Agronomic performance, grain quality, and combining ability of newly developed two-line hybrid rice lines
摘要
This study evaluated the agronomic performance, pest and disease resistance, yield components, grain quality, and combining ability of newly developed two-line hybrid rice lines for potential use in breeding programs in northern Vietnam. Hybrid rice, developed through the crossing of genetically distinct parents, exploits heterosis to achieve higher yields than conventional inbred varieties. The experimental materials consisted of six thermosensitive genic male sterile (TGMS) lines and four restorer lines, with the commercial two-line hybrid MHC2 serving as a check variety. During the 2024 summer–autumn season, parental lines were evaluated for growth duration, plant height, stigma exertion, pollen fertility, and resistance to major pests and diseases. All TGMS lines exhibited complete male sterility with high stigma exertion rates, while the restorer lines showed pollen fertility above 89% and good resistance to stem borer, leaf folder, brown planthopper, sheath blight, blast, and bacterial leaf blight. In the 2025 spring season, 24 hybrid combinations were developed and evaluated alongside the check variety. Most hybrids matured within 124–135 days, exhibited medium plant height, high yield potential, and acceptable to good grain quality. Four hybrids including QH1 (118S/K50), QH23 (296S/K50), QH27 (297S/K50), and QH30 (297S/C117) produced actual yields exceeding 9.5 tons/ha, significantly outperforming the check variety. Grain quality assessment revealed that many hybrids had high milling recovery, desirable grain dimensions, and competitive cooking quality. Combining ability analysis identified C117, C118, 296S, and 297S as valuable parental lines for improving yield-related traits, and highlighted several hybrid combinations with both strong specific combining ability and superior field performance. These results provide a robust basis for the selection and development of high-yielding, high-quality two-line hybrid rice cultivars suited to the agro-ecological conditions of northern Vietnam.