Genetic dissection of the relationship of apparent biological yield, apparent harvest index with seed yield, and yield related traits in soybean

Improving seed yield is an important goal of soybean breeding programs. In this investigation, two sets of recombinant inbred line (RIL) populations with 184 and 151 RI lines derived from Kefeng No. 1 x Nannong 1138-2 (F-7:11, NJRIKY) and Bogao x Nannong 94-156 (F-7:10, NJ(SP) BN) were used to mapping QTLs for five agronomic and physiological traits including plant height (PH), days to maturity (MD), seed yield (SY), apparent biological yield (ABY) and apparent harvest index (AHI), and correlation analysis among the five traits were also conducted. 221 SSR markers and 248 markers were used to construct genetic maps in NJRIKY and NJ(SP) BN population, respectively. The QTL mapping was done with the program WinQTLCart. The results indicated there were 14 putative QTL significantly associated with five agronomic and physiological traits in two sets of RIL populations and several coincident QTLs associated to SY and it related traits were observed. For SY, two QTLs, qsyC2.1 mapped on LG-C2 in NJRIKY and qsyL.1 on LG-L in NJ(SP) BN coincided or neared with QTLs detected in previous reports, and one major SY QTLs were detected on LG-O in which none of QTLs for yield were identified before. QTLs for SY co-located with QTLs for ABY and/or AHI and these co-located QTLs in each of genomic regions all showed their additive effects in the same direction except for SY/AHI QTLs on LG-C2 in NJ(SP) BN. These revealed that SY increase could be genetically explained by either biological yield enhancement and/or harvest index improvement. It was also found that some QTLs for PH in both sets of RIL population co-located with some QTLs for yield and/or ABY, and all of the coincident showed the additive effects in the same direction, but none of the QTLs was found to co-locate to any of the AHI QTLs.