Performance and stability of yield in response to plant density, year and location in maize hybrids of Northwest China

Identifying desirable genotypes with the best performance in diverse environments is a perpetual aim of plant breeding, and the interaction between genotype and environment (G × E) always plays a key role. This study was conducted to elucidate the genetic behaviour of different hybrid combinations at various densities in diverse environments. According to a line × tester design, 32 hybrid combinations were obtained from 16 inbred individuals crossed with two testers and planted at three locations at three density levels (45,000, 67,500 and 90,000 plants ha−1) during 2014−2017. Genotype (G), environment (E) and the interaction of genotype and environment (G × E) significantly affected grain yield at different densities. Increasing planting density enhanced grain yield and improved the efficiency of germplasm screening, where the effect of location on grain yield at different densities was larger than that of year and the GCA was larger than the SCA. Finally, four inbred lines (KB102, KB081, KA105, and KB106) with a high GCA, environmental adaptability, and several combinations using them as parents have been approved in ShannXi Province and National of China. In conclusion, the evaluation of combining ability at multiple densities and locations can effectively screen inbred lines and improve breeding efficiency.