Early Season Cold Tolerance in Sorghum.

Soil temperatures at 15°C or below limit germination and seedling establishment for warm season cereal crops such as sorghum (Sorghum bicolor L.  [Moench]) during early season planting.  To better understand the genetics of early season cold tolerance in sorghum, mapping of quantitative trait loci (QTL) associated with germination, emergence and vigor using recombinant inbred mapping populations are under investigation.  Two mapping populations consisting of large number of  F₇-F₈ recombinant inbred lines (RILs)  have been developed and  QTLs for various traits related to early season response were identified.  The RILs were evaluated for cold and optimal temperature germinability in the laboratory, field emergence, and seedling vigor in three locations during early season planting.  In one of the populations, two or more QTLs were detected for all traits, except for seedling vigor where only one significant QTL was detected in the populations. Our study also showed alignment of QTLs in sorghum chromosome 1, SBi 1, (Fearlygerm-1.2 and Fgerm30-1.2) with previously reported QTLs associated with early season field emergence identified from  previously reported mapping population.  These results indicate that  the parents used in this study  share common loci with other known early season cold tolerant sorghum germplasm but also harbor novel QTLs that could be useful in introgression for enhanced laboratory early season field emergence and vigor.