Variation and Breeding of Kikuyu Grass (Pennisetum clandestinum)

This study examined the variation existing in naturalised populations of kikuyu grass (Pennisetum clandestinum Hochst. ex. Chiov) in Australia, as well as initiating a breeding programme aimed at producing new hybrid lines for the Australian turfgrass and agricultural market. The first part of the study examines the phenotypic variation which exists within kikuyu grass populations; the genotypic variation of those populations via DNA marking; and, the basis of male sterility within those populations. The second part examines kikuyu grass within a breeding perspective through pollen viability and storage; the potential presence of an endophyte within the seed; classical hybridisation of ecotypes through to field planting; and, whether the oomycete Verrucalvus flavofaciens can be controlled via a modern day fungicide programme. It also rewrites the history of kikuyu introduction, first seeding occurrence, and previously unrecorded importations into Australia. General observations record the first photographic images of kikuyu grass chromosomes. Significant phenotypic variation exists within naturalised kikuyu grass populations across Australia. From a collection of about 200 ecotypes 16 were selected for detailed study. Analysis of the ecotypes identified two lines from several which show great potential within the Australian turfgrass and agricultural market; the first selected at Grafton, NSW, which in the leaf width analysis displayed a leaf width over 18% finer than the mean; with the second selected at Morphettville, SA, which in the stolon width analysis displayed a stolon width over 15% thicker than the mean. Both selections, as well as others, displayed positive traits which would appeal to a wide range of end users. Genetic investigations using RAPD marker techniques are undertaken on kikuyu for the first time. A total of thirteen decamer primers produced 195 markers of which 93.85% were polymorphic. Genotypic variation amongst the Australian selections was found to range from 28.8% - 82.4%. Relatedness between the cluster accessions used in the phenotypic analysis and the dendogram produced in the genetic analysis was not found. Male sterility within Australian kikuyu grass was determined to exist as a recessive condition. From the F1 population, 100% transformation from male sterile to fully fertile was observed; with the F2 population segregating into a 52.5% fully fertile, 47.5% male sterile. Negative interactions between parental lines were observed. Kikuyu grass pollen is most viable in the first few hours after shedding, and deteriorates significantly within 24 hours, even at low temperatures, if it is stored. Pollen viability varies amongst genotypes. Prior additions of dry colloidal material does not assist in storage capabilities. Investigations into seedling mortality of kikuyu identified the possible presence of an endophyte within the seed. Surface sterilisation techniques provided no control, with an addition of 0.1% PPM to the base agar mixture the most effective form of control. Intercellular hyphae were identified and photographed after staining with Rose Bengal. Hybridisation studies of kikuyu grass resulted in several potential lines worthy of continued analysis. Selections from varying growing environments around Australia were hybridised with three pollen parents derived from chemical mutagenesis producing a total of 349 hybrid F2 seeds. Germination and screening in the glasshouse resulted in 14 hybrid lines being field planted alongside cv. ‘Whittet’ for comparison. The opportunity exists within the turfgrass market for elite lines of kikuyu, which will cover a wide range of uses from golf course tees and fairways, sporting grounds and race tracks, to pasture and commercial use. Efficacy with modern day fungicides in vitro was found not successful in controlling Kikuyu Yellows (Verrucalvus flavofaciens). Resistance of kikuyu grass to the oomycete will have to come in the form of genetically resistant cultivars; production of a specific fungicide; or both

A Bridge Program\u27s Effect on Non-College Ready Student Veterans

This study examined whether a bridge program designed to remediate academic deficiencies for a cohort of student veterans has any bearing on their post-secondary success and persistence. Specifically, this study examined the Veterans Bridge to College Success (VBCS) pilot program at Eastern Kentucky University, which provides an admission pathway for student veterans with low ACT or SAT test scores, no test scores, or marginal high school or college GPAs. The study utilized both quantitative and qualitative analyses to determine whether student veterans with known academic deficiencies prior to enrollment would persist and perform at similar rates as their academically proficient peers and examine whether their academic and social cohort experience in the VBCS program had any lasting effect upon their persistence. The study examined both groups during their third and fourth academic terms when all participants were considered fully academic ready and enrolled full-time in credit bearing coursework. The quantitative results of the study show evidence that the academic performance and retention rate of students who continued to pursue their degree after completing VBCS program did not differ significantly from their college-ready student veteran peers who did not participate in the cohort-based program. Furthermore, the qualitative portion of the study confirmed that members of the VBCS group reported lasting effects of the VBCS program on their desire to persist. Chapter 5 of the study reflects upon the value of the research in regards to policy, practice and for future research

AN EXAMINATION OF SINGLE-SEX SECONDARY AGRICULTURAL EDUCATION CLASSROOMS: THE EFFECTS OF TEACHER EXPECTANCY

The effectiveness of single-sex classrooms in the United States remains unclear. To address this issue, the purpose of this quasi-experiment was to examine single-sex classrooms in secondary agricultural education classrooms in Kentucky. Data were collected through quantitative pretests and posttests from student participants (n = 168) and teacher participants (n = 8). The findings indicated that student participants in single-sex classrooms had higher academic performance, better attendance, and an increased gain in interest in the agriculture, food, and natural resources career pathway. Students participants in coeducational classrooms had less discipline referrals. Teacher participants’ expectation were related to student performance. Recommendations are made for further research and changes in teacher preparation practice

A Relationship Between Stellar Age and Spot Coverage

We investigate starspot distributions consistent with space-based photometry of F, G, and K stars in six stellar associations ranging in age from 10 Myr to 4 Gyr. We show that a simple light curve statistic called the "smoothed amplitude" is proportional to stellar age as $t^{-1/2}$, following a Skumanich-like spin-down relation. We marginalize over the unknown stellar inclinations by forward modeling the ensemble of light curves for direct comparison with the Kepler, K2 and TESS photometry. We sample the posterior distributions for spot coverage with Approximate Bayesian Computation. We find typical spot coverages in the range 1-10% which decrease with increasing stellar age. The spot coverage is proportional to $t^n$ where $n =-0.37 \pm 0.16$, also statistically consistent with a Skumanich-like $t^{-1/2}$ decay of starspot coverage with age. We apply two techniques to estimate the spot coverage of young exoplanet-hosting stars likely to be targeted for transmission spectroscopy with the James Webb Space Telescope, and estimate the bias in exoplanet radius measurements due to varying starspot coverage.Comment: 21 pages, 11 figures, accepted in ApJ, software in review at JOSS https://github.com/openjournals/joss-reviews/issues/210

Observations of Transiting Exoplanets with Differential Photometry

Abstract: Preliminary observations and computational methods for analysis are presented for observing celestial objects with time-varying intensity, in particular transiting exoplanets. Transits occur when a planet orbiting a star other than the sun (an exoplanet) passes between the Earth and the host star, slightly dimming the apparent intensity of the star. CCD images of the host star of one such exoplanet, HD 189733b, are recorded during predicted transits at the University of Maryland Observatory (UMO) on a small (152 mm) refracting telescope. Differential photometry algorithms compare the relative brightness of the host star to other nearby, non-variable stars in the field and detect the small change in brightness associated with a planetary transit, on the order of tens of millimagnitudes. The first successful exoplanet observations at UMO are presented and discussed, as well as possible implications for exoplanetary studies conducted by amateur and small observatories