Call number: LD2668 .T4 1978 M67 / Master of Science

LD2668 .T4 1962 L66

Master of Science / Department of Agronomy / P. V. Vara Prasad / Drought is the single most limiting factor in crop production. This study was conducted to investigate if a cell viability assay could serve as an effective, efficient screen to determine post-anthesis drought tolerance in sorghum (Sorghum bicolor [L.] Moench) and maize (Zea mays [L]). The assay measured decline in chlorophyll fluorescence (Fv/Fm) over time from leaf punches collected from plants grown under optimum environmental conditions and placed in an incubator under high respiratory demand. A total of 300 lines of sorghum and 197 lines of maize were screened using this assay and potential post flowering drought tolerant staygreen lines and non-stay green lines were identified. Further testing of potential lines was done in both controlled and field environments, under drought conditions, to evaluate genotype performance for physiological, yield, and staygreen traits. Standard known staygreen and non-staygreen checks were also included in these studies for comparisons. Some relationships existed between results from the cell viability assay and performance measures under controlled environment and field conditions for both sorghum and corn. However, controlled experiments were limited due to space and time constraints, and field experiments were limited due to an absence of drought during the growing season. These studies showed that the staygreen trait was not clear in the known standards under controlled environment conditions. Few of the selected lines performed better under field condition. Further testing needs to be conducted to investigate the effectiveness of a cell viability assay as a feasible indicator of drought tolerance. Experiments under field conditions at different locations and with more replications would be necessary to evaluate relations between cell viability assay and expression of drought tolerance in field conditions.

Sweet sorghum has potential as an energy crop in the Southwest since, compared to corn, it requires less fertilizer and water, is cheaper to grow, and requires less energy to process into ethanol. The purpose of this study is to determine the feasibility of obtaining two crops of sweet sorghum from a single seeding. Two cultivars of sweet sorghum were seeded at early and late dates at the Maricopa Agricultural Center in 2006. Two crops of sweet sorghum were obtained in our study with a short season cultivar Bundle King, but not with the longer season cultivar MMR 327/36. The ethanol yield of Bundle King of 213 gal/acre from two crops planted on April 7 was not significantly greater statistically than the ethanol yield of 162 gal/acre from a single crop planted on June 1. Bundle King is an inherently low yielding variety, as are most short season sweet sorghum cultivars that may be used for double cropping. Thus, the problem with double cropping is identifying a suitable cultivar along with increased harvest costs, despite the advantage of providing a more even supply of feedstock to an ethanol plant.

No description available.

Doctor of Philosophy / Department of Plant Pathology / Christopher R. Little / Understanding the genetic structure of fungal pathogens enables the prediction of evolutionary forces that drive pathogen evolution, which assists informed decision-making regarding disease management. The genetic structure of Fusarium thapsinum and F. andiyazi, two important pathogens that cause grain mold and stalk rot of sorghum (Sorghum bicolor), are little understood. The genetic structure and pathogenicity of a F. thapsinum population from sorghum in Kansas were evaluated with amplified fragment length polymorphisms (AFLPs), vegetative compatibility groups (VCGs), sexual cross-fertility, and seedling pathogenicity. Two sympatric populations and a genetically intermediate "hybrid" group were identified in Kansas. Seedling pathogenicity of strains ranged from non-pathogenic to pathogenic, which may be partially attributable to genetic variability in the F. thapsinum populations. Genetic relatedness between populations of F. thapsinum from sorghum in Kansas, Australia, Thailand, and three African countries (Cameroon, Mali, and Uganda) were evaluated with AFLP markers and sexual crosses. Genetic diversity was high in all locations, but female fertility is very low. These results are consistent with the hypothesis that both sexual and asexual modes of reproduction are important components of the life cycle of F. thapsinum in these populations. More strains from Kansas and Africa were available for analysis than from Australia and Thailand, so the Kansas and Africa populations dominated the genetic structure observed. The two smaller populations from Australia and Thailand were more closely related to the Kansas population than they were to the African population. The three non-African populations contained information from the African population and from other, as yet unidentified, source population(s). Identifying the population(s) from which this genetic diversity originated is an important unanswered question. Stalk rot of sorghum was evaluated by inoculating stalk rot sensitive and stalk rot resistant sorghum lines with six genetically diverse F. thapsinum strains from Kansas under field and greenhouse conditions. One susceptible line (Tx7000) and two resistant lines (SC599 and BTx399) were evaluated in the field but only Tx7000 and SC599 were evaluated in the greenhouse. Disease severity was measured by major lesion length and the number of nodes crossed by the lesion. There were differences in aggressiveness amongst the F. thapsinum strains in both the greenhouse and field evaluations. This study provides the first evidence for differences in stalk rot aggressiveness amongst F. thapsinum strains and highlights the importance of challenging germplasm with well-characterized strains that represent the genetic spectrum of the entire population. The genetic diversity within F. andiyazi populations and some closely related strains was evaluated with AFLP markers. Phylogenetic and STRUCTURE analyses of the AFLP markers grouped the 81 F. andiyazi strains into three distinct clusters. The clusters were not based on the geographic origin of the strains. These results indicate the presence of at least one and possibly two undescribed sister taxa of F. andiyazi. More work is needed to further characterize these sister species of F. andiyazi and to understand their role in sorghum pathogenicity. There is genetic variation in global populations of F. thapsinum and the observed variation could be associated with variation in both seedling and adult plant pathogenicity. The study of F. andiyazi populations validated the need to properly identify and characterize Fusarium spp. associated with sorghum from different regions of the world.

Master of Science / Department of Grain Science and Industry / Jeffrey A. Gwirtz / Sorghum grain is underutilized in the United States. Most sorghum flour available in the market place is whole grain flour with inferior stability and baking characteristics. The demand exists for high quality stable sorghum flour with low fiber and fat content. However, the current decortication step used for separating the bran from endosperm in sorghum milling is not economically viable and the alternatives techniques, which are based on abrasion and frictions, do poor jobs and tend to increase endosperm loss. The lack of information regarding sorghum dry milling to obtain low fat and low ash white sorghum flour is the rationale for developing a suitable flow. Previous research works in this field made some progress towards the achievement of that goal, but not enough to meet the need for high quality white sorghum flour. The main method (named F20105) developed in this study for processing sorghum (without decortication) consists of the following systems: prebreak, a gradual reduction system with purification, and an impact technology. Also, two short laboratory methods were designed for obtaining white sorghum flour for comparison purposes. These were named F20106 and F20107. The method F20106 was based on the use of Buhler Experimental Mill, a Great Western Gyratory Sieve, and Quadrumat Brabender Sr. Experimental Mill. The method F20107 was based on processing decorticated sorghum in a process which uses a hammer mill, a Great Western Gyratory Sieve and an Alpine Pin Mill. A commercial flour was evaluated along with the flours from the different methods in order to make comparisons among them. The long reduction system (FS20105) which included impact detaching techniques produced white sorghum flour with high extraction rate and good baking properties. An impact dehulling machine and a prebreak roller mill were effective in collecting glumes and cracking the sorghum kernels before first break. The shattering effect of the fragile sorghum bran was avoided by implementing air separation of bran from endosperm before each break. A purification system effectively cleaned and sorted the sorghum grits by size. Sorghum flours with different protein contents were evaluated for their baking quality properties. The protein content of sorghum flour was found strongly positive correlated with the amount of water added to the batter, cell wall thickness, cell diameter and cell volume ([rho]>0.85; P<0.0001), and strongly negative correlated with the number of cells/cm2 and L-value of the bread crust (-0.95>[rho]>-0.91; P<0.0001). It was also correlated with the a-value and b-value of the bread crust ([rho]=0.620, P< 0.014 and [rho]=0.520, P< 0.047, respectively). The diagrams F20105, F20106, and F20107 can be used successfully in their current form or with small adjustments to obtain flour from different sorghum hybrids at the laboratory scale. These diagrams also fill a gap in the currently available milling literature. Additionally they can be scaled up in the sorghum processing industry. The growing gluten-free food product market would potentially provide a rapid return on the necessary investment.

Master of Science / Department of Agronomy / J.A. Dille / The availability of ALS-inhibitor herbicide-resistant grain sorghum hybrids will provide an opportunity to control grass weeds post-emergence with the ALS-inhibiting herbicide nicosulfuron (Zest[superscript]TM). More information on impact of grass weeds on sorghum yield are needed to optimize the application of nicosulfuron. The research objectives were to evaluate the impact of time of grass weed removal on grain sorghum yield when grown in different crop row spacing and seeding rates and to determine the critical duration of grass weed competition. Field studies were conducted in 2014 and 2015 at the KSU Agricultural Research Center at Hays, KS and the KSU Department of Agronomy Research Farm near Manhattan, KS. Four main treatments were grain sorghum row spacing of 25 and 76 cm at Hays or 20 and 76 cm at Manhattan, and two seeding rates of 125,000 and 150,000 seed ha⁻¹. Within each main plot, seven treatments were established including: weed-free all season using pre-emergence herbicides, weed-free all season by hand, weedy for 2, 3, 4, and 5 weeks after crop emergence in 2014 or weedy for 2, 4, 6, and 8 weeks after crop emergence in 2015, and weedy all season. The main grass weeds were giant, green, and yellow foxtail species, large crabgrass, and barnyardgrass. Grass weed biomass increased through the season at both locations in 2014 and in Manhattan in 2015. Hays 2014 grain sorghum aboveground stem and leaf biomass across row spacing and seeding rates decreased as weed removal time was delayed through the growing season. Grain sorghum yield decreased with increasing duration of grass weed competition in both years in Manhattan and in 2014 at Hays. Yield loss reached 5% at 2.3 to 25 weeks after sorghum emergence in narrow row spacing and 3.3 to 6.3 weeks after sorghum emergence in wide row spacing, depending on location, demonstrating that removing grass weed competition during these time frames will prevent more than 5% loss in grain sorghum yields.

Doctor of Philosophy / Department of Agronomy / P.V. Vara Prasad / The Ogallala Aquifer is a large underground water source located under the High Plains and is used as the primary irrigation source for producers in the region. Hyper-extraction of the Ogallala is causing a reduction in irrigation capacity for a large part of the region. Confined animal feeding operations in western Kansas rely upon irrigated crops, mainly corn [Zea mays (L.)] as a source of feed. Research has shown that forage sorghum [Sorghum bicolor (L.) Monech] could meet the demands of the confined animal feeding operations while using less water than corn. An experiment was designed to evaluate corn and forage sorghum in Western Kansas. The objective of this research was to evaluate the water use and growth characteristics of irrigated and dryland corn and forage sorghum. Field experiments were conducted at two locations (Tribune Experiment Station, Tribune and a cooperator’s field near Hoxie, Sheridan County Kansas) in 2011-2013. The experimental design at Tribune was a randomized complete block with four replications. A traditional replicated design was not possible at Hoxie. Multiple subsamples per plot were obtained and data are reported as means with standard errors. Corn and forage sorghum were grown under both dryland and fully irrigated conditions at both locations. Neutron access tubes were installed to monitor soil water. Aboveground biomass, intercepted solar radiation and volumetric soil water content were recorded at 5 sampling dates each growing season. Water use was similar between irrigated corn and forage sorghum. There were differences in biomass from year to year between the irrigated crops. Dryland water use was similar between the two crops and also had differences in biomass from year to year. Yields were significantly lower than average for all crops in 2012 due to drought conditions. Solar radiation interception correlated with aboveground biomass measurements. Aboveground biomass from the forage sorghum and corn was ensiled both years and analyzed for nutrient composition. This research suggests that forage sorghum silage may be an acceptable replacement for corn silage in areas with reduced irrigation capacities.

Call number: LD2668 .T4 1958 H37 / Master of Science