Date of Graduation

12-2019

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor

Richard Esten Mason

Committee Member

Margaret Leigh Worthington

Second Committee Member

Cammy Willett

Third Committee Member

Leandro Mozzoni

Keywords

Anther, Breeding, Heterosis, Hybrid, Imaging, Wheat

Abstract

Wheat (Triticum aestivum L.) is a self-pollinating species that is most often bred as a recombinant inbred line. When two inbred individuals are crossed, they produce progeny which experience heterosis; heterosis is the increased robustness experienced due to the reintroduction of heterozygosity. Hybrid wheat may be produced through the use of chemical hybridization agents, yet the structure of wheat flowers decreases the efficiency of outcrossing. The objectives of this study were to: assess the amount of heterosis experienced by a population of hybrid wheat and observe the effect of major gene loci on yield and yield components, phenotype anthers extruded using image analysis, and find marker-trait associations for anther extrusion. In 2018, 22 soft red winter wheat (SRWW) hybrid lines were planted in two replications of a randomized complete block design (RCBD) in Arkansas, Georgia, and Louisiana. The 22 hybrids were evaluated for yield components and two heterotic indexes: midparent heterosis (MPH) and better-parent heterosis (BPH). Significant (p<0.05) MPH and BPH was observed in all locations for multiple traits. Significant effects (p<0.05) on yield were detected for Vrn-A1, Vrn-B1, Ppd-A1, and Ppd-D1 loci allelic combinations. In 2019, 594 SRWW lines were planted in two replications of a RCBD in Arkansas and phenotyped using image analysis for area of anthers and area per spike. A significant regression (R^2=0.8007,p<0.0001) was found between the area of anthers extruded (AOAE) and the number of anthers extruded (NOAE). Variety was found to play a significant role (F_0.05,530,583=1.36,p=0.0002) in the area per spike (APS) experienced. The presence or absence of awns was also found to play a significant role (F_0.05,1,583=1074.67,p<0.0001) in the area per spike experienced. Several significant (p<0.0001) marker-trait associations were found for NOAE, AOAE, and APS. This information will be used to make selections for male lines in hybrid crossing blocks.

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