Semester of Graduation

Fall 2018


Master of Science (MS)


School of Plant Environment and Soil Sciences

Document Type



Wheat is one of the world’s most important food crops and provides nearly 20% of the calories consumed. Wheat is the third most important crop after corn and rice on a global production scale. In Louisiana wheat harvest was about 6000 hectares in 2017. Wheat production is negatively affected by several biotic and abiotic factors including weather, diseases, and weeds. Metribuzin is a broad-spectrum herbicide commonly used in wheat because it is inexpensive and controls most of the common weeds in wheat fields. Metribuzin has benefits for the grower controlling weeds that might cause yield loss in varieties or lines that are tolerant to its application. Reactions of wheat varieties to metribuzin vary from tolerant to sensitive and the severity of the injury damage is influenced by the environmental conditions. The interaction of environmental conditions and wheat variety sensitivity makes metribuzin reaction rating more difficult and time consuming. Lack of accurate variety ratings causes growers decide not to use this inexpensive and effective chemical to control weeds in the field. Understanding the genetics of metribuzin reaction and breeding for resistance are desirable goals. Metribuzin tolerance is quantitative and is controlled by a combination of genes. Identification of markers closely linked to metribuzin tolerance will facilitate marker assisted selection (MAS) and improve the efficiency of breeding for metribuzin tolerance. Through field screening in two locations in Louisiana, some lines have shown significant levels of resistance to metribuzin with minimal foliar damage. The present project focuses on the identification of single nucleotide polymorphism (SNP) markers controlling metribuzin tolerance in wheat using a doubled haploid population of the progeny of AGS2035 and AGS2060, and a diversity panel designated “Gulf Atlantic Wheat Nursery” (GAWN). Following the results obtained in this study, eight SNP markers were selected in the GAWN population that are relevant for metribuzin tolerance, while in the doubled haploid population we found 15 QTLs related to metribuzin resistance. An analysis of markers in the two populations revealed that information in six chromosomes are common between the two populations.



Committee Chair

Harrison, Stephen