Research and utilization of mixed seed production technology for two-line hybrid wheat

Abstract

<p indent="0mm">China’s Two-line Hybrid Wheat Technology System is an important achievement resulting from novel domestic use of sterile lines to realize agroindustrial application of hybrid wheat. However, compared with hybrid rice and maize, the industrial application level of hybrid wheat is still in its early stage. The unstable production of hybrids, as well as their high cost and the large sowing amount of seeds required for their cultivation, have always limited the rapid industrialization of two-line hybrid wheat. Two-line hybrid wheat research and cultivation show that high-efficiency seed production is the core key technology for the successful industrialization of hybrid wheat. Moreover, the outcrossing performance of wheat photo-thermo sensitive sterile lines is the key to the success of seed production. Wheat photo-thermo sensitive sterile lines can change from selfing to outcrossing under seed production conditions, and their seed production characteristics are affected by various factors of both sterile lines and restorer lines. Breeding sterile lines and restorer lines with high combining ability and excellent outcrossing traits can effectively improve the seed setting rate and yield of outcrossing in seed production and also greatly reduce the cost of wheat hybrid seed production. In our study, the influencing factors and results of the seed production process were assessed based on related seed production experiments with two-line hybrid wheat conducted from 2016 to 2020. Outcrossing traits, such as female bloom traits of floret opening size and stigma exposure rate and male fertility traits of pollen dispersal distance, anther size, anther exposure rate, and pollen amount were significantly correlated with outcrossing performance. In the pollination stage, larger pollen amounts, shorter pollen dispersal distances, longer pollination durations of the restorer line, higher stigma exposure rates, and larger floret opening angles of the sterile line can greatly improve the outcrossing seed setting rate, production yield, and quality of the sterile line. The flowering period of male parents was 2–3 days later than that of female parents, which could be utilized to realize the effective preparation of temporal-spatial and physiological synergy. With the male parent comprising 5% of a mixed population, the yield of mixed seed production was significantly increased by 28.2% compared with even row ratio seed production. From 2019 to 2021, large-scale mixed seed production in the Nanyang area has achieved excellent results with large-scale seed production of BS1453/JS1 reaching 5273.4 kg/hm². The establishment of a simple, scientific, safe, and efficient technology system for large-scale mixed seed production has solved the technical bottleneck of large-scale seed production of two-line hybrid wheat, providing theoretical and technical support for the popularization and widespread application of two-line hybrid wheat.