Call number: LD2668 .T4 1964 E34 / Master of Science

Call number: LD2668 .T4 1966 K76 / Master of Science

LD2668 .T4 1966 W891 / Master of Science

Call number: LD2668 .T4 1978 F58 / Master of Science

Call number: LD2668 .T4 1955 H78 / Master of Science

LD2668 .T4 1962 P37

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 / Ignacio Ciampitti / Sorghum [Sorghum bicolor (L.) Moench] has greater drought resilience than many other crops, producing food in the most stressful environments. Sorghum is a reasonable crop choice for farmers working with limited-water supply. The objective of this study was to compare sorghum hybrids differing in yield strategies under varying water supply environments. Yield, biomass, grain harvest index (HI), and yield components (seed number and seed weight) were compared in both rainfed and irrigated situations. Field experiments were established in 2014 and 2015 at Topeka, Scandia, Hutchinson, Garden City, and Tribune, KS. Three sorghum hybrids (Pioneer 85Y40, Pioneer 84G62, and Dekalb 53-67) with different yield potentials at varying water supply were studied. Hybrids 85Y40 and 84G62 tended to have greater yields than hybrid 53-67 when the environment's average yield level was greater than 8.5 Mg haˉ¹. The opposite scenario where hybrid 53-67 had greater yields than the other two hybrids tended to occur for environments yielding less than 8.5 Mg haˉ¹. Both biomass and HI were significantly correlated with grain yield (r values of 0.62 and 0.32 respectively), with biomass having an overall stronger correlation than HI in all environments. In yield group 3 (<8.5 Mg haˉ¹), biomass was much more strongly correlated (r=0.85) to yield than in the yield groups 1 and 2 (>9.5 Mg haˉ¹ and 8.5-9.5 Mg haˉ¹ with r values of 0.35 and 0.52 respectively) suggesting that biomass production is of utmost importance for yield production in drought prone environments. Harvest index on the other hand had a much stronger correlation with yield in group 1 (r=0.62) when compared to group 2 and 3 (r 0.13 and 0.36 respectively) showing the importance of not only biomass, but also of HI to maximize yield in high yielding environments. Hybrids 85Y40 and 84G62 had larger HI values relating to the yield trends in the highest yielding environments. Seed number had a stronger correlation with yield (r=0.77) than seed weight (r=0.37) supporting the importance of increasing seed number to improve yield in sorghum.

published_or_final_version / abstract / Botany / Doctoral / Doctor of Philosophy

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.