QTL detection for node of first fruiting branch and its height in upland cotton (Gossypium hirsutum L.)

The selection and popularization of early-maturing cotton is paramount in resolving the conflict between occupying farmlands utilizing grain and cotton while optimizing agricultural structure. Node of first fruiting branch (NFFB) and its height (HNFFB) can be used as the important indicators to measure cotton earliness. In this study, Baimian2, an early-maturing upland cotton (Gossypium hirsutum L.) variety, was used as the female parent crossed with a late-maturing material (TM-1) and intermediate-maturing variety (CIR12), respectively. Quantitative trait locus (QTL) detection for NFFB and HNFFB was performed within the two F2:3 populations, Baimian2 × TM-1 and Baimian2 × CIR12 by composite interval mapping (CIM) and mixed model CIM (MCIM). Eight QTL (three suggestive and five significant) for NFFB and six QTL (three suggestive and three significant) for HNFFB were detected in both populations, located on C1(A1), C5(A5), C6(A6), C9(A9), C11(A11), C13(A13), C17(D3), C25(D6), C12(A12)/C26(D12) and LG1. Results of QTL are consistent with separation analysis to some extent. The two significant major QTL, qNFFB-17-I for NFFB and qHNFFB-17-I for HNFFB, were detected simultaneously by CIM and MCIM. They had high reliability and could be used for the marker-assisted breeding to improve cotton earliness. Single marker-analysis showed that 11 molecular markers, such as CGR5222, are linked with NFFB and/or HNFFB.