Precision drill sowing in seedling trays combined with narrow hill spacing improves yield performance in machine-transplanted high-quality hybrid rice

Precision drill sowing in seedling trays offers an innovative seedling-raising approach to reducing sowing rates per tray and thereby decreasing seed input and production costs in machine-transplanted high-quality hybrid rice production. However, farmers may be concerned that reduced seed input could decrease grain yield by limiting panicle number. We hypothesized that combining precision drill sowing in seedling trays with an appropriately reduced hill spacing could alleviate this concern. To test this hypothesis, two-year field experiments were conducted using two high-quality hybrid rice varieties. Grain yield and associated agronomic traits were compared between a conventional machine-transplanted system involving broadcast sowing in seedling trays followed by transplanting at the standard hill spacing (T1) and an alternative system involving precision drill sowing in seedling trays followed by machine transplanting at a reduced hill spacing (T2). Compared with T1, T2 had 38%, 24%, and 17% lower sowing rate per tray, hill spacing, and seed input, respectively. Averaged across two varieties and two years, T2 achieved a 7% higher grain yield and a 29% higher yield-to-seed ratio than T1. Compared with T1, T2 increased the productive tiller rate and panicles per m2 by 12%, specific leaf weight at heading by 7%, radiation use efficiency by 9%, and aboveground biomass at maturity by 11%. These results confirm our hypothesis, indicating that T2 improves yield performance in machine-transplanted high-quality hybrid rice by increasing productive tiller rate and panicle number per m2, as well as enhancing specific leaf weight, radiation use efficiency, and biomass production.