Objective  A new variety of super-sweet corn characterized with the desirable properties of high-quality, high-yield, wide-adaptability, and strong resistance to lodging, diseases, and hot climate was bred.

  Methods  A tropical yellow-kernel, super-sweet inbred Mintian T146 line of corn germplasm was crossbred with Mintian AS67, a temperate white-kernel, super-sweet corn inbred line newly developed by the Crop Research Institute at Fujian Academy of Agricultural Sciences. The new variety of corn was submitted to regional trials followed by test production held in two regions in the nation.

  Results   Super-sweet Minshuangse No. 6 bearing both yellow and white kernels on a cob was successfully bred in the winter of 2015. From 2018 to 2021, it was certified at the southeast and southwest regional trails for fresh consumption corn cultivars by the National Science and Enterprise Consortium. At the southeast regional trial from 2018 to 2019, Minshuangse No. 6 delivered an average fresh ear yield of 13,587.8 kg·hm⁻², which was 7.6% higher than that of the reference Yuetian No. 16 with a yield point rate of 80.9%. A similar yield of 13 505.3 kg·hm⁻² was shown at the southwest regional trial that was 3.6% higher than that of Yuetian 16 with a yield point rate of 70%. On the resistance to diseases under natural infectious conditions in the field, Minshuangse No. 6 was judged to be moderately resistant to the small spot disease, moderately to highly resistant to the grain wilt, moderately to highly resistant to the nodulation smuddery, moderately resistant to the stem rot, and moderately resistant to susceptible to the large spot disease and the southern rust. By artificial inoculation, it was identified to be susceptible to the head smut, susceptible to moderately resistant to the small spot, susceptible to the nodular smut, susceptible to the sheath blight, and susceptible to moderately resistant to the southern rust. In terms of quality, the comprehensive scores it received at the southeast regional trial was 89.2 and at the southwest 86.8, as compared to 85.0 for the reference. The physical and chemical quality analyses conducted by the Agricultural College at Yangzhou University indicated that the average residue percentage, total soluble sugars, and reducing sugars of the corn kernels sampled from Minshuangse No. 6 at the regional trials were 11.8%, 26.7%, and 11.25%, respectively. They were all higher than those of Yuetan 16. The new variety was officially granted certificates under the National Jade No. 20200523 in 2020 and the National jade No. 20220577 in 2022 by the National Crop Variety Certification Committee. In the 2021 and 2022 thousand-mu production tests, Minshuangse No. 6 had a production yield at Huizhou, Guangdong of 17 982 kg·hm⁻², representing an increase of 5.9% over control and an improved revenue of 7 014 yuan·hm⁻². And it scored higher than the reference at 90.8 on sensory evaluation. The results of the trial held at Jianou, Fujian, Minshuangse No. 6 showed a yield of 18 889.5 kg·hm^-2, which was 9.44% higher than that of reference and 7 173.6 yuan·hm⁻² more on revenue. It received 89.7 on the sensory score, which was also higher than the reference.

  Conclusion  Minshuangse No. 6 displayed superior quality, yield, adaptability, and resistance to lodging, diseases, and heat. Consequently, it was recommended for promotion in the regions. Furthermore, the successful heterosis demonstrated by this study confirmed the validity of the "temperate germplasm × tropical germplasm" mode for corn breeding in general.