Master of Science / Department of Agronomy / Johanna A. Dille / Curtis R. Thompson / The acetolactate synthase inhibitor herbicide-resistant grain sorghum technology introduced will allow for the application of nicosulfuron for postemergence (POST) grass control, however it is essential to determine a program-based approach to ensure broad spectrum weed control. Field experiments were conducted at three locations across Kansas in 2015 and 2016 to assess a range of possible herbicide programs for grass and broadleaf weed control and crop tolerance using Inzen™ Sorghum. The experiments consisted of 1 early pre-plant (EPP), 2 preemergence (PRE), and 3 POST, and 5 PRE followed by POST herbicide treatments. Weed control and crop response were evaluated visually at 1, 2, and 4 weeks after POST treatment (WAPT). Treatments containing nicosulfuron and/or bromoxynil & pyrasulfotole caused 10 to 20% crop injury at 1 WAPT in both 2015 and 2016 at the three locations. Treatments containing nicosulfuron + dicamba caused up to 30% injury with more injury in 2015 than in 2016. In 2015 at Manhattan the nicosulfuron-only treatment provided 64% control of Palmer amaranth and, when tank mixed with dicamba or bromoxynil & pyrasulfotole, control ranged from 71 to 76%. When nicosulfuron POST followed PRE of S-metolachlor & atrazine, Palmer amaranth control was 96 to 100%. At both locations, nicosulfuron provided 35, 55, and 61% control of large crabgrass, yellow foxtail, and stinkgrass, respectively. Annual grass control ranged from 85 to 100% when nicosulfuron followed a PRE S-metolachlor & atrazine. Greenhouse experiments were set up to determine the efficacy of nicosulfuron on four annual grass species at six different rates, two different rates, and the addition of atrazine. The four grass species evaluated were large crabgrass, yellow foxtail, barnyardgrass, and wheat. Nicosulfuron was applied at 0.125, 0.25, 0.5, 1, 2 times its labeled rate of 35 g ha⁻¹. A full factorial of rate by height by atrazine was applied for a total of 24 treatments replicated 4 times on each species. Each nicosulfuron rate was applied with and without atrazine at 840 g ha⁻¹ on 5 to 10 cm tall plants and on 15 to 20 cm tall plants. Visual ratings were taken 1, 2, and 4 weeks after treatment (WAT). Aboveground biomass was harvested 4 WAT, dried and weighed. Treatments containing nicosulfuron from 4.4 to 70 g ha⁻¹ all caused similar reduction in biomass compared to the nontreated check. Averaged over the inclusion of atrazine, nicosulfuron applied at 35 and 70 g ha⁻¹ provided 17% less control when treating 15 to 20 cm large crabgrass compared to the 5 to 10 cm large crabgrass, respectively. Overall barnyardgrass, yellow foxtail, and wheat can be effectively controlled with nicosulfuron when applied at proper heights, rate, and atrazine.

Doctor of Philosophy / Department of Agronomy / Kassim Al-Khatib / Field experiments were conducted to evaluate the efficacy of nicosulfuron and nicosulfuron + rimsulfuron applied alone or in combination with various broadleaf herbicides in acetolactate synthase (ALS)-resistant grain sorghum. Herbicides were applied when weeds were 5 to 15 cm in height. Overall weed control was greater when nicosulfuron + rimsulfuron were applied with other herbicides than when it was applied alone. Results indicated that postemergence (POST) application of nicosulfuron and nicosulfuron + rimsulfuron is effective at controlling grasses including barnyardgrass, green foxtail, and giant foxtail. The research also showed that broadleaf weed control was more effective when nicosulfuron + rimsulfuron were applied with other broadleaf herbicides. A field study was conducted to evaluate the differential response of ALS-resistant grain sorghum to POST applications of nicosulfuron + rimsulfuron at three growth stages. Grain sorghum was treated with nicosulfuron + rimsulfuron at the 3- to 5-leaf, 7- to 9-leaf, or 11- to 13-leaf collar stage. Nicosulfuron + rimsulfuron injured grain sorghum when applied at the 3- to 5-leaf, and 7- to 9-leaf collar stage, however, sorghum yields and plant height were only reduced for the 3- to 5-leaf collar stage. Results indicated that nicosulfuron + rimsulfuron application at the 3- to 5-leaf collar stage injured ALS-resistant grain sorghum, but application at 7- to 9-leaf and 11- to 13-leaf collar stages did not result in grain yield reduction. Greenhouse experiments were conducted to evaluate the efficacy, absorption, and translocation of nicosulfuron, rimsulfuron, and nicosulfuron + rimsulfuron. Barnyardgrass, green foxtail, longspine sandbur, and large crabgrass were treated at 5 to 10 cm in height. Barnyardgrass GR[subscript]50 was the lowest and was the most susceptible to all herbicides whereas, large crabgrass had the highest GR[subscript]50 for all herbicides and was the most tolerant. Barnyardgrass and large crabgrass were treated with [superscript]14 C-nicosulfuron, [superscript]14 C-rimsulfuron, or both and radioactivity was recovered at 7 DAT. Barnyardgrass absorption and translocation of nicosulfuron, rimsulfuron and nicosulfuron + rimsulfuron was higher than large crabgrass. Results may indicate that greater absorption and translocation of the herbicides may attribute to the differential response of the species to nicosulfuron, rimsulfuron, and nicosulfuron + rimsulfuron.

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.

Master of Science / Agronomy / Ignacio Ciampitti / P. V. Vara Prasad / Mid-west grain sorghum (Sorghum bicolor (L.) Moench) producers are currently obtaining much lower than attainable yields across varying environments, therefore, closing yield gaps will be important. Yield gaps are the difference between maximum economic attainable yield and current on-farm yields. Maximum economic yield can be achieved through the optimization of utilizing the best genotypes and management practices for the specific site-environment (soil-weather) combination. This research project examines several management factors in order to quantify complex farming interactions for maximizing sorghum yields and studying nutrient partitioning. The factors that were tested include narrow row-spacing (37.5 cm) vs. standard wide row-spacing (76 cm), high (197,600 seeds haˉ¹) and low (98,800 seeds haˉ¹) seeding rates, balanced nutrient management practices including applications of NPKS and micronutrients (Fe and Zn), crop protection with fungicide and insecticide, the use of a plant growth regulator, and the use of precision Ag technology (GreenSeeker for N application). This project was implemented at four sites in Kansas during 2014 (Rossville, Scandia, Ottawa, and Hutchinson) and 2015 (Topeka, Scandia, Ottawa, Ashland Bottoms) growing seasons. Results from both years indicate that irrigation helped to minimize yield variability and boost yield potential across all treatments, though other factors affected the final yield. In 2014, the greatest significant yield difference under irrigation in Rossville, KS (1.32 Mg haˉ¹) was documented between the ‘low-input’ versus the ‘high-input’ treatments. The treatment difference in grain sorghum yields in 2014 was not statistically significant. In 2014, the Ottawa site experienced drought-stress during reproductive stages of plant development, which resulted in low yields and was not influenced by the cropping system approach. In 2015 the treatments were significant, and in Ottawa, narrow row spacing at a lower seeding rate maximized yield for this generally low-yielding environment (<6 Mg haˉ¹) (treatment two at 6.26 vs. treatment ten at 4.89 Mg haˉ¹). Across several sites, including Rossville, Hutchinson, Scandia, Topeka, and Ashland, a similar trend of narrow row spacing promoting greater yields has been documented. Additionally, when water was not limiting sorghum yields (i.e., under irrigation), a balanced nutrient application and optimization of production practices did increase grain sorghum yields (‘high-input’ vs. ‘low-input’; the greatest difference was seen in 2014 in Rossville, 1.2 Mg haˉ¹, and in 2015 in Ashland, 1.98 Mg haˉ¹). In the evaluation of nutrient uptake and partitioning in different plant fractions, there was variability across all site-years which did not always follow the same patterns as the yield, however, the low-input treatment was shown to have significantly lower nutrient uptakes across all the nutrients evaluated (N, P, K, S, Fe, Zn) and across most fractions and sampling times. The objectives of this project were to identify management factors that contributed to high sorghum yields in diverse environments, and to investigate nutrient uptake and partitioning under different environments and crop production practices.

During 2016 and 2017, studies were conducted to determine the effects of Spodoptera frugiperda (J.E. Smith) on both damage and yield of Sorghum bicolor (L.) Moench and Zea mays (L.) when infested during the whorl stage. Results from damage ratings suggest that as the amount of overall plants infested increased, overall damage rating increased. However, yield results suggested that there was no yield loss as percent infested plants increased. Other studies were conducted to determine the most sensitive vegetative growth stages of grain sorghum and field corn. Manual damage studies suggests that extensive damage to field corn during growth stages V9 to V15 will cause significant yield loss. Also, damage to grain sorghum after growth stage V8 and prior to boot stage can cause significant yield loss.

Doctor of Philosophy / Department of Agronomy / Kassim Al-Khatib / Growth chamber, greenhouse and field experiments using conventional grain sorghum were conducted to 1) evaluate the differential response of grain sorghum hybrids to POST application of mesotrione at various rates and application timings, and 2) determine the physiology of tolerance of grain sorghum hybrids to mesotrione. Sorghum response ranged from susceptible to tolerant. Mesotrione dose-response studies on four sorghum hybrids revealed that injury symptoms were greatest in Pioneer 85G01 and least in Asgrow Seneca. Mesotrione applied EPOST (early POST) injured sorghum more than when applied at MPOST (mid POST) or LPOST (late POST) timings. Observed injury symptoms were not well correlated with grain yield and were transient, thus injury did not reduce sorghum grain yield. Foliar absorption or translocation of mesotrione in tolerant hybrids did not differ with that of susceptible hybrids but metabolism was more rapid in tolerant than in susceptible hybrids. Initial grain sorghum injury was severe and will likely be a major concern to producers. Field and growth chambers studies were conducted on herbicide-resistant grain sorghum to 1) determine the effect of quizalofop rates, application timings, and herbicide tank mixes on acetyl-coenzyme A carboxylase (ACCase)-resistant grain sorghum injury and yield, and 2) determine if herbicide metabolism is an additional mechanism that could explain the resistance of ACCase- and acetolactate synthase (ALS)-resistant grain sorghum. Depending on rate, EPOST application caused the greatest injury while the least injury occurred with LPOST application. Crop injury from quizalofop was more prominent at rates higher than the proposed use rate (62 g ha [superscript]-1) in grain sorghum. Sorghum grain yield was not affected by quizalofop regardless of rates or application timings. Weed control was greater when quizalofop was applied with other herbicides than when applied alone. Herbicide treatments except those that included 2,4-D caused slight to no sorghum injury. Results of the quizalofop metabolism study do not support the involvement of differential metabolism in the observed response of grain sorghum to quizalofop. Rimsulfuron metabolism by ALS-resistant sorghum is more rapid than the susceptible genotypes, thus explaining the observed rapid recovery of grain sorghum plants from rimsulfuron injury in the field.

Doctor of Philosophy / Department of Agronomy / Kraig L. Roozeboom / Previous research has revealed that winter wheat (Triticum aestivum L.) yields are often reduced following grain sorghum [Sorghum bicolor (L.) Moench] compared to wheat after other summer crops. The objectives of the study were to: (a) evaluate grain sorghum residue management strategies to improve the performance of a following winter wheat crop in no-till systems; (b) determine grain sorghum hybrid characteristics that facilitate planting wheat following grain sorghum, and identify winter wheat cultivars that are suitable for planting after grain sorghum; (c) evaluate effect of environment, sampling time, and grain sorghum hybrid plant pigmentation on phenolic acid concentration in sorghum residues. Experiments were conducted in environments suitable for planting winter wheat following a summer crop. Treatments for objective one were: glyphosate (pre-harvest application, post-harvest, none), residue (removed, chopped, left standing), and nitrogen (34 kg ha⁻¹ applied to residue, none). Treatments for objective two and three were grain sorghum hybrids representing three maturities (early, medium, medium-late) and two plant pigmentations (red, tan), wheat cultivars occupying significant planted acreage and having favorable performance within the region. Wheat yields increased in two environments by 217 and 630 kg ha⁻¹ when glyphosate was applied to the sorghum pre-harvest. Residue chopping or removal either had no effect or a negative effect on wheat yields compared to residue left standing. Nitrogen applied to the sorghum residue increased wheat yields in only one environment. Grain sorghum hybrid characteristics did not influence winter wheat yields in any environment, but winter wheat cultivar did influence grain yields of the winter wheat in three of the four environments. Breakdown of phenolic acids depended on environment. Results for these studies indicate that wheat yield after a grain sorghum crop can be maximized by planting a red-pigmented sorghum hybrid of an early or medium maturity, desiccating the sorghum crop with pre-harvest glyphosate if it can be applied to the sorghum roughly 45 to 50 days before a frost, and with a wheat cultivar that is well suited to no-till planting.

The potential of high digestible grain sorghum (HDGS) with a modified starch protein endosperm matrix to replace corn in ethanol production was investigated using dry grind simultaneous saccharification and fermentation (SSF). Preliminary experiments showed that HDGS yielded higher amounts of glucose and ethanol than normal digestible grain sorghum (NDGS) and corn particularly in the first 48 hrs of fermentation. It was hypothesized that fast conversion of starch to glucose and ethanol during hydrolysis and fermentation are results of improved protein digestibility of HDGS. The invagination of protein structures in HDGS produced a flourier endosperm texture, softer kernels and lower starch content than the normal digestible protein (ND) lines. Highly digestible protein (HD) lines have better pasting properties (significantly lower pasting temperature, faster rate of gelatinization and higher peak viscosity) than ND lines based on the RVA profile. Increasing protein digestibility of the HDGS improved starch digestibility (increased rate of glucose conversion and total glucose yield during saccharification), which is supported by highly significant correlation of turbidity with rate of glucose conversion and efficiency of enzymatic conversion. The efficiency of ethanol conversion is significantly correlated with starch digestibility, pasting properties, and protein digestibility. Results also showed that HD sorghum lines had significantly faster rate of conversion and shorter reaction time needed to achieve completion than ND sorghum lines and corn. Increasing the dry solid concentration from 22% to 30% (w/v) increased the ethanol yield from 8% v/v to 13%v/v. This will allow considerable saving of water, reduced distillation cost and increased ethanol production for a given plant capacity and labor cost. Fineness of grind influences the amount of sugar formed due to variation in surface area of the flour. The hypothesis that finer particles has faster and higher glucose yield, defined as g of glucose converted per g of theoretical glucose, is supported by highly significant correlation of mass fraction of 3 to 60 mu m size range and mass median diameter (MMD) of 60 to 1000 mu m size range with glucose conversion efficiency and glucose conversion rate during saccharification and fermentation.

Master of Science / Department of Agronomy / J. A. Dille / Weed control in grain sorghum has always presented a challenge to producers in the semi-arid Great Plains. Cultural control tactics such as narrowing of row spacings and increasing seeding rates can be effective control methods. The objective of this research was to determine the row spacing and seeding rates that maximizes yield while suppressing weeds. Grain sorghum row spacings of 25, 51, and 76-cm and seeding rates of 75,000, 100,000, 125,000, and 150,000 seeds ha[superscript]-1 were evaluated in Kansas at Beloit and Manhattan in 2013 and Beloit, Manhattan, and Hays in 2014. Grain sorghum growth and yield response were measured in response to natural weed communities. After evaluation, Beloit was considered a low weed pressure site while Manhattan and Hays were considered to be moderate and high weed pressure sites, respectively. Grain sorghum biomass was different while weed biomass was consistent across row spacings. Yield loss equations and profit functions were derived to determine the amount of grain yield and $ ha[superscript]-1 loss from each of the three locations. Yield and profit lost was greatest amongst weedy observations. Results indicated that grain sorghum grown on wide row spacings and seeding rates of 125,000 seeds ha[superscript]-1 out yielded all other treatments under a low weed pressure site (Beloit) and narrow row spacings out yielded wider spacings in moderate and high weed pressure sites (Manhattan and Hays). These results imply that a Kansas grain sorghum producer should evaluate potential weed pressure before determining a final row spacing and seeding rate.

Master of Science / Biological & Agricultural Engineering / Donghai Wang / The growing demands for renewable energy sources have led researchers to investigate other biomass sources, aside from maize. Grain sorghum is comparable to maize in its starch content and can be grown in regions with drier climates, where maize is a less suitable crop for these areas. In attempts to increase yield prior to harvest and for ethanol production, this study focuses on mutant grain sorghum. One hundred and nine mutant grain sorghum samples were analyzed for their chemical and physical properties and fermented into ethanol. The current method for starch analysis is time-consuming and tedious. Near infrared spectroscopy (NIR) models were developed as fast, cost-effective, and non-destructive methods for grain sorghum starch content analysis. Each mutated grain sorghum sample was scanned in a wavelength range from 4,000 to 10,000 cmˉ¹ as a whole grain and in flour form. Partial Least Squares (PLS) regression method was used for NIR model development. The coefficients of determination (R²) of 0.77 and 0.90 were achieved for starch content calibration and prediction models, respectively. This model demonstrates the possibility of a positive correlation between the actual and calculated values for starch content. Another PLS first derivative model with R² = 0.95 for calibration and a reduced wavelength range (4,000-5,176 cmˉ¹), using 39 of the original 109 samples (27 for calibration and 8 for validation), was created to predict the fermentation efficiency.