Genetic Anaysis of Productive Tiller Number in Spring Wheat.

The number of productive (spike-producing) tillers is a major determinant of yield potential in wheat. We determined productive tiller number (PTN) and its relationship to other agronomic traits in spring wheat. Recombinant inbred lines (RILs) derived from three different crosses, Reeder/Conan, Reeder/McNeal and McNeal/Thatcher, were evaluated over environments and years in Bozeman MT. There was significant genetic variation for PTN in every population with heritability ranging between 0.65–0.75. Correlation of PTN with yield ranged from r = 0.4-0.6 based on combined means over years. A genetic map generated in the Reeder/Conan RILs allowed identification of quantitative trait loci (QTL) for PTN, including a QTL on chromosome 6B that explained 9 -19 % of the variation. Single marker analysis with markers within the 6B QTL showed that the Reeder allele significantly increased PTN by 7.0–8.7% in the Reeder/McNeal RILs and approximately 4% in the McNeal/Thatcher RILs. The Reeder allele also had a significant positive effect on yield and test weight in the McNeal/Reeder RILs, and test weight in the McNeal/Thatcher RILs. There was a negative effect on seed number per spike in the McNeal/Thatcher RILs. Our results suggest the 6B QTL for PTN may be useful for the marker assisted selection to increase productive tiller number in spring wheat.