non irrigated system.

京都大学 / 新制・課程博士 / 博士(農学) / 甲第24239号 / 農博第2518号 / 新制||農||1094(附属図書館) / 学位論文||R4||N5410(農学部図書室) / 京都大学大学院農学研究科農学専攻 / (主査)教授 白岩 立彦, 教授 中﨑 鉄也, 教授 那須田 周平 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Every anthropogenic activity causes environmental impact in some extent. Rice paddy fields area are pointed out as an activity with high potential of pollution due to the large amount of water used to maintain the flooding and the intensive use of pesticides and nutrients that can be transported to the environment. Though, there are other irrigation management practices that can reduce the environmental impact caused by the rice farming. Based on that, the objective of this study was to investigate the effect of the continuous and intermittent flooding on the amount of water applied and the amount of water transported to the environment, on water use efficiency, on weed control, on agronomic parameters of the rice plants and on dissipation of imazethapyr, imazapic and fipronil. The intermittent flooding resulted in crop yield similar to continuous irrigation. In addition, it reduced in 32% the amount of water applied, resulting in a better water use efficiency (1.68 kg m-3) than the continuous flooding (1.14 kg m-3). Water saving is promoted by the higher amount of rainfall stored in the intermittent flooding. The intermittent flooding reduces 40% of the run-off and less environmental contamination, resulting, on the average of the three pesticides a reduction higher than 90% on the mass of pesticide transported to the environment in comparison to the total applied on the rice Field. / Toda a atividade antrópica causa impacto ambiental de algum nível. A lavoura de arroz irrigado é apontada como uma atividade com alto potencial poluidor por usar grande volume de água para manter a lâmina de irrigação e também por ser um cultivo que demanda o intenso uso de agrotóxicos e nutrientes que podem ser transportados para o ambiente. Entretanto existem alternativas de manejar a lâmina de irrigação que podem diminuir esse impacto ocasionado pela orizicultura. Nesse sentido, o presente trabalho tem por objetivo avaliar o efeito do manejo de irrigação contínua e intermitente no balanço de água (lâmina de água aplicada e lâmina de água extravasada), na eficiência do uso da água, no controle de plantas daninhas, nos parâmetros agronômicos e na dissipação de imazethapyr, imazapic e fipronil. A irrigação intermitente ocasiona produtividade de grãos semelhante à irrigação contínua. Além disso, proporciona economia de 32% do volume de água aplicado, resultando em uma maior eficiência do uso de água (1,68 kg m-3) do que a irrigação contínua (1,14 kg m-3). Essa economia está relacionada devido ao maior volume de água da chuva armazenada. Dessa forma, a irrigação intermitente também promove redução de 40% no volume de água escoada superficialmente e menor contaminação ambiental, proporcionando uma redução, na média dos três agrotóxicos avaliados, de 90% da massa de ingrediente ativo de agrotóxicos transportados para o ambiente em relação ao total aplicado na lavoura.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Weed control is one of the main agricultural practices indispensable to ensure profitability and crop success. In paddy rice field, red rice is the most important weed due to its difficult control. A widespread control method is the use of rice cultivars resistant to herbicides which are inhibitors of ALS, since it is possible to have a selective chemical control. Studies showed that the late control with imazamox promotes efficient control of red rice escapes. Thus, the objective of this research was to check the effects of imazamox application in the reproductive phase of two rice cultivars that differ in the level of resistance to imidazolinones. Two studies were carried out at the Federal University of Santa Maria in the years of 2009/10 and 2010/11. Imazamox was applied in different stadium of development and doses. At the end of the application the final dose was 80 g a.i ha-1 for all treatments. Results showed that independent of the date of the imazamox application in the reproductive phase of rice, the grain yield reduced and spikelet sterility of IRGA 422 CL increased. In general, the parameters 1000-grain weight, flag leaf length, panicule length, fresh and dry weight of panicles, and panicles per m2 showed a reduction in practically all imazamox treatments in the IRGA 422 CL cultivar. Changes in the biochemical parameters (chlorophyll, carotenoids, thiobarbituric acid reactive substances, superoxide dismutase, catalase and ascorbate peroxidase) were observed in leaves and panicles from main culm in some treatments, demonstrating that the oxidative stress promoted by imazamox may have contributed to grain yield reduction and the high percentage of sterile spikelet from IRGA 422 CL cultivar. Morphologic and anatomical changes showed that imazamox application in the panicle differentiation promoted similar changes to homeotic changes observed in rice mutant. Moreover, in the other treatments different morphologic and anatomical changes were observed. Therefore, morphologic and anatomical changes were likely to be responsible for grain yield reduction and high percentage of spikelet sterile from IRGA 422 CL. / O controle de plantas daninhas é uma das práticas agrícolas indispensáveis para garantir rentabilidade e sucesso no cultivo. No cultivo de arroz irrigado, o arroz vermelho é a planta daninha de maior importância, devido sua dificuldade de controle. Um método de controle bastante difundido é o uso de cultivares resistentes aos herbicidas inibidores da ALS, pois permite um controle químico seletivo. Estudos demonstram que o controle tardio com o herbicida imazamox promove controle eficiente de escapes de arroz vermelho. Por isso, o objetivo deste trabalho foi verificar os efeitos da aplicação do imazamox na fase reprodutiva de duas cultivares de arroz irrigado (IRGA 422 CL e PUITÁ INTA CL) que diferem quanto ao nível de resistência as imidazolinonas. Em vista do exposto, foram conduzidos dois estudos na área experimental da Universidade Federal de Santa Maria (2009/10 e 2010/11). O imazamox foi aplicado em diferentes estádios de desenvolvimento e doses, sendo que a dose final foi de 80 g i.a ha-1. Com os resultados obtidos conclui-se que independente da data de aplicação do imazamox na fase reprodutiva da cultura ocorreu redução da produtividade de grãos e aumentou a esterilidade de espiguetas da cultivar IRGA 422 CL. De maneira geral, os parâmetros: peso de mil grãos, comprimento da folha bandeira, comprimento de panícula, peso fresco e seco de panículas, e número de panículas por metro quadrado mostraram redução em praticamente todos os tratamentos na cultivar IRGA 422 CL. Alterações nos parâmetros bioquímicos (clorofila, carotenoides, substâncias reativas ao ácido tiobarbitúrico, superóxido dismutase, catalase e ascorbato peroxidase) foram observadas em folhas e panículas do colmo principal em alguns tratamentos, demonstrando que o estresse oxidativo provocado pela aplicação do imazamox pode ter contribuído para a redução da produtividade de grãos e o elevado percentual de espiguetas estéreis da cultivar IRGA 422 CL. A cultivar PUITÁ INTA CL não sofreu alterações em todos os parâmetros avaliados neste estudo. As alterações morfológicas e anatômicas demonstraram que a aplicação de 80 g i.a ha-1 imazamox na diferenciação da panícula promoveu alterações semelhantes às alterações homeóticas observadas em arroz mutante. Além disso, nas plantas que receberam a dose de 80 g i.a ha-1 após 14 dias da diferenciação do primórdio floral (DPF) e as plantas que receberam a dose de 80 g i.a ha-1 em aplicação fracionada (metade da dose 7 dias após DPF e metade da dose aos 14 dias após DPF) mostraram alterações morfológicas e anatômicas do grão de pólen. Dado o exposto, os resultados obtidos sugerem que as alterações morfológicas e anatômicas foram responsáveis pela redução da produtividade de grãos e alto percentual de espiguetas estéreis da cultivar IRGA 422 CL.

Rice have highly derived florets borne on a short branch called ‘spikelet’ comprised of a pair of rudimentary glumes and sterile lemma (empty glumes) that subtends a single fertile floret. The floral organs consist of a pair of lodicules, six stamens and a central carpel that are enclosed by a pair of bract-like organs, called lemma and palea. A progressive reprogramming of meristem identity during the floral development of flowers, on branches on the inflorescence, is correlated with changes in transcriptional status of regulatory genes that execute cascades of distinct developmental events. On the other hand phytohormones such as auxin and cytokinin that are critical in predetermining the sites of new organ primordia emergence and in maintaining the size or populations of meristems. Molecular genetic analyses of mutants have expanded the repository of genes regulating floral organ specification and identity, yet the finer mechanistic details on process downstream to these regulatory genes and co-ordination with phytohormone signalling pathways needs further investigation. One aim of the study presented in this thesis is to develop a tool that would display of spatial description of dynamic auxin or cytokinin accumulation in developing rice inflorescence and floral meristems and to evaluate auxin distribution defects of OsMADS1-RNAi florets using this tool. Additionally, we aim to understand the regulatory effects on OsMADS1 on candidate floral organ and meristem fate determining genes during two temporal phases of flower development to decipher other regulatory cascades controlled by OsMADS1. Spatial distribution profile of phytohormones in young and developing meristems of rice Cytokinin promotes meristem activity (Su et al., 2011) while auxin accumulation, directed by auxin efflux transport PIN proteins predicts sites of new organ initiation (Reinhardt et al., 2003; van Mourik et al., 2012). Previous studies in the lab deciphered that OsMADS1 exerts positive regulatory effects on genes in auxin pathways and repressive effects on cytokinin signaling and biosynthetic genes (Khanday et al., 2013). Thus, the need for a reliable system to understand auxin and cytokinin activity in live inflorescence and floral meristems of rice motivated us to raise promoter: reporter tools to map the spatial and temporal phytohormone distribution. Confocal live imaging conditions in primary roots of IR4DR-GFP and DR5-CyPet lines was performed and responsiveness of the DR5 elements to auxin was authenticated. Auxin maxima were distinctly seen in the epidermal and sub-epidermal cells of inflorescence branch primordia anlagen and apices of newly emerged branch primordia. As floral organs were being initiated, on the floret meristem, we discerned the sequential appearance of auxin accumulation at sites of organ primordia while apices of early floral meristems (FM) showed low auxin content. We clearly detect canalization of auxin streams marking regions of vascular inception. Using this live imaging system we probed auxin patterns and levels in malformed and indeterminate OsMADS1-RNAi florets and we observed a significant reduction in the levels of auxin. Two oppositely positioned peaks of auxin were noted in the persistent FM of OsMADS1-RNAi florets, a pattern similar to auxin dynamics at sites of rudimentary glume primordia on the wild-type (WT) spikelet meristem. These studies were followed up with immunohistochemistry (IHC) on fixed tissues for “PIN” transport proteins that suggest PIN convergence towards organ initiation sites, regions where auxin accumulation was clearly visualized by the IR4DR5-GFP and DR5-CyPet reporters. IHC experiments that detected GFP, in fixed tissues of TCSn-mGFP ER (WT) and TCSn-mGFP ER;OsMADS1-RNAi (OsMADS1-RNAi) inflorescence and florets showed an ectopic increase in the domain of cells with cytokinin response in OsMADS1-RNAi florets, compared to that of WT. Intriguingly, cytokinin responsive cells persisted in the central FM of OsMADS1-RNAi florets that might partially account for some of the FM indeterminacy defects seen in these florets. A correlative observation of these different imaging data hint at some exclusive patterns of the IR4DR5/DR5 and TCSn reporters that in turn lead us to speculate that a cross talk between auxin and cytokinin distribution may contribute to the precise phyllotaxy of lateral organs in rice inflorescence. Studies on novel targets of OsMADS1 in floral organ identity and meristem determinacy Loss of OsMADS1 function results in rice florets with miss specified floral organs and an indeterminate carpel produces new abnormal florets. Despite having several mutants in OsMADS1, mechanisms of how OsMADS1 regulates meristem maintenance and termination is not well understood. Global expression profile in OsMADS1-RNAi vs. WT tissues encompassing a wide range of developing florets (0.2 to 2cm panicles), gave an overview of OsMADS1 functions in many aspects of floret development. Here, a gene-targeted knockout of OsMADS1 named - osmads1ko (generated in a collaborative study) was characterized and found to display extreme defects in floral organs and an indeterminate FM. Strikingly, in addition to loss of determinacy, FM reverts to a prior developmental fate of inflorescence on whose new rachis are leaf-like malformed florets. We suggest these phenotypes reflect the null phenotype of OsMADS1 and its role in meristem fate maintenance. We tested gene expression levels for some proven targets of OsMADS1 (Khanday et al., 2013) and utilized panicles in two developmental phases- young early FMs (panicles of 0.2 to 0.5 cm) and older florets with organ differentiation (panicles of 0.5 to 1cm). We observed temporally different effects on the regulation of OsMADS34 that together with histology of young osmads1ko inflorescences suggest that the mutant is impeded for spikelet to floral meristem transition. In addition, OsMADS1 had a positive regulatory effect on genes implicated for lemma and palea organ identity such as OsIDS1, OsDH1, OsYABBY1, OsMADS15, OsMADS32, OsDP1 and OsSPL16 in both young and old panicles while OsIG1 was negatively regulated in both phases of development. MADS-box genes important for carpel and ovule development - OsMADS13 and OsMADS58 were had significantly reduced expression in florets undergoing organ differentiation. OsMADS1 positively regulated several other non MADS-box developmental genes - OsSPT, OsHEC2 and OsULT1, whose Arabidopsis homologs control carpel development and FM determinacy. These genes are de-regulated in later stages of osmads1ko floret development and are unaffected in younger panicles. Finally, OsMADS1 continually activated meristem maintenance genes - OsBAM2-like and OsMADS6 while the activation of OSH1 in early floral meristems was later altered to a repressive effect in developing florets. Perhaps such dynamic temporal effects on meristem genes are instrumental in the timely termination of the floral meristem after floral organ differentiation. More importantly, we show that regulation of many of these genes is directly affected by OsMADS1, through our studies on expression levels before and after chemical induction of OsMADS1-GR protein in amiRNAOsMADS1 florets. Further, some key downstream targets were re-affirmed by studying expression status in transgenic lines, with the OsMADS1-EAR repressive protein variant. These results provide new insights into the developmentally phased roles of OsMADS1 on floral meristem regulators and determinants of organ identity to form a determinate rice floret. Gene networks regulated by OsMADS1 during early flower development To identify global targets in early floret meristems, we determined the differential RNA transcriptome in osmads1ko tissues as compared to wild-type tissues. These data revealed regulators of inflorescence architecture, floral organ identity including MADS-box floral homeotic factors, factors for meristem maintenance, auxin response, transport and biosynthesis as some of the important functional classes amongst the 2725 differentially expressed genes (DEGs). Integrating DEGs with OsMADS1 ChIP-seq data (prior studies from our lab) we deciphered direct vs. indirect and positive vs. negatively regulated targets of OsMADS1. These datasets reveal an enrichment for functional categories such as metabolic processes, signaling, RNA transcription and processing, hormone metabolism and protein modification. Using Bio-Tapestry plot as a tool we present a visualization of a floral stage-specific regulatory network for genes with likely functional roles in meristem specification and in organ development. Further, to examine if indirect targets regulated by OsMADS1 could be mediated through transcription factors (that are themselves direct targets), we constructed a small network with the transcription factors OSH1, OSH15 and OsYABBY1 as key nodal genes and we predicted their downstream effects. Taken together, these analyses provide examples of the complex networks that OsMADS1 controls during the process of rice floret development. In summary, we surmise that defect in phytohormone distribution in OsMADS1 knockdown florets results in irregular patterns of lateral organ primordia emergence. In addition, the derangements in the developmentally stage specific expression of floral meristems identity and organ identity genes culminates in miss-specified and irregularly patterned abnormal organs in Osmads1 florets. Thus, our study highlights the versatility of OsMADS1 in regulating components of hormone signaling and response, and its effects on various floral development regulators results in the formation of a single determinate floret on the spikelet. References: Khanday I, Yadav S.R, and Vijayraghavan U. (2013). Plant Physiol 161, 1970–1983. van Mourik S , Kaufmann K, van Dijk AD, Angenent G.C, Merks R.M.H, Molenaar J. (2012). PLOS One 1, e28762 Reinhardt D, Pesce E, Stieger P, Mandel T, Baltensperger K, Bennett M, Traas J, Friml J and Kuhlemeier C. (2003). Nature 426, 255-260 Su Y, Liu Y and Zhang X. (2011) Mol Plant 4, 616–625