Parental row ratios changed pollen spread, altering the sterile-line seed set rate. Pollination effectiveness outweighs more than pollen amount in mechanized seed set. Florets with pollen on single stigmas contributed over 50% of total seed set. Mechanized seed production with a large restorer-to-sterile parental row ratio is a developmental trend; however, the effects of different parental row ratios on spikelet pollination effectiveness and seed-setting rates remain unclear. In this study, a single-factor randomized block experiment was conducted in Sichuan, China, to evaluate the influence of parental row ratio designs on spikelet pollination effectiveness and seed-setting rate in sterile lines under unmanned aerial vehicle-assisted pollination conditions. In 2021 and 2022, R2 treatment significantly reduced the number of pollen grains and pollen grain number per spikelet position in the middle (M) and far (F) rows of the plot. However, this treatment yielded a significantly higher pollination rate of exposed stigma florets at each spikelet position in the near (N) and middle rows when compared to the results of the R1 and R3 treatments, resulting in a greater seed-setting rate. The number of pollen grains per stigma (1–3) did not significantly differ among the R1, R2, and R3 patterns in 2022. Over 50% of successfully pollinated florets had pollen loaded on a single stigma. In the C1 combination, the seed-setting rate of R2 increased by 43.07% ( vs . R1) and 34.23% ( vs . R3), with yield increases of 42.35% ( vs . R1) and 18.53% ( vs . R3). In the C2 combination, R2 seed-setting rate increased by 13.75% ( vs . R1) and 34.62% ( vs . R3), with final yield increases by 14.87% ( vs . R1) and 29.80% ( vs . R3). The R2 pattern reduced pollen loss by optimizing the matching degree between pollination wind field and parental strip width, providing a stable pollen supply for the sterile lines (N, M). This supply enhanced stigma pollen capture, thereby significantly increasing floret pollination rates, seed-setting rates, and yield. This study provides a theoretical basis and practical guidance for pollination strategies and optimization of parental row ratios in mechanized seed production.
Huang et al. (Thu,) studied this question.