Dissecting the yield components of oats (PhD)

Abstract

Yield is a complex trait and many procedures have been developed to monitor yield formation. This study comprised of a genetic diversity study and three sets of field experiments to help elucidate yield and its components.

• Both the marker data and the kinship analysis indentified five main ancestral cultivars within this study.
• The ancestral lines Solva and Bulwark tended to cluster closely with their progeny. 
• Dry matter accumulation was positively correlated with yield.
• There was a negative relationship between height and panicle emergence. 
• Grain size distribution was shown to be bimodal. When measured separately, primary KC and TGW had a highest correlation to the mixed grain sample. 
• Grain shape altered with year of release with grain becoming more elongated. 
• Yield increased with increased nitrogen application. 
• For individual cultivars the amount of the nitrogen needed to produce optimal yield varies. 
• Balado, Fusion, Hendon and Tardis had the highest yield at the RB209+70 nitrogen treatment. The remaining cultivars, 00-61Cn1, Brochan, Gerald and Racoon had the highest yield at the RB209+50 treatment. 
• Total nitrogen content of the crop and the grain and total biomass increase with increasing nitrogen application. 
• NUE and its components NUpE, crop NUtE and grain NUtE displayed a negative relationship with nitrogen applied to the crop. 
• Fertile shoot number, grain number and height all increased with increasing nitrogen treatment. 
• TGW was not greatly affected by nitrogen application but grain number per metre2 increased with increasing nitrogen suggesting that this is a major determinant of grain yield.
• Dwarf cultivars had a later emergence date for both flag leaf and panicle than the conventional height cultivars. 
• Little difference was seen in maturity dates of conventional height and dwarf lines.
• In a mapping population developed from a cross between a dwarf and tall population, the segregating population mean was closer to the conventional height mean than the dwarf mean for the majority of traits. 
• Dwarf lines had a poorer panicle extrusion, grain quality and yield than tall cultivars. They also had a short period between panicle extrusion and maturity.