Abstract: 【Objective】Kernel shape traits are important components of 100-kernel weight and show high heterosis. Identifying the heterotic loci for kernel related traits and subsequently dissecting the genetic basis architecture of heterosis for kernel related traits can provide useful information for cloning heterotic QTL and the development of elite hybrids by molecular breeding.【Method】A set of chromosome segment substitution lines (CSSLs) population was constructed using the inbred line lx9801 as the receptor parent and the inbred line Chang7-2 as the donor parent, which was used as the martial and test with the inbred line T7296 to construct a set of 184 test hybrid population. The test population, CSSLs population as well as other materials were evaluated in the field by following three replicates in randomized complete blocks with at Changge and Xunxian locations in Henan province in 2013. Ten plants were harvested after the physiological maturity period. Then, four kernel-related traits were investigated as follows: Including kernel length (KL, mm), kernel width (KD, Mm), kernel thickness (KT, mm) and 100-kernel weight (KW, g). The heterotic loci for kernel related traits were identified through significant analysis comparing to each test hybrid and the CK T7296×lx9801 by mean of variance analysis and t test.【Result】The kernel shape traits of the two parents in the CSSLs population had obvious differences; the kernel length and 100-kernel weight of the parent Chang7-2 was higher than lx9801, and the kernel thickness was lower lx9801. The four kernel shape traits in the test population had certain heterosis, the mid-parent heterosis of kernel length were 19.32% and 15.30% in Changge and Xunxian locations respectively, the mid-parent heterosis of kernel width were 10.86% and 10.07%, the mid-parent heterosis of kernel thickness were 6.23% and 4.78%, and the mid-parent heterosis of 100-kernel weight were 20.97% and 25.09%. The results of correlation analysis showed that kernel length expressed a significant positive relationship with kernel width and 100-kernel weight, and kernel width and kernel thickness also showed a significant positive relationship with 100-kernel weight;. kernel width, however, had a negative relationship with kernel thickness. A total of 13 heterotic loci for kernel length were identified for two environments, and one heterotic locus was detected for two environments simultaneously. For kernel width, fourteen heterotic loci were detected, including one main heterotic loci identified at Changge and Xunxian locations respectively. There were twenty-five heterotic loci detected for kernel thickness, and the common heterotic loci on chromosome 2, 3, 7 and 9 were identified for two environments simultaneously. Twenty-four heterotic loci for 100-kernel weight were detected, above of them, two heterotic loci hKW1a and hKW1b were identified on chromosome 1 at the two locations simultaneously. On the chromosome 7, one main heterotic locus hKW7a was identified, which had 20.12% and 11.03% contributions at Changge and Xunxian locations. Additionally, the heterotic locus hKW8a on chromosome 8 had 18.64% and 8.76% contributions at the two environments respectively.【Conclusion】The heterosis of kernel shape traits followed the order: kernel length > kernel width > kernel thickness, and a total of 75 heterotic loci (HL) were identified for three kernel related traits and 100-kernel weight, and 11 HL were identified at the two environments simultaneously. Owing to kernel length having a high correlation with high seed removal rate, and that it is difficult to predict the heterosis of kernel related traits, so the molecular markers linked with the heterotic loci of kernel length could be used for select elite hybrid with high seed removal rate in maize breeding.

Key words: maize, kernel related traits, heterotic loci, mapping, single segment substitution lines