a SCR disease phenotypes of wild-type lines (Jing724 and Jing92) and improved lines (Jing724RppK and Jing92RppK) carrying the RppK allele under field conditions. b The field performance of hybrid JK968wt, improved hybrid JK968a (Jing724 × Jing92RppK) and improved hybrid JK968b (Jing724RppK × Jing92RppK) in the field in the presence of SCR disease. Hybrid JK968a was derived from a cross between Jing724 and Jing92RppK and Hybrid JK968b was derived from a cross between Jing724RppK and Jing92RppK. c SCR disease phenotypes of hybrid JK968wt and hybrid JK968a under field conditions and ear phenotypes of hybrid JK968wt and hybrids JK968a in the presence or absence of SCR disease. Scale bars = 3 cm. d SCR disease phenotypes of hybrid JK968wt and hybrid JK968b under field conditions and ear phenotypes of hybrid JK968wt and hybrids JK968b in the presence or absence of SCR disease. Scale bars = 3 cm. e The SCR disease phenotypes of hybrids JK968wt, JK968a, and JK968b in field trials were evaluated in Bozhou (20BZ, P = 8.48818E-06) and Yongcheng (20YC, P = 1.38435E-33) China, in 2020. f The grain yields of JK968wt, JK968a, and JK968b in the presence or absence of SCR disease in field trials in China in 2020. SCR disease conditions: 20BZ (n = 9 repeat plots; 38 plants of each line in each plot; P = 0.005498515), Bozhou, China, in 2020; 20YC (n = 16 repeat plots; 11 plants of each line in each plot; P = 1.96453E-05), Yongcheng, China, in 2020; non-SCR disease conditions: 20TZ (n = 3 repeat plots; 38 plants of each line in each plot; P = 0.4957928), Tongzhou, China, in 2020; 20CP (n = 9 repeat plots; 38 plants of each line in each plot; P = 0.100474299), Changping, China in 2020; 20HG (n = 16 repeat plots; 11 plants of each line in each plot; P = 0.212607571), Huanggang, China, in 2020. Values are means ± SDs. **P < 0.01; ****P < 0.0001 (Student’s t-test, two-tailed). Source data are provided as a Source Data file.