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‘CL151’ a Clearfield long-grain rice cultivar, was released in 2008, based upon excellent agronomic characteristics, including excellent yield and moderately resistant rating for lodging. Further experience has indicated it’s susceptibility to lodging. Lodging can reduce harvest efficiency, yield, and cause grain quality loss. The purpose of this research was to evaluate multiple management practices such as nitrogen rates and timings, seeding rate, trinexapac-ethyl application, potassium, and fungicide application to mitigate lodging for CL151. The results of this research indicate that N rate and application timing largely influence lodging incidence and grain yield. Fungicide application decreased, but did not eliminate lodging, while potassium application did not impact lodging or grain yield. Seeding rate also has a significant impact on grain yield and lodging incidence. Trinexapac-ethyl also decreased lodging incidence, but negatively impacted grain yield which was most evident when applied at 48 g ha-1 and applied at PD +14d growth stage.

Prohexadione-calcium (Pro-Ca), a plant growth regulator used primarily in fruit trees to suppress excessive vegetative growth and to inhibit disease incidence, is known to inhibit dioxygenase enzymes and to inhibit GA biosynthesis. It induces genes for polyphenols synthesis. The objective of this project was to determine if the bioregulator Pro-Ca would alter the yield of essential oil, secondary metabolites, and growth in spearmint. Spearmint shoot cuttings from the same mother plant were used in this study. The plants were treated with 0, 125, 250, 375, and 500 mg/L a.i. of Pro-Ca over four weeks, and growth responses were measured every week and at harvest. Compared with the untreated control plants, plant height, branch length, number of nodes, and fresh weight were decreased with increased concentration of Pro-Ca treatment, and total phenolics accumulation increased. Rosmarinic acid and total chlorophyll content were reduced relative to control after treatment. Treatment with increased concentration of Pro-Ca altered the accumulation of flavonoids compounds. Increased concentration of catechin and eriodictyol-7-glucoside, and decreased concentrations of procyanidin and luteolin occurred compared with the untreated plant. Modification of newly formed flavonoid synthesis could be used as a new potential strategy in plant protection.

Mangrove forests are highly productive ecosystems widespread in tropical and subtropical coastlines, with a coverage of 75% of the world’s tropical shorelines. Mangrove plants developed specific physiological and morphological adaptation to thrive in such unique environments. Together with plant adaptations, mangroves develop a tight partnership with microorganisms, mainly bacteria and fungi, that form the so-called mangrove-microbiome. Plant-associated microorganisms are generally recruited by the root system (root tissues and rhizosphere) and the colonization process starts with the release of root-related exudates detected by the surrounding edaphic microorganisms that are attracted in the rhizosphere zone. Then, root surface selects those microorganisms that can enter the tissues as endophytes. The microorganisms recruited belowground can migrate through the plant tissues by using the plant vessels and may colonize the aboveground compartments of the plant. Here, I aimed to evaluate the environmental origin and compartmentalization of the mangrove microbiome. To do this, I sampled bulk sediments, sea water, and mangrove plant compartments (root rhizosphere and endosphere, pneumatophores, shoot, leaves, flowers and propagules) of 20 gray mangrove trees (Avicennia marina L.) across two sites on the Red Sea coast of the King Abdullah University of Science and Technology (KAUST), Saudi Arabia. By high-throughput sequencing of the bacterial 16S rRNA gene, I showed that the bacterial assembly in A. marina plant compartments follows a clear niche partition process in which bacterial communities are actively recruited from the surrounding ecosystem (sediment and sea water) by the root system, and further distributed across the different plant organ and compartments. Moreover, the composition of microbiome detected had many similitudes with others previously described around the world, suggesting that certain bacteria represent a mangrove “core microbiome”. The conservation of microbiome composition, mainly driven by environmental and host selection, that beneficial bacteria provide to the plant and contribute to its growth and fitness by several mechanisms. Thus, the characterization and identification of mangrove microbiome can meliorate our knowledge regarding plant–microbe interactions, as well as put the bases for the development of Nature-based Solution (NBS) to enhance reforestation and rehabilitation of mangrove ecosystems

Active disease resistance in plants is induced during the pathogen infection process that triggers multiple defense-related genes to establish broad-spectrum resistance. Several biotic and abiotic agents can mimic natural induced resistance (IR), categorized as systemic acquired (SAR) or induced systemic resistance (ISR). IR, triggered by acibenzolar-S-methyl (ASM) or plant growth-promoting rhizobacteria (PGPR), was evaluated on two-to-three types of tobacco in greenhouse and field studies. Tobacco mosaic virus (TMV) local lesion assays monitored induction and maintenance of ASM-induced SAR over a 21 day period via proportional reduction in the number of TMV local lesions between an untreated control and ASM-treated plants. Intraspecific variation in SAR was found among tobacco types; burley and flue-cured tobaccos responded by day 3, while oriental tobacco responded between day 3 and 6. The SAR signal was greatest between 6 and 15 days following ASM application, but IR was slightly evident even at 21 days after ASM application in all three tobacco types. Bottom and middle leaves responded similarly on all sample dates, but top leaves showed the weakest SAR response. Tobacco cyst nematode (TCN; Globodera tabacum solanacearum) is one of the most destructive pathogens of tobacco in Virginia. Among four PGPR combinations tested, a mixture of Bacillus amyloliquefaciens IN937a (GB99) and B. subtilis A13 (GB122) most consistently suppressed TCN reproduction in flue-cured and oriental tobacco. Application of ASM similarly reduced final numbers of TCN cysts, but also resulted in chlorosis, stunting, and lower plant fresh weight. GB99+GB122 also suppressed TCN development and reproduction in susceptible and resistant flue-cured cultivars, but reductions by ASM were less consistent. In a split-root trial, soil amendment with GB99+GB122 in one half of an oriental tobacco root system lowered final numbers of TCN more than did ASM. ASM exhibited undesirable effects in phytotoxicity trials in flue-cured and oriental tobacco, but GB99+GB122 was not phytotoxic. When oriental tobacco seedlings were grown in a GB99+GB122-treated soil-less media, a single application of 200 mg ASM/L one week after transplanting significantly suppressed TCN reproduction in the field without phytotoxicity. Further field research is needed to confirm this effect in flue-cured tobacco. / Ph. D.

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No description available.

No description available.

This report investigates how to build a compact, optimizable and at the same time user friendly hydroponic systemfor growing plants as efficiently as possible. Hydroponics grows plants using water with dissolved nutrients instead of soil, allowing faster and more efficient growth.The focus has been on the implementation and the usability of such a system, centering around monitoring and to some degree controlling important parameters for growth such as humidity, air temperature, nutrition concentration and light intensity, colour and exposure time. The plant is enclosed in a confined space with artificial lighting which allows thorough control of the light environment. In order to achieve the desired level of control over the growth parameters, several sensors along with a microcontroller were used. A touch screen with a custom built graphical user interface was also connected to allow the user to control and monitor important aspects of growth conditions. The conclusion drawn from this project is that there is ahigh order of optimizability within the boundaries of this project. The measured factors are easily read on an intuitive, easily navigated touch screen for direct feedback. Regarding the lights’ effect on plant growth, the conclusionis drawn that plants grow well with many types of lights, but more time is needed to thoroughly investigate different light exposure times, colour and intensity. / I denna rapport undersöks hur man kan bygga ett kompakt, optimerat och samtidigt användarvänligt hydroponiskt system för att odla växter så effektivt som möjligt. Hydroponiska system får plantor att växa genom att användavatten med näring istället för jord, vilket tillåter snabbare och mer effektiv tillväxt. Fokuset i denna rapport har varit på implementeringen och användbarheten av ett sådant system, med tyngpunkt på övervakning och till viss grad styrning av viktiga faktorer i en plantas tillväxt såsom luftfuktighet, temperatur, näringskoncentration och ljusintensitet, färg och exponeringstid. Växten är innesluten i ett begränsat utrymme med artificiellt ljus, vilket tillåter genomgående kontroll av ljusmiljön. För att uppnå önskad kontroll av tillväxtparametrarna, användes ett flertal sensorer tillsammans med en mikrokontroller. Till detta kopplades en pekskärm med ett egen tillverkat användargränssnitt, som tillåter användaren att kontrollera och övervaka viktiga aspekter i tillväxten. Slutsatsen från detta projekt är att det finns en hög grad av optimerbarhet inom denna konstruktion. De uppmätta parametrarna kan enkelt avläsa ljusexponering, ljusintesitet och färg.

A preliminary experiment evaluated the effect of plant growth regulators (PGRs) or mechanical stimulation (brushing) on branching of sweet basil (Ocimum basilicum L.), cilantro (Coriandrum sativium L.), and parsley (Petroselinum crispum (Mill.) Nyman ex A.W. Hill). Dikegulac sodium increased branching in sweet basil up to 400 ppm and thereafter branching decreased compared to control plants. Ethephon increased branching in sweet basil as rate increased up to 500 mg/L compared to control plants. Mechanical stimulation resulted in a significant decrease in plant height, plant width, number of branches, and number of leaders for all species compared to control plants. Benzyladenine and metaconazole had no effect on these species. In the main experiment the effect of colored shade cloth and PGRs or brushing were assessed on sweet basil, Thai basil (Ocimum basilicum "Siam Queen" L.), Genovese basil (Ocimum basilicum "Genovese" L.), cilantro, and parsley. All crops were grown under conventional black, blue ChromatiNet®, or red ChromatiNet® shade cloth. Subplot treatments included: dikegulac sodium at 400 ppm; benzyladenine at 300 ppm; ethephon at 350 ppm; brushing at 10 strokes applied twice daily. We assessed volatile compunds on all crops and conducted a sensory panel on sweet basil. Red shade cloth increased the number of branches and shoot fresh weight in sweet basil, Thai basil, and Genovese basil. Number of leaf stalks and shoot fresh weight also increased in cilantro plants grown under red shade cloth. Red shade cloth increased fresh weight of parsley plants. Sensory panel results showed a preference for the appearance of sweet basil grown under red shade cloth. Red shade cloth can be used to grow sweet basil, Thai basil, Genovese basil, cilantro, and parsley plants that have more branches and higher fresh weights. / Master of Science