| Quantitative trait loci (QTL) mapping of earliness in short-season cotton could be very helpful in increaseing the effeciency of cotton breeding. The cross of CCRI36×G2005 was made, which included a short season cotton variety and a introgression line of island cotton . QTL analysis of earliness-related traits in F2 segregating populations were proceeded by Composite Interval Mapping.In the present study,5043 SSR primer pairs were used to screen the polymorphic primers between CCRI36 and G2005,and 169 polymorphic primer pairs were obtained for the two parents.The polymorphic primer pairs were used to genotype the 141 individual plants of F2 population derived from CCRI36 and G2005,and 200 loci were obtained,With the software of Joinmap3.0 with LOD of 5.0, Linkage test indicated that 200 loci could be mapped to 35 linkage groups , which covered a total genetic distance of 1012.5 cM , approximately 22.5 % of cotton genome. The average distance of neighbor markers was 10.54 cM. 35 linkage groups were assigned to corresponding chromosome.Based on Composite Interval Mapping (CIM) method of WinQTLCartographer2.5, the result showed that 15 QTLs for earliness-related traits were detected in F2 populations.These QTLs expained 8.35%-44.76% of the corresponding phenotypic variations,2 for growth date,4 for percent of pre-frost lint,3 for sowing to sprouting ,5 for flowering to boll opening,1 for plant height.The correlation analysis indicated that growth date was positive significant correlation with percent of pre-frost lint, sprouting to squaring, squaring to flowering, flowering to boll opening and, plant height, not significant correlation with first fruiting branch node. Percent of pre-frost lint was negative significant correlation with squaring to flowering, flowering to boll opening.Sowing to sprouting was negative significant correlation withflowering to boll opening.We found that correlated traits often had QTLs mapped to the similar chromosomal regions.
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