Efficiency of Recurrent Selection for Combining Ability of Yield Trait in Maize Population Yuzong 5

Population improvement is a basis of germplasm enhancement and developing inbred lines in maize (Zea mays L.). For evaluating the combing abilities of Yuzong 5 developed populations derived from 5 cycles of recurrent selection, 30 testcrossing combinations were made using Huangzao 4, Dan 340, Zhongzong 5, Qi 319, Ye 478, and Mo17 as the female parents in 2 locations under the NCII design. The yield per plant of testcrossing combinations was enhanced by 3.57% per cycle, showing a remarkable effect of recurrent selection. Both half-sib recurrent selection (HS-RS) and half-sib reciprocal recurrent selection (HS-RRS) were effective for improving the general combining ability (GCA) of kernel yield and the GCA was improved in each cycle of the populations. After 3 cycles of improvement in Yuzong 5 by HS-RS, the GCA significantly increased from (11.63 of C₀ to 5.57 of C₃ population (P < 0.01). After 1 cycle of improvement by HS-RRS, the GCA increased from 5.57 of C₃ to 9.75 of C₄ population. The specific combining ability (SCA) of improved Yuzong 5 × Huangzao 4 was enhanced, which indicated an approaching Reid × SiPT heterotic pattern during Yuzong 5 improvement cycle by cycle.